Minerals

17 pages, 868 KiB

Open AccessArticle

Machine Learning Approaches for Predicting the Elastic Modulus of Basalt Fibers Combined with SHapley Additive exPlanations Analysis

by Ling Zhang, Ning Lin and Lu Yang

Minerals 2025, 15(4), 387; https://doi.org/10.3390/min15040387 (registering DOI) - 5 Apr 2025

Abstract

The elastic modulus of basalt fibers is closely associated with their chemical composition. In this study, eight machine learning models were developed to predict the elastic modulus, with hyper-parameter tuning implemented through the GridSearchCV technique. Model performance was evaluated using the coefficient of [...] Read more.

The elastic modulus of basalt fibers is closely associated with their chemical composition. In this study, eight machine learning models were developed to predict the elastic modulus, with hyper-parameter tuning implemented through the GridSearchCV technique. Model performance was evaluated using the coefficient of determination (R²), root-mean-square error (RMSE), and mean absolute error (MAE). SHAP analysis was employed to uncover the relevance of oxide compositions and their interactions with the elastic modulus. Among these models, the Categorical Boosting algorithm exhibited the best results, with an R² of 0.9554, an RMSE of 4.7556, and an MAE of 2.0323. SHAP analysis indicated that CaO had the most significant influence on elastic modulus predictions. The importance of other oxides was ranked as follows: SiO₂, Al₂O₃, MgO, K₂O, Na₂O, Fe₂O₃, FeO, and TiO². Additionally, SHAP analysis determined oxide ranges for positive elastic modulus prediction. This research provides new insights into leveraging machine learning to optimize the mechanical properties of basalt fibers. Full article

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

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15 pages, 4134 KiB

Open AccessArticle

Characterization of Cd and Pb Bioavailability in Agricultural Soils Using DGT Technique and DIFS Model

by Shujuan Cheng, Jing Liao, Fangyan Jia and Yubo Wen

Minerals 2025, 15(4), 386; https://doi.org/10.3390/min15040386 (registering DOI) - 5 Apr 2025

Abstract

Elevated levels of cadmium (Cd) and lead (Pb) in the edible parts of rice (Oryza sativa L.) grown in agricultural soils may enter the human body through the food chain, posing significant health risks. In this study, rice and paired rhizosphere soil [...] Read more.

Elevated levels of cadmium (Cd) and lead (Pb) in the edible parts of rice (Oryza sativa L.) grown in agricultural soils may enter the human body through the food chain, posing significant health risks. In this study, rice and paired rhizosphere soil samples were collected from 194 locations in Jiangsu Province, China, with 60 samples selected for diffusive gradients in thin films (DGT) extraction analysis. The findings indicate that total soil concentrations of Cd and Pb are inadequate for assessing cadmium bioavailability, implying that current soil quality standards may not accurately reflect the bioaccessible fractions of these metals. Both DGT and soil solution measurements effectively predicted crop Cd levels, with the effective concentration (C_E) derived from the DGT-induced soil flux (DIFS) model showing the strongest correlation with rice Cd content. Pearson correlation analysis and a random forest (RF) model further identified critical factors influencing rice uptake of Cd and Pb, including soil iron (Fe) content, cation exchange capacity (CEC), pH, and the levels of zinc (Zn) and selenium (Se), which antagonize Cd uptake. Full article

(This article belongs to the Special Issue Heavy Metal and Rare Earth Element Pollution in Soil and Water: Sources, Geochemical Behaviors and Ecological Effects)

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18 pages, 2162 KiB

Open AccessArticle

Development and Optimization of Bentonite-Based Slurry Sealing Material

by Qingsong Zhang, Changyuan Xiao, Zhaoyang Su, Hui Zhuo and Tuo Qiang

Minerals 2025, 15(4), 385; https://doi.org/10.3390/min15040385 (registering DOI) - 5 Apr 2025

Abstract

Gas extraction from coal seams can significantly mitigate gas accidents and improve resource utilization. The effectiveness of borehole sealing directly determines the concentration and efficiency of gas drainage. In recent years, liquid-phase sealing materials, represented by non-solidifying pastes, gel-based materials, and inorganic retarders, [...] Read more.

