Minerals

20 pages, 3268 KB

Open AccessEditor’s ChoiceArticle

Optimization and Validation of Multi-Size Ball Load Scheme for an Industrial Ball Mill Based on Semi-Theoretical Calculations and DEM Simulations: A Case Study of a Copper Mine

by Zhong Luo, Qingfei Xiao, Mengtao Wang, Saizhen Jin, Guobin Wang, Yanwei Zhao, Sheng Jian and Feng Xie

Minerals 2026, 16(6), 563; https://doi.org/10.3390/min16060563 - 23 May 2026

Viewed by 147

Abstract

A comprehensive and systematic study was conducted to address a series of key technical challenges encountered in the grinding process at a copper mine. These issues included the complex mechanical properties of the feed ore, which led to low grinding efficiency, difficulty in [...] Read more.

A comprehensive and systematic study was conducted to address a series of key technical challenges encountered in the grinding process at a copper mine. These issues included the complex mechanical properties of the feed ore, which led to low grinding efficiency, difficulty in achieving the required grinding fineness for flotation, uneven particle size distribution in the grinding products, and severe occurrences of overgrinding and undergrinding. Based on the semi-theoretical ball diameter formula, the optimal initial ball size distribution for the ball mill was precisely calculated as Φ70:Φ50:Φ40:Φ30 = 15:25:35:25. Through laboratory-scale grinding tests and Discrete Element Method (DEM) simulations, a systematic analysis of multiple indicators under three different ball loading schemes was performed, including the motion state of particles inside the mill, the collision behavior of the grinding media, and the energy distribution. This analysis confirmed the rationality and effectiveness of the literature scheme. Industrial trial results showed the following: the yield of the +0.20 mm fraction decreased by 4.15 percentage points, and the yield of the −0.010 mm fraction and its proportion relative to the −0.074 mm fraction decreased by 10.17 and 19.10 percentage points, respectively. Conversely, the yields of the intermediate separated fraction (−0.20 + 0.010 mm), the easily separated fraction (−0.074 + 0.018 mm) and the −0.074 mm qualified fraction increased by 14.32, 14.13, and 7.29 percentage points, respectively. The grinding technical efficiency improved by 19.55 percentage points. Furthermore, the specific steel ball consumption decreased by 46 g/t, a reduction of 5.07%. The copper concentrate recovery increased by 0.65 percentage points, resulting in an annual increase of 40.51 tons of copper metal, additional revenue of CNY 3.2483 million, and steel ball cost savings of CNY 603,500. Collectively, this optimization generated a total economic benefit of CNY 3.8518 million. By optimizing the ball size distribution, the particle size composition of the grinding products was significantly improved, the flotation indicators were enhanced, and the grinding media consumption cost was reduced, achieving quality improvement and efficiency increase in the mineral processing. This study provides a valuable reference for solving similar grinding problems. Full article

(This article belongs to the Special Issue Advances and Applications of High-Pressure Grinding Rolls Designs and Operational Strategies)

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25 pages, 21082 KB

Open AccessEditor’s ChoiceArticle

Probabilistic Modeling of Lateritic Nickel Mineral Resources

by Roberto Rolo, Jafar Arief and Selvi Yuminti

Minerals 2026, 16(5), 551; https://doi.org/10.3390/min16050551 - 20 May 2026

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Abstract

Lateritic nickel deposits exhibit complex weathering-driven geometries, strong vertical variability, and complex multivariate geochemical relationships. These characteristics challenge conventional deterministic resource modeling. This paper presents a unified probabilistic workflow for lateritic nickel mineral resource modeling that integrates lithology and grade simulation within a [...] Read more.

Lateritic nickel deposits exhibit complex weathering-driven geometries, strong vertical variability, and complex multivariate geochemical relationships. These characteristics challenge conventional deterministic resource modeling. This paper presents a unified probabilistic workflow for lateritic nickel mineral resource modeling that integrates lithology and grade simulation within a consistent geostatistical framework. The methodology combines unfolding, plurigaussian simulation, multivariate imputation of incomplete datasets, projection pursuit multivariate transformation (PPMT) for decorrelation, and conditional simulation using the Turning Bands algorithm. Application to an Indonesian lateritic nickel deposit demonstrates reproduction of lithological proportions, spatial continuity, marginal distributions, and complex multivariate relationships. The proposed workflow enables explicit quantification of geological and grade uncertainty, providing a basis for uncertainty assessment in recoverable resource estimation and supporting downstream applications such as resource classification and drillhole spacing analysis. Full article

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

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23 pages, 9250 KB

Open AccessEditor’s ChoiceArticle

Fluid Evolution and Controls on Gold Precipitation at the Dongga Au Deposit, Tibet, China: Insights from Pyrite Trace Elements

by Hongyu Zhan, Qing He, Yulin Deng, Chen Li, Zuopeng Xiang, Changyi Wu, Kai Jiang and Xinghai Lang

Minerals 2026, 16(5), 539; https://doi.org/10.3390/min16050539 - 17 May 2026

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Abstract

The Dongga Au deposit is located in the giant Xiongcun porphyry Cu-Au ore district within the Southern Lhasa terrane; however, the evolution of ore-forming fluids and the mechanisms of gold precipitation during the main mineralization stage remain poorly constrained. This study integrates geological [...] Read more.

The Dongga Au deposit is located in the giant Xiongcun porphyry Cu-Au ore district within the Southern Lhasa terrane; however, the evolution of ore-forming fluids and the mechanisms of gold precipitation during the main mineralization stage remain poorly constrained. This study integrates geological observations and in situ LA-ICP-MS trace element analyses of pyrite to address the above issues. Three generations of pyrite are identified: Py1 occurring in quartz–sulfide veins, Py2 in chlorite–sulfide veins, and Py3 in pyrite veins. Trace element data show that Au and As contents are relatively low in all three pyrite generations and mainly occur as lattice-bound elements, whereas Pb, Ag, Bi, Cu, and Zn are predominantly hosted in micro- to nano-scale mineral inclusions. Ore-forming temperatures estimated from Se concentrations in pyrite indicate progressive cooling from ~400 °C to ~270 °C (Py1 to Py3). Combined with thermodynamic modeling and mineral assemblage constraints, this suggests that the ore-forming fluid experienced significant meteoric water input, accompanied by decreasing temperature, sulfur fugacity, and oxygen fugacity, as well as increasing pH. The principal gold mineralization stage occurred at approximately 340 °C, where temperature and pH conditions jointly stabilized Au transport primarily as Au(HS)₂⁻. We propose the mixing between meteoric water and mineralized magmatic fluid caused a decrease in sulfur fugacity, oxygen fugacity and temperature, thereby limiting the availability of HS⁻ required for stabilizing Au(HS)₂⁻ complexes and thus resulting in the decoupling of Au(HS)₂⁻, which triggered gold precipitation. Full article

(This article belongs to the Special Issue Geology, Geochemistry, Genesis, Modeling, Structure and Exploration of Copper Polymetallic Deposits)

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25 pages, 11535 KB

Open AccessEditor’s ChoiceArticle

Selective Screening of Efficient Chalcopyrite Depressants and Their Mechanisms in Copper–Molybdenum Separation

by Lujing Liang, Jianhua Chen and Anruo Luo

Minerals 2026, 16(5), 535; https://doi.org/10.3390/min16050535 - 16 May 2026

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Abstract

Molybdenum (Mo) is a strategic raw material for high-end equipment manufacturing, aerospace technologies, and advanced alloys, and approximately 50% of global molybdenum resources are hosted in porphyry Cu–Mo deposits. To address the long-standing challenge of selectively separating chalcopyrite and molybdenite by flotation, this [...] Read more.

Molybdenum (Mo) is a strategic raw material for high-end equipment manufacturing, aerospace technologies, and advanced alloys, and approximately 50% of global molybdenum resources are hosted in porphyry Cu–Mo deposits. To address the long-standing challenge of selectively separating chalcopyrite and molybdenite by flotation, this study screened five sulfur-containing organic depressants and investigated their effects on the flotation responses of the two minerals, motivated by the strong affinity of sulfur donor atoms for surface Cu sites on chalcopyrite. The results indicate that thiomalic acid, 4-hydroxythiobenzamide, and 6-methyl-2-thiouracil markedly depress chalcopyrite flotation, whereas 2-(methylthio)acetic acid and N-phenylthiourea exert only minor effects. In contrast, none of the five reagents significantly affects the floatability of molybdenite. Among these depressants, thiomalic acid exhibited the best selectivity. In practical Cu–Mo bulk concentrate flotation, it showed a clear dosage advantage at low addition levels and improved Cu–Mo separation performance; at a Mo recovery of 76.09% and a Mo grade of 5.45%, Cu recovery was reduced to 9.54%. The adsorption mechanism of thiomalic acid on chalcopyrite was further investigated using FT-IR spectroscopy, X-ray photoelectron spectroscopy, and self-consistent charge density-functional tight-binding (SCC-DFTB) calculations. The results suggest that thiomalic acid interacts strongly with surface Cu sites on chalcopyrite via its S- and O-containing functional groups, likely increasing surface hydrophilicity and inhibiting collector adsorption (and subsequent bubble attachment), thereby contributing to selective chalcopyrite depression. Full article

(This article belongs to the Collection Flotation Theory and Technology)

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37 pages, 87925 KB

Open AccessEditor’s ChoiceArticle

Spatial Patterns and Source Apportionment of Potentially Toxic Elements in Flood-Affected Fluvisol Soils of the Bosna River Alluvial Plain

by Elvir Babajić, Alisa Babajić, Samir Ustalić, Zoran Kovač, Tomislav Brenko, Marko Cvetković and Stanko Ružičić

Minerals 2026, 16(5), 524; https://doi.org/10.3390/min16050524 - 14 May 2026

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Abstract

This study quantifies the concentrations, spatial patterns, and sources of potentially toxic elements (PTEs) in Fluvisols from the Bosna River floodplain. Total As, Cr, Ni, Cu, Zn, Ba, V, and Co contents locally exceed national thresholds (e.g., As > 15 mg/kg, Cr > [...] Read more.

This study quantifies the concentrations, spatial patterns, and sources of potentially toxic elements (PTEs) in Fluvisols from the Bosna River floodplain. Total As, Cr, Ni, Cu, Zn, Ba, V, and Co contents locally exceed national thresholds (e.g., As > 15 mg/kg, Cr > 80 mg/kg, Ni > 40 mg/kg), yet Ti-normalised enrichment factors mostly remain in the “no to minor” range (EF ≈ 1–3) and contamination factors in the “low to moderate” range (CF ≈ 1–3), indicating only slight to moderate enrichment even where absolute concentrations are high. Cr, Ni, Co, Ba, and V display similar spatial patterns, strong positive correlations with Mg and Fe, and consistently low EF values, confirming their predominantly geogenic origin linked to ultramafic and mafic parent rocks. In contrast, Cu, Zn, Pb, and Cd form coherent spatial clusters, share positive correlations, and show slightly elevated EF and CF values in flooded soils (typically EF and CF between 1 and 3), indicating diffuse industrial and agricultural inputs superimposed on a strong natural background. Flooding did not uniformly increase PTE concentrations but enhanced spatial heterogeneity and reorganised geochemical associations, particularly for Zn, As, and Cd, while the observed links between inorganic carbon (TIC), Ca, and Mg indicate that carbonate buffering and base cations help constrain metal mobility rather than exert a dominant control on all elements. The novelty of this work lies in integrating Ti-normalised EF and CF referenced to a local Fluvisol background with high-resolution GIS mapping and paired flooded versus control multivariate analysis, providing a quantitative, transferable framework to disentangle geogenic and anthropogenic signals and to prioritise post-flood monitoring of As, Cu, Zn, Pb, and Cd in naturally metal-rich floodplains. Full article

(This article belongs to the Special Issue Mineralogical and Chemical Characterization of Rocks, Soils, Sediments, and Water Containing Hazardous Substances)

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26 pages, 5861 KB

Open AccessEditor’s ChoiceArticle

Assessment of Soil Contaminants and Human Health Risks in the Petaquilla Mine (Panama): Implications for Site Restoration

by Ana C. Gonzalez-Valoys, Felipe Segundo, Johanna L. Zambrano-Anchundia, Samantha Jiménez-Oyola, José R. Gallego, Efrén García-Ordiales, Jonatha Arrocha, Javier Lloyd, Francisco Jesús García-Navarro and Pablo Higueras

Minerals 2026, 16(5), 522; https://doi.org/10.3390/min16050522 - 14 May 2026

Viewed by 369

Abstract

The Petaquilla gold mine in Panama was abruptly closed without restoring the site. The objective of this study is to assess mine soils from a geochemical perspective, identify potential contaminants, and conduct a human health risk assessment (HHRA). Soil samples were analysed to [...] Read more.

The Petaquilla gold mine in Panama was abruptly closed without restoring the site. The objective of this study is to assess mine soils from a geochemical perspective, identify potential contaminants, and conduct a human health risk assessment (HHRA). Soil samples were analysed to determine pH, EC, OM, texture, hydrocarbons (TPHs), enzymatic activity (DHA), and the following potentially toxic elements (PTEs): As, Ba, Cd, Cu, Hg, Sb, Pb and Zn. The Igeo, PLI and HHRA indexes were evaluated. The Igeo indicates that the processing zone has atypical values of Cu (1.47), indicating moderate pollution (1 < Igeo ≤ 2), Zn (3.80), indicating strong pollution (3 < Igeo ≤ 4), and Pb (7.62), indicating extreme pollution (Igeo > 5), with enrichment due to mining activity. The PLI map shows that the affected areas are surrounding the Molejon River (1.62) and the processing zone (1.21), which are slightly contaminated (1 ≤ PLI < 2), and one site in the processing zone with moderate to considerable contamination (PLI ≥ 3) at the warehouse (6.07). Regarding TPHs, the processing area in front of transformer (54,844.47 mg kg⁻¹) and the workshop entrance (2045.26 mg kg⁻¹) have values above industrial use (620 mg kg⁻¹) due to visible hydrocarbon spills. In terms of HHRA, the non-carcinogenic risk associated with exposure to PTEs exceeds the reference threshold for both children and adults under a residential exposure scenario, whereas the non-carcinogenic risk for TPHs remains below the acceptable limit. Regarding carcinogenic risk, exposure to Pb and As remains within acceptable limits for both receptors. With a view to restoring the mine’s soil, the processing area and the workshop entrance are the first areas that need to be addressed. Full article

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

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42 pages, 57289 KB

Open AccessEditor’s ChoiceArticle

Clay Minerals in Carboniferous Ash-Rich Coals of Kazakhstan: Roles in Geochemical Signatures and Elemental Distribution Patterns

by Medet Junussov, Geroy Zh. Zholtayev, Zamzagul T. Umarbekova, Moldir A. Mashrapova, Shattyk Miniskul, Mohamed Abdelnaby Oraby, Yerzhan Nurmakanov and Maxat K. Kembayev

Minerals 2026, 16(5), 514; https://doi.org/10.3390/min16050514 - 13 May 2026

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Abstract

Clay minerals in coal play a key role in controlling mineralogical composition, geochemical signatures, and the industrial behavior of coal and its combustion residues. This study investigates the occurrence, provenance, and potential applications of clay minerals in Carboniferous ash-rich coals from the Bogatyr, [...] Read more.

