Minerals

26 pages, 7042 KiB

Open AccessEditor’s ChoiceArticle

Thermodynamic Stability of Clay Minerals in Boreal Forest Soil and Its Relationship to the Properties of Soil Organic Matter

by Igor V. Danilin, Yulia G. Izosimova, Ruslan A. Aimaletdinov and Inna I. Tolpeshta

Minerals 2025, 15(4), 430; https://doi.org/10.3390/min15040430 - 20 Apr 2025

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Abstract

This paper assesses the thermodynamic stability of clay minerals in the upper organo-mineral horizon of podzolic soil, as well as in the rhizosphere of Norway spruce (Picea abies (L.) H. Karst.) and Norway maple (Acer platanoides L.). Moreover, it determines the [...] Read more.

This paper assesses the thermodynamic stability of clay minerals in the upper organo-mineral horizon of podzolic soil, as well as in the rhizosphere of Norway spruce (Picea abies (L.) H. Karst.) and Norway maple (Acer platanoides L.). Moreover, it determines the impact of soil organic matter on the thermodynamic stability of clay minerals. Calculations of ΔG_f and the saturation index (SI) for clay minerals in laboratory experiments simulating soil conditions without soil moisture outflow allowed us to find out that the thermodynamic stability of clay minerals decreased in the series kaolinite > illite > vermiculite > chlorite. In the rhizosphere of spruce, kaolinite, vermiculite and illite have the lowest, and in the soil under maple-the highest thermodynamic stability, which is associated with differences in the properties of soil organic matter of rhizospheres of different tree species. Laboratory experiments on the sorption of soil humic acid (HA) on clay minerals demonstrated that sorbed HA decreased the thermodynamic stability of biotite and increased the thermodynamic stability of kaolinite and muscovite. Thermodynamic stability of clay minerals decreased with increased proportion of sorbed thermolabile organic matter. Full article

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

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22 pages, 17789 KiB

Open AccessEditor’s ChoiceArticle

Mafic Enclaves Reveal Multi-Magma Storage and Feeding of Shangri-La Lavas at the Nevados de Chillán Volcanic Complex

by Camila Pineda, Gloria Arancibia, Valentina Mura, Diego Morata, Santiago Maza and John Browning

Minerals 2025, 15(4), 418; https://doi.org/10.3390/min15040418 - 17 Apr 2025

Viewed by 398

Abstract

The Nevados de Chillán Volcanic Complex is one of the most active of the Southern Volcanic Zone. It is formed by NW-SE-aligned eruptive centers divided into two subcomplexes, namely Cerro Blanco (basaltic andesitic) and Las Termas (dacitic), and two satellite cones (to the [...] Read more.

The Nevados de Chillán Volcanic Complex is one of the most active of the Southern Volcanic Zone. It is formed by NW-SE-aligned eruptive centers divided into two subcomplexes, namely Cerro Blanco (basaltic andesitic) and Las Termas (dacitic), and two satellite cones (to the SW and NE of the main alignment). Our study of the Shangri-La volcano, which is located between the two subcomplexes, in alignment with the satellite cones, and which produced dacitic lavas with basaltic andesitic enclaves, sheds light on the compositional and structural diversity of the volcanic complex. Detailed petrography along with mineral chemistry allows us to suggest partial hybridization between the enclaves and the host lavas and that mixing processes are related to the generation of the Shangri-La volcano and to other volcanic products generated in the complex. This is supported by mixing trends between the enclaves and the most differentiated units from Las Termas. We argue the presence of two main magma storage areas genetically related to crustal structures. A dacitic reservoir (~950 °C) is fed along NW-SE structures, whereas a deeper mafic reservoir (>1100 °C) utilizes predominantly NE-SW structures. We suggest that the intersection between these sets of structures facilitates magma ascent and controls the Nevados de Chillán plumbing system dynamics. Full article

(This article belongs to the Special Issue Magmatic Evolution through Time of Volcanic Zones: Evidence from Isotopic, Geochemical and Geochronological Data of Eruption Products)

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50 pages, 21988 KiB

Open AccessEditor’s ChoiceArticle

Transforming LCT Pegmatite Targeting Models into AI-Powered Predictive Maps of Lithium Potential for Western Australia and Ontario: Approach, Results and Implications

by Oliver P. Kreuzer and Bijan Roshanravan

Minerals 2025, 15(4), 397; https://doi.org/10.3390/min15040397 - 9 Apr 2025

Viewed by 1202

Abstract

Here, we present holistic targeting models for lithium–cesium–tantalum (LCT) pegmatites in Western Australia, the world’s largest supplier of hardrock lithium ores, and Ontario, an emerging hardrock lithium mining jurisdiction. In this study, the LCT pegmatite targeting models, informed by a review of this [...] Read more.

Here, we present holistic targeting models for lithium–cesium–tantalum (LCT) pegmatites in Western Australia, the world’s largest supplier of hardrock lithium ores, and Ontario, an emerging hardrock lithium mining jurisdiction. In this study, the LCT pegmatite targeting models, informed by a review of this deposit type and framed in the context of a mineral system approach, served to identify a set of targeting criteria that are mappable in the publicly available exploration data for Western Australia and Ontario. This approach, which formed the basis for artificial intelligence (AI)-powered mineral potential modeling (MPM), using multiple, complimentary modeling techniques, not only delivered the first published regional-scale views of lithium potential across the Archean to Proterozoic terrains of Western Australia and Ontario, but it also delivered an effective framework for exploration and revealed hidden trends. For example, we identified a statistically verifiable proximity relationship between lithium, gold, and nickel occurrences and confirmed a significant size differential between LCT pegmatites in Western Australia and Ontario, with the former typically containing much larger resources than the latter. Overall, this regional-scale targeting study served to demonstrate the power of precompetitive, high-quality geoscience data, not only for regional-scale targeting but also for the development of camp-scale targets that have the resolution to be investigated using conventional prospecting techniques. Importantly, MPM does not generate ‘treasure maps’. Rather, MPM provides another tool in the ‘exploration toolbox’, and its output should be taken as the starting point for further investigations. Full article

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

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18 pages, 2936 KiB

Open AccessEditor’s ChoiceArticle

Knowledge-Inference-Based Intelligent Decision Making for Nonferrous Metal Mineral-Processing Flowsheet Design

by Jiawei Yang, Chuanyao Sun, Junwu Zhou, Qingkai Wang, Kanghui Zhang and Tao Song

Minerals 2025, 15(4), 374; https://doi.org/10.3390/min15040374 - 3 Apr 2025

Viewed by 323

Abstract

With the increasing diversification of ore types and the complexity of processing techniques in the mining industry, traditional decision-making methods for mineral processing flowsheets can no longer meet the high efficiency and intelligence requirements. This paper proposes a knowledge graph-based framework for constructing [...] Read more.

With the increasing diversification of ore types and the complexity of processing techniques in the mining industry, traditional decision-making methods for mineral processing flowsheets can no longer meet the high efficiency and intelligence requirements. This paper proposes a knowledge graph-based framework for constructing a mineral-processing design knowledge base and knowledge reasoning, aiming at providing intelligent and efficient decision support for mining engineers. This framework integrates Chinese NLP models for text vectorization, optimizes prompt generation through Retrieval Augmented Generation (RAG) technology, realizes knowledge graph construction, and implements knowledge reasoning for nonferrous metal mineral-processing design using large reasoning models. By analyzing the genetic characteristics of ores and the requirements of processing techniques, the framework outputs reasonable flowsheet designs, which could help engineers save research time and labor in optimizing processes, selecting suitable reagents, and adjusting process parameters. Through decision analysis of the mineral-processing flowsheets for three typical copper mines, the framework demonstrates its advantages in improving process flowsheet design, and shows good potential for further application in complex mineral-processing environments. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Extractive Metallurgy of Base and Precious Metals)

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26 pages, 6453 KiB

Open AccessEditor’s ChoiceArticle

Petrological Studies and Geochemical Modelling of Water–Rock Interactions in the Grønnedal-Íka Alkaline Complex Generating Ikaite Deposition in Ikka Fjord, SW Greenland

by Sigríður María Aðalsteinsdóttir, Gabrielle J. Stockmann, Erik Sturkell, Enikő Bali, Guðmundur H. Guðfinnsson and Andri Stefánsson

Minerals 2025, 15(4), 373; https://doi.org/10.3390/min15040373 - 2 Apr 2025

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Abstract

The Mesoproterozoic alkaline Grønnedal-Íka complex (1325 ± 6 Ma) is intruded into old Archean gneissic bedrock between Ikka Fjord and Kangilinnguit (Grønnedal) by Arsuk Fjord in Southwestern Greenland. This 8 × 2.8 km oval-shaped complex constitutes the oldest part of the Gardar Province, [...] Read more.

The Mesoproterozoic alkaline Grønnedal-Íka complex (1325 ± 6 Ma) is intruded into old Archean gneissic bedrock between Ikka Fjord and Kangilinnguit (Grønnedal) by Arsuk Fjord in Southwestern Greenland. This 8 × 2.8 km oval-shaped complex constitutes the oldest part of the Gardar Province, representing a failed continental rift across southern Greenland. It comprises outer rings of mainly nepheline syenites with a central plug of Fe- and Ca-rich carbonatites. Here, we present petrological data on the syenites and carbonatites combined with geochemical modelling of groundwater percolating through the Grønnedal-Íka complex and the secondary minerals and fluid chemistry arising from these fluid–rock reactions. The results show that modelling using input data of (1) meteoric water in a closed system with respect to atmospheric CO₂ can (2) dissolve the primary minerals of the syenites and carbonatites and (3) simulate the fluid chemistry of the natural sodium carbonate springs of 3–4 °C and pH 10–11 seeping up through fractures at the bottom of Ikka Fjord, which (4) leads to the deposition of nearly a thousand tufa columns of the cold carbonate mineral ikaite (CaCO₃•6H₂O). Our results thereby support the geochemical relationship between fluid–rock reactions inside the Grønnedal-Íka alkaline complex and the precipitation of ikaite in the shape of submarine tufa columns in Ikka Fjord. The modelling indicates that the groundwater itself can be supersaturated with respect to ikaite and provide the seed crystals that lead to the columnar growth of ikaite up to 20 m tall in the seawater of Ikka Fjord. Full article

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

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22 pages, 7574 KiB

Open AccessEditor’s ChoiceArticle

Evaluating Depositional Environment and Organic Matter Accumulation of Datangpo Formation in Central Hunan Province, South China

by Peng Jiao, Rong Xiao, Shimin Tan, Yu Xie, Hanqi Fang, Zhigang Wen and Zhanghu Wang

Minerals 2025, 15(4), 366; https://doi.org/10.3390/min15040366 - 31 Mar 2025

Viewed by 328

Abstract

The interglacial period of the Cryogenian glaciation is a pivotal interval in geological history, marked by two “Snowball Earth” events and the emergence of early animals. Currently, there is considerable debate regarding the paleo-oceanic environment and the dominant factors controlling organic matter enrichment. [...] Read more.

The interglacial period of the Cryogenian glaciation is a pivotal interval in geological history, marked by two “Snowball Earth” events and the emergence of early animals. Currently, there is considerable debate regarding the paleo-oceanic environment and the dominant factors controlling organic matter enrichment. Here, based on inorganic geochemical data and mineral composition from the Datangpo Formation in Xiangtan (South China), combined with previous research, we have analyzed the paleo-climate, redox condition, seawater restriction, and primary productivity across different sedimentary facies during this critical interval. The results exhibit that the Datangpo Formation can be divided into three members (Da1–Da3) based on lithology. Paleoclimatic proxies suggest the environment was relatively cold during the deposition of the Da-1 Member, while it was relatively warm and humid during the deposition of the Da 2–3 members. Compared to shallow water areas, deep-water areas experienced a more rapid transition in paleotemperature following the Sturtian glaciation event. Combining Mo-U elements, Ce_N/Ce*_N, and C_org/P ratios, the environment was characterized by an oxic environment during the early deposition period of the Datangpo Formation, then gradually transitioned to suboxic, and finally anoxic conditions. Furthermore, the decompression of terrestrial magma chambers led to intense volcanic/hydrothermal activity during the deglaciation period. Hydrothermal activity was most intense during the Da-1 depositional period, followed by Da-2, and gradually declined during Da-3 depositional period. Hydrothermal activity not only provided essential materials for the formation of Mn carbonate ores but also significantly enhanced the primary productivity by introducing large amounts of nutrients in the paleo-ocean. The primary productivity indicators (Ni/Al, Cu/Al) exhibited an obvious coupling with Ce_N/Ce*_N and C_org/P ratios in the Datangpo Formation, indicating that oxygen-rich environments were favorable for biological proliferation, thereby providing abundant organic matter. Anoxic conditions further facilitated the preservation of organic matter, which may be the primary factor driving organic matter enrichment in the Datangpo Formation. Full article

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

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26 pages, 12333 KiB

Open AccessEditor’s ChoiceArticle

Exploring High PT Experimental Charges Through the Lens of Phase Maps

by Balz S. Kamber, Marco A. Acevedo Zamora, Rodrigo Freitas Rodrigues, Ming Li, Gregory M. Yaxley and Matthew Ng

Minerals 2025, 15(4), 355; https://doi.org/10.3390/min15040355 - 28 Mar 2025

Viewed by 470

Abstract

High pressure and temperature (PT) experimental charges are valuable systems composed of minerals, often with quenched melt and/or fluid, synthesized to inform petrological processes deep within Earth. We explored the utility of phase mapping for the analysis of 5 GPa partial [...] Read more.