Gas extraction from coal seams can significantly mitigate gas accidents and improve resource utilization. The effectiveness of borehole sealing directly determines the concentration and efficiency of gas drainage. In recent years, liquid-phase sealing materials, represented by non-solidifying pastes, gel-based materials, and inorganic retarders, have gradually become a research hotspot. Compared to the traditional solid sealing materials such as cement-based or organic polymers, liquid-phase sealing materials can effectively seal secondary fractures caused by mining vibration through grout replenishment. However, the influence of each component in liquid-phase non-solidified materials on sealing properties such as fluidity, water retention, and permeability remains unclear. To address these issues, a novel liquid-phase non-solidified hole sealing material was developed using bentonite as the base material, sodium dodecyl benzene sulfonate as the dispersant, and sodium carboxymethyl cellulose as the thickener. Initially, single-factor experiments were applied to investigate the effects of material ratios on the fluidity, water retention, and permeability. Subsequently, orthogonal experimental design and response surface methodology were used to establish nonlinear quadratic regression models relating these properties to water–bentonite ratio, dispersant content, and thickener content. The results indicated that an optimal water–bentonite ratio enhances both fluidity and permeability, while dispersants improve water retention and permeability and thickeners primarily boost water retention. Finally, the optimized composition was determined as a water–bentonite ratio of 4.41:1, a dispersant content of 0.38%, and a thickener content of 0.108%. We believe that the developed slurry materials will maintain excellent sealing performance through the entire gas extraction period. Full article

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

29 pages, 19503 KiB

Open AccessArticle

Study of Sulfide Ore from the Perspective of the Hierarchical Oxidation and Asymmetric Corrosion Mechanism of Minerals: (I) Chalcopyrite

by Runqing Liu, Yacong Wu, Changtao Wang, Yuehua Hu, Xian Xie, Wei Sun and Xiong Tong

Minerals 2025, 15(4), 384; https://doi.org/10.3390/min15040384 (registering DOI) - 5 Apr 2025

Abstract

It is known that sulfide minerals are affected by the pulp oxygen content during flotation, while few studies have been conducted on the specific oxidation and kinetic processes. This study adopted DO, ICP, XPS and SEM-EDS measurements to reveal the oxidation–corrosion characteristics of [...] Read more.

It is known that sulfide minerals are affected by the pulp oxygen content during flotation, while few studies have been conducted on the specific oxidation and kinetic processes. This study adopted DO, ICP, XPS and SEM-EDS measurements to reveal the oxidation–corrosion characteristics of chalcopyrite systematically because they dominate the surface properties and flotation behavior of minerals. The results confirm the hierarchical oxidation–asymmetric corrosion characteristics of chalcopyrite firstly. More precisely, the ore-forming elements Fe and Cu are prone to corrosion under acidic conditions while S is to corrosion under alkaline conditions, and pulp aeration could further enlarge their difference of corrosion rate. Owing to their asymmetric corrosion characteristics, a “metal-deficient and S-rich” layer and a “metal-rich and S-deficient” layer are generated under acidic and alkaline conditions, correspondingly. Surface etching further revealed that the hierarchical oxidation process of Cu, Fe and S sites are Cu(I)-S → Cu(II)-O, Fe(III)-S → Fe(III)-O → sulfate and S²⁻→ S₂²⁻→ S_n²⁻→ SO₄²⁻. Moreover, the oxidation–corrosion of chalcopyrite was non-uniform, and the micro-zone of oxidation and corrosion were greatly overlapping. Finally, the hierarchical oxidation and asymmetric corrosion model was established to further promote the understanding of the oxidation–corrosion process and its impact on surface properties. Full article

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

28 pages, 8989 KiB

Open AccessArticle

Mechanochemical Treatments of Commercial Vermiculites

by Celia Marcos, Javier F. Reynes and Pedro Álvarez-Lloret

Minerals 2025, 15(4), 383; https://doi.org/10.3390/min15040383 (registering DOI) - 5 Apr 2025

Abstract

This study investigates the mechanochemical transformation of commercial vermiculites from Uganda and China, processed for 30 minutes (30 min), 8 hours (8 h), and 24 hours (24 h). Structural and textural modifications were analyzed using X-ray diffraction (XRD), thermogravimetric analysis (TGA), BET surface [...] Read more.