Clay minerals in coal play a key role in controlling mineralogical composition, geochemical signatures, and the industrial behavior of coal and its combustion residues. This study investigates the occurrence, provenance, and potential applications of clay minerals in Carboniferous ash-rich coals from the Bogatyr, Lenin, and Saradyr coal mines in northeastern Kazakhstan. A total of 60 coal samples were analyzed using XRD, SEM–EDS/BSE, XRF, and ICP-OES following acid leaching. Based on ash yield, 52 samples were classified as coal (<50% ash), while 8 samples were classified as carbonaceous shale or mudstone (>50% ash). Mineralogical assemblages show clear variability among the studied mines. Saradyr samples are strongly quartz-dominated with lower clay proportions, Bogatyr samples exhibit highly heterogeneous quartz–clay–mica assemblages, whereas Lenin samples are relatively more clay-rich and dominated by kaolinite and illite-group minerals. Across all samples, kaolinite is the dominant clay mineral (16.6–46 wt.%), occurring mainly as authigenic pore- and cell-filling aggregates. Minor phases include illite–muscovite (7.1–29.9 wt.%), illite–smectite (up to 7.6 wt.% in Bogatyr), and smectite–montmorillonite (0.4–0.7 wt.%). Clay minerals occur as discrete particles, coatings, and pore fillings, contributing to ash formation; however, their correlation with ash yield is weak (R = 0.03–0.05), reflecting heterogeneous mineral inputs and diagenetic overprinting. All geochemical data are reported on a high-temperature coal ash (HTA) basis (815 °C). Geochemical indices (CIA, CIW, CIX) and Al₂O₃/TiO₂ ratios (1.8–17.4) indicate variable provenance and moderate to high weathering intensity, reflecting mixed mafic to intermediate source rocks. A total of 23 trace elements were identified. Au occurs at trace levels (up to 0.02 ppm), while selected rare earth elements (REE: Ce, Dy, Eu, La, Nd, Sm, Y, Yb) average 0.2–0.3 ppm, indicating negligible economic recovery potential. REEs show a strong positive correlation with clay minerals (r = 0.93), indicating adsorption and minor structural incorporation. In contrast, Au correlates with As, V, Zn, Cu, Ni, and Nb, suggesting sulfide association. HTA is enriched in SiO₂–Al₂O₃ phases dominated by kaolinite and quartz, indicating strong potential for cement, geopolymer, ceramic, and zeolite applications. Full article

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

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30 pages, 79781 KB

Open AccessEditor’s ChoiceArticle

Reconstructing Depositional Environments with Decision Tree Classifier (A Machine Learning Model): A Grain-Size Study of the Tredian Formation, Salt Range, Pakistan

by Muhammad Idrees, Shahid Iqbal, Abdul Bari Qanit, Michael Wagreich, Mehwish Bibi, Mansoor Ahmad and Bilal Wadood

Minerals 2026, 16(5), 512; https://doi.org/10.3390/min16050512 - 13 May 2026

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Abstract

The Middle Triassic Tredian Formation of the Salt Range, Pakistan, consists of sandstones with interbedded shale in the lower part and minor dolomite in the upper part. Conventional grain-size analysis has been widely used as a sedimentological tool to elucidate depositional environments and [...] Read more.

The Middle Triassic Tredian Formation of the Salt Range, Pakistan, consists of sandstones with interbedded shale in the lower part and minor dolomite in the upper part. Conventional grain-size analysis has been widely used as a sedimentological tool to elucidate depositional environments and the mode of transportation of detrital sediments. This study presents the first integrated application of a Decision Tree Classifier (a machine learning model) with field and petrographic evidence to interpret grain-size statistics for the analysis of depositional environments of the Tredian Formation in the Salt Range, Pakistan. Stratigraphic sections of the Tredian Formation were measured and sampled in the Nammal Gorge and Zaluch Nala in the Salt Range for detailed sedimentological and grain-size analyses. The lower part of the Tredian Formation (Landa Member) consists of interbedded sandstone and shale (LF-1) characterized by large-scale slumps, parallel lamination, ripple marks, and cross-bedding. The LF-1 is overlain by the Katkhiara Member, which is dominated by thick sandstone (LF-2) with planar and trough cross-bedding and contains dolomite beds (LF-3) in the upper part. Grain-size statistics show that the sandstones are fine-to-medium-grained, well-to-very-well-sorted, near-symmetrical, and very platykurtic. Machine learning-based bivariate plots suggest that most of the samples are grouped, with some showing scattered trends. The Linear Discriminant Function (LDF) analysis indicates that the Tredian Formation was deposited in fluvial–deltaic to shallow marine environments with sand reworking and redistribution under aeolian/beach settings. The Decision Tree Classifier Model (DTCM) predicted fluvial to shallow marine depositional environments for the Tredian Formation and shows strong agreement with field-based lithofacies interpretation, demonstrating its reliability as a predictive tool. Thus, the present study demonstrates that integrating grain-size-based machine learning and statistical analysis with traditional sedimentology provides valuable insights into depositional settings and enhances the reliability of interpretations of ancient sedimentary environments. Full article

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

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37 pages, 2334 KB

Open AccessEditor’s ChoiceReview

The Mineralogy and Geochemistry of Volcanogenic Massive Sulfides and Their Contribution to Human Evolution: Past, Present and Future

by Stavros Savvas Triantafyllidis

Minerals 2026, 16(5), 486; https://doi.org/10.3390/min16050486 - 4 May 2026

Viewed by 387

Abstract

Volcanogenic Massive Sulfides (VMS) are considered major base (Cu-Zn±Pb) and precious metal (Au and Ag) sources with paramount contribution in the development and evolution of mankind through the ages. They are characterized by variable ore mineralogy and geochemistry, largely attributed to the variety [...] Read more.

Volcanogenic Massive Sulfides (VMS) are considered major base (Cu-Zn±Pb) and precious metal (Au and Ag) sources with paramount contribution in the development and evolution of mankind through the ages. They are characterized by variable ore mineralogy and geochemistry, largely attributed to the variety in the geotectonic regime of formation (both divergent and convergent margins) and the variability in the host lithologies. Several VMS types are distinguished depending on the type of volcanism and host-rock lithology. The lens-shaped-to-stratiform bodies composed of fine-grained sulfides, usually accounting for more than 60% of the rock mass, have been exploited since prehistoric times. Recent studies reveal that VMS continue to be formed in deep marine settings and along plate margins on the ocean floor. Besides base and precious metals, nowadays, VMS are considered significant sources of critical and strategic metals, such as Co, Ni, Ga, Ge, In, Bi, As, Sb, Se, Mo, Cd, Sn, Hg, Tl and Bi, particularly after extensive research of the ocean floors in the years following World War II (WWII). Since the late 1970s, the potential of VMS has been further enhanced after the successful deep-sea mining (DSM) pilot tests, with the pipeline-lift mining system considered the most suitable for seabed massive sulfide (SMS) recovery. Full article

(This article belongs to the Special Issue Volcanogenic Massive Sulfide Deposits: Genesis, Tectonics and Exploration)

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16 pages, 11146 KB

Open AccessEditor’s ChoiceArticle

Genesis of the Longkou Gold Deposit in the Northeastern Jiaolai Basin: Constraints from Sericite Rb-Sr Geochronology and Pyrite Geochemistry

by Jin-Shuai Zhang, Hao-Cheng Yu, Guo-Long Yan, Ming Ma, Tao Cui, Ya-Peng Li, Lian-Yuan Qin and Chun-Ting Xu

Minerals 2026, 16(5), 485; https://doi.org/10.3390/min16050485 - 3 May 2026

Viewed by 475

Abstract

Whether the genesis of gold deposits in the Northeastern Jiaolai Basin is consistent with that in the Northwestern Jiaodong area remains controversial. This study presents in situ Rb-Sr dating of sericite, along with in situ trace element and sulfur isotope analyses of pyrite [...] Read more.

Whether the genesis of gold deposits in the Northeastern Jiaolai Basin is consistent with that in the Northwestern Jiaodong area remains controversial. This study presents in situ Rb-Sr dating of sericite, along with in situ trace element and sulfur isotope analyses of pyrite in the Longkou gold deposit. The sericite Rb-Sr inverse isochron yields an age of 120.9 ± 2.4 Ma, indicating that gold mineralization occurred in the Early Cretaceous. Two generations of pyrite, Py1 and Py2, were identified. Py1 is anhedral and hosted in relatively low-grade, weakly altered marble wall rock. Py2 is euhedral to subhedral and hosted in relatively high-grade, strongly altered marble ore. The δ³⁴S value of Py1 is 7.38‰, whereas that of Py2 is 6.79‰. The decrease in δ³⁴S values from Py1 to Py2 reflects an increase in the oxygen fugacity of the ore-forming system. These features suggest that fluid–rock interaction led to an increase in oxygen fugacity, thereby triggering gold precipitation. The mineralization age and precipitation mechanism of the Longkou gold deposit are consistent with those of the Northwestern Jiaodong area. The Longkou gold deposit is best classified as a Jiaodong-type gold deposit. Full article

(This article belongs to the Special Issue Gold–Polymetallic Deposits in Convergent Margins)

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34 pages, 11347 KB

Open AccessEditor’s ChoiceReview

Core Spectral Technology in Sandstone-Type Uranium Deposits of Basins in Northern China: Applications and Challenges—A Review

by Wenyi Wu, Mingsen Fan, Pei Ni, Junyi Pan, Yihan Lin, Zhe Chi and Junying Ding

Minerals 2026, 16(5), 471; https://doi.org/10.3390/min16050471 - 30 Apr 2026

Viewed by 514

Abstract

Sandstone-type uranium deposits represent one of the most significant uranium deposit types in China, predominantly hosted in Meso-Cenozoic sedimentary basins in the northern part of the country. Due to characteristics such as deep burial of orebodies, fine grain size of ores, and strong [...] Read more.

Sandstone-type uranium deposits represent one of the most significant uranium deposit types in China, predominantly hosted in Meso-Cenozoic sedimentary basins in the northern part of the country. Due to characteristics such as deep burial of orebodies, fine grain size of ores, and strong heterogeneity, traditional geological logging methods have limitations in rapidly and accurately identifying alteration minerals and mineralization indicator information. Core spectral technology (wavelength range approximately 400–2500 nm), particularly short-wave infrared spectroscopy (SWIR, 1300–2500 nm), enables rapid, non-destructive, and quantitative extraction of alteration mineral information from drill cores. This provides robust technical support for reconstructing metallogenic environments, delineating oxidation–reduction zones, and prospecting and prediction in sandstone-type uranium deposits. This review systematically examines the spectral absorption characteristics and geological significance of key alteration minerals (e.g., clay minerals, carbonate minerals, iron oxides, and hydrocarbon substances) in sandstone-type uranium deposits. It elaborates on the current application status of core spectral technology in sandstone-type uranium exploration within typical basins in northern China, such as the Ordos, Songliao, Erlian, and Qaidam Basins. These applications include alteration mineral mapping, oxidation–reduction zone delineation, and metallogenic fluid tracing. Due to the unique characteristics of host rock lithology, alteration mineral assemblages, and fluid properties in sandstone-type uranium deposits, the application of this technology also faces certain challenges, such as difficulties in spectral interpretation and insufficient accuracy in quantitative inversion. Integrating this technique with multiple methods, including petrography and X-ray diffraction (XRD), will facilitate more effective applications in both metallogenic research and prospecting practices for sandstone-type uranium deposits in northern China. Full article

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

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14 pages, 3488 KB

Open AccessEditor’s ChoiceArticle

Variability of Crushability and Grindability of Iron Ores in an Itabirite Deposit

by Luís Marcelo Tavares, Gabriel K. P. Barrios, Luciana P. Alves, Elias F. de Castro and José N. S. Silva

Minerals 2026, 16(5), 473; https://doi.org/10.3390/min16050473 - 30 Apr 2026

Viewed by 329

Abstract

The identification of ore types that share similar geological characteristics and metallurgical performance in a deposit is of great relevance in mine planning. In the case of a low-grade iron ore from Brazil, called itabirite, ore types are usually classified as compact and [...] Read more.

The identification of ore types that share similar geological characteristics and metallurgical performance in a deposit is of great relevance in mine planning. In the case of a low-grade iron ore from Brazil, called itabirite, ore types are usually classified as compact and friable, in addition to canga. As itabirites become more widely exploited, friable itabirites have become scarcer, leaving more competent ores to be processed. The work investigates the response of 19 iron ore samples from the Serra do Sapo deposit (Minas Gerais, Brazil), through a variety of bench-scale comminution tests. In the context of crushing (>25 mm), one subtype of compact itabirite, called supercompact, presented substantially higher resistance to fragmentation than those of compact itabirite and canga. In the context of grinding (<19 mm), an inversion occurs, with canga presenting the highest resistance to comminution, followed by the itabirites (friable, compact, and supercompact), nearly indistinctively. This demonstrates that the relative competence of iron ores to withstand comminution in the studied mineral deposits varies significantly as a function of particle size and, therefore, size reduction stage. Finally, grouping of the samples using cluster analysis demonstrated the relevance of discrimination between compact and supercompact itabirites, besides canga, with supercompact itabirite having a greater affinity to canga than with its compact counterpart. This shows the importance of further discriminating itabirites, particularly in the context of comminution at coarser sizes. Full article

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

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32 pages, 14836 KB

Open AccessEditor’s ChoiceArticle

Petrogenesis of Serpentinites and Chromitites in the Neoproterozoic Bou Azzer Ophiolite, Morocco: From Mantle Depletion to High-Pressure Exhumation

by Amina Wafik, Mohamed Ben Massoude, Youssef Atif, Atman Ait Lamqadem, Reza Rooki, Aref Shirazi, Adel Shirazy and Amin Beiranvand Pour

Minerals 2026, 16(5), 460; https://doi.org/10.3390/min16050460 - 29 Apr 2026

Cited by 1 | Viewed by 814

Abstract

Serpentinites and associated chromitites of the Neoproterozoic Bou Azzer ophiolite (Central Anti-Atlas, Morocco) provide key constraints on mantle depletion, melt–rock interaction, and the tectono-metamorphic evolution of a supra-subduction zone (SSZ) system. This study integrates field observations, petrography, Raman spectroscopy, and whole-rock/mineral chemistry to [...] Read more.