High pressure and temperature (PT) experimental charges are valuable systems composed of minerals, often with quenched melt and/or fluid, synthesized to inform petrological processes deep within Earth. We explored the utility of phase mapping for the analysis of 5 GPa partial melting experiments of peridotite. We further developed an open-source software workflow to generate phase maps, which is scanning electron microscope (SEM) instrument agnostic. Phase maps were constructed offline, combining high-quality back-scattered electron images and selected element maps, and compared and verified with maps obtained with commercial automated mineralogy software. One sub-solidus assemblage, one charge containing a small percentage of melt, and a melting experiment that displayed reactions (caused by a strong thermal gradient) were analyzed. For the sub-solidus experiment, the phase map returned an accurate modal mineralogy. For the quenched melt experiments, the phase map located low-abundance phases and identified the best-suited targets for chemical analysis. Using modal mineralogy of sub-regions on maps and mutual neighboring relationships, the phase maps helped to establish equilibrium conditions and verify melting reactions inferred from mass balance. We propose phase maps as valuable tools for documenting high PT charges, particularly for layered reaction experiments. We conclude with a set of recommended instrument settings for high-quality phase maps on small experimental charges. Full article

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

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31 pages, 7924 KiB

Open AccessEditor’s ChoiceReview

Techniques of Pre-Concentration by Sensor-Based Sorting and Froth Flotation Concentration Applied to Sulfide Ores—A Review

by Evandro Gomes dos Santos, Irineu Antonio Schadach de Brum and Weslei Monteiro Ambrós

Minerals 2025, 15(4), 350; https://doi.org/10.3390/min15040350 - 27 Mar 2025

Cited by 1 | Viewed by 856

Abstract

The use of pre-concentration and optimization of concentration methods have been the focus of the modern mineral industry. Sensor-based sorting equipment and flotation are key players in that movement. This study provides an overview of the main sensor-based sorting techniques and their uses, [...] Read more.

The use of pre-concentration and optimization of concentration methods have been the focus of the modern mineral industry. Sensor-based sorting equipment and flotation are key players in that movement. This study provides an overview of the main sensor-based sorting techniques and their uses, focusing on sulfides, addressing performance analysis methodologies, and giving the advantages and limitations of the method. An overview of the flotation technique is also presented, covering its basic principles of operation, as well as its main applications in sulfides, its interactions with pre-concentration, and some opportunities and perspectives on the method, such as water reuse impacts, tailing reprocessing, etc. Case studies are presented addressing the influence of the techniques on each other and some future prospects for the mining sector, such as deep-sea mining (DSM) and the use of artificial intelligence (AI). Full article

(This article belongs to the Special Issue Mineral Processing Technologies of Low-Grade Ores)

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29 pages, 20187 KiB

Open AccessEditor’s ChoiceArticle

Applying Mineral System Criteria to Develop a Predictive Modelling for Epithermal Gold Mineralization in Northern New Brunswick: Using Knowledge-Driven and Data-Driven Methods

by Farzaneh Mami Khalifani, David R. Lentz, James A. Walker and Fereshteh Khammar

Minerals 2025, 15(4), 345; https://doi.org/10.3390/min15040345 - 27 Mar 2025

Viewed by 609

Abstract

Using mineral prospectivity mapping (MPM), the mineral systems approach enables the identification of geological indicators linked to ore formation. This approach streamlines exploration by minimizing the time and cost required to identify areas with the highest mineral potential. With its extensive till cover [...] Read more.

Using mineral prospectivity mapping (MPM), the mineral systems approach enables the identification of geological indicators linked to ore formation. This approach streamlines exploration by minimizing the time and cost required to identify areas with the highest mineral potential. With its extensive till cover and dense forests limiting bedrock exposure, New Brunswick provides an ideal environment to test this approach. The New Brunswick portion of the Canadian Appalachians hosts a diverse range of gold deposits and occurrences that formed during various stages of the Appalachian orogeny. In northern New Brunswick and the adjacent Gaspé Peninsula, the Tobique–Chaleur Zone contains several orogenic and epithermal gold systems that are closely associated with a large-scale crustal fault and its offshoots, i.e., the long-lived trans-crustal Rocky Brook–Millstream Fault system. To identify favorable zones for epithermal gold mineralization in northwestern New Brunswick, this study employed MPM by translating key mineral system components—such as ore metal sources, fluid pathways, traps, and geological controls—into mappable criteria for regional-scale analysis. The data were modeled through the integration of knowledge-based and data-driven methods, including fuzzy logic, geometric average, and logistic regression approaches. The concentration–area (C–A) fractal model was applied to reclassify the final maps based on prospectivity values obtained from these three approaches, dividing the mineral prospectivity maps into six classes, with threshold values emphasizing high-favorability zones. The fuzzy overlay model had the highest predictive accuracy (AUC 0.97), followed by the geometric average model (AUC 0.93), whereas the logistic regression identified more tightly constrained high-potential zones. In the prospectivity models, known epithermal gold mineralization consistently overlaps with regions of high favorability. This suggests a positive result from the use of MPM, indicating that this approach could be applicable to other regions and types of ore deposits. Full article

(This article belongs to the Special Issue Smart Exploration of Critical Minerals: Integrating Multi-Source Data for Enhanced Mineral Prospectivity Mapping)

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17 pages, 23171 KiB

Open AccessEditor’s ChoiceArticle

Thermal Decomposition and Phase Transformation of Chrysotile in Asbestos-Containing Waste

by Chaewon Kim, Yumi Kim and Yul Roh

Minerals 2025, 15(4), 344; https://doi.org/10.3390/min15040344 - 27 Mar 2025

Cited by 1 | Viewed by 384

Abstract

In Korea, asbestos-containing waste (ACW) is disposed of in landfills. However, due to the limited landfill capacity and the potential health risks of asbestos contamination, alternative, safer disposal methods are needed. Heat treatment has been suggested as an alternative disposal method for ACW. [...] Read more.

In Korea, asbestos-containing waste (ACW) is disposed of in landfills. However, due to the limited landfill capacity and the potential health risks of asbestos contamination, alternative, safer disposal methods are needed. Heat treatment has been suggested as an alternative disposal method for ACW. Therefore, it is necessary to determine the optimal conditions for the thermal decomposition of chrysotile in ACW and reveal the mineralogical composition of heat-treated ACW. In this study, asbestos cement roof (ACR) and asbestos gypsum board (AGB) samples were heat-treated at 600, 700, 800, and 900 °C to identify the optimal heat treatment parameters to eliminate chrysotile fibers. The thermal, chemical, and mineralogical characteristics of the ACW were determined before and after heat treatment using multiple analytical methods. The ACR consisted of chrysotile, calcite, and ettringite, and the AGB consisted of chrysotile, gypsum, and calcite. After heat treatment at 900 °C, the ACR was mainly composed of cement component minerals and lime, while the AGB additionally contained anhydrite. SEM-EDS analysis confirmed the persistence of fibrous minerals in the ACW up to 800 °C. Furthermore, TEM-EDS analysis revealed hollow tubular morphology of chrysotile in the heat-treated ACR at up to 700 °C and in the heat-treated AGB at 600 °C. These results suggest that heat treatment at temperatures of at least 900 °C may be necessary for the complete thermal decomposition of chrysotile in ACW. Full article

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

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29 pages, 11095 KiB

Open AccessEditor’s ChoiceArticle

Uranium Mineral Particles Produced by Weathering in Sierra Peña Blanca, Chihuahua, Mexico: A Synchrotron-Based Study

by Cristina Hernández-Herrera, Jesús G. Canché-Tello, Yair Rodríguez-Guerra, Fabián G. Faudoa-Gómez, Diane M. Eichert, Konstantin Ignatyev, Rocío M. Cabral-Lares, Victoria Pérez-Reyes, Hilda E. Esparza-Ponce and María-Elena Montero-Cabrera

Minerals 2025, 15(4), 333; https://doi.org/10.3390/min15040333 - 22 Mar 2025

Viewed by 283

Abstract

Some of the largest Mexican uranium (U) deposits are located in Chihuahua. The most important is in Sierra Peña Blanca, northwest of the capital, which was explored and partially exploited in the 1980s. After the closure of activities, the mining projects were left [...] Read more.

Some of the largest Mexican uranium (U) deposits are located in Chihuahua. The most important is in Sierra Peña Blanca, northwest of the capital, which was explored and partially exploited in the 1980s. After the closure of activities, the mining projects were left exposed to weathering. To characterize the spread of U minerals towards the neighboring Laguna del Cuervo, sediment samples were collected in the main streams of the drainage pattern of the largest deposits. The U mineral fragments from the fine sand portion were extracted using fluorescence light at 365 nm. The morphology and elemental composition of these particles were analyzed by focused ion beam microscopy (FIB) and scanning transmission electron microscopy (STEM). The particle density in samples close to the U sources was quantified using gamma spectrometry. The highest density was 2500 part./g, and the lowest was 124 part./g. X-ray absorption spectroscopy (XAS) allowed us to establish via XANES the speciation of U in the U particles, confirming the U(VI) oxidation state, while the exploitation of the EXAFS spectrum put in evidence of the presence of uranophane. Finally, the Fe, Sr, and U distributions in the particle and its matrix were obtained via X-ray fluorescence microtomography (XRF-µCT). It was concluded that the particle is composed of uranophane, imbricated with quartz and other oxides. 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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22 pages, 3192 KiB

Open AccessEditor’s ChoiceArticle

Effect of Domaining in Mineral Resource Estimation with Machine Learning

by Fırat Atalay

Minerals 2025, 15(4), 330; https://doi.org/10.3390/min15040330 - 21 Mar 2025

Cited by 1 | Viewed by 616

Abstract

Machine learning (ML) is increasingly applied in earth sciences, including in mineral resource estimation. A critical step in this process is domaining, which significantly impacts estimation quality. However, the importance of domaining within ML-based resource estimation remains under-researched. This study aims to directly [...] Read more.

Machine learning (ML) is increasingly applied in earth sciences, including in mineral resource estimation. A critical step in this process is domaining, which significantly impacts estimation quality. However, the importance of domaining within ML-based resource estimation remains under-researched. This study aims to directly assess the effect of domaining on ML estimation accuracy. A copper deposit with well-defined, hard-boundary, low- and high-grade domains was used as a case study. Extreme Gradient Boosting (XGBoost), Support Vector Regression (SVR), and ensemble learning were employed to estimate copper distribution, both with and without domaining. Estimation performance was evaluated using summary statistics, swath plot analyses, and the quantification of out-of-range blocks. The results demonstrated that estimations without domaining exhibited substantial errors, with approximately 30% of blocks in the high-grade domain displaying values outside their expected range. These findings confirm that, analogous to classical methods, domaining is essential for accurate mineral resource estimation using ML algorithms. Full article

(This article belongs to the Special Issue Mineral Prospectivity Mapping (MPM) Using Multi-Source Datasets, Geo-Statistical Algorithms and Machine Learning Techniques)

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36 pages, 9140 KiB

Open AccessEditor’s ChoiceArticle

The Geochemical Characteristics of Ore-Forming Fluids in the Jebel Stah Fluorite Deposit in Northeast Tunisia: Insights from LA-ICP-MS and Sr Isotope Analyses

by Chaima Somrani, Fouad Souissi, Radhia Souissi, Giovanni De Giudici, Eduardo Ferreira da Silva, Dario Fancello, Francesca Podda, José Francisco Santos, Tamer Abu-Alam, Sara Ribeiro and Fernando Rocha

Minerals 2025, 15(4), 331; https://doi.org/10.3390/min15040331 - 21 Mar 2025

Cited by 1 | Viewed by 830

Abstract

The Zaghouan Fluorite Province (ZFP) encloses F-Ba(Pb-Zn) ores hosted within Jurassic carbonate series, in northeastern Tunisia. Critical breakthroughs on the Jebel Stah fluorite deposits, an MVT-style F-mineralization, have been made within the Lower Jurassic limestones along the Zaghouan Fault, which is a major [...] Read more.

The Zaghouan Fluorite Province (ZFP) encloses F-Ba(Pb-Zn) ores hosted within Jurassic carbonate series, in northeastern Tunisia. Critical breakthroughs on the Jebel Stah fluorite deposits, an MVT-style F-mineralization, have been made within the Lower Jurassic limestones along the Zaghouan Fault, which is a major target for mineralization. This study presents the first REE-Y analyses conducted by LA-ICP-MS on fluorites in Tunisia, and specifically on the fluorites of Jebel Stah deposit. This analytical technique provides highly accurate insights into the geochemical regime of mineralizing fluids and the related scavenging sources. Distinct geochemical characteristics between two fluorite generations (G1 and G2) were revealed. Fluorites (Fl2) from the early generation (G1) showed low ΣREE + Y (36.3 and 39.73 ppm, respectively). When normalized to chondrites, early fluorite G1 displayed a bell-shaped REE + Y pattern with a depletion in LREE relative to HREE and a slight MREE hump. Late fluorite (Fl3) generation (G2) displayed higher ΣREE + Y concentrations (77.43 ppm), but an almost similar REE pattern. Ce/Ce* ratios demonstrated strong negative Ce anomalies in all fluorites, while Eu/Eu* ratios indicated weak negative Eu anomalies. The positive Y anomaly observed in the REE + Y patterns of fluorites G1 and G2 suggests Y-Ho fractionation in the fluid system. Moreover, significant degrees of differentiation between terbium (Tb) and lanthanum (La) have been observed in all fluorite samples. The plot of fluorites from both fluorite generations on the Tb/La–Tb/Ca diagram gives evidence of the sedimentary hydrothermal origin of the ore-forming fluids in the Jebel Stah F-deposit. Sr isotopes show that the mineralizing fluids are radiogenic and deeply sourced basinal brines, whereas the small variation in ⁸⁷Sr/⁸⁶Sr ratios suggests a similar source for Sr in fluorites G1 and G2. These results allow us to conclude that the economic fluorite (G1) ore of Jebel Stah was deposited due to the interaction of the deeply sourced hydrothermal fluid with the carbonated host rocks (dolomitization, an increase in pH, and Ca activity), whereas the late fluorite (G2) is an accessory and could have resulted from the mixing of the hydrothermal fluid with shallow meteoric waters. Full article

(This article belongs to the Special Issue Mineralogical and Geochemical Characterization of Zn-Pb Ore Deposits: Insights into Their Genesis, Implications for Exploration, and Environmental Issues)

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30 pages, 5838 KiB

Open AccessEditor’s ChoiceReview

Natural Mineral Materials for Enhanced Performance in Aqueous Zinc-Ion Batteries

by Peilin Chen, Qinwen Zheng, Ke Wang and Yingmo Hu

Minerals 2025, 15(4), 328; https://doi.org/10.3390/min15040328 - 21 Mar 2025

Viewed by 469

Abstract

Aqueous zinc-ion batteries (AZIBs) have emerged as promising candidates for large-scale energy storage due to their inherent safety, cost-effectiveness, and environmental compatibility. However, challenges such as zinc -dendrite growth, hydrogen evolution reactions, and cathode dissolution hinder their practical application. To tackle these issues, [...] Read more.