This study investigates the mechanochemical transformation of commercial vermiculites from Uganda and China, processed for 30 minutes (30 min), 8 hours (8 h), and 24 hours (24 h). Structural and textural modifications were analyzed using X-ray diffraction (XRD), thermogravimetric analysis (TGA), BET surface area measurements, and scanning electron microscopy (SEM). Characterization via X-ray diffraction (XRD), thermogravimetric analysis (TGA), BET surface area measurements, and scanning electron microscopy (SEM) revealed substantial structural and textural modifications. Crystallinity decreased significantly, from 66.37% to 3.47% in the Ugandan sample, whereas the three mixed-phase Chinese samples exhibited greater structural resilience, with final crystallinity ranging from 3.82% to 6.30%. Mechanochemical treatment induced mineral phase transformations, including hydrobiotite formation in the Ugandan sample and Fe₃Si, quartz, moganite, and NaMgH₃ in the Chinese samples. Particle size reduced significantly, reaching submicrometric dimensions after 24 h, with C1 showing the smallest mean size (0.39 µm). BET analysis showed an initial increase in specific surface area, peaking at 31.83 m²/g for C1 after 8 h, followed by a decrease due to pore collapse. The optimal treatment time varied by sample, with 30 min maximizing adsorption in C2 and C3, while 8 h was most effective for C1. These findings highlight mechanochemical treatment as a viable method for tuning vermiculite properties for applications in adsorption, catalysis, and composite materials. Full article

(This article belongs to the Special Issue Use of Clay Minerals in Adsorption and Photocatalysis Technologies)

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17 pages, 5669 KiB

Open AccessArticle

The Potential of Grinding Media Shape to Enhance the Selective Flotation Separation of Ilmenite

by Jing Wang, Chuan Dai and Pan Chen

Minerals 2025, 15(4), 382; https://doi.org/10.3390/min15040382 (registering DOI) - 5 Apr 2025

Abstract

Ilmenite, the most widely distributed titanium ore resource globally, often coexists with titanaugite, one of its primary gangue minerals, which shares similar surface properties. This similarity significantly hampers the selective flotation separation efficiency of ilmenite. This study investigated the influence of grinding media [...] Read more.

Ilmenite, the most widely distributed titanium ore resource globally, often coexists with titanaugite, one of its primary gangue minerals, which shares similar surface properties. This similarity significantly hampers the selective flotation separation efficiency of ilmenite. This study investigated the influence of grinding media shape—specifically steel balls, steel rods, and steel cylpebs—on the grinding characteristics of ilmenite and titanaugite through single-mineral micro-flotation experiments and related characterizations, and explored the potential of media shape to enhance the selective flotation separation of ilmenite. Experimental results demonstrate that in a weakly alkaline sodium oleate (NaOL) system at pH ≈ 8, the floatability of ilmenite milled with cylpebs is approximately 1.7% higher than that with balls and slightly lower than that with rods. In contrast, the floatability of titanaugite milled with cylpebs is similar to that with balls but almost 4% lower than that with rods. Compared to balls and rods, the difference in floatability between ilmenite and titanaugite increases from 29.96% and 29.04% to 32.71% with cylpeb milling. The primary reason is that cylpebs increase the exposure of the (104) face of ilmenite by approximately 2%, enhancing its interaction with NaOL, while minimizing the (−221) faces in titanaugite, thereby reducing its adverse impact on ilmenite flotation. Therefore, the use of cylpebs may facilitate the selective flotation separation of ilmenite. Full article

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

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28 pages, 9297 KiB

Open AccessArticle

Petrogenesis and Tectonic Setting of Late Permian Granitoids in the East Kunlun Orogenic Belt, NW China: Constraints from Petrology, Geochemistry and Zircon U-Pb-Lu-Hf Isotopes

by Chao Hui, Fengyue Sun, Tao Wang, Yanqian Yang, Yun Chai, Jiaming Yan, Bakht Shahzad, Bile Li, Yajing Zhang, Tao Yu, Xingsen Chen, Chengxian Liu, Xinran Zhu, Yuxiang Wang, Zhengsong Wang, Haoran Li, Renyi Song and Desheng Dou

Minerals 2025, 15(4), 381; https://doi.org/10.3390/min15040381 (registering DOI) - 4 Apr 2025

Abstract

Permian magmatic rocks are extensively distributed in the East Kunlun Orogenic Belt (EKOB), yet controversies persist regarding the petrogenesis of granitoid rocks and the tectonic evolution of the Buqingshan-A’nyemaqing Ocean (BAO), which is a part of the Paleo-Tethys. This study addresses these debates [...] Read more.