Serpentinites and associated chromitites of the Neoproterozoic Bou Azzer ophiolite (Central Anti-Atlas, Morocco) provide key constraints on mantle depletion, melt–rock interaction, and the tectono-metamorphic evolution of a supra-subduction zone (SSZ) system. This study integrates field observations, petrography, Raman spectroscopy, and whole-rock/mineral chemistry to decipher the history of this highly dismembered ultramafic suite. The mantle sequence is dominated by antigorite-bearing serpentinites derived primarily from refractory harzburgitic and dunitic protoliths. Whole-rock geochemistry and highly depleted chromite compositions (Cr# = 0.50–0.68; Mg# = 0.43–0.77; TiO₂ ≤ 0.18 wt.%) demonstrate that these peridotites represent refractory residues formed after high degrees of partial melting (~15–25%). The data delineate a clear evolutionary trend from abyssal to fore-arc and back-arc environments, where infiltrating boninitic melts drove localized podiform chromitite formation through intense melt–rock interaction. Crucially, thermodynamic and mineral–chemical constraints challenge previous models of simple greenschist-facies obduction. Equilibration temperatures exceeding 600 °C and chromite stability within the lower amphibolite to near-granulite facies indicate that the oceanic lithosphere underwent deep subduction prior to its exhumation. This high-temperature, high-pressure metamorphism was followed by multistage retrogressive serpentinization and intense CO₂-rich metasomatism (talc-magnesite alteration) during Pan-African transpressional tectonics. Ultimately, the Bou Azzer ophiolite represents a mature SSZ mantle wedge, recording a complete geodynamic cycle from deep subduction-zone metamorphism to final tectonic emplacement along the northern margin of the West African Craton. Full article

(This article belongs to the Special Issue Platinum-Group Elements, Chromium and Nickel in Ultrabasic-Basic Complexes: New Results)

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38 pages, 4961 KB

Open AccessEditor’s ChoiceSystematic Review

Application of Hydrogeochemistry in Mineral Exploration: A Systematic Review of Global Practices, Emerging Trends, and Future Directions

by Joseph Ndago Amoldago and Emmanuel Daanoba Sunkari

Minerals 2026, 16(5), 451; https://doi.org/10.3390/min16050451 - 26 Apr 2026

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Abstract

Hydrogeochemistry is a practical and low-impact tool for mineral exploration that relies primarily on groundwater as sampling media. It is particularly valuable for blind or deeply buried deposits where surface geochemical methods are ineffective, as groundwater acts as a natural integrator of geochemical [...] Read more.

Hydrogeochemistry is a practical and low-impact tool for mineral exploration that relies primarily on groundwater as sampling media. It is particularly valuable for blind or deeply buried deposits where surface geochemical methods are ineffective, as groundwater acts as a natural integrator of geochemical signals from depth. This study presents a PRISMA 2020-compliant systematic review of hydrogeochemical exploration practices published between 1946 and 2025, synthesizing 118 empirically screened case studies from diverse geological and climatic settings. The review evaluates the geochemical processes governing aqueous dispersion halos, including sulphide oxidation, water–rock interaction, redox controls, and physicochemical speciation, and assesses how these processes influence pathfinder behaviour and anomaly expression. Quantitative synthesis highlights consistent patterns in hydrogeochemical footprints across major mineral systems and demonstrates the effectiveness of thermodynamically informed and multivariate interpretation strategies over simple concentration-based approaches. Emerging trends identified include the growing application of non-traditional stable isotope fractionation, nanoparticle geochemistry using single-particle ICP-MS, and integration of hydrogeochemical datasets with GIS, geophysics, and machine learning-based prospectivity modelling. Unlike recent narrative reviews, this study provides a fully reproducible, structured evaluation of the global evidence base and formalizes a standardized end-to-end workflow. Full article

(This article belongs to the Special Issue Novel Methods and Applications for Mineral Exploration, Volume III)

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16 pages, 7097 KB

Open AccessEditor’s ChoiceArticle

Sodium Polyacrylate as a Rheological Modifier and Selective Depressant in Cu²⁺-Activated Kaolin–Chalcopyrite Flotation Under Saline Conditions

by Matías Jeldres, Eder Piceros, Luis A. Cisternas and Ricardo I. Jeldres

Minerals 2026, 16(5), 449; https://doi.org/10.3390/min16050449 - 25 Apr 2026

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Abstract

This study investigates sodium polyacrylate (NaPA) as a rheology modifier and selective depressant in the flotation of Cu²⁺-activated kaolin–chalcopyrite under industrial water (IW) and seawater (SW) conditions. The work addresses a critical gap in saline systems: how an anionic polymer simultaneously [...] Read more.

This study investigates sodium polyacrylate (NaPA) as a rheology modifier and selective depressant in the flotation of Cu²⁺-activated kaolin–chalcopyrite under industrial water (IW) and seawater (SW) conditions. The work addresses a critical gap in saline systems: how an anionic polymer simultaneously influences clay activation, sulfide floatability, aggregate dispersion, and pulp rheology by varying the medium’s ionic composition. Microflotation, zeta potential, adsorption, yield strength, and Focused Beam Reflectance Measurement (FBRM) assays were used to establish structure–property–response relationships. In IW, Cu²⁺ strongly promoted NaPA adsorption onto both minerals, shifting them toward more negative potentials and significantly reducing selectivity: kaolin recovery decreased from 86.5% to 40.0% at 50 ppm NaPA. In comparison, chalcopyrite recovery fell below 30% at 100 ppm NaPA. In SW, NaPA maintained its depressant effect on kaolin without affecting chalcopyrite flotation, which remained above 90%. This behavior is consistent with reduced polymer adsorption at high ionic strength, where ionic shielding and coiling limit its interaction with chalcopyrite but allow sufficient adsorption onto kaolin to inhibit the collector’s action. Rheological and FBRM results support this interpretation, showing a decrease in yield strength and aggregate size after NaPA addition, with a more pronounced effect in IW than in SW. Full article

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

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18 pages, 1623 KB

Open AccessEditor’s ChoiceArticle

Prediction of Solid Mineral Phases Controlling the Solubility of Zn, Cd, Pb and Ni in Contaminated Soils Using WHAM-VII Modeling

by Debasis Golui, Md. Basit Raza, Siba P. Datta, Brahma S. Dwivedi, Mahesh C. Meena and Prasenjit Ray

Minerals 2026, 16(5), 441; https://doi.org/10.3390/min16050441 - 24 Apr 2026

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Abstract

The chemical equilibria of metal ions between soil solution and solid phases govern the solubility of metals in soil. However, the identity of these controlling phases remains poorly understood in historically polluted environments. This study aimed to identify the dominant mineral phases regulating [...] Read more.

The chemical equilibria of metal ions between soil solution and solid phases govern the solubility of metals in soil. However, the identity of these controlling phases remains poorly understood in historically polluted environments. This study aimed to identify the dominant mineral phases regulating the activities of Zn²⁺, Cd²⁺, Pb²⁺, and Ni²⁺ in soils subjected to long-term contamination from sewage sludge, municipal solid waste, river water, and industrial effluents across India. The soil samples were collected from various locations historically polluted by sewage sludge, municipal solid waste, polluted river water and industrial effluents. The free ion activities of Zn²⁺ (pZn²⁺), Cd²⁺ (pCd²⁺), Pb²⁺ (pPb²⁺) and Ni²⁺ (pNi²⁺) in soil pore water were estimated using the geochemical speciation model WHAM-VII. The metal ion activities were higher in industrial effluents and solid waste-treated soils as compared to other contaminated soils. The solubility of Zn and Cd in soils contaminated with Zn-smelter effluents was controlled by franklinite (ZnFe₂O₄) in equilibrium with goethite (α-FeOOH) and otavite (CdCO₃), respectively. Identification of minerals further reveals that nickel ferrite (NiFe₂O₄) in equilibrium with lepidocrocite (γ-FeOOH) governs the activity of Ni²⁺ in cycle factory effluent-irrigated soils of Sonepat, Haryana. At the municipal solid waste-contaminated site, the Pb²⁺ activity was controlled by exchangeable Pb in soils, whereas Zn²⁺ activity was governed by willemite (Zn₂SiO₄) in equilibrium with quartz (SiO₂). These findings provide new insights into mineralogical controls on heavy metal solubility under diverse contamination scenarios. Formation of highly soluble minerals like otavite, willemite, and nickel ferrite suggested the potential ecological risk of Cd, Zn, and Ni, respectively, in polluted soils. Full article

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

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26 pages, 6703 KB

Open AccessEditor’s ChoiceArticle

Could Ambient-Temperature Melting of a Fertile Mantle Explain Abrolhos Magmatism? An Alternative to Classical Plume Models

by Nicholas Machado Lima, Rogério Guitarrari Azzone, Lucas Martins Lino, Anderson Costa dos Santos, Thais Mothé Maia, Leandro Arrais Bevilaqua, Sergio de Castro Valente, Gabriel Medeiros Marins and Vincenza Guarino

Minerals 2026, 16(5), 437; https://doi.org/10.3390/min16050437 - 23 Apr 2026

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Abstract

The Abrolhos Magmatic Province (AMP), situated along the southeastern Brazilian passive margin, comprises a Paleocene–Eocene transitional basalt series of alkaline affinity. Despite the lack of mineral chemistry and thermobarometric estimates, it has long been linked to a classical deep-mantle plume model. This study [...] Read more.

The Abrolhos Magmatic Province (AMP), situated along the southeastern Brazilian passive margin, comprises a Paleocene–Eocene transitional basalt series of alkaline affinity. Despite the lack of mineral chemistry and thermobarometric estimates, it has long been linked to a classical deep-mantle plume model. This study integrates mineral chemistry, calculations of intensive parameters (P, T, H₂O), geochronology, and geochemical modeling to evaluate an alternative explanation for AMP magmatism. Whole-rock and clinopyroxene compositions from different AMP localities are consistent with parental magmas derived from fertile, pyroxenite-enriched mantle sources that melted under ambient mantle potential temperatures (~1300–1400 °C). Inverse petrological modeling using alphaMELTS and MeltPT, together with trace-element systematics, suggests low degrees of partial melting within asthenospheric domains. These results indicate that shallow (upper-mantle) processes and high mantle fertility were important controls on melt generation. New ⁴⁰Ar/³⁹Ar ages of 24.3–28.4 Ma for southern AMP rocks are also difficult to reconcile with a simple age-progressive evolution of the previously proposed plume model. Taken together, the data support ambient-temperature melting of a fertile mantle as a plausible explanation for Abrolhos magmatism and reduce the need to invoke a classical high-temperature mantle plume as the sole model. Here, we favor a tectonically controlled model, involving localized shallow mantle processes such as edge-driven convection and/or lithospheric delamination as triggers for intraplate magmatism along the South Atlantic margins. Full article

(This article belongs to the Special Issue Geochronology and Geochemistry of Alkaline Rocks)

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45 pages, 10083 KB

Open AccessEditor’s ChoiceSystematic Review

The Conservation of Architectural Heritage Structures Built with Tuff and Coral Rock: A Systematic Review and Bibliometric Analysis of Geopolymer Formulation, Application, Compatibility and Durability

by Kent Benedict Aleonar Salisid, Raul Lucero, Jr., Reymarvelos Oros, Mylah Villacorte-Tabelin, Theerayut Phengsaart, Shengguo Xue, Jiaqing Zeng, Ivy Corazon A. Mangaya-ay, Takahiko Arima, Ilhwan Park, Mayumi Ito, Sanghee Jeon and Carlito Baltazar Tabelin

Minerals 2026, 16(4), 426; https://doi.org/10.3390/min16040426 - 20 Apr 2026

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Abstract

The conservation of tuff- and coral rock-built architectural heritage structures (AHS) is challenging because access to original tuff and coral rock has become difficult and severely limited due to urbanization, land reclamation, the depletion of stone quarries, anti-mining and anti-quarrying legislation. An emerging [...] Read more.

The conservation of tuff- and coral rock-built architectural heritage structures (AHS) is challenging because access to original tuff and coral rock has become difficult and severely limited due to urbanization, land reclamation, the depletion of stone quarries, anti-mining and anti-quarrying legislation. An emerging approach to address this issue is to create compatible “replacement” rocks via geopolymerization, a process that is more sustainable and greener than the use of conventional cement and concrete. To explore the potential of geopolymers for AHS conservation strategies, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were implemented; 103 eligible articles were identified and classified into geopolymers for AHS (34 articles), tuff-built AHS (60 articles), and coral rock-built AHS (9 articles). Tuff substrates in AHSs appear in a variety of colors (yellowish-brown, grayish-cream, reddish-brown, pale greenish-gray and pink hues), densities (1.0–2.5 g/m³), and compressive strengths (3–100 MPa). Meanwhile, coral rock substrates in AHSs appear in whitish-cream color and are coarse-pored (1–5 MPa), fine-grained (8–15 MPa), and calcarenite (50–60 MPa). In terms of geopolymer formulation, metakaolin was reported as the most popular main precursor or admixture, while NaOH and Na₂SiO₃ were used simultaneously as alkaline activators. Aggregates used in geopolymer formulations depended on local availability, including quartz sand, river sand, crushed stones, carbonate stones, volcanic rock, volcanic sand, tuff, brick, ceramic tiles, and waste materials. Aesthetics, chemical composition, physical attributes, and mechanical properties have been identified as key criteria to ensure geopolymer compatibility for AHS conservation application. To date, geopolymers have been applied for AHS conservation as repair mortars, consolidants (i.e., grout and adhesives), and masonry strengthening (i.e., fiber-reinforced mortar). Finally, geopolymers formulated for AHS conservation have similar durability as the original substrate based on accelerated aging tests (i.e., salt mist, wet-dry, and freeze–thaw) and long-term outdoor exposure experiments. Full article

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

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32 pages, 46734 KB

Open AccessEditor’s ChoiceReview

The Rio Grande Rise: Current Knowledge and Future Frontiers for Deep-Sea Science, Mineral Resources and Governance

by Luigi Jovane, Carina Ulsen, Douglas Galante, Simone Bernardini, Natascha Menezes Bergo, Elisabete de Santis Braga, Frederico P. Brandini, Ronaldo Carrion, David Lopes de Castro, Renata R. Constantino, Muhammad Bin Hassan, Valdecir de Assis Janasi, Izabel King Jeck, Luciano de Oliveira Junior, Marco Antonio Couto Junior, Fabiola A. Lima, Simone Marques, Gustavo M. Massola, Nelia C. C. Mestre, Webster Mohriak, Eduardo F. Monlevade, Carina Costa de Oliveira, Vivian Helena Pellizari, Marcelo Cecconi Portes, Adriane G. P. Praxedes, Fabio Rodrigues, Lucas C. V. Rodrigues, Francisco Javier González Sanz, Ilson C. A. da Silveira, Jules M. R. Soto, Pedro Walfir Souza-Neto, Paulo Y. G. Sumida, Gabriel T. Tagliaro, Solange Teles da Silva, Alexander Turra, Roberto Ventura Santos, Marcio Yamamoto and Sidney L. M. Mello Show full author list Hide full author list

Minerals 2026, 16(4), 418; https://doi.org/10.3390/min16040418 - 17 Apr 2026

Cited by 1 | Viewed by 1967

Abstract

The Rio Grande Rise (RGR) is the largest oceanic plateau in the South Atlantic and represents a key natural laboratory for understanding oceanic plateau formation, deep-sea circulation, ecosystem functioning, and ferromanganese crust development. This study presents a critical synthesis of current scientific knowledge [...] Read more.