Aqueous zinc-ion batteries (AZIBs) have emerged as promising candidates for large-scale energy storage due to their inherent safety, cost-effectiveness, and environmental compatibility. However, challenges such as zinc -dendrite growth, hydrogen evolution reactions, and cathode dissolution hinder their practical application. To tackle these issues, a wide range of investigative approaches have been conducted to improve the performance of AZIBs. Recently, much attention has been paid to the application of natural mineral materials in AZIBs, since these low-cost minerals align well with the high sensitivity of battery costs in large-scale energy storage. This review systematically explores the application of natural mineral materials to address these issues across battery components, including protective layers on anodes and cathodes, functional films of separators, additives in electrolytes, etc. A multitude of minerals, such as halloysite, montmorillonite, attapulgite, diatomite, and dickite, are highlighted for their unique structural and physicochemical properties, including hierarchical porosity, ion-selective channels, and surface charge regulation. Finally, prospects for future research are discussed to construct AZIBs with a combination of excellent performance and cost efficiency and to bridge laboratory innovations with commercial viability. Full article

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

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43 pages, 41722 KiB

Open AccessEditor’s ChoiceArticle

Massive Dolomitization of Interior and Slope to Basin-Margin Facies of the Triassic Yangtze Platform Through Superposed Earth-Surface and Burial Mechanisms, Nanpanjiang Basin, South China

by Nathaniel S. Ledbetter Ferrill, Xiaowei Li, Josephine Tesauro, Madison Sears, George M. Bradley, Arianna Hilbert, Eryn Carney, Justice Saxby, Neda Mobasher, Brian M. Kelley, E. Troy Rasbury, Kathleen M. Wooton, Jason D. Kirk, John A. Luczaj and Daniel J. Lehrmann

Minerals 2025, 15(3), 324; https://doi.org/10.3390/min15030324 - 19 Mar 2025

Viewed by 601

Abstract

Triassic strata of the Yangtze Platform at Guanling contain a dolomitized interior, undolomitized margin, and partially dolomitized slope to basin margin. Dolomitized microbial laminate caps of peritidal cycles and massive dolomite with associated evaporite nodules and solution collapse breccias are consistent with penecontemporaneous [...] Read more.

Triassic strata of the Yangtze Platform at Guanling contain a dolomitized interior, undolomitized margin, and partially dolomitized slope to basin margin. Dolomitized microbial laminate caps of peritidal cycles and massive dolomite with associated evaporite nodules and solution collapse breccias are consistent with penecontemporaneous tidal flat and evaporative dolomitization in the platform interior. The preferential dolomitization of the slope and basin margin (up to 7 km basinward of the margin), dolomitization along fractures, and selective dolomitization of the matrix in slope breccia that diminishes toward the margin are interpreted to have resulted from the incursion of basin-derived fluids during burial. Integrated analysis of fluid-inclusion microthermometry, oxygen, carbon, and strontium isotopes, trace element geochemistry, U-Pb age dates of carbonate phases, and burial history support the recrystallization of interior dolomite and slope to basin-margin dolomitization by brines at high temperatures during burial. The Yangtze Platform at Guanling provides an excellent example of widespread stratiform dolomitization resulting from the superposition of multiple mechanisms, including penecontemporaneous dolomitization by evaporative seawater brines, high-temperature dolomitization of the slope and basin margin by basinal brines, and high-temperature recrystallization of dolomite by brines during burial. This study provides an example that suggests that widespread stratiform dolomite may result from superposed Earth surface and high-temperature burial dolomitization processes and provides a valuable analog for other carbonate platforms in which the margin remains undolomitized while the interior and basin margin are dolomitized. Similar mechanisms likely contributed to the widespread dolomitization of platforms across the Nanpanjiang and Sichuan basins. Full article

(This article belongs to the Special Issue Paleoenvironment Evolution Proxy in Carbonates: Sedimentary Geochemistry)

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26 pages, 28443 KiB

Open AccessEditor’s ChoiceArticle

Diagenetic Evolution and Formation Mechanism of Middle to High-Porosity and Ultralow-Permeability Tuff Reservoirs in the Huoshiling Formation of the Dehui Fault Depression, Songliao Basin

by Siya Lin, Xiaobo Guo, Lili Li, Jin Gao, Song Xue, Yizhuo Yang and Chenjia Tang

Minerals 2025, 15(3), 319; https://doi.org/10.3390/min15030319 - 19 Mar 2025

Viewed by 363

Abstract

The fluid action mechanism and diagenetic evolution of tuff reservoirs in the Cretaceous Huoshiling Formation of the Dehui fault depression are discussed herein. The fluid properties of the diagenetic flow are defined, and the pore formation mechanism of the reservoir space is explained [...] Read more.

The fluid action mechanism and diagenetic evolution of tuff reservoirs in the Cretaceous Huoshiling Formation of the Dehui fault depression are discussed herein. The fluid properties of the diagenetic flow are defined, and the pore formation mechanism of the reservoir space is explained by means of thin sections, X-ray diffraction, electron probes, scanning electron microscopy (SEM), cathodoluminescence, and stable carbon and oxygen isotopic composition and fluid inclusion tests. The results reveal that the tuff reservoir of the Huoshiling Formation is moderately acidic, and the physical properties of the reservoir are characterized by middle to high porosity and ultralow permeability. The pore types are complex, comprising both primary porosity and secondary porosity, with dissolution pores and devitrification pores being the most dominant. Mechanical compaction and cementation are identified as key factors reducing reservoir porosity and permeability, while dissolution and devitrification processes improve pore structure and enhance pore connectivity. Diagenetic fluids encompass alkaline fluids, acidic fluids, deep-seated CO₊-rich hydrothermal fluids, and hydrocarbon-associated fluids. These fluids exhibit dual roles in reservoir evolution: acidic fluids enhance the dissolution of feldspar, tuffaceous materials, and carbonate minerals to generate secondary pores and improve reservoir quality, whereas alkaline fluids induce carbonate cementation, and clay mineral growth (e.g., illite) coupled with late-stage mineral precipitation obstructs pore throats, reducing permeability. The interplay among multiple fluid types and their varying dominance at different burial depths collectively governs reservoir evolution. This study underscores the critical role of fluid–rock interactions in controlling porosity–permeability evolution within tuff reservoirs. Full article

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

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23 pages, 4220 KiB

Open AccessEditor’s ChoiceReview

Utilization of Natural Mineral Materials in Environmental Remediation: Processes and Applications

by Di Xu, Yongkui Yang and Lingqun Gan

Minerals 2025, 15(3), 318; https://doi.org/10.3390/min15030318 - 19 Mar 2025

Viewed by 441

Abstract

The discharge of wastewater containing persistent organic pollutants presents significant ecological and health challenges due to their toxicity and resilience. Recent advances in advanced oxidation processes (AOPs) and other remediation mechanisms, notably utilizing natural mineral materials (NMMs), offer promising solutions to these challenges. [...] Read more.

The discharge of wastewater containing persistent organic pollutants presents significant ecological and health challenges due to their toxicity and resilience. Recent advances in advanced oxidation processes (AOPs) and other remediation mechanisms, notably utilizing natural mineral materials (NMMs), offer promising solutions to these challenges. NMMs, with their cost-effectiveness, accessibility, eco-friendly nature, non-toxicity, and unique structural properties, have shown significant promise in environmental remediation and could effectively replace conventional catalysts in related applications. These minerals enable the activation of oxidants, generating reactive oxygen species crucial for the degradation of pollutants. This article reviews the mechanisms of NMMs in various AOPs, including photocatalysis, Fenton-like reactions, and persulfate-activation-based processes, and discusses the potential of these materials in enhancing pollutant degradation efficiency, with a focus on the activation of persulfates and the photo-induced redox processes. The synergy between photocatalytic properties and catalytic activation provided by NMMs offers a robust approach to managing water pollution without the drawbacks of secondary waste production, thus supporting sustainable remediation efforts. Full article

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

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31 pages, 16566 KiB

Open AccessEditor’s ChoiceArticle

The Role of Fluid Chemistry in the Diagenetic Transformation of Detrital Clay Minerals: Experimental Insights from Modern Estuarine Sediments

by Anas Muhammad Salisu, Abdulwahab Muhammad Bello, Abduljamiu O. Amao and Khalid Al-Ramadan

Minerals 2025, 15(3), 317; https://doi.org/10.3390/min15030317 - 19 Mar 2025

Viewed by 467

Abstract

The diagenetic transformation of detrital clay minerals significantly influences sandstone reservoir quality, with fluid chemistry and temperature playing key roles in dictating transformation pathways during burial diagenesis. While these processes are well-documented in basinal settings, the diagenetic alterations of sediments in dynamic environments [...] Read more.

The diagenetic transformation of detrital clay minerals significantly influences sandstone reservoir quality, with fluid chemistry and temperature playing key roles in dictating transformation pathways during burial diagenesis. While these processes are well-documented in basinal settings, the diagenetic alterations of sediments in dynamic environments like estuaries remain underexplored. This study investigates the impact of fluid composition on the transformation of modern estuarine sediments through hydrothermal experiments using sediments from the Gironde estuary, SW France. A range of natural and synthetic solutions including seawater (SW), 0.1 M KCl (SF1), 0.1 M NaCl, KCl, CaCl₂·2H₂O, MgCl₂·6H₂O (SF2), estuarine water (EW), and 0.1 M Na₂CO₃ (SF3) were used under temperatures from 50 °C to 250 °C for 14 days, with a fixed fluid-to-sediment ratio of 10:1. The results revealed distinct mineralogical transformations driven by fluid composition. Dissolution of detrital feldspars and clay materials began at lower temperatures (<100 °C). The authigenic formation of smectite and its subsequent illitization in K-rich fluids (SW, SF1) occurred between 150 °C and 250 °C, replicating potassium-driven illitization processes observed in natural sandstones. Additionally, chlorite formation occurred through the conversion of smectite in SF2 and EW. Geochemical analysis showed that SF2 produced Mg-rich chlorites, while EW yielded Fe-rich chlorites. This aligns with diagenetic trends in coastal environments, where Fe-rich chlorites are typically associated with estuarine systems. The resulting authigenic illite and chlorite exhibited morphological and chemical characteristics similar to those found in natural sandstones, forming through dissolution-crystallization and solid-state transformation mechanisms. In contrast to illite and chlorite, SF3 produced entirely different mineral phases, including halite and analcime (zeolite), attributed to the high alkalinity and Na-rich composition of the solution. These findings provide valuable insights into the role of fluid chemistry in the diagenetic alteration of modern sediments and their implications for the evolution of sandstone reservoirs, which is critical for energy exploration and transition. Full article

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

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12 pages, 2785 KiB

Open AccessEditor’s ChoiceArticle

Crystal Chemistry, High-Pressure Behavior, Water Content, and Thermal Stability of Natural Spodumene

by Yuhui Jiang, Jiayi Yu, Yuanze Ouyang, Li Zhang, Xiaoguang Li, Zhuoran Zhang and Yunxuan Li

Minerals 2025, 15(3), 307; https://doi.org/10.3390/min15030307 - 16 Mar 2025

Viewed by 424

Abstract

Spodumene (LiAlSi₂O₆) is a member of pyroxene-group minerals. It has the highest theoretical lithium abundance among all of the Li-bearing minerals. In the present work, in situ high-pressure Raman spectroscopic investigation of natural spodumene have been conducted up to [...] Read more.

Spodumene (LiAlSi₂O₆) is a member of pyroxene-group minerals. It has the highest theoretical lithium abundance among all of the Li-bearing minerals. In the present work, in situ high-pressure Raman spectroscopic investigation of natural spodumene have been conducted up to 19.04 GPa. Unheated spodumene and spodumene recovered after heat treatments (up to 1000 °C) have also been analyzed by X-ray diffraction and infrared spectroscopy. The results indicate that spodumene, after the displacive C2/c–P2₁/c transformation triggered at ~3.2 GPa, remains stable at pressures up to 19 GPa at ambient temperature without undergoing decomposition, amorphization, or a second phase transition. The major OH bands of the spodumene samples are observed within the wavenumber range of 2580–3220 cm⁻¹, implying a strong hydrogen bond interaction. The water content of the spodumene is estimated to be 19–97 ppm wt. H₂O based on the integrated absorption area of the OH bands. The FTIR analysis of the spodumene samples recovered after heat treatments implies that spodumene can retain a significant amount of water (up to ~100 ppm H₂O by weight) under high-temperature conditions up to 1000 °C. This suggests that spodumene in subducted slabs is unlikely to undergo dehydration at temperatures below 1000 °C, and is therefore not expected to trigger partial melting. Thus, spodumene may serve as a key carrier for Li, transporting it into the deep mantle without releasing Li into melts during subduction. Full article

(This article belongs to the Special Issue High-Pressure and High-Temperature Mineral Physics)

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21 pages, 8306 KiB

Open AccessEditor’s ChoiceArticle

Magmatic–Hydrothermal Processes of the Pulang Giant Porphyry Cu (–Mo–Au) Deposit, Western Yunnan: A Perspective from Different Generations of Titanite

by Mengmeng Li, Xue Gao, Guohui Gu and Sheng Guan

Minerals 2025, 15(3), 263; https://doi.org/10.3390/min15030263 - 3 Mar 2025

Viewed by 579

Abstract

The Yidun island arc was formed in response to the Late Triassic westward subduction of the Ganzi–Litang oceanic plate, a branch of the Paleo-Tethys Ocean. The Zhongdian arc, located in the south of the Yidun island arc, has relatively large number of porphyry [...] Read more.