Permian magmatic rocks are extensively distributed in the East Kunlun Orogenic Belt (EKOB), yet controversies persist regarding the petrogenesis of granitoid rocks and the tectonic evolution of the Buqingshan-A’nyemaqing Ocean (BAO), which is a part of the Paleo-Tethys. This study addresses these debates through petrological analyses, whole-rock geochemistry and zircon U-Pb-Lu-Hf isotopic investigations of newly identified granitoids in the EKOB. Monzogranite (MG) and quartz porphyry (QP) yield weighted mean ages of 254.7 ± 1.1 Ma and 254.3 ± 1.1 Ma, respectively. Geochemically, the MG shows metaluminous to weakly peraluminous low-K calc-alkaline I-type affinity, characterized by high SiO₂ and low K₂O, MgO and FeO^T contents, as well as marked enrichment in light rare earth elements (LREEs), but depletion in Eu, Ba, Sr, P and Ti anomalies. In contrast, the QP exhibits a peraluminous high-K calc-alkaline I-type affinity, displaying high SiO₂ but low Na₂O and P₂O₅ contents. It is enriched in LREEs and Rb but displays negative Nb, Sr, P and Ti anomalies. Zircon ε_Hf(t) values range from −1.6 to 2.6 for MG and −4.4 to 1.5 for QP. We suggest that both MG and QP were derived from the partial melting of juvenile mafic lower crust, and that MG underwent a high degree of fractional crystallization. A synthesis of multiscale geological evidence allows us to propose a five-stage tectonic evolution for the BAO in the EKOB: (1) oceanic basin initiation before ca. 345 Ma; (2) incipient northward subduction commencing at ca. 278 Ma; (3) slab rollback stage (263–240 Ma); (4) syn-collisional compression (240–230 Ma); (5) post-collisional extension (230–195 Ma). Full article

(This article belongs to the Special Issue Genesis of Calc-Alkaline Granitic Rocks: Evidence from Petrology and Geochemistry)

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16 pages, 7909 KiB

Open AccessArticle

Zircon U-Pb Geochronology and Hf Isotopes of the Granitoids from Cahanwusu Cu Deposit in Awulale Mountain, Western Tianshan: Implication for Regional Mineralization

by Wei Zhang, Mao-Xue Chen, Mei-Li Yang, Wen-Hui Yang and Xing-Chun Zhang

Minerals 2025, 15(4), 380; https://doi.org/10.3390/min15040380 - 4 Apr 2025

Abstract

Awulale Mountain is one of the most important Fe-Cu concentration areas situated in the eastern part of Western Tianshan. The Cu deposits in the belt are genetically associated with the Permian intermediate and felsic intrusions. However, the precise age and magma source of [...] Read more.

Awulale Mountain is one of the most important Fe-Cu concentration areas situated in the eastern part of Western Tianshan. The Cu deposits in the belt are genetically associated with the Permian intermediate and felsic intrusions. However, the precise age and magma source of the causative intrusions are currently not confirmed, constraining our understanding of regional mineralization. The Cahanwusu porphyry Cu deposit is located in the western part of Awulale Mountain. Field investigations have shown that the mineralization in the deposit is genetically associated with granitic porphyry and diorite porphyry. In this paper, we provide detailed zircon U-Pb ages and in-situ Hf isotopic compositions of the granitic porphyry and diorite porphyry. The granitic porphyry and diorite porphyry have zircon U-Pb ages of 328.6 ± 2.6 Ma (MSWD = 0.52; n = 23) and 331 ± 2.8 Ma (MSWD = 0.95; n = 21), respectively. This indicates that the Cahanwusu deposit was formed in the Carboniferous in a subduction setting. This is distinguishable from other porphyry Cu deposits in the belt, which were generally formed in the Permian in the post-collision extensional setting. The granitic porphyry and diorite porphyry exhibit positive ε_Hf(t) values varying from +2.8 to +5.4 (average of +4.1) and +2.0 to +5.1 (average of +4.1), respectively. The magmas of these causative intrusions were interpreted to be derived from the partial melting of the juvenile lower crust which originated from cooling of mantle-derived magmas related to the subduction process. Our new results highlight that the Cahanwusu deposit represents a new episode of Cu mineralization in the belt and the Carboniferous granitoids in Awulale Mountain are potential candidates for Cu exploration. Full article