The Rio Grande Rise (RGR) is the largest oceanic plateau in the South Atlantic and represents a key natural laboratory for understanding oceanic plateau formation, deep-sea circulation, ecosystem functioning, and ferromanganese crust development. This study presents a critical synthesis of current scientific knowledge on the RGR, integrating geological, geophysical, oceanographic, biological, and geochemical evidence published over the last two decades. Geophysical data reveal a complex tectono-magmatic evolution involving Late Cretaceous plume-related volcanism, crustal thickening, rifting, and subsequent subsidence. The structural framework of the plateau is dominated by the Cruzeiro do Sul Rift, which plays a central role in controlling sedimentation, magmatism, and seawater circulation. Oceanographic studies demonstrate that the interaction between the southern branch of the South Equatorial Current and the complex topography of the RGR generates intense internal tides and bottom currents, strongly influencing sediment transport and benthic habitats. Biological investigations indicate that the RGR hosts diverse deep-sea communities, including sponge grounds, cold-water corals, and associated fauna, whose distribution is tightly linked to geomorphology and hydrodynamics. Ferromanganese crusts occurring on the plateau preserve valuable geochemical records of oceanographic and redox conditions, although their spatial distribution, thickness, and metal budgets remain incompletely constrained. Despite major advances, significant knowledge gaps persist regarding crustal structure, sedimentary evolution, ecosystem functioning, and mineral formation processes. This review highlights these uncertainties and outlines research priorities necessary to improve understanding of oceanic plateaus and deep-sea systems in the South Atlantic. Full article

(This article belongs to the Special Issue Geology, Exploration and Mining of Deep-Sea Mineral Resources)

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20 pages, 14326 KB

Open AccessEditor’s ChoiceArticle

Hydrodynamic Mechanisms of a Fractal Blade Enhancing the Pulp Conditioning and Flotation Separation of Fine-Grained Malachite and Quartz

by Binqing Liu, Guohua Gu, Yanhong Wang, Yuan Chen, Yanming Wu, Yuankun Yang, Shengli Yu, Chongzhong Ouyang and Bingchao Lv

Minerals 2026, 16(4), 409; https://doi.org/10.3390/min16040409 - 16 Apr 2026

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Abstract

High-intensity conditioning (HIC) is a common pretreatment process for enhancing the flotation of fine-grained minerals. This study introduces fractal theory into the structural design of pulp conditioning impellers. A fractal blade with multi-scale fractal edge features was proposed, and its separation performance was [...] Read more.

High-intensity conditioning (HIC) is a common pretreatment process for enhancing the flotation of fine-grained minerals. This study introduces fractal theory into the structural design of pulp conditioning impellers. A fractal blade with multi-scale fractal edge features was proposed, and its separation performance was evaluated in a fine-grained malachite (−20 μm) and quartz flotation system. Computational fluid dynamics simulation revealed that the fractal blade altered the energy dissipation pattern. Compared with conventional rectangular blades, it induced stronger fluid compression and collision effects in localized regions. These hydrodynamic changes improved the suspension homogeneity and dispersion efficiency of fine-grained malachite. Furthermore, the fractal blade reduced the scale of turbulent vortices while increasing local turbulent kinetic energy and shear rates. This optimized turbulent flow field effectively reduced mass-transfer resistance and promoted interfacial interactions between flotation reagents and mineral particles. Adsorption experiments and optical microscopy indicated that after conditioning at 1500 rpm for 3 min, the fractal blade increased sodium oleate adsorption on malachite compared to the conventional blade. This enhanced adsorption promoted the aggregation of fine-grained malachite, increasing its aggregate size by 15.52%, while no significant aggregation was observed for quartz particles. Consequently, the single mineral flotation recovery of fine-grained malachite increased by 4.13%. For artificial mixed minerals, the copper concentrate grade and recovery were improved by 2.28% and 1.04%, respectively. This study provides a theoretical basis for equipment optimization and structural innovation design in HIC processes. Full article

(This article belongs to the Special Issue Innovative Strategies for the Sustainable Processing of Complex Polymetallic Resources)

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36 pages, 17973 KB

Open AccessEditor’s ChoiceArticle

A Multi-Analytical Approach to the Study of Phosphatic Materials from the Lower Cambrian of Spain

by Yihao Xie, Aili Zhu, Ting Huang, Lei Jin and David C. Fernández-Remolar

Minerals 2026, 16(4), 405; https://doi.org/10.3390/min16040405 - 15 Apr 2026

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Abstract

Phosphatic deposits from the Lower Cambrian Pedroche Formation (Sierra de Córdoba, Spain) provide key insights into early diagenetic mineralization processes during the Cambrian radiation. This study applies an integrated multi-analytical approach combining Raman spectroscopy, SEM–EDS, LA-ICP-MS, and ToF-SIMS to investigate mineralogical, elemental, and [...] Read more.

Phosphatic deposits from the Lower Cambrian Pedroche Formation (Sierra de Córdoba, Spain) provide key insights into early diagenetic mineralization processes during the Cambrian radiation. This study applies an integrated multi-analytical approach combining Raman spectroscopy, SEM–EDS, LA-ICP-MS, and ToF-SIMS to investigate mineralogical, elemental, and molecular signatures of phosphatized bioclastic carbonates and associated siliciclastic facies from the Los Lagares-1 borehole. Results reveal a systematic phosphatization gradient from carbonate-dominated skeletal rims to phosphate-rich interiors composed of carbonate fluorapatite with variable carbonate and hydroxyl substitution. Trace-element systematics and REE patterns indicate seawater-influenced phosphogenesis under suboxic porewater conditions, coupled to iron reduction and early diagenetic clay mineral formation. In contrast, the siliciclastic siltstone facies preserves poorly crystalline phosphate phases associated with detrital aluminosilicates and chlorite, reflecting distinct porewater chemistry and crystallization kinetics. ToF-SIMS mapping demonstrates spatial coupling between fluorine and phosphate within fossil structures, confirming fluorapatite formation and localized organic matter entombment. These results highlight the strong control of host lithology on phosphate crystallization pathways and trace-element redistribution, and provide new constraints on microbially mediated phosphogenesis in restricted Early Cambrian reef–lagoon systems along the northern Gondwanan margin. Full article

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

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26 pages, 12108 KB

Open AccessEditor’s ChoiceArticle

Mineralogy, Geochemistry, and Geochronology of Hydrothermal and Magmatic Apatites in the Xiangshan Ore Field, South China: Implications for U-Pb-Zn Polymetallic Mineralization

by Qingkun Yang, Yubin Liu, Fusheng Guo, Hao Jiang, Yongjie Yan and Yun Wang

Minerals 2026, 16(4), 389; https://doi.org/10.3390/min16040389 - 7 Apr 2026

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Abstract

The timing of uranium mineralization in the Xiangshan ore field has long been controversial. Although various geochronometers have been applied by previous researchers, including pyrite Rb-Sr, mica Ar-Ar, and fluorite Sm-Nd, the results remain inconsistent and inconclusive. In recent years, the discovery of [...] Read more.

The timing of uranium mineralization in the Xiangshan ore field has long been controversial. Although various geochronometers have been applied by previous researchers, including pyrite Rb-Sr, mica Ar-Ar, and fluorite Sm-Nd, the results remain inconsistent and inconclusive. In recent years, the discovery of abundant Pb-Zn veins in the deeper parts of the Xiangshan ore field has further complicated the interpretation of its metallogenic history. In this study, abundant vein-type hydrothermal apatites closely associated with U-Pb-Zn polymetallic mineralization were identified in both uranium and Pb-Zn ore veins. Combined major-element Electron Probe Microprobe Analysis (EPMA), Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) U-Pb dating, and trace-element analysis were conducted on these apatite grains. The results suggest a mineralization age of 130.9 ± 1.1 Ma for the Shannan uranium deposit, which is consistent with the previously reported apatite U-Pb age of 131.3 ± 7.2 Ma from the Zoujiashan uranium deposit and coincides with the main pulse of volcanic-intrusive activity in the Xiangshan ore field (133–137 Ma). The deep Niutoushan Pb-Zn deposit suggests a younger mineralization age of 124.5 ± 1.3 Ma, which is consistent with a thermal event age of 125.6 Ma determined by zircon fission-track dating and the zircon LA-ICP-MS U-Pb age of late-stage granite porphyry (125.4 ± 1.0 Ma). These ages may constrain the timing of U-Pb-Zn polymetallic mineralization in the Xiangshan ore field. Both magmatic and hydrothermal apatites are classified as fluorapatite and exhibit similar chondrite-normalized rare earth element (REE) patterns. Compared with magmatic apatites, hydrothermal apatites are characterized by elevated Th, U, Ca, and Sr contents, depletion in light rare earth elements (LREEs), Mn, and Na, and distinctly lower Th/U ratios. On major-element variation diagrams, magmatic and hydrothermal apatites define coherent trends but display clear compositional differences related to their formation stages. Apatites from uranium ore veins show strongly negative Eu anomalies and weakly positive Ce anomalies, similar to magmatic apatites. In contrast, apatites from Pb-Zn ore veins display positive Eu anomalies and weakly negative Ce anomalies, with lower Mn and Ga contents and higher SO₃ contents relative to both magmatic apatites and hydrothermal apatites from uranium ore veins. These features indicate that the ore-forming fluids during Pb-Zn mineralization were characterized by significantly higher oxygen fugacity than those during uranium mineralization and magmatism. Combined with published Sr isotopic data for the Xiangshan ore field, we propose that both uranium and Pb-Zn mineralization were genetically linked to the prolonged magmatic evolution of the deep volcanic-intrusive complex. The subsequent incursion of meteoric water modified the physicochemical conditions of the ore-forming system, particularly during the formation of the Pb-Zn mineralization. Full article

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

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37 pages, 8695 KB

Open AccessEditor’s ChoiceArticle

DIGIT: An In Situ Experiment for Studying the Diffusion of Water and Solutes Under Thermal Gradient in the Toarcian Clayrock at the Tournemire URL; Part 2—Lessons Learned After 20 Months of Heat

by Maïwenn Humbezi Desfeux, Jean-Michel Matray, Aurelie Noret, Uy Vo, Son T. Nguyen, Mamadou Fall, Julio Á. I. Sedano, Charles Wittebroodt and Manuel Marcoux

Minerals 2026, 16(4), 380; https://doi.org/10.3390/min16040380 - 3 Apr 2026

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Abstract

The DIGIT experiment was launched at the Tournemire Underground Research Laboratory (URL) with the aim of determining the effects of temperature on the transfer of tracers mimicking the most mobile radionuclides in the Toarcian clay rock. The properties of this rock are similar [...] Read more.

The DIGIT experiment was launched at the Tournemire Underground Research Laboratory (URL) with the aim of determining the effects of temperature on the transfer of tracers mimicking the most mobile radionuclides in the Toarcian clay rock. The properties of this rock are similar to those of the host rocks being considered for a future deep geological repository for high-level radioactive waste (HLW). The experiment involves the monitoring of the interaction between a test water doped with stable halides and deuterium at constant concentration, and the porewater of the Toarcian clay rock under constant ambient conditions, as well as at higher temperature induced by artificial heating. This experiment seeks to partially address questions regarding the potential spread of contaminants during the thermal phase of HL waste packages. Specifically, the in situ experiment aims to evaluate the role of scale effects, thermodiffusion, a process that combines Fick’s law, the Soret effect, and convection in the transfer of radionuclides. This paper is the second part of a companion paper dedicated to predictive calculations and the installation of the experimental device. It presents the main experimental and modeling results obtained since the beginning of the installation and after 20 months of heat at 70 °C. The test was carried out in five phases, finishing with a sampling campaign: a phase 0 called “initial conditions”, followed by a pure diffusion phase (5 months), then three phases in a heated period lasting 1 year and 8 months. In total, 47 rock cores were analyzed, with approximately 170 samples tested by four diffusion methods (radial, outgoing, through and in vapor-phase) to determine the tracer concentrations in the porewater, their water content and their diffusive transport parameters. The results show a decrease in tracer concentrations with distance from the test zone, in the directions parallel and perpendicular to the stratification. The anisotropy of the medium results in greater migration in the direction parallel to the stratification. Thermal properties also confirm anisotropy with a higher thermal conductivity in the direction parallel to the stratification. Finally, an activation energy of 22.9 ± 1.7 kJ·mol⁻¹ could be proposed by NMR for deuterium, indicating diffusion behavior following an Arrhenius law between 30 and 70 °C. The experimental data allowed for the calibration of a 2D axisymmetric numerical model using the commercial finite element software COMSOL Multiphysics^®. The Fick’s law corrected by an Arrhenius law best reproduces the penetration of deuterium and anions. The Soret effect, integrated into certain scenarios, is only significant for anions’ migration, using a fitted Soret coefficient of 0.1 K⁻¹, as proposed in the literature for the Callovo-Oxfordian, the host rock of the Cigéo project in the east of France. The calibration of the simulated data with the experimental data allowed for the characterization of damaged and/or disturbed zones evolving over time. Simulations over 150 years, the duration of the thermal maximum for HLW packages, show that advection—modeled by Darcy’s law—would have a negligible role in this context due to the low permeability of the upper Toarcian. In conclusion, the DIGIT test showed that, for the Upper Toarcian clay rocks at the Tournemire URL in France, diffusion, corrected for the effect of temperature, is the mechanism that characterizes the transport of radionuclide analogues. The study showed that thermodiffusion has a limited influence on deuterium migration but remains significant for anions in the case of a coupling between temperature correction and thermodiffusion. The test also highlighted the impact of temperature on the spatiotemporal development of a damaged and/or disturbed zone. These new and relevant results in the field will need to be confirmed later through additional experiments. Full article

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

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15 pages, 6872 KB

Open AccessEditor’s ChoiceArticle

Age and Geochemistry of Rutile as an Indicator of Tungsten Source in the Wangu Au-W-Sb Deposit, Northeastern Hunan, China

by Miao Yang, Teng Deng, Zhilin Wen, Yueqiang Zhou, Hongmei Tang, Haonan Cui and Yilin Xiong

Minerals 2026, 16(4), 363; https://doi.org/10.3390/min16040363 - 30 Mar 2026

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Abstract

The Jiangnan Orogenic Belt is a world-renowned metallogenic region for Au-W-Sb mineralization, with the Wangu deposit being a representative one. Previous research has demonstrated that tungsten in this Au-W-Sb deposit is sourced from the hosting metasedimentary rocks, but the specific mineral that provides [...] Read more.