The Yidun island arc was formed in response to the Late Triassic westward subduction of the Ganzi–Litang oceanic plate, a branch of the Paleo-Tethys Ocean. The Zhongdian arc, located in the south of the Yidun island arc, has relatively large number of porphyry (skarn) type Cu–Mo ± Au polymetallic deposits, the largest of which is the Pulang Cu (–Mo–Au) deposit with proven Cu reserves of 5.11 Mt, Au reserves of 113 t, and 0.17 Mt of molybdenum. However, the relationship between mineralization and the potassic alteration zone, phyllic zone, and propylitic zone of the Pulang porphyry deposit is still controversial and needs further study. Titanite (CaTiSiO₅) is a common accessory mineral in acidic, intermediate, and alkaline igneous rocks. It is widely developed in various types of metamorphic rocks, hydrothermally altered rocks, and a few sedimentary rocks. It is a dominant Mo-bearing phase in igneous rocks and contains abundant rare earth elements and high-field-strength elements. As an effective geochronometer, thermobarometer, oxybarometer, and metallogenic potential indicator mineral, titanite is ideal to reveal the magmatic–hydrothermal evolution and the mechanism of metal enrichment and precipitation. In this paper, major and trace element contents of the titanite grains from different alteration zones were obtained using electron probe microanalysis (EPMA) and laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to define the changes in physicochemical conditions and the behavior of these elements during the process of hydrothermal alteration at Pulang. Titanite in the potassic alteration zone is usually shaped like an envelope. It occurs discretely or is enclosed by feldspar, with lower contents of CaO, Al, Sr, Zr and Hf; a low Nb/Ta ratio; high ∑REE + Y, U, Th, Ta, Nb, and Ga content; and high FeO/Al₂O₃ and LREE/HREE ratios. This is consistent with the characteristics of magmatic titanite from fresh quartz monzonite porphyry in Pulang and other porphyry Cu deposits. Titanite in the potassium silicate alteration zone has more negative Eu anomaly and a higher U content and Th/U ratio, indicating that the oxygen fugacity decreased during the transformation to phyllic alteration and propylitic alteration in Pulang. High oxygen fugacity is favorable for the enrichment of copper, gold, and other metallogenic elements. Therefore, the enrichment of copper is more closely related to the potassium silicate alteration. The molybdenum content of titanite in the potassium silicate alteration zone is 10²–10⁴ times that of the phyllic alteration zone and propylitic alteration zone, while the copper content is indistinctive, indicating that molybdenum was dissolved into the fluid or deposited in the form of sulfide before the medium- to low-temperature hydrothermal alteration, which may lead to the further separation and deposition of copper and molybdenum. Full article

(This article belongs to the Special Issue Thermal History and Preservation Mechanisms of Porphyry-Cu Deposits: Evidence from Thermochronology, Mineral and Isotopic Geochemistry)

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51 pages, 28157 KiB

Open AccessEditor’s ChoiceArticle

Alteration Lithogeochemistry of an Archean Porphyry-Type Au(-Cu) Setting: The World-Class Côté Gold Deposit, Canada

by Laura R. Katz, Daniel J. Kontak and Benoit Dubé

Minerals 2025, 15(3), 256; https://doi.org/10.3390/min15030256 - 28 Feb 2025

Viewed by 725

Abstract

Characterizing alteration and its geochemical signature provides critical information relevant to ore-deposit genesis and its related footprint; for porphyry-type deposits, zoned potassic-phyllic-propylitic alteration and metal enrichment are critical features. Here we integrate earlier lithological and mineralogical studies of the (10+ Moz Au) Archean [...] Read more.

Characterizing alteration and its geochemical signature provides critical information relevant to ore-deposit genesis and its related footprint; for porphyry-type deposits, zoned potassic-phyllic-propylitic alteration and metal enrichment are critical features. Here we integrate earlier lithological and mineralogical studies of the (10+ Moz Au) Archean Côté Gold porphyry-type Au(-Cu) deposit (Ontario, Canada) with identified alteration types to provide exploration vectors. The ca. 2740 tonalite-quartz diorite-diorite intrusive complex and co-temporal Au(-Cu) mineralization as disseminations, breccias and veins are co-spatial with ore-related alteration types (amphibole, biotite, muscovite). An early, locally developed amphibole event coring the deposit is followed by emplacement of a Au(-Cu) mineralized biotite-rich magmatic-hydrothermal breccia body and broad halo of disseminated biotite and quartz veining. These rocks record gains via mass balance calculations of K, Fe, Mg, LILE, and LREE with Au, Cu, Mo, Ag, Se and Bi. Later muscovite alteration is enriched in K, Rb, Cs, Ba, CO₂, and LOI with varied Au, Cu, Mo, Te, As, and Bi values. A strong albite overprint records extreme Na gains with the loss of most other elements, including ore metals (i.e., Au, Cu). Together these data define an Au-Cu-Mo-Ag-Te-Bi-Se core co-spatial with biotite breccia versus a peripheral stockwork and sheeted vein zone with a Te-Se-Zn-Pb-As association. These features further support the posited porphyry-type model for the Côté Gold Au(-Cu) deposit. Full article

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

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15 pages, 15358 KiB

Open AccessEditor’s ChoiceArticle

Comparative Study of Colloidal and Rheological Behaviors of Mixed Palygorskite–Montmorillonite Clays in Freshwater and Seawater

by Jiajun Zhang, Guanzheng Zhuang, Jinrong Chen, Wenxiao Fan, Jixing Fan, Zhuhua Kuang and Dong Liu

Minerals 2025, 15(3), 251; https://doi.org/10.3390/min15030251 - 28 Feb 2025

Viewed by 443

Abstract

This study systematically investigates the colloidal stability, rheological properties, and filtration behavior of palygorskite–montmorillonite mixed clays in both freshwater and seawater systems. By varying the mass content and dispersion medium (freshwater/seawater), we analyze the colloidal stability, zeta potential, flow curves, viscosity, shear-thinning behavior, [...] Read more.

This study systematically investigates the colloidal stability, rheological properties, and filtration behavior of palygorskite–montmorillonite mixed clays in both freshwater and seawater systems. By varying the mass content and dispersion medium (freshwater/seawater), we analyze the colloidal stability, zeta potential, flow curves, viscosity, shear-thinning behavior, thixotropy, and fluid loss of the dispersions. The results show that palygorskite exhibits good rheological performance in both freshwater and seawater, while montmorillonite performs better in freshwater but suffers a significant decline in seawater. However, palygorskite demonstrates high fluid loss, which is unfavorable for drilling fluid function. Mixed clays can mitigate the limitations of individual clays to some extent, but the specific performance depends on the clay mineral content and dispersion medium. In freshwater, a small amount of montmorillonite improves the viscosity and shear-thinning behavior of the dispersion, with optimal montmorillonite contents of 22% and 38%, respectively. The thixotropy and fluid loss reduction in the mixed clays are positively correlated with montmorillonite content. In seawater, the rheological performance inversely correlates with Mt content due to montmorillonite’s high sensitivity to electrolytes. The addition of Pal enhances the colloidal stability and rheological properties of the mixed clays in seawater. This work provides theoretical insights into the behavior of mixed clays in different media, offering valuable guidance for the design of seawater-based drilling fluids. Full article

(This article belongs to the Collection Clays and Other Industrial Mineral Materials)

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23 pages, 24426 KiB

Open AccessEditor’s ChoiceArticle

Geometallurgical Characterization of the Arthur River Magnesite Deposit, Northwestern Tasmania for Pathways to Production

by Alfredtina Akua Abrafi Appiah, Julie Hunt, Mohammadbagher Fathi, Owen P. Missen, Wei Hong, Ivan Belousov, Verity Kameniar-Sandery and Mick Wilson

Minerals 2025, 15(3), 247; https://doi.org/10.3390/min15030247 - 27 Feb 2025

Viewed by 638

Abstract

The Arthur River magnesite deposit is in the northwestern part of Tasmania, Australia, within the Arthur Metamorphic Complex. Physical, mineralogical, and chemical characteristics of the deposit were studied using geological drill core logging and analytical techniques (scanning electron microscopy, portable x-ray fluorescence, and [...] Read more.

The Arthur River magnesite deposit is in the northwestern part of Tasmania, Australia, within the Arthur Metamorphic Complex. Physical, mineralogical, and chemical characteristics of the deposit were studied using geological drill core logging and analytical techniques (scanning electron microscopy, portable x-ray fluorescence, and laser ablation–inductively coupled plasma–mass spectrometry). The results document variations within the ore body, and three ore types have been identified for the potential production of an economic magnesite concentrate separated from associated gangue minerals (dolomite, quartz, and talc and iron bearing minerals such as pyrite and pyrrhotite). The ore types were identified based on a combination of physical, chemical, and mineralogical differences. Type 1 has a relatively high magnesium content and appears in drill core as hard white crystalline magnesite. Type 2 has relatively lower magnesium and higher iron contents than type 1 and occurs visibly as creamy-yellowish soft magnesite. Type 3 ore has the lowest magnesium and the highest iron content of the three ore types and is reddish brown in color. From the characterization studies, potential beneficiation routes for each ore type are suggested along with potential processing challenges. Examples of processing challenges include magnesium present in both magnesite and in dolomite, and the association of magnesite with quartz and talc results in a relatively high silica content. Full article

(This article belongs to the Special Issue Microanalysis Applied to Mineral Deposits)

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24 pages, 4725 KiB

Open AccessEditor’s ChoiceArticle

Unlocking Subsurface Geology: A Case Study with Measure-While-Drilling Data and Machine Learning

by Daniel Goldstein, Chris Aldrich, Quanxi Shao and Louisa O’Connor

Minerals 2025, 15(3), 241; https://doi.org/10.3390/min15030241 - 26 Feb 2025

Cited by 2 | Viewed by 888

Abstract

Bench-scale geological modeling is often uncertain due to limited exploration drilling and geophysical wireline measurements, reducing production efficiency. Measure-While-Drilling (MWD) systems collect drilling data to analyze mining blast hole drill rig performance. Early MWD studies focused on penetration rates to identify rock types. [...] Read more.

Bench-scale geological modeling is often uncertain due to limited exploration drilling and geophysical wireline measurements, reducing production efficiency. Measure-While-Drilling (MWD) systems collect drilling data to analyze mining blast hole drill rig performance. Early MWD studies focused on penetration rates to identify rock types. This paper investigates Artificial Intelligence (AI)-based regression models to predict geophysical signatures like density, gamma, magnetic susceptibility, resistivity, and hole diameter using MWD data. The machine learning (ML) models evaluated include Linear Regression (LR), Decision Trees (DTs), Support Vector Machines (SVMs), Random Forests (RFs), Gaussian Processes (GP), and Neural Networks (NNs). An analytical method was validated for accuracy, and a three-tier experimental method assessed the importance of MWD features, revealing no performance loss when excluding features with less than 2% importance. RF, DTs, and GPs outperformed other models, achieving R² values up to 0.98 with a low RMSE, while LR and SVMs showed lower accuracy. The NN’s performance improved with larger datasets. This study concludes that the DT, RF, and GP models excel in predicting geophysical signatures. While ML-based methods effectively model relationships in the data, their predictive performance remains inherently constrained by the underlying geological and physical mechanisms. Model selection depends on computational resources and application needs, offering valuable insights for real-time orebody analysis using AI. These findings could be invaluable to geologists who wish to utilize AI techniques for real-time orebody analysis and prediction. Full article

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

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23 pages, 8147 KiB

Open AccessEditor’s ChoiceArticle

Thermochronology of the Kalba–Narym Batholith and the Irtysh Shear Zone (Altai Accretion–Collision System): Geodynamic Implications

by Alexey Travin, Mikhail Buslov, Nikolay Murzintsev, Valeriy Korobkin, Pavel Kotler, Sergey V. Khromykh and Viktor D. Zindobriy

Minerals 2025, 15(3), 243; https://doi.org/10.3390/min15030243 - 26 Feb 2025

Viewed by 458

Abstract

The granitoids of the Kalba–Narym batholith and the Irtysh shear zone (ISZ) are among the main geological features of the late Paleozoic Altai accretion–collision system (AACS) in Eastern Kazakhstan. Traditionally, it is believed that late Paleozoic strike-slip faults played a pivotal role at [...] Read more.