(This article belongs to the Special Issue Igneous Rocks and Related Mineral Deposits)

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24 pages, 5066 KiB

Open AccessArticle

Physicochemical and Mineralogical Characterizations of Two Natural Laterites from Burkina Faso: Assessing Their Potential Usage as Adsorbent Materials

by Corneille Bakouan, Louise Chenoy, Boubié Guel and Anne-Lise Hantson

Minerals 2025, 15(4), 379; https://doi.org/10.3390/min15040379 - 4 Apr 2025

Abstract

In the framework of lateritic material valorization, we demonstrated how the geological environment determines the mineralogical characterizations of two laterite samples, KN and LA. KN and LA originate from the Birimian and Precambrian environments, respectively. We showed that the geological criterion alone does [...] Read more.

In the framework of lateritic material valorization, we demonstrated how the geological environment determines the mineralogical characterizations of two laterite samples, KN and LA. KN and LA originate from the Birimian and Precambrian environments, respectively. We showed that the geological criterion alone does not determine the applicability of these laterites as potential adsorbents but must be associated with their physicochemical properties. The characterizations were carried out using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Thermal analysis, and Atomic Emission Spectrometry Coupled with an Inductive Plasma Source. The major mineral phases obtained by X-ray diffraction analysis coupled with infrared analysis showed that the KN and LA laterite samples were composed of quartz (33.58% to 45.77%), kaolinite (35.64% to 17.05%), hematite (13.36% to 11.43%), and goethite (7.44% to 6.31%). The anionic exchange capacity of the KN and LA laterites ranged from 86.50 ± 3.40 to 73.91 ± 9.94 cmol(-)·kg⁻¹ and from 73.59 ± 3.02 to 64.56 ± 4.08 cmol(-)·kg⁻¹, respectively, and the cation exchange capacity values are in the order of 52.3 ± 2.3 and 58.7 ± 3.4 cmol(+)/Kg for the KN and LA samples, respectively. The specific surface values determined by the BET method were 58.65 m²/g and 41.15 m²/g for the KN and LA samples, respectively. The effects of adsorbent doses on As(III,V), Pb(II), and Cu(II) adsorption were studied. At 5 mg/L As and 15 g/L adsorbent (pH 6.5–7), arsenate removal was 99.72 ± 0.35% and 99.58 ± 0.45% for KN and LA, respectively, whereas arsenite removal reached 83.52 ± 2.21% and 98.59 ± 0.64% for LA and KN, respectively. The Pb(II) and Cu(II) removal rates were 74.20 ± 0.95% for 2.4 g/L KN and 54.18 ± 0.01% for 8 g/L KN, respectively. Based on their physicochemical and mineralogical characteristics, the KN and LA laterite samples were shown to possess a high potential as adsorbent material candidates for removing heavy metals and/or anionic species from groundwater. Full article

(This article belongs to the Special Issue Clay Minerals: From Paleoclimatic and Paleoenvironmental Indicators to Industrial Raw Materials)

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17 pages, 2772 KiB

Open AccessArticle

Trace Metal and Phosphorus Enrichments in Cyanobacteria Cells and Cyanobacterial Precipitated Minerals

by Hanna Leapaldt, Miquela Ingalls, Georgia Soares and Christopher H. House

Minerals 2025, 15(4), 378; https://doi.org/10.3390/min15040378 - 4 Apr 2025

Abstract

The enrichment of trace metals and other life-essential elements, like phosphorus, in carbonates may be a signature of microbial life. Enrichments of such elements in microbial carbonate facies in the rock record have been attributed to life in previous studies, but the biologic [...] Read more.