The Jiangnan Orogenic Belt is a world-renowned metallogenic region for Au-W-Sb mineralization, with the Wangu deposit being a representative one. Previous research has demonstrated that tungsten in this Au-W-Sb deposit is sourced from the hosting metasedimentary rocks, but the specific mineral that provides tungsten is still unclear. This study evaluates the tungsten source by conducting petrographic observations and geochemical and geochronological analyses on the rutile from the host slate the Wangu deposit. The results show that rutile from wall rocks of the Wangu deposit yields an age of 955 ± 13 Ma, which is older than both the ore-forming age of the deposit and the age of the host strata. Electron microprobe analyses (EMPA) and laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) elemental analyses show that detrital rutile is enriched in elements such as Fe, Cr, V, and W, as well as high-field-strength elements (HFSE) including Nb, Ta, Zr, and Hf. The total rare earth element (ΣREE) ranges from 3.37 ppm to 156.85 ppm. The samples are generally enriched in light rare earth elements (LREEs) and exhibit distinct negative Eu anomalies. These geochemical features and a geochronological age of 955 ± 13 Ma suggest that the rutile is of detrital origin and they are possibly derived from the Grenvillian rocks. It is concluded that the detrital rutile in the metasediments could be an important source for hydrothermal tungsten enrichment. Full article

(This article belongs to the Section Mineral Deposits)

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32 pages, 9247 KB

Open AccessEditor’s ChoiceArticle

Deciphering Middle–Late Eocene Paleoenvironmental Conditions Using Geochemical Trends: Insights from the Beni Suef Area, Northeastern Desert, Egypt

by Mostafa M. Sayed, Michael Wagreich, Petra Heinz, Ibrahim M. Abd El-Gaied, Susanne Gier, Erik Wolfgring, Ramadan M. El-Kahawy, Ahmed Ali, Ammar Mannaa, Rabea A. Haredy and Dina M. Sayed

Minerals 2026, 16(4), 361; https://doi.org/10.3390/min16040361 - 29 Mar 2026

Viewed by 858

Abstract

The reconstruction of detrital flux, paleoclimate, paleosalinity, paleo-primary productivity, paleohydrodynamic conditions, and paleo-water depth enhances understanding of sedimentary processes and their drivers during deep-time greenhouse-icehouse transitions, such as the Eocene–Oligocene transition. This study uses detailed geochemical analyses of major oxides and trace elements [...] Read more.

The reconstruction of detrital flux, paleoclimate, paleosalinity, paleo-primary productivity, paleohydrodynamic conditions, and paleo-water depth enhances understanding of sedimentary processes and their drivers during deep-time greenhouse-icehouse transitions, such as the Eocene–Oligocene transition. This study uses detailed geochemical analyses of major oxides and trace elements in sediment samples collected from the Beni Suef Formation (Bartonian–Priabonian) and the Maadi Formation (Priabonian) in the southern Tethys shelf (Egypt, northeastern Desert). Detrital proxies, including Si/Al, Ti/Al, and Zr/Al, indicate an enhanced influx of terrigenous sediments in the middle portion of the Qurn Member of the Beni Suef Formation, as further supported by noticeable facies variations, particularly the transition from shale to coarser silt- and sand-sized fractions. Paleoclimate indicators (Sr/Ba, Rb/Sr, K₂O/Al₂O₃, and Sr/Cu) point to a climatic shift from humid to arid conditions, consistent with the regional Late Eocene aridification across the Tethyan realm. Paleosalinity proxies (Sr/Ba, Ca/Al, and Mg/Al×100) suggest episodic intensification of open-marine influence and a reduction in freshwater input, with an upsection increase in Sr/Ba ratios, reflecting phases of enhanced marine water settings or decreased terrestrial runoff. Primary productivity was evaluated using multiple geochemical proxies, including P, Ni/Al, Cu/Al, P/Al, P/Ti, and Babio ratios. These collectively indicate generally low primary productivity interrupted by intervals of enhanced paleoproductivity or increased organic matter export to the sediments. This interpretation is further supported by the low total organic carbon (TOC) values. These results highlight the sensitivity of the southern Tethys shelf to Middle–Late Eocene climatic variability and the key role of prevailing paleoenvironmental conditions in controlling sediment supply, water chemistry, and biological productivity. Full article

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

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26 pages, 2202 KB

Open AccessEditor’s ChoiceReview

Use of Mining Waste Classification in the Context of a Circular Economy—A Review

by Bruno Lemière and Richard Lord

Minerals 2026, 16(4), 358; https://doi.org/10.3390/min16040358 - 28 Mar 2026

Cited by 2 | Viewed by 651

Abstract

The beneficial use of mining waste aligns with circular economy thinking: saving primary resources can extend their lifetime and maintain availability, reduce the volume of legacy mining waste and its environmental impacts, and develop a resource beneficiation industry that is less energy and [...] Read more.

The beneficial use of mining waste aligns with circular economy thinking: saving primary resources can extend their lifetime and maintain availability, reduce the volume of legacy mining waste and its environmental impacts, and develop a resource beneficiation industry that is less energy and water intensive; mining lower grades at larger scale inevitably requires more beneficial reuse. Existing classifications applicable to different types of mine waste were reviewed. These include factors such as the mode of origin during the mining operation, grain size, chemical composition and stability. The result shows that these factors also largely control their civil engineering applications, suitability for end use sectors and potential hazards. Long-term liabilities related to chemical stability were identified as the most difficult challenge. When developing a reuse project, either by the end users or by the mine operator, it is likely that resource screening covering a comprehensive range of factors will be required, as none of the existing schemes individually cover all of the aspects needed to fully assess suitability for beneficial use. In conclusion, there is a need for a systematic and structured approach to classification of mining waste to facilitate reuse as raw materials, such as that presented in our review. Full article

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

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23 pages, 12467 KB

Open AccessEditor’s ChoiceArticle

Key Ore-Controlling Factors and Genetic Model of the Tamusu Super-Large Sandstone-Type Uranium Deposit, Bayingobi Basin

by Chao Lu, Zhongyue Zhang, Yangquan Jiao, Zhao Li, Xiaoyi Yuwen, Yinan Zhuang, Chengyuan Jin, Chengcheng Zhang, Weihui Zhong and Qilin Wang

Minerals 2026, 16(4), 357; https://doi.org/10.3390/min16040357 - 27 Mar 2026

Viewed by 582

Abstract

Tamusu, the only identified super-large sandstone-hosted uranium deposit in the Bayingobi Basin, provides an important natural laboratory for evaluating ore-controlling factors and genetic models of sandstone-type uranium mineralization. Based on core descriptions from more than 200 boreholes, log facies analysis and geochemical environmental [...] Read more.

Tamusu, the only identified super-large sandstone-hosted uranium deposit in the Bayingobi Basin, provides an important natural laboratory for evaluating ore-controlling factors and genetic models of sandstone-type uranium mineralization. Based on core descriptions from more than 200 boreholes, log facies analysis and geochemical environmental proxies, this study constrains the sedimentary–mineralization architecture and key controlling factors of the deposit. Uranium orebodies are mainly hosted in the upper member of the Lower Cretaceous Bayingobi Formation (Sq2) within a gravity flow-dominated fan-delta–lacustrine system. Braided distributary channel sands on the fan-delta plain and subaqueous distributary channel sands on the delta front constitute the principal uranium reservoirs, controlling both the migration pathways and storage space for U-bearing fluids. Mineralization is jointly governed by fan-delta architecture, interlayer oxidation zonation and reducing agents. The interlayer oxidation zone displays a north-thick–south-thin geometry, and uranium orebodies are concentrated at redox transition positions, with grades of 0.01–0.33 wt%. The metallogenic evolution can be summarized in three stages: syndepositional uranium pre-enrichment, interlayer oxidation mineralization, and a late hydrothermal/diagenetic overprint that mainly modified reservoir properties, favored ore preservation, and did not contribute to the primary uranium budget. Accordingly, a genetic model of “fan-delta architecture + interlayer oxidation control + late overprint and preservation” is proposed to guide exploration in the Bayingobi Basin and analogous sandstone-type uranium systems. Full article

(This article belongs to the Special Issue Genesis of Uranium Deposit: Geology, Geochemistry, and Geochronology)

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21 pages, 6646 KB

Open AccessEditor’s ChoiceArticle

Whole-Rock Element Analyses Constraining the Magmatic Evolution and Metallogenesis of the Jiaojia Fault Zone, Jiaodong Gold Province

by Jiabao Jia, Yueliang Hu, Lin Gao, Yulu Lv, Junjie Wang, Xiaomei Yang, Yan Liu, Xiaoliang Shi, Jing Lv, Yanbo Xu, Mengmeng Zhang and Wu Li

Minerals 2026, 16(4), 350; https://doi.org/10.3390/min16040350 - 26 Mar 2026

Viewed by 539

Abstract

The Jiaodong Peninsula constitutes a world-class gold province in eastern China, containing more than 5000 t of identified gold resources. The Jiaojia gold deposit is one of the largest deposits within this gold province, and mineralization is primarily distributed along the northern segment [...] Read more.

The Jiaodong Peninsula constitutes a world-class gold province in eastern China, containing more than 5000 t of identified gold resources. The Jiaojia gold deposit is one of the largest deposits within this gold province, and mineralization is primarily distributed along the northern segment of the Jiaojia Fault. The structural characteristics and mineralization processes of the northern segment have been extensively documented. In contrast, the ore-forming mechanisms of the southern Jiaojia Fault remain poorly constrained, hindering further exploration targeting. We chose several gold deposits and one drill core along the Jiaojia Fault, then present whole-rock major and trace elements data to evaluate magmatic affinities and their ore-forming potential. The results show that the lithological differences in plutonic and stratigraphic units suggest that variations in petrogenesis may have exerted a fundamental control on mineralization styles. Almost all samples are characterized by enrichment in light rare earth elements, relative enrichment in Europium, and pronounced depletion in heavy rare earth elements. Alteration characteristics indicate the northern segment is dominated by advanced argillic alteration, whereas phyllic alteration is more prevalent in the southern segment. The rare earth elements discrimination plot clearly suggests differentiation from the northern and southern fault segments. Consequently, we propose that the northern segment records synorogenic arc magmatism, while the southern segment experienced both synorogenic and a subsequent intraplate extensional transitional stage. Full article

(This article belongs to the Special Issue Gold–Polymetallic Deposits in Convergent Margins)

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32 pages, 12683 KB

Open AccessEditor’s ChoiceArticle

Model-Space Processing and Inversion of Magnetotelluric Data: A Multi-Model Jackknife Method

by Shaoting Feng, Dikun Yang and Lian Liu

Minerals 2026, 16(4), 345; https://doi.org/10.3390/min16040345 - 25 Mar 2026

Viewed by 461

Abstract

Magnetotelluric (MT) inversion models are widely used to interpret crustal conductivity structures related to fluid pathways, deformation zones, and mineralization processes; however, evaluating the reliability of inversion-derived anomalies remains challenging when datasets contain subtle station-dependent distortions or residual cultural noise. We present a [...] Read more.

Magnetotelluric (MT) inversion models are widely used to interpret crustal conductivity structures related to fluid pathways, deformation zones, and mineralization processes; however, evaluating the reliability of inversion-derived anomalies remains challenging when datasets contain subtle station-dependent distortions or residual cultural noise. We present a jackknife-inspired, model-space diagnostic framework based on leave-one-station-out (LOSO) inversion to quantify station influence and improve interpretation reliability. The workflow consists of (1) generating a LOSO inversion ensemble using identical inversion settings, (2) computing ensemble statistics and standardized perturbation metrics to identify sensitive zones, and (3) applying distribution-based diagnostics to classify station influence and guide construction of an ensemble-refined model. Synthetic experiments demonstrate that the framework distinguishes localized station-controlled artifacts from broadly supported structural responses, allowing targeted correction without altering robust features. Application to a field MT dataset acquired in a noise-affected environment shows that a mid-crustal conductive structure remains stable across the LOSO ensemble, while some shallow anomalies exhibit strong station dependence. The resulting ensemble-refined model introduces only localized modifications, demonstrating that ensemble-based model-space diagnostics provide a practical and reproducible strategy for validating MT inversion results and improving confidence in exploration-oriented conductivity interpretations. Full article

(This article belongs to the Special Issue Advances in Magnetic and Electromagnetic Techniques for Mineral Exploration: Enhancing Resource Discovery, 2nd Edition)

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19 pages, 4742 KB

Open AccessEditor’s ChoiceArticle

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

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

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

Viewed by 406

Abstract

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

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

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

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25 pages, 2146 KB

Open AccessEditor’s ChoiceArticle

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

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

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

Viewed by 1175

Abstract

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

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

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

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29 pages, 6927 KB

Open AccessEditor’s ChoiceArticle

Chemical Signatures of Apatite in the AQW2 Deposit: Petrogenetic Insights on a Wide Archean–Paleoproterozoic Iron Oxide–Copper–Gold Mineral System in the Carajás Mineral Province

by Ligia Stama, Lena V. S. Monteiro, Nazaré A. Barbosa, Luiz F. Dutra, Giovanna C. Moreira, Sarah A. S. Dare, Rodrigo Oliveira de Araujo Mabub and Fernando Martins Vieira Matos

Minerals 2026, 16(3), 308; https://doi.org/10.3390/min16030308 - 15 Mar 2026

Viewed by 1063

Abstract

Iron oxide–copper–gold (IOCG) deposits are widespread throughout the Carajás Province, Brazil, reflecting multiple Precambrian hydrothermal events. The Aquiri region is a relatively unexplored geological frontier in the northwestern Carajás Province. The AQW2 IOCG deposit is hosted by a Neoarchean mafic intrusive suite within [...] Read more.