The granitoids of the Kalba–Narym batholith and the Irtysh shear zone (ISZ) are among the main geological features of the late Paleozoic Altai accretion–collision system (AACS) in Eastern Kazakhstan. Traditionally, it is believed that late Paleozoic strike-slip faults played a pivotal role at all stages of the development of the AACS, they were supposed to control deformation, magmatism, and ore deposits. This work is devoted to solving the problem of the tectonic evolution of the AACS based on the reconstruction of the thermal history of granitoids of the Kalba–Narym batholith in connection with the Chechek metamorphic dome structure, which is one of the highly metamorphosed blocks mapped within the ISZ. The new geological and geochronological data presented in this work allowed us to establish the sequence of formation of the Kalba–Narym granitoid batholith and link it with the evolution of the Irtysh shear zone (ISZ). It was revealed that in the late Carboniferous–early Permian (312–289 Ma), during the NE–SW compression, the Irtysh shear zone formed as a gently dipping thrust system into which gabbro of the Surov massif intruded. The combined manifestation of magmatic and tectonic processes caused the formation of tectonic mélange with cataclastic gabbro and metamorphic rocks of the Chechek metamorphic dome structure (312–289 Ma). Compression caused the formation of a cover-thrust structure. The thickening of the crust under the probable thermal action of the Tarim plume led to the formation of the early Permian Kalba–Narym batholith (297–284 Ma) within the Kalba–Narym terrane. Denudation of the orogen occurred before the Early Triassic (280–229 Ma). In this way the sequence of formation of the Kalba–Narym batholith and the ISZ is consistent with the concepts of the stages of plume-lithosphere interaction within the AACS under the influence of the late Carboniferous–early Permian Tarim igneous province, but in the cover-thrust tectonic setting. Full article

(This article belongs to the Special Issue Developments in Geochronology and Dating of Shear Zone Deformation)

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20 pages, 5571 KiB

Open AccessEditor’s ChoiceArticle

Utilization of the Finer Particle Fraction of Arsenic-Bearing Excavated Rock Mixed with Iron-Based Adsorbent as Sorption Layer

by Daisuke Ishigami, Takahiko Arima, Satoshi Shinohara, Yutaka Kamijima, Keijirou Ito, Tasuma Suzuki, Keita Nakajima, Walubita Mufalo and Toshifumi Igarashi

Minerals 2025, 15(3), 242; https://doi.org/10.3390/min15030242 - 26 Feb 2025

Viewed by 1404

Abstract

Excavated rocks generated during tunnel construction may pose an environmental hazard due to the release of acidic leachate containing potentially toxic elements (PTEs). Addressing this concern requires strategic countermeasures against mitigating the release of PTEs. This study investigated the efficacy of a novel [...] Read more.

Excavated rocks generated during tunnel construction may pose an environmental hazard due to the release of acidic leachate containing potentially toxic elements (PTEs). Addressing this concern requires strategic countermeasures against mitigating the release of PTEs. This study investigated the efficacy of a novel approach for managing altered excavated rocks that generate acidic leachates with elevated arsenic (As) by utilizing the finer altered rock as a base material for the sorption layer. The proposed method involves classifying the altered excavated rocks into coarse (9.5–37.5 mm) and finer (<9.5 mm) fractions, with the finer fractions incorporated with iron (Fe)-based adsorbent to form a bottom sorption layer for the disposal of coarser rock samples. Leaching behavior and As immobilization efficiency were assessed through shaking, stirring leaching tests, batch sorption tests, and column tests under varying particle size fractions of the rock samples. Results indicate that altered finer rock fractions exhibit increased As leaching under shaking conditions due to enhanced dissolution. The addition of >1% of Fe-based adsorbent to the finer rock in the sorption layer effectively suppressed As leaching concentration, meeting the management criterion of <0.3 mg/L for specially controlled contaminated soils in Japan. Batch sorption tests using the finer rock samples with the Fe-based adsorbent confirmed their efficacy as effective adsorbents. This efficacy was further elucidated in column experiments consisting of the coarse rock samples and fine altered rock samples mixed with the Fe based adsorbent at the bottom as a sorption layer. Results showed that the sorption layer effectively decreased the As leached from the rock layer, utilizing the altered excavated fine rock as a base material in the sorption layer. This approach highlights the potential for repurposing excavated rocks as sorption media, enabling sustainable management strategies for As-contaminated rocks. This study provides an innovative framework for integrating adsorption-based remediation, contributing to sustainable countermeasure strategies for excavated rocks. Full article

(This article belongs to the Special Issue Environmental Geochemistry of Heavy Metals: Contamination, Impacts, and Countermeasure Strategies)

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21 pages, 4966 KiB

Open AccessEditor’s ChoiceArticle

Influence of Particle Shape and Size on Gyratory Crusher Simulations Using the Discrete Element Method

by Manuel Moncada, Christian Rojas, Patricio Toledo, Cristian G. Rodríguez and Fernando Betancourt

Minerals 2025, 15(3), 232; https://doi.org/10.3390/min15030232 - 26 Feb 2025

Cited by 1 | Viewed by 534

Abstract

Gyratory crushers are fundamental machines in aggregate production and mineral processing. Discrete Element Method (DEM) simulations offer detailed insights into the performance of these machines and serve as a powerful tool for their design and analysis. However, these simulations are computationally intensive due [...] Read more.

Gyratory crushers are fundamental machines in aggregate production and mineral processing. Discrete Element Method (DEM) simulations offer detailed insights into the performance of these machines and serve as a powerful tool for their design and analysis. However, these simulations are computationally intensive due to the large number of particles involved and the need to account for particle breakage. This study aims to investigate the effect of particle shape and size distribution on the performance of a DEM model of a gyratory crusher. The selected study case corresponds to a primary gyratory crusher operating in a copper processing industry. As particle shapes, spheres and polyhedrons are used with a particle replacement scheme. This study utilizes two different size distributions, with variations also applied to the minimum particle size. The results are analyzed in terms of the impact of these factors on the power draw, mass flow, and product size distribution for each of the combinations explained. The findings demonstrate that particle shape primarily influences the product size distribution, whereas variations in particle size distribution have a pronounced effect on power draw, mass flow rate, and product size distribution. Based on the results, recommendations are provided regarding the selection of the minimum particle size. It is concluded that the minimum particle size should not exceed a third of the closed-side setting to ensure accurate and reliable simulation outcomes. Full article

(This article belongs to the Special Issue Process Modelling and Applications for Aggregate Production)

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17 pages, 2921 KiB

Open AccessEditor’s ChoiceArticle

Melting Curve of Potassium Carbonate K₂CO₃ at High Pressures

by Jiaqi Lu, Siyuan He, Rebecca Lange and Jie Li

Minerals 2025, 15(3), 217; https://doi.org/10.3390/min15030217 - 24 Feb 2025

Viewed by 624

Abstract

Melting of carbonated rocks in the mantle influences the Earth’s deep carbon cycle and the long-term evolution of the atmosphere. Previous studies of the high-pressure melting curve of K₂CO₃ have yielded inconsistent results, with discrepancies of nearly 200 °C at [...] Read more.

Melting of carbonated rocks in the mantle influences the Earth’s deep carbon cycle and the long-term evolution of the atmosphere. Previous studies of the high-pressure melting curve of K₂CO₃ have yielded inconsistent results, with discrepancies of nearly 200 °C at 3 GPa and more than 400 °C at 12 GPa. Here, we report constraints on the melting curve of K₂CO₃ at pressures up to 20 GPa from in situ ionic conduction experiments and Pt sphere experiments. To help resolve the large discrepancies, we tested the ionic conduction method against the well-established differential thermal analysis (DTA) method and conventional Pt sphere method at the ambient pressure of 1 bar. Furthermore, ionic conduction experiments were conducted on sodium chloride (NaCl) to reduce uncertainties in pressure calibration of the multi-anvil press. We also modified the configuration of the in situ ionic conduction experiments to minimize the influence of thermal gradient on melting point determination. Finally, we inspected the effect of water by varying the initial sample state and container wall thickness in the Pt sphere experiments and applied X-ray radiography as a reliable and efficient method to examine the products. Compared with the results from the ionic conduction experiments, the melting point of K₂CO₃ from the Pt sphere experiments was found to be 200~400 °C lower, likely due to a small amount of water trapped by hygroscopic K₂CO₃ in closed platinum (Pt) capsules. We find that anhydrous K₂CO₃ remains more refractory than Na₂CO₃ at elevated pressures. Full article

(This article belongs to the Special Issue Phase Transitions and Physical Properties of Minerals under Extreme Conditions of Pressure and Temperature)

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20 pages, 5757 KiB

Open AccessEditor’s ChoiceArticle

Mineral Chemistry of Li-Bearing Minerals at the Giant Tanco Pegmatite, Canada

by Paul Alexandre and Stefano Salvi

Minerals 2025, 15(3), 221; https://doi.org/10.3390/min15030221 - 24 Feb 2025

Viewed by 622

Abstract

The highly fractionated late Archean Tanco pegmatite (Bernic Lake, SE Manitoba, Canada) is a world-class producer of tantalum and cerium but is also a major source of lithium. In order to better understand the major Li hosts and the overall Li budget of [...] Read more.

The highly fractionated late Archean Tanco pegmatite (Bernic Lake, SE Manitoba, Canada) is a world-class producer of tantalum and cerium but is also a major source of lithium. In order to better understand the major Li hosts and the overall Li budget of the Tanco pegmatite, the lithium-bearing minerals present here were analyzed for major and trace elements by electron microprobe and laser ablation ICP-MS, respectively. The major Li-bearing minerals present in the Tanco pegmatite are eucryptite (approximately 11.0 wt% Li₂O), montebrasite (~11.2 wt%), lithiophilite (9.1 wt%), spodumene (~8.8 wt%), petalite (5.45 wt%), lepidolite (4.36 wt%), and tancoite (5.2 wt%); Li is also present in lithiowodginite, tourmaline, muscovite, beryl, pollucite, and apatite (between 0.1 and 1.3 wt% Li₂O). Most of the Li present in Tanco is contained in petalite (69.4% of all the Li present here), followed by spodumene (11.4%), montebrasite (11.1%), and eucryptite (4.0%); all remaining Li-bearing minerals contain 4.0% of the Li present in the Tanco pegmatite. Overall, the Tanco pegmatite contains approximately 0.71 wt% Li₂O, on par with previous estimates. The major practical implications of these finding are that (1) all Li-bearing minerals have to be considered to properly estimate the Li endowment of any pegmatite; (2) the main Li-bearing mineral is not always spodumene; (3) the exact and detailed Li mineralogy of a pegmatite will directly affect extraction and processing; and (4) a significant proportion of Li in any pegmatite is contained in other minerals than the main one, be it spodumene of petalite. Full article

(This article belongs to the Section Mineral Deposits)

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29 pages, 7079 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Comparison of Ferronickel Alloys Produced via Microwave and Conventional Thermal Concentration of Pyrrhotite Tailings

by Michael Jaansalu and Christopher Pickles

Minerals 2025, 15(3), 196; https://doi.org/10.3390/min15030196 - 20 Feb 2025

Viewed by 557

Abstract

In modern nickel mineral processing operations, the aim is to separate pentlandite from gangue minerals. One of these gangue minerals, pyrrhotite, contains up to 1 wt% Ni but is disposed of as waste, i.e., as tailings. Declining sulfide ore grades and increasing nickel [...] Read more.

In modern nickel mineral processing operations, the aim is to separate pentlandite from gangue minerals. One of these gangue minerals, pyrrhotite, contains up to 1 wt% Ni but is disposed of as waste, i.e., as tailings. Declining sulfide ore grades and increasing nickel demand have led to renewed interest in extracting nickel from pyrrhotite tails. One proposed process is thermal concentration, which aims to recover the nickel as a ferronickel alloy via thermal treatment at temperatures greater than 900 °C. Achieving these temperatures requires substantial energy input as the reactions involved are highly endothermic. In the present research, microwave radiation was used to process a reaction mixture consisting of a concentrate of pyrrhotite tails, iron ore, and metallurgical coke. The fundamental property that determines the interaction of microwaves with a material is complex permittivity. It was found that the reaction mixture had very high real and imaginary permittivities, making it a good candidate for microwave treatment. An input power of 800 W of microwave radiation (2450 MHz) was then employed to heat various reaction mixtures for thermal treatment times of 120, 300, and 600 s. The ferroalloy grades (6–7.5 wt% Ni) were comparable to those produced by conventional heating and to those obtained by other authors using conventional heating techniques. The microwaved samples had increased metallization of nickel, which was attributed to increased melting due to the higher internal temperatures. Full article

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

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17 pages, 3450 KiB

Open AccessEditor’s ChoiceArticle

Research on Optimization of Lifter of an SAG Mill Based on DEM Simulation and Orthogonal Tests and Applications

by Guobin Wang, Qingfei Xiao, Xiaojiang Wang, Yunxiao Li, Saizhen Jin, Mengtao Wang, Yunfeng Shao, Qian Zhang, Yingjie Pei and Ruitao Liu

Minerals 2025, 15(2), 193; https://doi.org/10.3390/min15020193 - 19 Feb 2025

Viewed by 442

Abstract

The unreasonable parameters of mill liner lifter bars will not only decrease the operating rate of the mill and increase electricity consumption but, also, seriously restrict the production capacity of the mill. Therefore, optimizing the parameters of liner lifter bars is helpful to [...] Read more.

The unreasonable parameters of mill liner lifter bars will not only decrease the operating rate of the mill and increase electricity consumption but, also, seriously restrict the production capacity of the mill. Therefore, optimizing the parameters of liner lifter bars is helpful to save energy, improve its production capacity, and increase benefits for enterprises. Given the unreasonable parameters of the lifter bars of the semi-autogenous grinding (SAG) mill in a beneficiation plant in Yunnan (China), the distinct element method (DEM) with orthogonal tests was used to conduct simulation, the simulation results demonstrating that the three parameters all had significant influence on the collision energy, with the order of group numbers > angles > heights by the analysis of range and variance, and the optimal parameters combination, with angles of 20°, groups of 12, and heights of 210 mm, was obtained. Then, the lifer bars optimized were applied in industrial tests to verify their effect, and the results illustrated that all of the service life of lifter bars, the operating rate, production capacity, and electricity consumption were significantly improved at 159 days, 92.32%, 54.37 t/h, and 21.45 kW·h/t, respectively. This paper proposes a reference for the similar design and optimization of lifter bars for the other beneficiation plants. Full article

(This article belongs to the Special Issue Recent Advances in Ore Comminution)

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17 pages, 4237 KiB

Open AccessEditor’s ChoiceArticle

Prediction of Mine Waste Rock Drainage Quantity Using a Machine Learning Model with Physical Constraints

by Can Zhang, Liang Ma and Wenying Liu

Minerals 2025, 15(2), 194; https://doi.org/10.3390/min15020194 - 19 Feb 2025

Viewed by 442

Abstract

Mining activities generate substantial amounts of waste rock, which are often disposed of in waste rock piles. Drainage from these piles can pose serious environmental risks. It is crucial to reliably predict drainage properties in order to effectively manage them. In previous work, [...] Read more.