The enrichment of trace metals and other life-essential elements, like phosphorus, in carbonates may be a signature of microbial life. Enrichments of such elements in microbial carbonate facies in the rock record have been attributed to life in previous studies, but the biologic origin of these enrichments is contentious. We experimentally tested the hypothesis that enrichments of life-important trace elements occur in both cells and carbonate minerals that form as a result of cellular photosynthesis for the cyanobacteria Synechococcus PCC 8806. We grew Synechococcus PCC 8806 and measured the trace element concentrations of the cells and the minerals that precipitate with the cells, and we compared the results to abiotically precipitated mineral material from the same growth medium conditions. We found that for all the tested trace elements (B, P, K, Mn, Fe, Co, Cu, and Zn, chosen for their requirements in the growth medium of Synechococcus PCC 8806 and known uses in cellular machinery), nearly all the sample types were enriched relative to the medium concentrations. The dominant pattern for most elements was that cells were the most enriched, followed by biotic minerals, and then abiotic minerals. However, this pattern was complicated by varying concentrations of Mg in the mineral samples because the data were normalized to Mg (Mg was the dominant cation in the solution next to Na). Nonetheless, however the data are normalized, Fe was the most enriched element in the cells and both the biotic and abiotic minerals relative to the medium concentrations. Fe had the largest enrichment factor (E.F.) for all the sample types, with an E.F. of approximately 2800 in the biotic minerals, 1620 in the cells, and 230 in the abiotic minerals. Fe was followed by Zn (E.F. of ~329 in cells, 198 in biotic minerals, and 78 in abiotic minerals), Cu (E.F. of ~424 in cells, 171 in biotic minerals, and 50 in abiotic minerals), Mn (E.F. of ~200 in cells, 95 in biotic minerals, and 53 in abiotic minerals), and P (E.F. of ~149 in cells, 37 in biotic minerals, and 6 in abiotic minerals), suggesting that these elements can be useful as biosignatures when used in combination with other evidence. Full article

(This article belongs to the Special Issue Life and Carbonate: Biotic and Abiotic Fingerprints in Past and Recent Carbonate Sediments)

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15 pages, 7318 KiB

Open AccessArticle

Identification of Lithium-Bearing Pegmatite Dikes Based on WorldView-3 Data: A Case Study of the Shaligou Area in Western Altyn

by Xiaoqian Zhang, Fang Xia, Shiqi Xu, Lingling Gao, Wei Wang, Xiaofei Du and Chuan Chen

Minerals 2025, 15(4), 377; https://doi.org/10.3390/min15040377 - 3 Apr 2025

Abstract

Shaligou, located in the southwestern Altyn Mountains, is a newly discovered lithium-bearing pegmatite deposit that is driving increased exploration in the region. However, the challenging environmental conditions of the Altyn Mountains pose challenges for the exploration of lithium-bearing pegmatites. Consequently, remote sensing technology [...] Read more.

Shaligou, located in the southwestern Altyn Mountains, is a newly discovered lithium-bearing pegmatite deposit that is driving increased exploration in the region. However, the challenging environmental conditions of the Altyn Mountains pose challenges for the exploration of lithium-bearing pegmatites. Consequently, remote sensing technology has emerged as an effective exploration tool. In this study, the spectral data of typical samples were collected to establish a spectral library of rocks and minerals in the study area capable of serving as a foundation for remote sensing analysis. Firstly, ASTER data were utilized successfully for lithological interpretation of the area. Secondly, high-resolution WorldView-3 data with a spatial resolution of 0.31 m were used to establish interpretation criteria for pegmatite dikes. Ground validation results were highly consistent with the remote sensing interpretations, confirming that the use of WorldView-3 data significantly enhances the accuracy of lithium-bearing pegmatite dike identification, providing valuable guidance for further exploration. Full article

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

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14 pages, 826 KiB

Open AccessCommentary

Four Decades of Efforts to Reduce or Eliminate Mercury Pollution in Artisanal Gold Mining

by Marcello M. Veiga, Nnamdi C. Anene and Emiliano M. Silva

Minerals 2025, 15(4), 376; https://doi.org/10.3390/min15040376 - 3 Apr 2025

Abstract

Throughout the past four decades, most projects related to mercury in Artisanal Gold Mining (AGM) have been dedicated to monitoring the environmental and health impacts of the activity without actually proposing effective solutions to tackle the issue. Recently, the UN and a few [...] Read more.