Iron oxide–copper–gold (IOCG) deposits are widespread throughout the Carajás Province, Brazil, reflecting multiple Precambrian hydrothermal events. The Aquiri region is a relatively unexplored geological frontier in the northwestern Carajás Province. The AQW2 IOCG deposit is hosted by a Neoarchean mafic intrusive suite within metavolcano–sedimentary rocks. The pre-mineralization (Na and Na-K) and mineralization (Fe-Ca and Fe-P) hydrothermal stages appear as replacement fronts and as cement within ductile-deformed breccias. Late-mineralization (Fe-K, chlorite, and calcic-rich) assemblages occur in multidirectional veins controlled by brittle structures. Early- and main-mineralization apatite (Ap I-III) is enriched in F, Mn, and Sr, depleted in Y, shows unusually high Fe and Si (Ap III), and exhibits a pronounced positive Eu anomaly (Ap II). These characteristics indicate an alkaline fluid composition, substantial fluid–rock interaction, and episodic CO₂ degassing with the release of overpressured fluids, resulting in multiple brecciation events. A rapid decrease in temperature due to boiling is interpreted as a principal mechanism for copper precipitation. Late-mineralization apatite (Ap V–VI) is characterized by relatively higher Cl, Y, and LREE contents, lower Sr and Mn, and negative Eu-anomaly ratios, suggesting control by shallower paleostructures and more oxidizing conditions associated with the influx of basinal brines. These results highlight the evolution of the AQW2 deposit within a broader IOCG system and provide new insights into the metallogenic processes responsible for copper resources essential to the clean energy transition. Full article

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

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40 pages, 6177 KB

Open AccessEditor’s ChoiceReview

Extraction of Nickel and Cobalt from Complex Low-Grade Lateritic Ores: Challenges and Opportunities

by Gertrude Acquah, William Skinner, George Abaka-Wood, Pavel Spiridonov, Jonas Addai-Mensah and Richmond Asamoah

Minerals 2026, 16(3), 287; https://doi.org/10.3390/min16030287 - 9 Mar 2026

Cited by 2 | Viewed by 1875

Abstract

The accelerating transition to low carbon energy systems has intensified the demand for nickel and cobalt from low-grade (<1.5 wt.%) refractory lateritic ores. These low-grade laterites are however not amenable to conventional beneficiation due to their complex mineralogy, eclectic physicochemical properties, and fine [...] Read more.

The accelerating transition to low carbon energy systems has intensified the demand for nickel and cobalt from low-grade (<1.5 wt.%) refractory lateritic ores. These low-grade laterites are however not amenable to conventional beneficiation due to their complex mineralogy, eclectic physicochemical properties, and fine Ni–Co dissemination. This review examines recent advances made in the extraction of nickel and cobalt from complex low-grade lateritic ores, emphasizing the interplay between ore mineralogy, chemistry, beneficiation, pretreatment, and processing route selection. Developments in selective ore comminution–classification have led to the generation of Ni-rich fine fractions (undersize) and Co-rich coarse fractions (oversize), enabling differentiated extraction strategies that improve resource utilization, frugal energy use, and process efficiency. Mechanical activation via stirred media milling, thermal calcination-induced structural disorder, and dehydroxylate goethite products, are shown to significantly enhance Ni–Co leaching kinetics under both atmospheric and heap leaching conditions. A critical comparison of pyrometallurgical (rotary-kiln electric furnace) and hydrometallurgical (HPAL, EPAL, heap, atmospheric, bioleaching) routes demonstrates that ore-specific optimization is essential to balance recovery, acid consumption, and greenhouse gas emissions. The novel resin in moist mix (RIMM) process, which integrates ambient leaching and in situ ion exchange selective recovery, is shown to offer potential for sustainable values extraction from sub-economic resources. Furthermore, the review highlights the key innovation challenges and concomitant opportunities for enhanced critical battery metal recovery from complex laterite ores. Full article

(This article belongs to the Special Issue Advances in Precious and Critical Mineral Beneficiation and Extraction)

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24 pages, 8000 KB

Open AccessEditor’s ChoiceArticle

Petrogenesis of Epimetamorphic Rock from an Ion-Adsorption-Type REE Deposit in Ningdu County, Southern Jiangxi, China: Contraints from U–Pb Geochronology and the Geochemistry of Zircon and Apatite

by Wei Wan, Huihu Fan, Dehai Wu, Fuyong Qi, Zhenghui Chen, Shuilong Wang, Guangming Xu and Bimin Zhang

Minerals 2026, 16(3), 283; https://doi.org/10.3390/min16030283 - 9 Mar 2026

Viewed by 497

Abstract

In recent years, an ion-adsorption type REE deposit has been discovered for the first time in the weathering crust of epimetamorphic rocks in Ningdu County, Jiangxi Province, which provides a new idea for the exploration of ion-adsorption-type REE deposits. However, most previous studies [...] Read more.

In recent years, an ion-adsorption type REE deposit has been discovered for the first time in the weathering crust of epimetamorphic rocks in Ningdu County, Jiangxi Province, which provides a new idea for the exploration of ion-adsorption-type REE deposits. However, most previous studies on the ore-forming parent rocks of ion-adsorption-type REE deposits have focused on granites and volcanic rocks, while studies on epimetamorphic rocks remain extremely scarce. In this paper, petrographic analysis of epimetamorphic rocks, LA-ICP-MS U–Pb dating and trace element analysis of zircon and apatite were conducted on the metamorphic tuff from the Kuli Formation in Ningdu County, Jiangxi Province, so as to constrain the formation age and tectonic dynamic setting of the rock mass, investigate the petrogenesis and material source of the rock mass, and reveal the metallogenic potential of the rock mass. The results of zircon and apatite U–Pb dating show that the protolith of the metamorphic tuff from the Kuli Formation formed at ca. 770 Ma, representing a product of mid-Neoproterozoic magmatic activity. The protolith restoration of metamorphic rocks suggests that the protolith of the metamorphic tuff from the Kuli Formation is magmatic rock. The estimated results of zircon Ti thermometry indicate that the magmatic crystallization temperature ranges from 623 to 723 °C, with an average value of approximately 696 °C, and the calculated zircon oxygen fugacity values vary from −18.7 to −9.4, with an average of −13.8, implying that the rock formed under conditions of relatively low temperature and high oxygen fugacity. The correlation diagrams of trace elements and element ratios in zircon and apatite reveal that the magmatic evolution involved extensive fractional crystallization of minerals such as zircon, monazite, apatite, titanite, rutile, and plagioclase during the formation of the rock mass. The discrimination diagrams of trace elements in zircon and apatite demonstrate that the metamorphic tuff from the Kuli Formation was formed in a continental margin arc or arc-related orogenic belt, and the magmatic source is characterized by crust–mantle mixing. Combined with previous research findings on regional tectonic-magmatic activities, it can be concluded that the metamorphic tuff from the Kuli Formation was formed in a tectonic setting of back-arc extension and intra-arc rifting caused by the rollback of the subducting oceanic slab. The upwelling of the asthenospheric mantle induced the partial melting of arc-derived sediments in the continental crust, which was subsequently mixed with mantle-derived magma, ultimately generating the parent magma of the metamorphic tuff. The metamorphic tuff from the Kuli Formation in Ningdu County, Jiangxi Province, has high REE abundance and relatively easily weathered REE mineral assemblages, which can provide sufficient material sources for ion-adsorption REE mineralization and have a great metallogenic potential for ion-adsorption REE deposits. Full article

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

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22 pages, 4073 KB

Open AccessEditor’s ChoiceArticle

A Comparative Study of Machine Learning and Traditional Techniques for Grade Prediction and Grade-Tonnage Evaluation in a Small VMS Deposit

by Cemile Dilara Bağ, Ben M. Frieman and Erik Westman

Minerals 2026, 16(3), 280; https://doi.org/10.3390/min16030280 - 7 Mar 2026

Viewed by 973

Abstract

Estimating grades in small-volume, high-grade volcanogenic massive sulfide (VMS) deposits can be difficult due to sharp changes in mineralization and limited data coverage around high-grade zones. This study compares ensemble machine learning models with interpolation and geostatistical methods to compare gold estimation and [...] Read more.

Estimating grades in small-volume, high-grade volcanogenic massive sulfide (VMS) deposits can be difficult due to sharp changes in mineralization and limited data coverage around high-grade zones. This study compares ensemble machine learning models with interpolation and geostatistical methods to compare gold estimation and grade-tonnage results. Random Forest and Gradient Boosting were trained using drillhole composites and evaluated against Inverse Distance Weighting (IDW), Simple Kriging (SK), and Ordinary Kriging (OK). The trained models were applied across the block model to generate continuous grade predictions and support grade-tonnage calculations at multiple cutoff grades. The ensemble models showed lower RMSE and higher R² values and captured grade patterns more efficiently than traditional methods. Grade-tonnage comparison indicated that IDW generated the highest contained gold equivalent at low cutoff grades, while OK and Gradient Boosting produced more consistent and geologically reasonable estimates. Overall, the results show that machine learning methods can complement traditional estimation techniques when combined with geological domain control and appropriate model tuning. Full article

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

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22 pages, 3149 KB

Open AccessEditor’s ChoiceArticle

Hydro-Mechanical Modelling of Anisotropic Deformation and Failure Behaviour of Opalinus Clay Under Saturated and Unsaturated Conditions

by Eike Radeisen, Hua Shao, Jürgen Hesser and Wenqing Wang

Minerals 2026, 16(3), 279; https://doi.org/10.3390/min16030279 - 6 Mar 2026

Viewed by 749

Abstract

Opalinus Clay (OPA) is a key host rock for the geological disposal of high-level radioactive waste in Switzerland and is also under investigation in Germany. Reliable prediction of the long-term performance of deep geological repositories requires constitutive models capable of capturing the coupled [...] Read more.

Opalinus Clay (OPA) is a key host rock for the geological disposal of high-level radioactive waste in Switzerland and is also under investigation in Germany. Reliable prediction of the long-term performance of deep geological repositories requires constitutive models capable of capturing the coupled hydro-mechanical (HM) behaviour of the host rock, including mechanical anisotropy, strain-dependent stiffness, suction effects, and stress-dependent failure. This study presents a hydro-mechanically coupled constitutive model incorporating anisotropic yield behaviour, hardening/softening, and strain-dependent permeability. The model is calibrated against laboratory triaxial, Brazilian tensile strength (BTS), and uniaxial compressive strength (UCS) tests on OPA, with bedding orientations between 0° and 90°. Implemented in OpenGeoSys (OGS), the model represents bedding-controlled plastic anisotropy using a microstructure tensor approach. The simulations reproduce key experimental trends relevant to repository-induced perturbations, including bedding-dependent strength and stiffness, suction effects on UCS, and the orientation-dependent tensile strength observed in Brazilian tests. Remaining discrepancies under high confining stress indicate the need for improved regularization and dilatancy formulations. Overall, the proposed framework provides a robust building block for HM process modelling and long-term safety assessments of deep geological repositories. Full article

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

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18 pages, 28855 KB

Open AccessEditor’s ChoiceArticle

Mantle Heterogeneity at the Arc–Back-Arc Transition: Insights from Peridotites of the Southern Mariana Trench

by Kana Miyata, Katsuyoshi Michibayashi, Shigeki Uehara and Yasuhiko Ohara

Minerals 2026, 16(3), 274; https://doi.org/10.3390/min16030274 - 3 Mar 2026

Viewed by 1086

Abstract

Peridotites exposed in the southern Mariana Trench provide a rare opportunity to investigate mantle processes operating at the interface between arc and back-arc tectonic domains. This study presents petrographic observations and major element mineral chemistry of 41 depleted mantle harzburgites collected from three [...] Read more.

Peridotites exposed in the southern Mariana Trench provide a rare opportunity to investigate mantle processes operating at the interface between arc and back-arc tectonic domains. This study presents petrographic observations and major element mineral chemistry of 41 depleted mantle harzburgites collected from three sites (Sites A–C) in the southern Mariana Trench. Site A is located on the east-facing slope of the West Santa Rosa Bank Fault, whereas Sites B and C are situated on the southern slope of the South Mariana Forearc Ridge along the eastern side of the Challenger Deep. The harzburgites exhibit variable microstructures ranging from coarse-grained (>1 mm) to medium-grained (<1 mm) to small-grained (>0.1 mm) textures, with or without porphyroclasts, and commonly contain amphibole associated with orthopyroxene and spinel. Olivine Mg# (Mg/[Mg + Fe]) (0.902–0.925) and spinel Cr# (Cr/[Cr + Al]) (0.304–0.720) indicate a wide range of mantle depletion across the three sites. Based on the integrated chemical characteristics of olivine, spinel, and amphibole, the harzburgites are classified into three distinct compositional trends (Trends 1–3). Trend 1 is characterized by high olivine Mg# (~0.925), high spinel Cr# (>0.6), low TiO₂ contents (<0.1 wt%), and K₂O-enriched but TiO₂-poor amphibole (TiO₂/K₂O < ~0.5), consistent with strongly depleted forearc mantle modified by slab-derived hydrous melts or fluids. In contrast, Trend 2 is defined by relatively high olivine Mg# (>~0.91), lower spinel Cr# (<0.6), slightly higher TiO₂ contents (up to ~0.2 wt%), and amphibole moderately enriched in both K₂O and TiO₂ (TiO₂/K₂O = 1–4), recording an intermediate geochemical signature that cannot be uniquely attributed to a purely forearc origin. Trend 3 is characterized by lower olivine Mg# (~0.90), lower spinel Cr# (<0.6), distinctly higher TiO₂ contents (up to ~0.8 wt%), and TiO₂-rich but K₂O-poor amphibole (TiO₂/K₂O > 4), indicating a back-arc mantle origin related to decompression melting. Trends 1 and 2 occur in harzburgites from Sites B and C of the South Mariana Forearc Ridge, whereas Trend 3 is exclusively identified in harzburgites from Site A of the West Santa Rosa Bank Fault, highlighting the juxtaposition of forearc-type, transitional, and back-arc-type mantle domains within a single forearc region. Full article

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

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20 pages, 9486 KB

Open AccessEditor’s ChoiceReview

A Review of Micro-Nanobubbles Applications in Fine-Grained Mineral Flotation

by Hefu Li, Youfeng Lu, Hui Li and Wei Xiao

Minerals 2026, 16(3), 271; https://doi.org/10.3390/min16030271 - 28 Feb 2026

Cited by 1 | Viewed by 889

Abstract

Micro-nanobubbles have emerged as a transformative technology in mineral flotation, offering superior performance in the recovery of fine-grained minerals. Conventional flotation processes often struggle with low recovery rates due to inefficient particle–bubble interactions and the formation of slimes, which increase pulp viscosity and [...] Read more.