Mining activities generate substantial amounts of waste rock, which are often disposed of in waste rock piles. Drainage from these piles can pose serious environmental risks. It is crucial to reliably predict drainage properties in order to effectively manage them. In previous work, we developed a machine learning model to predict waste rock drainage quantity using weather monitoring data as the input and drainage flow rate as the output. However, this model lacked physical constraints, limiting its interpretability, reliability, and applicability. In this study, we introduced a new machine learning model designed with physical constraints to improve the predictions of drainage quantity. This new model incorporates a weather refining sub-model and integrates physical constraints to enhance the overall reliability of the model predictions. The weather refining sub-model transforms primary weather features (total precipitation and temperature) into secondary features (rainfall, snowmelt, and evaporation) through established mathematical relationships. These secondary features were then used as inputs for the machine learning model to predict drainage quantity. To embed physical principles within the machine learning model, we integrated a water balance equation into the neural network architecture and modified the loss function accordingly. In addition, we included an adjustable bias term to optimize the balance between model performance and interpretability. Compared with our previous model, the incorporation of physical constraints into the machine learning model improved the accuracy of the drainage quantity predictions. More importantly, this approach ensures that the model outputs adhere to physical laws, thereby enhancing its interpretability, reliability, and applicability. Full article

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

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27 pages, 11125 KiB

Open AccessEditor’s ChoiceArticle

Geochemical Insights and Mineral Resource Potential of Rare Earth Elements (REE) in the Croatian Karst Bauxites

by Erli Kovačević Galović, Nikolina Ilijanić, Nikola Gizdavec, Slobodan Miko and Zoran Peh

Minerals 2025, 15(2), 192; https://doi.org/10.3390/min15020192 - 19 Feb 2025

Viewed by 693

Abstract

Karst bauxites are valuable terrestrial records of paleoclimate and tectonic evolution formed under tropical to subtropical conditions during the subaerial exposure of carbonate platforms. This study explores Croatian bauxite deposits within the Adriatic–Dinaric Carbonate Platform (ADCP), with a focus on the distribution and [...] Read more.

Karst bauxites are valuable terrestrial records of paleoclimate and tectonic evolution formed under tropical to subtropical conditions during the subaerial exposure of carbonate platforms. This study explores Croatian bauxite deposits within the Adriatic–Dinaric Carbonate Platform (ADCP), with a focus on the distribution and enrichment of rare earth elements (REE) across eight bauxite horizons from the Triassic to Neogene periods. The research applies statistical analyses of geochemical data, as well as developed models, to assess the factors influencing REE distribution and fractionation. The study found that variations in parent material, along with changes in paleogeographical and paleotectonic settings, significantly affected the REE content. The median REE concentrations in the analyzed bauxite horizons range from approximately 250 to 570 mg/kg. Notable REE enrichment was observed in the Late Paleogene, particularly in the Middle and Upper Eocene horizons. The analysis highlights the importance of physicochemical conditions, such as Eh and pH, during the weathering processes that lead to bauxite formation. The results suggest that the presence of REE-bearing minerals, rather than clay minerals, could possibly contribute to elevated concentrations of heavy REE (HREE). These findings indicate that Croatian bauxites, enriched in REE and associated trace elements, are significant not only as geological markers of past climatic and tectonic events but also as potential sources of critical raw materials. This study underscores the potential for the economic exploitation of these deposits in the context of modern technological demands. Full article

(This article belongs to the Special Issue Trace Elements in Bauxite Deposits: Critical Georesource and Significant Indicators of Paleoenvironmental Conditions)

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27 pages, 26571 KiB

Open AccessEditor’s ChoiceArticle

Sources and Enrichment Mechanisms of Rare-Earth Elements in the Mosuoying Granites, Sichuan Province, Southwest China

by Xuepeng Xiao, Guoxin Li, Shuyi Dong, Lijun Qian and Lihua Ou

Minerals 2025, 15(2), 185; https://doi.org/10.3390/min15020185 - 17 Feb 2025

Viewed by 1014

Abstract

Ion-adsorption-type rare-earth element (iREE) deposits, a primary source of global heavy REE (HREE) ores, have attracted wide attention worldwide due to their concentrated distributions and irreplaceable role in the field of cutting-edge technologies. In recent years, iREE mineralization has been reported in the [...] Read more.

Ion-adsorption-type rare-earth element (iREE) deposits, a primary source of global heavy REE (HREE) ores, have attracted wide attention worldwide due to their concentrated distributions and irreplaceable role in the field of cutting-edge technologies. In recent years, iREE mineralization has been reported in the overlying weathering crust of the Mosuoying granites within the Dechang counties, Sichuan Province, Southwest China, suggesting great potential for the formation of iREE deposits. The Mosuoying granites, acting as the primary carrier of REE pre-enrichment, govern the contents and distribution patterns of REEs in their weathering crust. Therefore, investigating the sources and enrichment mechanisms of REEs in the parent rocks will provide a critical theoretical basis for the scientific exploitation and utilization of iREE deposits. In this study, we investigated the migration and enrichment of REEs in the Mosuoying granites (850–832 Ma) using petrography, geochronology, geochemical, and Sr-Nd-Hf isotopic data. The results reveal that the REE enrichment in the Mosuoying granites might be associated with both the melting of crustal felsic rocks and the magmatic-hydrothermal evolution. On the one hand, the granites exhibit different REE patterns. Compared to the light REE (LREE)-rich granites, the HREE-rich granites feature higher SiO₂ contents, higher differentiation index (DI), lower Nb/Ta and Zr/Hf ratios, and more significant negative Eu anomalies, indicating that the crystal fractionation of magmas governed the differentiation of REEs. Furthermore, the hydrothermal fluids further promoted the formation of the HREE-rich granites. On the other hand, the geochemical characteristics suggest that they are A-type granites. Regarding the isotopic characteristics, the Mosuoying granites exhibit negative whole-rock εNd(t) and zircon εHf(t) values, suggesting an evolved crustal source. Therefore, we suggest that the high REE contents in the Mosuoying A-type granites might originate from the partial melting of felsic rocks in a shallow crustal source under high-temperature and low-pressure conditions. Specifically, the high-temperature A-type granitic magmas caused the partial melting of the felsic crustal materials to release REEs; concurrently, these magmas enhanced the solubility of REEs in melt during magmatic evolution, inhibiting the separation of REE-bearing minerals from the melts. These increased the REE contents of the granites. The high-temperature heat source might be associated with the process where the asthenospheric mantle experienced upwelling along slab windows and heated continental crust in the Neoproterozoic extensional setting. Full article

(This article belongs to the Section Mineral Deposits)

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16 pages, 8572 KiB

Open AccessEditor’s ChoiceArticle

Effect of Flotation Variables on Slurry Rheological Properties and Flotation Performance of Lead–Zinc Sulfide Ores

by Kehua Luo, Chuanyao Sun and Tichang Sun

Minerals 2025, 15(2), 187; https://doi.org/10.3390/min15020187 - 17 Feb 2025

Viewed by 466

Abstract

A slurry’s rheological properties significantly affect flotation performance. Flotation variables—including mineral composition, slurry concentration, and ore particle size—influence these properties by altering the interaction forces between mineral particles and the slurry’s microstructure, thereby impacting flotation outcomes. This study investigated the effects of flotation [...] Read more.

A slurry’s rheological properties significantly affect flotation performance. Flotation variables—including mineral composition, slurry concentration, and ore particle size—influence these properties by altering the interaction forces between mineral particles and the slurry’s microstructure, thereby impacting flotation outcomes. This study investigated the effects of flotation variables on the rheological properties and flotation performance of lead–zinc sulfide ores in two ternary systems comprising galena or sphalerite + kaolinite and quartz. Cryo-scanning electron microscopy and atomic force microscopy were used to analyze the slurries’ interaction forces and microstructure. The results show that finer ore particle sizes increase the formation of particle agglomerates, leading to larger structures and higher slurry apparent viscosity. This improves the metal mineral recovery rate during flotation but simultaneously increases gangue mineral entrainment, reducing concentrate grade. As the slurry concentration increases, the ternary system with kaolinite as the main gangue mineral forms a denser and more rigid honeycomb network structure. This results in higher yield stress and apparent viscosity, which negatively impacts lead and zinc sulfide separation during flotation. In contrast, the quartz-dominated system forms a slightly denser, stacked structure that lacks a solid network and thus maintains lower yield stress and apparent viscosity, which favors mineral separation. Adding sodium hexametaphosphate enhances particle dispersion by increasing repulsive forces between mineral particles. This thins or disrupts the kaolinite network structure, reducing the slurry’s apparent viscosity and yield stress, thereby improving its rheological properties and facilitating the flotation separation of lead and zinc sulfide minerals. Full article

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

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14 pages, 5211 KiB

Open AccessEditor’s ChoiceArticle

Multianalytical Study of Archaeological Iron Nails of the Roman Period (First to Third Century) in Northern Spain

by Céline Rémazeilles, Maria Cruz Zuluaga, Egle Conforto, Abdelali Oudriss, Luis Ángel Ortega, Ana Martínez-Salcedo and Juan José Cepeda-Ocampo

Minerals 2025, 15(2), 168; https://doi.org/10.3390/min15020168 - 11 Feb 2025

Viewed by 613

Abstract

In the archaeometallurgical study of iron nails to investigate Roman manufacturing processes, multi-analyte characterization provides information on alloy composition and microstructure. Nails from the Roman sites of Forua, Aloria, and Iuliobriga (northern Spain) were studied. To characterize the iron phases and microstructures of [...] Read more.

In the archaeometallurgical study of iron nails to investigate Roman manufacturing processes, multi-analyte characterization provides information on alloy composition and microstructure. Nails from the Roman sites of Forua, Aloria, and Iuliobriga (northern Spain) were studied. To characterize the iron phases and microstructures of the nails, optical microscopy (OM), scanning electron microscopy coupled with electron-dispersive spectroscopy (SEM-EDX), micro-Raman spectroscopy, electron backscatter diffraction (EBSD) realized in environmental mode, and microhardness measurements were carried out. The chemical composition of the metal was determined by X-ray fluorescence (XRF). The corrosion mineralogical composition was determined by powder X-ray diffraction (XRD). Aggressive burial conditions had a significant effect on the forms of corrosion of the Forua nails to the point of complete iron loss. Examination of the metal of the nails from the Aloria site revealed that most of the ironwork was made in the villa’s own forge. In the case of the Iuliobriga nails, different degrees of forging were identified associated with different workshops. Full article

(This article belongs to the Special Issue The Significance of Applied Mineralogy in Archaeometry)

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29 pages, 20123 KiB

Open AccessEditor’s ChoiceReview

Secrets from the Depths of Space and Earth: Unraveling Newly Discovered High-Pressure Polymorphs in Meteorites and Diamond Inclusions

by Dmitry Pushcharovsky and Luca Bindi

Minerals 2025, 15(2), 144; https://doi.org/10.3390/min15020144 - 31 Jan 2025

Cited by 1 | Viewed by 975

Abstract

Significant recent discoveries of a large group of high-pressure (HP) minerals are reviewed. These minerals can be classified into two genetic types: those formed in shocked meteorites and impact craters and those formed under static P-T conditions and found as inclusions in diamonds. [...] Read more.

Significant recent discoveries of a large group of high-pressure (HP) minerals are reviewed. These minerals can be classified into two genetic types: those formed in shocked meteorites and impact craters and those formed under static P-T conditions and found as inclusions in diamonds. Of particular interest are the HP-polymorphic modifications of minerals such as olivine, ilmenite, ulvöspinel, wollastonite, and feldspars. Some examples include asimowite, poirierite, ohtaniite, liuite, wangdaodeite, tschaunerite, breyite, davemaoite, lingunite, and liebermannite. Special attention is also devoted to new dense hydrous silicates, which show much better stability than other known hydrous minerals to act as water reservoirs in the early stage of Earth’s geological history. The crystal structures and compositions of these new HP-minerals provide valuable insights into the complex petrology of deep geospheres, otherwise not obtainable in laboratory experiments. Using such a rich database, further steps became appropriate and possible toward the directions of a more advanced knowledge of evolution, composition, and structure of Earth. Full article

(This article belongs to the Special Issue Crystal Structures and Phase Transitions of Minerals at Extreme Conditions, 2nd Edition)

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39 pages, 48972 KiB

Open AccessEditor’s ChoiceArticle

Volcanic Response to Post-Pan-African Orogeny Delamination: Insights from Volcanology, Precise U-Pb Geochronology, Geochemistry, and Petrology of the Ediacaran Ouarzazate Group of the Anti-Atlas, Morocco

by Mohamed Achraf Mediany, Nasrrddine Youbi, Mohamed Ben Chra, Oussama Moutbir, Ismail Hadimi, João Mata, Jörn-Frederik Wotzlaw, José Madeira, Miguel Doblas, Ezz El Din Abdel Hakim Khalaf, Rachid Oukhro, Warda El Moume, Jihane Ounar, Abdelhak Ait Lahna, Moulay Ahmed Boumehdi and Andrey Bekker

Minerals 2025, 15(2), 142; https://doi.org/10.3390/min15020142 - 31 Jan 2025

Viewed by 1474

Abstract

Post-collisional volcanism provides valuable insights into mantle dynamics, crustal processes, and mechanisms driving orogen uplift and collapse. This study presents geological, geochemical, and geochronological data for Ediacaran effusive and pyroclastic units from the Taghdout Volcanic Field (TVF) in the Siroua Window, Anti-Atlas Belt. [...] Read more.

Post-collisional volcanism provides valuable insights into mantle dynamics, crustal processes, and mechanisms driving orogen uplift and collapse. This study presents geological, geochemical, and geochronological data for Ediacaran effusive and pyroclastic units from the Taghdout Volcanic Field (TVF) in the Siroua Window, Anti-Atlas Belt. Two eruptive cycles are identified based on volcanological and geochemical signatures. The first cycle comprises a diverse volcanic succession of basalts, basaltic andesites, andesites, dacites, and rhyolitic crystal-rich tuffs and ignimbrites, exhibiting arc calc-alkaline affinities. These mafic magmas were derived from a lithospheric mantle metasomatized by subduction-related fluids and are associated with the gravitational collapse of the Pan-African Orogen. The second cycle is marked by bimodal volcanism, featuring tholeiitic basalts sourced from the asthenospheric mantle and felsic intraplate magmas. These units display volcanological characteristics typical of facies models for continental basaltsuccessions and continental felsic volcanoes. Precise CA-ID-TIMS U-Pb zircon dating constrains the volcanic activity to 575–557 Ma, reflecting an 18-million-year period of lithospheric thinning, delamination, and asthenospheric upwelling. This progression marks the transition from orogen collapse to continental rifting, culminating in the breakup of the Rodinia supercontinent and the opening of the Iapetus Ocean. The TVF exemplifies the dynamic interplay between lithospheric and asthenospheric processes during post-collisional tectonic evolution. Full article

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

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12 pages, 1105 KiB

Open AccessEditor’s ChoiceArticle

Cyanide Storage on Ferroan Brucite (Mg_xFe_1−x(OH)₂): Implications for Prebiotic Chemistry

by Ellie K. Hara and Alexis S. Templeton

Minerals 2025, 15(2), 141; https://doi.org/10.3390/min15020141 - 31 Jan 2025

Cited by 1 | Viewed by 1041

Abstract

Cyanide is a crucial reagent for the synthesis of biomolecules in prebiotic chemistry. However, effective organic synthesis requires cyanide to be concentrated. One proposed mechanism for cyanide storage and concentration on Early Earth involves the formation of aqueous ferrocyanide complexes. In basic pH [...] Read more.

Cyanide is a crucial reagent for the synthesis of biomolecules in prebiotic chemistry. However, effective organic synthesis requires cyanide to be concentrated. One proposed mechanism for cyanide storage and concentration on Early Earth involves the formation of aqueous ferrocyanide complexes. In basic pH conditions, cyanide will spontaneously form ferrocyanide complexes in the presence of aqueous Fe(II). While ferrocyanide aqueous complex formation is well defined, the potential for Fe(II)-bearing minerals to react with cyanide to form ferrocyanide complexes or store cyanide on the mineral surface has yet to be explored under prebiotically relevant conditions. In this study, we demonstrate that when cyanide interacts with ferroan brucite (Mg_xFe_1−x(OH)₂), cyanide will both form aqueous and mineral-surface-adsorbed ferrocyanide implying that there are two reservoirs that cyanide will partition into. In addition, we found that cyanide decreased the amount of hydrogen gas produced by the oxidation of ferroan brucite, indicating that cyanide alters the mineral’s redox reactivity. The cyanide adsorbed on brucite can be released by a decrease in pH, which leads to the dissolution of ferroan brucite, thus releasing the adsorbed cyanide. Our findings suggest that iron-bearing minerals may represent an overlooked storage reservoir of cyanide on Hadean Earth, potentially playing a significant role in cyanide availability for prebiotic chemistry. Full article

(This article belongs to the Special Issue Redox Reactivity of Iron Minerals in the Geosphere, 2nd Edition)

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17 pages, 1551 KiB

Open AccessEditor’s ChoiceArticle

Bioavailable and Bioaccessible Fractions of Potentially Toxic Elements in Copper Mining Wastes in the Southeastern Amazon

by Gabriela Vilhena de Almeida Pereira, Wendel Valter da Silveira Pereira, Sílvio Junio Ramos, José Tasso Felix Guimarães, Watilla Pereira Covre, Yan Nunes Dias and Antonio Rodrigues Fernandes

Minerals 2025, 15(2), 140; https://doi.org/10.3390/min15020140 - 30 Jan 2025

Viewed by 1342

Abstract

The Brazilian Amazon presents several artisanal and industrial Cu mines that generate significant amounts of waste. The objective of this study was to evaluate the risks to the environment and human health based on the bioavailable and bioaccessible concentrations of potentially toxic elements [...] Read more.

The Brazilian Amazon presents several artisanal and industrial Cu mines that generate significant amounts of waste. The objective of this study was to evaluate the risks to the environment and human health based on the bioavailable and bioaccessible concentrations of potentially toxic elements (PTEs; Ba, Co, Cr, Cu, Mo, Ni, Pb, and Zn) in artisanal and industrial Cu mining areas in the Carajás Mineral Province (CMP), eastern Amazon. For this purpose, samples (0–20 cm depth) were collected from natural forest soils (considered as a reference), as well as areas where artisanal mining wastes (artisanal overburden–AO and artisanal rock waste–AR) and industrial mining tailings (IT) were deposited. Total PTE concentrations were obtained via acid digestion, bioavailable concentrations were obtained via sequential extraction, and oral bioaccessible concentrations were obtained via the simple bioaccessibility extraction test. Environmental indices were obtained from PTE concentrations. The results indicated contamination by elements such as Mo, Cr, Ni, and Cu, mainly in AR, which had the highest contamination levels. Sequential extraction revealed that most PTEs are in residual form, suggesting low environmental risk from the bioavailable fraction. The bioaccessible concentrations of Cr and Ni were associated with health risks for children in AR. The results of this study will be important for protecting the environment and public health in artisanal mining areas in the region. Full article

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

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22 pages, 9743 KiB

Open AccessEditor’s ChoiceArticle

Machine Learning-Based Tectonic Discrimination Using Basalt Element Geochemical Data: Insights into the Carboniferous–Permian Tectonic Regime of Western Tianshan Orogen

by Hengxu Li, Mengqi Gao, Xiaohui Ji, Zhaochong Zhang, Zhiguo Cheng and M. Santosh

Minerals 2025, 15(2), 122; https://doi.org/10.3390/min15020122 - 26 Jan 2025

Viewed by 886

Abstract

Identifying the tectonic setting of rocks is essential for gaining insights into the geological contexts in which these rocks were formed, aiding in tectonic plate reconstruction and enhancing our comprehensive understanding of the Earth’s history. The application of machine learning algorithms helps identify [...] Read more.

Identifying the tectonic setting of rocks is essential for gaining insights into the geological contexts in which these rocks were formed, aiding in tectonic plate reconstruction and enhancing our comprehensive understanding of the Earth’s history. The application of machine learning algorithms helps identify complex patterns and relationships between big data that may be overlooked by binary or ternary tectonomagmatic discrimination diagrams based on basalt compositions. In this study, three machine learning algorithms, i.e., Support Vector Machine (SVM), Random Forest (RF), and eXtreme Gradient Boosting (XGBoost), were employed to classify the basalts from seven diverse settings, including intraplate basalts, island arc basalts, ocean island basalts, mid-ocean ridge basalts, back-arc basin basalts, oceanic flood basalts, and continental flood basalts. Specifically, for altered and fresh basalt samples, we utilized 22 immobile elements and 35 major and trace elements, respectively, to construct discrimination models. The results indicate that XGBoost demonstrates the best performance in discriminating basalts into seven tectonic settings, achieving accuracies of 85% and 89% for the altered and fresh basalt samples, respectively. A key innovation of our newly developed tectonic discrimination model is the establishment of tailored models for altered and fresh basalts. Moreover, by omitting isotopic features during model construction, the new models offer broader applicability in predicting a wider range of basalt samples in practical scenarios. The classification models were applied to investigate the Carboniferous to Permian evolution in the Western Tianshan Orogen (WTO), revealing that the subduction of Tianshan Ocean ceased at the end of Carboniferous and the WTO evolved into a post-collisional orogenesis during the Permian. Full article

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

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27 pages, 15736 KiB

Open AccessEditor’s ChoiceArticle

Predicting Manganese Mineralization Using Multi-Source Remote Sensing and Machine Learning: A Case Study from the Malkansu Manganese Belt, Western Kunlun

by Jiahua Zhao, Li He, Jiansheng Gong, Zhengwei He, Ziwen Feng, Jintai Pang, Wanting Zeng, Yujun Yan and Yan Yuan

Minerals 2025, 15(2), 113; https://doi.org/10.3390/min15020113 - 24 Jan 2025

Viewed by 1687

Abstract

This study employs multi-source remote sensing information and machine learning methods to comprehensively assess the geological background, structural features, alteration anomalies, and spectral characteristics of the Malkansu Manganese Ore Belt in Xinjiang. Manganese mineralization is predicted, and areas with high mineralization potential are [...] Read more.

This study employs multi-source remote sensing information and machine learning methods to comprehensively assess the geological background, structural features, alteration anomalies, and spectral characteristics of the Malkansu Manganese Ore Belt in Xinjiang. Manganese mineralization is predicted, and areas with high mineralization potential are delineated. The results of the feature factor weight analysis indicate that structural density and lithological characteristics contribute most significantly to manganese mineralization. Notably, linear structures are aligned with the direction of the manganese belt, and areas exhibiting high controlling structural density are closely associated with the locations of mineral deposits, suggesting that structure plays a crucial role in manganese production in this region. The Area Under the Curve (AUC) values for the Random Forest (RF), Naïve Bayes (NB), and eXtreme Gradient Boosting (XGBoost) models were 0.975, 0.983, and 0.916, respectively, indicating that all three models achieved a high level of performance and interpretability. Among these, the NB model demonstrated the highest performance. By algebraically overlaying the predictions from these three machine learning models, a comprehensive mineralization favorability map was generated, identifying 11 prospective mineralization zones. The performance metrics of the machine learning models validate their robustness, while regional tectonics and stratigraphic lithology provide valuable characteristic factors for this approach. This study integrates multi-source remote sensing information with machine learning methods to enhance the effectiveness of manganese prediction, thereby offering new research perspectives for manganese forecasting in the Malkansu Manganese Ore Belt. Full article

(This article belongs to the Special Issue Advancements in Mineral Resource Characterization Using Machine Learning)

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15 pages, 8741 KiB

Open AccessEditor’s ChoiceArticle

Iridescent Iron Oxides

by George R. Rossman and Chi Ma

Minerals 2025, 15(2), 108; https://doi.org/10.3390/min15020108 - 23 Jan 2025

Viewed by 1090

Abstract

Iridescent iron oxides known as rainbow hematite and turgite are found in a variety of localities worldwide and display a variety of beautiful interference colors. Usually, there is a thin layer of nanocrystals containing aluminum and phosphorous coats, such as with hematite, although [...] Read more.

Iridescent iron oxides known as rainbow hematite and turgite are found in a variety of localities worldwide and display a variety of beautiful interference colors. Usually, there is a thin layer of nanocrystals containing aluminum and phosphorous coats, such as with hematite, although one example of aluminum with arsenic is presented. Infrared spectra of samples with thicker layers of these nanocrystals show absorption in the phosphate region. The thin films that range from tens to hundreds of nanometers thick are believed to cause the color. High-resolution secondary electron imaging shows that the thin film consists of nanocrystals arranged in three directions (120° apart). The rod-shaped crystals have a width from 5 to 35 nm and display the same morphology on all samples, irrespective of if they contain phosphorus or arsenic. The minute crystals have failed to produce either an X-ray powder diffraction pattern, an electron back-scatter diffraction pattern in SEM, or an electron diffraction ring pattern under TEM. Raman spectra are dominated by hematite features. Infrared ATR spectra of the bulk material show mostly hematite with occasional minor amounts of goethite and phosphate. Full article

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

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20 pages, 10254 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Discernible Orientation for Tortuosity During Oxidative Precipitation of Fe(II) in Porous Media: Laboratory Experiment and Micro-CT Imaging

by Wenran Cao, Ekaterina Strounina, Harald Hofmann and Alexander Scheuermann

Minerals 2025, 15(1), 91; https://doi.org/10.3390/min15010091 - 19 Jan 2025

Cited by 1 | Viewed by 1107

Abstract

In the mixing zone, where submarine groundwater carrying ferrous iron [Fe(II)] meets seawater with dissolved oxygen (DO), the oxidative precipitation of Fe(II) occurs at the pore scale (nm~μm), and the resulting Fe precipitation significantly influences the seepage properties at the Darcy scale (cm~m). [...] Read more.