Micro-nanobubbles have emerged as a transformative technology in mineral flotation, offering superior performance in the recovery of fine-grained minerals. Conventional flotation processes often struggle with low recovery rates due to inefficient particle–bubble interactions and the formation of slimes, which increase pulp viscosity and reduce selectivity. Micro-nanobubbles, characterized by their smaller size, larger specific surface area, and high stability, overcome these limitations by enhancing collision efficiency, promoting particle aggregation through the “bubble bridge” effect, and improving flotation recovery rates and concentrate quality. This review systematically examines the generation mechanisms of micro-nanobubbles, critically appraises their laboratory and industrial applications through specific case studies, and elucidates their fundamental roles in enhancing fine-grained mineral recovery by increasing collision-attachment efficiency and promoting hydrophobic aggregation. Additionally, the study highlights real-world application cases and discusses future directions for optimizing micro-nanobubbles flotation technology through equipment improvements, process integration, and synergies with emerging techniques. The findings underscore the potential of micro-nanobubbles to revolutionize mineral processing by increasing recovery efficiency, reducing reagent usage, and enhancing sustainability. Full article

(This article belongs to the Special Issue Advances in Fine Particles and Bubbles Flotation, 2nd Edition)

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29 pages, 21139 KB

Open AccessEditor’s ChoiceArticle

Composition of Chlorite as a Proxy for Fluid Evolution and Gold Precipitation Mechanisms in the Jinshan Gold Deposit, Dexing District, South China

by Danli Wang, Tao Zhang, Minjuan Zhou, Shaohao Zou, Xilian Chen, Deru Xu, Yongwen Zhang and Cui Yang

Minerals 2026, 16(3), 269; https://doi.org/10.3390/min16030269 - 28 Feb 2026

Viewed by 547

Abstract

The physicochemical controls on gold precipitation in orogenic gold deposits remain poorly constrained, with traditional fluid inclusion and isotopic studies often yielding ambiguous results due to overprinting or incomplete records. This study addresses this challenge using chlorite—a sensitive mineral proxy for fluid conditions—as [...] Read more.

The physicochemical controls on gold precipitation in orogenic gold deposits remain poorly constrained, with traditional fluid inclusion and isotopic studies often yielding ambiguous results due to overprinting or incomplete records. This study addresses this challenge using chlorite—a sensitive mineral proxy for fluid conditions—as a quantitative sensor in the Jinshan orogenic gold deposit (>200 t Au) of the Jiangnan orogenic belt, South China. Hosted in Neoproterozoic phyllite within NE–NNE-trending ductile–brittle shear zones, Jinshan features auriferous quartz–polymetallic sulfide veins with prominent chlorite alteration. Integrating high-resolution SEM-EPMA analyses of multi-generational chlorite with thermodynamic modeling, we reconstruct the temporal evolution of temperature, oxygen fugacity (fO₂), pH and sulfur fugacity (fS₂) during ore formation. Four paragenetic stages are identified: Stage 1 (ankerite–quartz), Stage 2 (pyrite–arsenopyrite–quartz), Stage 3 (quartz–gold–polymetallic sulfide), and Stage 4 (chlorite–carbonate–quartz). Electron microprobe analysis reveals that the chlorite composition changes from Fe-rich chamosite (Stage 2) to Mg-rich clinochlore (Stage 3) and then to Fe-rich chamosite (Stage 4). Chlorite from Stage 2 (Chl-1) formed metasomatically at low fluid/rock ratios, while Stage 3 and 4 chlorites (Chl-2 and Chl-3) precipitated directly from higher fluid/rock ratio fluids. Chlorite compositions record a critical Stage 2–3 transition involving cooling from ~320 °C to ~260 °C, reduction (log fO₂ from −33.6 to −39.7), and alkalinization, and sulfur fugacity remained stable within a narrow range (log fS₂ = −13.6 to −8.0), followed in Stage 4 by minor reheating to ~280 °C, re-acidification, and a slight rebound in oxygen fugacity. Thermodynamic simulations reveal that the destabilization of Au(HS)₂⁻ complexes, primarily driven by the synergistic effects of cooling, pH increase, and decreasing oxygen fugacity, triggered gold precipitation during the main ore stage. Results demonstrate that abrupt cooling coupled with fluid alkalinization and reduction exerted the dominant control on gold precipitation in Jinshan, resolving long-standing debates on ore-forming mechanisms and highlighting chlorite as a robust quantitative sensor for fluid evolution. Full article

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

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39 pages, 31758 KB

Open AccessEditor’s ChoiceReview

Tectonics and Metallogeny of the Neoproterozoic Paraguay Belt Gold Province, Western Brazil

by Pedro Maciel de Paula Garcia, Weslley Guimarães Silva, Willian Valentin Coqueiro Sanches, Mauro César Geraldes, Cláudia do Couto Tokashiki and Victor Gabriel Moreira de Arruda

Minerals 2026, 16(3), 246; https://doi.org/10.3390/min16030246 - 27 Feb 2026

Viewed by 1731

Abstract

The Neoproterozoic Paraguay Belt (western Brazil), formed by the Brasiliano/Pan-African Orogenic Cycle during Western Gondwana amalgamation, hosts tens of gold occurrences and deposits. This review provides new insights into the metallogeny and tectonics of the Paraguay Belt Gold Province, based on previous and [...] Read more.

The Neoproterozoic Paraguay Belt (western Brazil), formed by the Brasiliano/Pan-African Orogenic Cycle during Western Gondwana amalgamation, hosts tens of gold occurrences and deposits. This review provides new insights into the metallogeny and tectonics of the Paraguay Belt Gold Province, based on previous and new data on stratigraphy, structural geology, metamorphism, hydrothermal alteration, and gold grades. The mineralizations correspond to turbidite-hosted orogenic gold systems, with quartz veins cutting metasedimentary rocks with minor metavolcanics. A six-phase tectonic–metallogenic evolution model is proposed. The early stages correspond to glaciolacustrine deposition in a rift that evolved into a passive margin and then into a foreland basin, with glaciomarine sediments. Late sedimentation corresponds to glacial-to-post-glacial shallow marine units in the foreland. The orogeny progressed with cratonic collisions, resulting in three deformation (two compressional and one extensional) and three metamorphic (regional, dynamic, and contact) phases. The Au mineralization results from metamorphic fluids that transported metals from the metasedimentary pile and deposited them in reactive rocks (rich in magnetite or organic carbon). Gold occurs in sulfide-rich (pyrite and galena) veins and hydrothermal alteration zones. The metallotects and structural controls highlighted here are useful tools for prospecting gold in the Paraguay Belt and similar geological terranes. Full article

(This article belongs to the Special Issue Geochronology, Mineralogy, and Genesis of Orogenic Gold Deposit: Implications for Gold Prospecting)

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15 pages, 14742 KB

Open AccessEditor’s ChoiceArticle

Stepwise Separation and Extraction of Aluminum, Iron and Titanium from Bayer Red Mud in Guangxi, China

by Yin Zhang, Weijian Zhou, Xiaohu Xiong, Yue Sun, Meixia Wang, Shentao Hu, Xuan Li and Qinyu Zhao

Minerals 2026, 16(3), 251; https://doi.org/10.3390/min16030251 - 27 Feb 2026

Viewed by 598

Abstract

Red mud, a strongly alkaline solid waste generated during alumina production, contains valuable metals including aluminum, iron, titanium, and others. Efficient extraction of these metals is of great significance for promoting circular economy development and regional ecological conservation. This paper proposes a stepwise [...] Read more.

Red mud, a strongly alkaline solid waste generated during alumina production, contains valuable metals including aluminum, iron, titanium, and others. Efficient extraction of these metals is of great significance for promoting circular economy development and regional ecological conservation. This paper proposes a stepwise extraction process involving alkali roasting-water leaching to separate Al from Fe and Ti, hydrochloric acid leaching to separate Fe from Ti, and sulfuric acid leaching to extract Ti. Bayer red mud from Guangxi, China was used as the raw material, and the effects of process parameters on the stepwise leaching of Al, Fe, and Ti were systematically investigated. The overall leaching results indicated that the total leaching rates of Al, Fe, and Ti were 99.61%, 99.02%, and 92.75%, respectively. Through comparative analysis of the chemical composition, phase composition, and micromorphology of the raw red mud, roasted clinker, and leaching residues, the stepwise leaching mechanisms of Al, Fe, and Ti were elucidated. Furthermore, the second-stage acid leachate was hydrolyzed, and the H₂TiO₃ content in the obtained hydrolyzate reached 89.43%, approximately 12 times that of the titanium component in the raw red mud. The Ti hydrolysis recovery rate was 90.41%, and the total Ti recovery rate was 78.65%. Overall, the process enables stepwise extraction of Al, Fe, and Ti, along with the enrichment and recovery of titanium resources, providing an effective reference route for the technical chain of resource utilization of valuable components in red mud. Full article

(This article belongs to the Collection Mining/Metallurgical Solid Waste Treatment and Resource Utilization: Towards a Circular Economy)

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18 pages, 1778 KB

Open AccessEditor’s ChoiceArticle

Adsorption of Quercetin on Mesoporous Silica Modified with Cationic Surfactants

by Eleonora Sočo, Andżelika Domoń and Dorota Papciak

Minerals 2026, 16(3), 230; https://doi.org/10.3390/min16030230 - 25 Feb 2026

Cited by 1 | Viewed by 602

Abstract

Ordered mesoporous silica (OMS) is widely investigated as a mineral carrier for bioactive compounds; however, the adsorption of poorly soluble flavonoids such as quercetin on unmodified silica remains limited, and the effect of cationic surfactant modification on adsorption performance is still insufficiently understood. [...] Read more.

Ordered mesoporous silica (OMS) is widely investigated as a mineral carrier for bioactive compounds; however, the adsorption of poorly soluble flavonoids such as quercetin on unmodified silica remains limited, and the effect of cationic surfactant modification on adsorption performance is still insufficiently understood. This study evaluates the adsorption of quercetin on OMS modified with tetrabutylammonium bromide (TBA-Br) and hexadecyltrimethylammonium bromide (HDTMA-Br). Batch adsorption experiments were analyzed using various adsorption isotherm models, and the quality of fit was evaluated based on the coefficient of determination (R²) and the reduced chi-square statistic (χ²/DoF). The results indicated that quercetin adsorption followed a physisorption mechanism, predominantly governed by hydrophobic interactions and surface heterogeneity. Silica modified with HDTMA-Br exhibited a significantly higher maximum sorption capacity compared to OMS-TBA-Br, reaching g_max values of up to 5.2 mg·g⁻¹, whereas the maximum adsorption for OMS-TBA-Br did not exceed 4.2 mg·g⁻¹. The best fit of the experimental data was obtained for models accounting for the heterogeneous nature of the adsorbent surface, particularly the Tóth model. The obtained results clearly demonstrate that modification of OMS with a cationic surfactant possessing a long alkyl chain significantly enhances the adsorption capacity of silica toward quercetin, which is of considerable importance for the design of mineral carriers for bioactive compounds. Full article

(This article belongs to the Special Issue Application of Biomodified Mineral Amendments in Industrial, Environmental and Agricultural Engineering)

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17 pages, 4363 KB

Open AccessEditor’s ChoiceArticle

Water Weakening Effects on Dislocation Creep of Polycrystalline Diopside Aggregates

by Zhexuan Jiang, Xiaoning Wang, Xiaodong Zheng, Jianfeng Li and Maoshuang Song

Minerals 2026, 16(3), 232; https://doi.org/10.3390/min16030232 - 25 Feb 2026

Viewed by 359

Abstract

To understand the dislocation creep behavior of water-saturated clinopyroxene in the upper mantle, we conducted high-temperature triaxial compression experiments on hot-pressed diopside aggregates under water-saturated conditions at confining pressures of ~300 MPa and temperatures of 1373–1473 K using a Paterson gas-medium apparatus. Fourier [...] Read more.

To understand the dislocation creep behavior of water-saturated clinopyroxene in the upper mantle, we conducted high-temperature triaxial compression experiments on hot-pressed diopside aggregates under water-saturated conditions at confining pressures of ~300 MPa and temperatures of 1373–1473 K using a Paterson gas-medium apparatus. Fourier transform infrared measurements of the water contents revealed that all experiments were performed under water-saturated conditions. Fitting the mechanical data with a power flow law yielded a stress exponent n of 2.2 ± 0.6, an activation energy Q of 442 ± 33 kJ/mol, and a material-dependent parameter A of 10^6.9±0.5 MPa^−2.2 s⁻¹. For comparison, a single deformation experiment was performed under anhydrous conditions at a temperature of 1473K. The mechanical results show that the water-saturated diopside aggregates deform approximately 1.5–3 orders of magnitude faster than their anhydrous counterpart, indicating a pronounced water-weakening effect. Furthermore, under water-saturated conditions, our mantle-derived diopside aggregates have comparable strengths to that of Fe-rich Sleaford Bay clinopyroxene at 1473 K and laboratory strain rates but significantly weaker than that of olivine aggregates. The results in this study provide key experimental constraints on the flow behavior of mantle-derived clinopyroxene aggregates under water-saturated conditions. Full article

(This article belongs to the Special Issue Rock and Mineral Behavior Under High Temperature and High Pressure: From Microphysics to Macroscopic Properties)

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21 pages, 1810 KB

Open AccessEditor’s ChoicePerspective

A Mechanistic Framework Linking Climate Forcing, Microbial Transformation, and Sedimentary Carbon Sinks in Deep-Time Oceans

by Jingxuan Zhang, Xi Zhang, Tingshan Zhang and Hao Huang

Minerals 2026, 16(2), 221; https://doi.org/10.3390/min16020221 - 22 Feb 2026

Viewed by 627

Abstract

The ocean constitutes the largest actively exchangeable carbon reservoir in Earth’s surface system, with the ocean–atmosphere system functioning as an integrated entity that modulates atmospheric CO₂ concentrations over geological timescales. While carbonate and organic-rich sedimentary carbon sinks have been the subject of [...] Read more.