In the mixing zone, where submarine groundwater carrying ferrous iron [Fe(II)] meets seawater with dissolved oxygen (DO), the oxidative precipitation of Fe(II) occurs at the pore scale (nm~μm), and the resulting Fe precipitation significantly influences the seepage properties at the Darcy scale (cm~m). Previous studies have presented a challenge in upscaling fluid dynamics from a small scale to a large scale, thereby constraining our understanding of the spatiotemporal variations in flow paths as porous media evolve. To address this limitation, this study simulated subsurface mixing by injecting Fe(II)-rich freshwater into a DO-rich saltwater flow within a custom-designed syringe packed with glass beads. Micro-computed tomography imaging at the representative elementary volume scale was utilized to track the development of Fe precipitates over time and space. Experimental observations revealed three distinct stages of Fe hydroxides and their effects on the flow dynamics. Initially, hydrous Fe precipitates were characterized by a low density and exhibited mobility, allowing temporarily clogged pathways to intermittently reopen. As precipitation progressed, the Fe precipitates accumulated, forming interparticle bonding structures that redirected the flow to bypass clogged pores and facilitated precipitate flushing near the syringe wall. In the final stage, a notable reduction in the macroscopic capillary number from 3.0 to 0.05 indicated a transition from a viscous- to capillary-dominated flow, which led to the construction of ramified, tortuous flow channels. This study highlights the critical role of high-resolution imaging techniques in bridging the gap between pore-scale and continuum-scale analyses of multiphase flows in hydrogeochemical processes, offering valuable insights into the complex groundwater–seawater mixing. Full article

(This article belongs to the Special Issue Mineral Dissolution and Precipitation in Geologic Porous Media)

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24 pages, 6969 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

The Short-Wave Infrared (SWIR) Spectral Exploration Identification and Indicative Significance of the Yixingzhai Gold Deposit, Shanxi Province

by Lifang Wang, Song Wu, Xiaodan Lai, Weili Yang, Rongliang Sun, Peng Liu, Yandong Yang and Yuxin Ren

Minerals 2025, 15(1), 83; https://doi.org/10.3390/min15010083 - 16 Jan 2025

Viewed by 834

Abstract

The Yixingzhai gold deposit is the largest gold deposit in Shanxi Province and develops three types of mineralization: porphyry, quartz vein, and breccia. Spectral characteristic parameters of muscovite are studied by short-wave infrared (SWIR) spectral, and the exploration significance is discussed. The Al-OH [...] Read more.

The Yixingzhai gold deposit is the largest gold deposit in Shanxi Province and develops three types of mineralization: porphyry, quartz vein, and breccia. Spectral characteristic parameters of muscovite are studied by short-wave infrared (SWIR) spectral, and the exploration significance is discussed. The Al-OH wavelength of muscovite associated with porphyry mineralization gradually becomes shorter from the periphery (>2206 nm) to the center (2201–2205 nm), and the crystallinity (>2.6) gradually increases. In quartz vein mineralization, the wavelength gradually increases from the periphery (<2203 nm) to the center (2210–2211 nm), while the crystallinity does not change significantly and in a small value (<1.5). The wavelength variation range of breccia mineralization is 2198~2214 nm and is concentrated in 2201~2204 nm near the center, while the overall crystallinity is lesser than 5.5 and concentrated around 1–2.2 near the center. The wavelength and crystallinity of muscovite are mainly affected by Tschermak substitution and temperature. When the contents of Si, Fe, and Mg are low and Al^VI is high, the wavelength tends toward the short-wave (SW) direction, while the opposite tends toward the long-wave (LW) direction. The high crystallinity (4.1–8.4) of muscovite can be used as an indicator of porphyry gold mineralization and also provides an important indicator to explore similar types of gold deposits. Full article

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

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19 pages, 5574 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Investigation of Interfacial Characteristics as a Key Aspect of the Justification of the Reagent Regime for Coal Flotation

by Tatyana N. Aleksandrova, Valentin V. Kuznetsov and Evgeniya O. Prokhorova

Minerals 2025, 15(1), 76; https://doi.org/10.3390/min15010076 - 14 Jan 2025

Cited by 1 | Viewed by 693

Abstract

This work presents a comprehensive approach for the justification of the reagent regime of coal flotation by investigating the interfacial characteristics of flotation phases with various techniques. For the energy characterization of the surface processes in flotation systems, a method of establishing the [...] Read more.

This work presents a comprehensive approach for the justification of the reagent regime of coal flotation by investigating the interfacial characteristics of flotation phases with various techniques. For the energy characterization of the surface processes in flotation systems, a method of establishing the components of the specific surface Gibbs energy on the basis of a numerical estimation of surface free energy change during the adsorption of flotation reagents using the Owens–Wendt–Rabel–Kaelble technique was proposed. Using the developed approach, the features of the kinetics of n-hexane sorption on the surface of coal samples were established. The substantiation of differences in the potential mechanisms of the fixation of strictly apolar and aromatic reagents is based on the results of the quantum–chemical modeling of the states of the coal–adsorbate system using the software packages Avogadro and Orca. The simulation shows the possibility of aliphatic and aromatic reagents’ synergetic effects on coal surface hydrophobization. Based on the results of quantum–chemical modeling, it was found that for the physical adsorption of an oxyethylated nonyl-phenol molecule on a molecular fragment of the coal surface, according to the Weiser model, the decrease in the energy of the system was 0.05562 eV, which indicates the high thermodynamic probability of the physical sorption of this compound. The parameters of the Langmuir monomolecular model for the sorption of oxyethylated nonyl-phenol on the surface of the studied coal samples were established. The criterion characterizing the interphase phenomena in the flotation system based on the results of potentiometric studies of the interfacial characteristics, E_f, was proposed. It was found that for the studied values of the flow rate of oxyethylated nonyl-phenol, the highest value of E_f was achieved when the value of the sorption of the reagent equaled 63.99% of the limiting sorption capacity. The performance of the proposed reagents for coal flotation was confirmed by flotation tests. Full article

(This article belongs to the Special Issue Harnessing Surface Chemistry for Enhanced Mineral Recovery)

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21 pages, 4425 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Transition of CO₂ from Emissions to Sequestration During Chemical Weathering of Ultramafic and Mafic Mine Tailings

by Xiaolin Zhang, Long-Fei Gou, Liang Tang, Shen Liu, Tim T. Werner, Feng Jiang, Yinger Deng and Amogh Mudbhatkal

Minerals 2025, 15(1), 68; https://doi.org/10.3390/min15010068 - 12 Jan 2025

Viewed by 1140

Abstract

Weather-enhanced sulphide oxidation accelerates CO₂ release into the atmosphere. However, over extended geological timescales, ultramafic and mafic magmatic minerals may transition from being sources of CO₂ emissions to reservoirs for carbon sequestration. Ultramafic and mafic mine tailings present a unique opportunity [...] Read more.

Weather-enhanced sulphide oxidation accelerates CO₂ release into the atmosphere. However, over extended geological timescales, ultramafic and mafic magmatic minerals may transition from being sources of CO₂ emissions to reservoirs for carbon sequestration. Ultramafic and mafic mine tailings present a unique opportunity to monitor carbon balance processes, as mine waste undergoes instantaneous and rapid chemical weathering, which shortens the duration between CO₂ release and absorption. In this study, we analysed 30 vanadium-titanium magnetite mine tailings ponds with varying closure times in the Panxi region of China, where ~60 years of mineral excavation and dressing have produced significant outcrops of mega-mine waste. Our analysis of anions, cations, saturation simulations, and ⁸⁷Sr/⁸⁶Sr; δ¹³C and δ³⁴S isotopic fingerprints from mine tailings filtrates reveals that the dissolution load of mine tailings may depend significantly on early-stage sulphide oxidation. Despite the abundance of ultramafic and mafic minerals in tailings, dolomite dominates chemical weathering, accounting for ~79.2% of the cationic load. Additionally, due to sulphuric-carbonate weathering, the filtrates undergo deacidification along with sulphide depletion. The data in this study suggest that pristine V-Ti-Fe tailings ponds undergo CO₂ emissions in the first two years but subsequently begin to absorb atmospheric CO₂ along with the filtrates. Our results provide valuable insights into monitoring weathering transitions and carbon balance in ultramafic and mafic rocks. Full article

(This article belongs to the Special Issue CO₂ Mineralization and Utilization)

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33 pages, 8053 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Geochemical and Mineralogical Insights into Organic Matter Preservation in the Gondwana and Post-Gondwana Shale of the Lesser Himalayas, Nepal

by Kumar Khadka, Shuxun Sang, Sijie Han, Junjie He, Upendra Baral, Saunak Bhandari and Debashish Mondal

Minerals 2025, 15(1), 63; https://doi.org/10.3390/min15010063 - 9 Jan 2025

Viewed by 747

Abstract

The depositional environments, weathering and provenance, organic matter enrichment, and preservation in the Gondwana and post-Gondwana units of the Lesser Himalayas, Nepal, are studied through geochemical and mineralogical analyses using petrography, X-ray diffraction, XRF, and ICP-MS. Mineralogical findings indicate that shales comprise 55% [...] Read more.

The depositional environments, weathering and provenance, organic matter enrichment, and preservation in the Gondwana and post-Gondwana units of the Lesser Himalayas, Nepal, are studied through geochemical and mineralogical analyses using petrography, X-ray diffraction, XRF, and ICP-MS. Mineralogical findings indicate that shales comprise 55% to 72% clay, 25% to 55% quartz, and less than 10% carbonate minerals, with a significant presence of illite, suggesting a transition from fluvial to shallow marine environments during post-Gondwana deposition. The thin sections of the post-Gondwana sandstone reveal an increase in quartz, feldspar, and plagioclase content, with rounded to sub-angular quartz grains indicating moderate transportation before lithification, resulting from the Indo-Asian collision. Geochemical data, including major, trace, and rare earth elements (REE), along with bivariate discrimination diagrams, reveal distinct environmental changes; Gondwana sediments exhibit oxic, arid conditions with continental provenance, while post-Gondwana deposits indicate humid environments favorable for organic matter enrichment, primarily sourced from felsic-intermediate igneous rocks. The TOC is less than 1 wt.% in the Gondwana and is 0.75 to 2 wt.% in the post-Gondwana shale, indicating better organic matter preservation. The existing geological structural data and the research findings highlight the pivotal role of Himalayan tectonism in enhancing the thermal maturity and hydrocarbon generation potential of organic-rich post-Gondwana shales, attributed to their substantial organic matter content. Full article

(This article belongs to the Special Issue Mineralogical, Petrophysical and Hydromechanical Properties of Reservoirs and Caprocks, 2nd Edition)

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18 pages, 3501 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Enhancing Biogenic Scorodite Formation Using Waste Iron Sludge: A Sustainable Approach for Arsenic Immobilization

by Kazuma Kimura and Naoko Okibe

Minerals 2025, 15(1), 56; https://doi.org/10.3390/min15010056 - 7 Jan 2025

Viewed by 782

Abstract

Arsenic (As) contamination in water poses significant environmental and health risks, particularly in mining regions. Scorodite (FeAsO₄·2H₂O) is a highly stable compound for As immobilization, traditionally synthesized under high As concentrations and extreme conditions, such as elevated temperatures and [...] Read more.

Arsenic (As) contamination in water poses significant environmental and health risks, particularly in mining regions. Scorodite (FeAsO₄·2H₂O) is a highly stable compound for As immobilization, traditionally synthesized under high As concentrations and extreme conditions, such as elevated temperatures and pressures. This study explores a sustainable alternative by utilizing Fe-sludge, a waste by-product from acid mine drainage (AMD) treatment, as a novel Fe source for biogenic scorodite formation mediated by the thermo-acidophilic archaeon Acidianus brierleyi. Through a systematic evaluation of Fe-sludge incorporation, the study investigates its impact on microbial activity, As immobilization efficiency, and scorodite crystallization mechanisms. Liquid and solid analyses demonstrate that Fe-sludge enhances the reaction rate and crystallinity of scorodite while bypassing the induction period required in Fe²⁺-only systems. Cross-sectional SEM imaging and EXAFS analysis reveal dynamic transformations on the Fe-sludge surface, supporting faster As adsorption and scorodite nucleation through Fe-S intermediates. Despite potential challenges to microbial activity at higher Fe-sludge concentrations, optimized conditions successfully balance cell viability and Fe utilization. This approach offers an eco-friendly, cost-effective pathway for As immobilization by repurposing AMD sludge, contributing to sustainable resource management and reducing environmental impact. Full article

(This article belongs to the Special Issue Microbial Biomineralization and Organimineralization)

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22 pages, 5456 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Chemical and Mineralogical Characterization of Waste from Abandoned Copper and Manganese Mines in the Iberian Pyrite Belt, Portugal: A First Step Towards the Waste-to-Value Recycling Process

by Daniel P. S. de Oliveira, Teresa P. Silva, Igor Morais and João A. E. Fernandes

Minerals 2025, 15(1), 58; https://doi.org/10.3390/min15010058 - 7 Jan 2025

Viewed by 1515

Abstract

This study examines the chemical and mineralogical composition of waste materials from abandoned copper and manganese mines in the Iberian Pyrite Belt, Portugal, as a first step toward their potential recycling for critical and strategic raw materials (CRM and SRM). Using portable X-ray [...] Read more.

This study examines the chemical and mineralogical composition of waste materials from abandoned copper and manganese mines in the Iberian Pyrite Belt, Portugal, as a first step toward their potential recycling for critical and strategic raw materials (CRM and SRM). Using portable X-ray fluorescence (pXRF) and other analytical techniques, this research highlights the presence of valuable elements, including copper, manganese, and rare earth elements, in concentrations significantly above their crustal abundance. The findings underscore the dual potential of these wastes: as sources of secondary raw materials and for mitigating environmental hazards such as acid mine drainage (AMD). Recovered materials include chalcopyrite, pyrolusite, and rhodochrosite, with critical elements like cobalt, lithium, and tungsten identified. pXRF proved to be a reliable, cost-effective tool for rapid field and laboratory analyses, demonstrating high precision and good correlation with standard laboratory methods. The study emphasizes the importance of characterizing historical mining waste to support a circular economy, reduce reliance on foreign material imports, and address environmental challenges. This approach aligns with the European Union’s Critical Raw Materials Act, promoting sustainable resource use and the recovery of strategic resources from historical mining sites. Full article

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

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