The ocean constitutes the largest actively exchangeable carbon reservoir in Earth’s surface system, with the ocean–atmosphere system functioning as an integrated entity that modulates atmospheric CO₂ concentrations over geological timescales. While carbonate and organic-rich sedimentary carbon sinks have been the subject of extensive research, their synergistic roles in long-term carbon–climate feedback loops, as well as the degree to which microbial mediation links ocean hydrographic states to basin-scale carbon sequestration efficiency, remain poorly synthesized. Here, we develop a mechanistic framework comprising five intercoupled components: (1) driving factors (tectonic–climatic forcing and anthropogenic analogs); (2) ocean state controls (basin restriction, water column stratification, and redox conditions); (3) microbial processes (microbial carbon pump-mediated transformation of dissolved organic carbon and the modulating influence of microbial carbonate formation); (4) sedimentary carbon sinks (carbonate platforms versus organic-rich shales underpinning organo-mineral stabilization); and (5) Earth system feedback expressions (e.g., carbon isotope excursions and sustained perturbations in atmospheric CO₂ levels). This framework is validated across three contrasting sedimentary basins, including the Western Tethys rift basins, the Cambrian South China platform system, and the Toarcian Lower Saxony restricted basin, and via three falsifiable propositions. Converging evidence from these case studies corroborates three key conclusions: (1) basin restriction and diminished water mass renewal foster water column stratification and hypoxic/anoxic conditions, thereby enhancing organic carbon preservation (P1); (2) the tectonic and depositional setting of a basin modulates the relative predominance of carbonate and organic carbon sinks (P2); and (3) post-extinction anachronistic facies record amplified microbial control over carbon burial pathways (P3). By emphasizing the context dependence of carbon sequestration processes and the significance of organo-mineral stabilization alongside particulate organic carbon export, this synthesis provides a transferable analytical framework for interpreting deep-time carbon cycle transitions and for contextualizing the impacts of modern ocean warming and deoxygenation on natural carbon sinks. Full article

(This article belongs to the Special Issue Element Enrichment and Gas Accumulation in Black Rock Series)

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30 pages, 7636 KB

Open AccessEditor’s ChoiceArticle

Advanced Resource Modelling and Agile Scenario Generation for Mineral Exploration at the Cu-Au (Mo-Ag) San Antonio–Potrerillos District, Chile

by Julian M. Ortiz, Sebastián Avalos, Paula Larrondo, Ximena Prieto, Nicolás Avalos, Bernabé Lopez, Javier Santibañez, Mónica Vukasovic, Nelson Cortés and Jaime Díaz

Minerals 2026, 16(2), 202; https://doi.org/10.3390/min16020202 - 14 Feb 2026

Viewed by 1281

Abstract

Agile and flexible resource modelling is essential for informed decision-making in early-stage mineral project assessment, and in more advanced stages, particularly when compared with conventional deterministic geological modelling and single-estimate resource evaluations. This study presents a case of rapid scenario generation to view, [...] Read more.

Agile and flexible resource modelling is essential for informed decision-making in early-stage mineral project assessment, and in more advanced stages, particularly when compared with conventional deterministic geological modelling and single-estimate resource evaluations. This study presents a case of rapid scenario generation to view, interpret and test the impact of alternative geological and modelling assumptions, including the definition of geological domains, geological interpretation, grade estimation within domains, and the associated uncertainty. The workflows are implemented in Annapurna™ Resource, a cloud-native geostatistical platform designed to support agile, advanced, and multivariate modelling workflows. Focusing on the multi-commodity San Antonio–Potrerillos district, we demonstrate how rapid model construction enables the systematic evaluation of geological and statistical assumptions, contrasting deterministic estimates with probabilistic outcomes and testing their impact on estimated grades and tonnage under multiple scenarios for five elements: copper (Cu), molybdenum (Mo), gold (Au), silver (Ag), and arsenic (As). The approach provides quantitative measures of model reliability, identifies areas of high uncertainty, and supports the prioritization of new drilling to improve geological knowledge, exploration targeting, and resource classification. This case study highlights the value of fast-turnaround, probabilistic modelling not as a replacement for traditional resource reporting, but as a decision-support framework that enhances understanding of the geology, tests the sensitivity of assumptions, and accelerates learning throughout exploration and into operations. The main results suggest that additional drilling can be strategically placed to reduce the geological uncertainty derived from comparing the current interpretation with the probabilistic model built with indicator kriging. Furthermore, this has relevance in reducing the risk in the assessment of the metal content in each area of the deposit. Sensitivity analysis performed over key parameters of the estimation suggests that outliers’ treatment is the most impactful step during estimation. With current technological tools, it is possible to maintain a live resource model, which can be continuously updated to assess the impact of new data and decisions in near real time. Full article

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

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15 pages, 7462 KB

Open AccessEditor’s ChoiceArticle

Shagamite, KFe₁₁O₁₇, a New Mineral with β-Alumina Structure from the Hatrurim Basin, Negev Desert, Israel

by Evgeny V. Galuskin, Hannes Krüger, Irina O. Galuskina, Biljana Krüger, Krzysztof Nejbert and Yevgeny Vapnik

Minerals 2026, 16(2), 180; https://doi.org/10.3390/min16020180 - 6 Feb 2026

Viewed by 643

Abstract

Shagamite, KFe₁₁O₁₇ (IMA 2020-091) was discovered in the ferrite zone of gehlenite hornfels from the Hatrurim Complex exposed near Mt. Ye’elim, Hatrurim Basin, Israel. The mineral occurs in outer zones of gehlenite rock blocks that were heterogeneously altered by high-temperature [...] Read more.

Shagamite, KFe₁₁O₁₇ (IMA 2020-091) was discovered in the ferrite zone of gehlenite hornfels from the Hatrurim Complex exposed near Mt. Ye’elim, Hatrurim Basin, Israel. The mineral occurs in outer zones of gehlenite rock blocks that were heterogeneously altered by high-temperature (>1200 °C) ferritization. Ferritization was induced by K-bearing fluids or melts, generated as a by-product of late combustion processes. Shagamite crystallized from a thin melt that formed on the rock surface during cooling to approximately 800–900 °C. It is mainly associated with minerals of the magnetoplumbite group like barioferrite, Sr-analog of barioferrite, and gorerite but also with magnetite, maghemite, harmunite, devilliersite and K(Sr,Ca)Fe₂₃O₃₆ hexaferrite. Shagamite is a modular compound with a β-alumina-type structure (P6₃/mmc, a = 5.9327 (5), c = 23.782 (3) Å, γ = 120°, V = 724.91 (13) Å³, Z = 2), and it is isostructural with diaoyudaoite, NaAl₁₁O₁₇, and kahlenbergite, KAl₁₁O₁₇. Its structure is also closely related, though non-isotypic, to those of the magnetoplumbite-group minerals. Shagamite is dark brown with a semi-metallic luster and forms platy crystals flattened on (001). Its mean empirical formula is: (K_1.00Ca_0.15Mn²⁺_0.05Na_0.04Rb_0.01)_Σ1.25(Fe_10.36Mn²⁺_0.15Al_0.14Mg_0.12Zn_0.10Ni_0.07Cu_0.03Cr³⁺_0.02Ti⁴⁺_0.01)_Σ11.00O₁₇. The Vickers microhardness VHN₂₅ = 507 kg/mm² corresponds to a Mohs hardness of ~5. The calculated density, based on the empirical formula and unit-cell parameters, is 4.12 g·cm⁻³. The main bands in the Raman spectrum of shagamite occur at 685 and 715 cm⁻¹ and are assigned to ν₁(FeO₄)⁵⁻ tetrahedral vibrations. Full article

(This article belongs to the Collection New Minerals)

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28 pages, 6252 KB

Open AccessEditor’s ChoiceReview

Engineering Zeolite Acidity and Porosity for Improved Esterification: A Review of Mechanisms, Kinetics, and Sustainability Processes

by Jelena Pavlović and Nevenka Rajić

Minerals 2026, 16(2), 179; https://doi.org/10.3390/min16020179 - 6 Feb 2026

Cited by 2 | Viewed by 1193

Abstract

Esterification, the reaction between carboxylic acids and alcohols that produces esters and water, plays a vital role in many industries, especially in biodiesel and pharmaceutical manufacturing. Traditional methods using homogeneous mineral acids pose environmental issues, prompting the search for sustainable alternatives—solid acid catalysts. [...] Read more.

Esterification, the reaction between carboxylic acids and alcohols that produces esters and water, plays a vital role in many industries, especially in biodiesel and pharmaceutical manufacturing. Traditional methods using homogeneous mineral acids pose environmental issues, prompting the search for sustainable alternatives—solid acid catalysts. Zeolites offer unique structural advantages, including shape selectivity and adjustable acidity, which improve reaction efficiency and reduce waste. This review provides a detailed examination of how zeolite topology—particularly pore structure and connectivity—influences the kinetics of long-chain fatty acid (LCFA) esterification. It investigates the optimization of acid sites via modifications to the silicon-to-aluminum ratio (Si/Al), ion exchange, and pore engineering to improve mass transfer. The study investigates key reaction mechanisms, specifically the Langmuir–Hinshelwood (LH) and Eley–Rideal (ER) models, to address issues such as mass-transfer limitations and water inhibition. The paper highlights recent advances in sustainable catalyst design, such as hierarchical zeolites and membrane-integrated reactors, for converting biomass-derived feedstocks into valuable esters. It also discusses current research challenges and suggests future directions, including the use of 3D-printed monoliths and machine learning integration, to develop next-generation, eco-friendly zeolite catalysts. Full article

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

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20 pages, 5882 KB

Open AccessEditor’s ChoiceArticle

Determination of the Jiufeng–Gandong Ductile Shear Zone in Northern Guangxi and Its Geological Significance

by Yuming Bai, Rongguo Hu, Zuohai Feng, Ya Qin, Chenglong Zhang, Saisai Li, Shehong Li and Jie Wu

Minerals 2026, 16(2), 169; https://doi.org/10.3390/min16020169 - 2 Feb 2026

Viewed by 444

Abstract

The ductile shear zones in northern Guangxi provide a crucial window for understanding Paleozoic collisional deformation and the tectonic evolution of the South China Block. The Jiufeng–Gandong ductile shear zone is located in the western part of the Motianling pluton in northern Guangxi. [...] Read more.

The ductile shear zones in northern Guangxi provide a crucial window for understanding Paleozoic collisional deformation and the tectonic evolution of the South China Block. The Jiufeng–Gandong ductile shear zone is located in the western part of the Motianling pluton in northern Guangxi. The penetrative mylonitic foliation within the ductile zone dips toward the ESE at angles of 55°–85°. Kinematic analyses indicate that the Jiufeng–Gandong ductile shear zone experienced sinistral thrust shearing. Anisotropy of magnetic susceptibility (AMS) results show that the shear zone generally strikes in an NNE direction, with a length exceeding 30 km and a maximum width of more than 2.5 km. The flattening degree (E value) of the magnetic susceptibility ellipsoid suggests that deformation within the shear zone is dominated by flattening strain, accompanied by a component of extensional strain. Quartz dynamic recrystallization mechanisms and electron backscatter diffraction (EBSD) analyses indicate that the sinistral thrust shearing occurred at deformation temperatures of approximately 350–650 °C. LA–ICP–MS U–Pb dating of zircons from a mafic mylonite yields a crystallization age of 443.0 ± 2.8 Ma. By integrating macro- and microstructural observations, magnetic fabric data, quartz EBSD fabric analyses, regional published geochronological constraints, and hydrothermal zircon U–Pb ages obtained in this study, we propose that the Jiufeng–Gandong ductile shear zone developed during Caledonian thrusting of the Cathaysia Block onto the Yangtze Block from SE to NW. Under collisional compression, the shear zone underwent medium- to high-temperature sinistral thrust shearing accompanied by dominant flattening strain. These results elucidate the geometry, strain characteristics, and tectonic regime of the Jiufeng–Gandong ductile shear zone, providing new insights into the Caledonian tectonic evolution of South China. Full article

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

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26 pages, 9911 KB

Open AccessEditor’s ChoiceArticle

Origins, Distribution, and Migration of Alkali Metals in High-Sodium Naomaohu Coal During Fixed-Bed Gasification

by Yaofeng Hu, Xin Guo, Yuegang Tang and Haonan Zhang

Minerals 2026, 16(2), 161; https://doi.org/10.3390/min16020161 - 30 Jan 2026

Viewed by 672

Abstract

Naomaohu coal from the Santanghu Basin, Xinjiang, is characterized by anomalously high Na and Ca contents, which strongly affect its gasification behavior and slagging tendency. However, the genetic linkage between geological alkali enrichment and their transformation during thermal processes remains insufficiently constrained. In [...] Read more.

Naomaohu coal from the Santanghu Basin, Xinjiang, is characterized by anomalously high Na and Ca contents, which strongly affect its gasification behavior and slagging tendency. However, the genetic linkage between geological alkali enrichment and their transformation during thermal processes remains insufficiently constrained. In this study, an integrated investigation combining coal seam profile analysis, coal petrography, mineralogical characterization, and fixed-bed gasification experiments was conducted to elucidate the enrichment mechanisms and transformation pathways of alkali and alkaline earth metals (AAEMs). A total of forty six samples were collected along a vertical seam profile to determine the depositional control of alkali and alkaline earth metals (AAEMs), and seven representative samples were further subjected to pressurized fixed-bed gasification. Alkali migration and mineral phase evolution were systematically analyzed using XRD, XRF, and SEM-EDS. The results indicate that Na enrichment is mainly controlled by groundwater infiltration and weak paleoweathering, while Ca accumulation reflects deposition in humid, Ca-rich mire environments. During gasification, Na volatilizes and recondenses as Na-feldspars (NaAlSi₂O₆) and NaCl, whereas Ca decomposes into gehlenite (Ca₂Al₂SiO₇) and brownmillerite (Ca₂AlFeO₅). The formation of these low-melting Na–Al–Si phases and Ca–Fe–Al phases dominate the ash fusion and slagging behavior. This study establishes a coupled geological–thermal transformation model for AAEMs in high-Na coal, providing mechanistic insight into mineralogical inheritance and offering guidance for mitigating alkali-induced slagging during gasification. Full article

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

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32 pages, 3597 KB

Open AccessEditor’s ChoiceReview

Advances in Magnetic and Electromagnetic Technique Interpretation

by Marc A. Vallée, Mouhamed Moussaoui and Khorram Khan

Minerals 2026, 16(2), 159; https://doi.org/10.3390/min16020159 - 30 Jan 2026

Viewed by 1564

Abstract

Magnetic and electromagnetic techniques have been applied successfully to mineral exploration discovery. Both techniques rely on inferring the distribution of subsurface physical properties based on ground, airborne or borehole field measurements. Consequently, interpretation methods relating field measurements to underground physical properties are key [...] Read more.

Magnetic and electromagnetic techniques have been applied successfully to mineral exploration discovery. Both techniques rely on inferring the distribution of subsurface physical properties based on ground, airborne or borehole field measurements. Consequently, interpretation methods relating field measurements to underground physical properties are key to geophysical method success. Over the last 15 years, with the evolution of computer processing techniques, interpretation methods have matured and have seen numerous developments, from approximate interpretation to 3D inversion. The recent study of the scientific literature on magnetic and electromagnetic interpretation followed by an analysis of the distribution of the publication of these studies publication (and the citation numbers quoted) outline the research on these topics. The majority of studies are on electromagnetism, with an emphasis on numerical modeling, approximations, superparamagnetism, and induced polarization. In magnetics, the most popular studies were on remanence magnetization inversion and Euler deconvolution. Studies applicable to both methods involved 3D inversion, artificial intelligence, and open-source software. The number of citations reveals a different picture than the number of publications, where the same categories are present but magnetic study citations dominate, indicating in general a time lag of 10 years. The results of this review may help direct future research in these areas. Full article

(This article belongs to the Special Issue Advances in Magnetic and Electromagnetic Techniques for Mineral Exploration: Enhancing Resource Discovery, 2nd Edition)

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