Throughout the past four decades, most projects related to mercury in Artisanal Gold Mining (AGM) have been dedicated to monitoring the environmental and health impacts of the activity without actually proposing effective solutions to tackle the issue. Recently, the UN and a few NGOs have been dedicated to bringing solutions to artisanal gold miners, but the outcomes remain modest, given the funds expended and the considerable effort invested by interventionists. This commentary paper critiques some of the interventions observed in the last four decades and suggests some technical strategies to approach artisanal miners to reduce mercury losses. It is stressed that mercury elimination is a consequence of good engagement with miners that creates opportunities to show them how to produce more gold with cleaner methods. We recommend that academics educate a new generation of engineers working with AGM to adopt a more practical approach, ensuring they understand the needs, motivations, and skills of artisanal miners before proposing solutions. Full article

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

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37 pages, 21085 KiB

Open AccessArticle

Unraveling the Protracted Magmatic Evolution in the Central Urumieh–Dokhtar Magmatic Arc (Northeast Saveh, Iran): Zircon U-Pb Dating, Lu-Hf Isotopes, and Geochemical Constraints

by Mohammad Goudarzi, Hassan Zamanian, Urs Klötzli, Jiří Sláma, Jitka Míková, Jolanta Burda, David R. Lentz, Matee Ullah and Jiranan Homnan

Minerals 2025, 15(4), 375; https://doi.org/10.3390/min15040375 (registering DOI) - 3 Apr 2025

Abstract

Cenozoic plutonic rocks in northeast Saveh, part of the central Urumieh–Dokhtar Magmatic Arc (UDMA) in Iran, comprise monzonite, monzodiorite, gabbro, and gabbrodiorite. Geochemical, zircon U-Pb geochronology, and Hf isotopic data reveal that these plutonic rocks belong to a medium-K calc-alkaline, metaluminous series with [...] Read more.

Cenozoic plutonic rocks in northeast Saveh, part of the central Urumieh–Dokhtar Magmatic Arc (UDMA) in Iran, comprise monzonite, monzodiorite, gabbro, and gabbrodiorite. Geochemical, zircon U-Pb geochronology, and Hf isotopic data reveal that these plutonic rocks belong to a medium-K calc-alkaline, metaluminous series with arc-related signatures. Zircon U-Pb ages (ca. 60 to 3 Ma) indicate prolonged magmatic evolution from the Middle Paleocene to the Middle Pliocene. Contrary to earlier reports of a 15 Ma period of reduced magmatic activity (ca. 72–57 Ma), our data indicate a shorter interval (ca. 10–12 Ma) during which magmatic activity decreased significantly. Key magmatic pulses occurred during the Late Eocene (ca. 40–47 Ma), Early Miocene (ca. 23–18 Ma), and Late Miocene–Pliocene (ca. 11–5.2 Ma), with geochemical data indicating a subduction-related origin. The most recent magmatic pulses in the central UDMA, potentially extending across the entire UDMA, are dated between 5 and 2.5 Ma, identified in a cluster of zircons from gabbroic rocks, which could correspond to the concluding stages of slab steepening related to continental subduction. Zircon εHf(t) values (−11.43 to 12.5) and geochemical data suggest fractional crystallization, crustal assimilation, and mantle-derived melts. The clinopyroxene crystallization temperatures (1150–1200 °C) and supporting geochemical data imply that magma was produced in a metasomatized spinel–lherzolite mantle at depths <80 km. This generation is associated with asthenospheric upwelling and slab rollback, which, in turn, triggered the partial melting of the lithosphere and fueled the region’s magmatic activity. Full article

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18 pages, 2936 KiB

Open AccessArticle

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

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 AccessArticle

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

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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28 pages, 6120 KiB

Open AccessArticle

Machine Learning Classification of Fertile and Barren Adakites for Refining Mineral Prospectivity Mapping: Geochemical Insights from the Northern Appalachians, New Brunswick, Canada

by Amirabbas Karbalaeiramezanali, Fazilat Yousefi, David R. Lentz and Kathleen G. Thorne

Minerals 2025, 15(4), 372; https://doi.org/10.3390/min15040372 - 2 Apr 2025

Abstract

This study applies machine learning (ML) techniques to classify fertile [for porphyry Cu and (or) Au systems] and barren adakites using geochemical data from New Brunswick, Canada. It emphasizes that not all intrusive units, including adakites, are inherently fertile and should not be [...] Read more.

This study applies machine learning (ML) techniques to classify fertile [for porphyry Cu and (or) Au systems] and barren adakites using geochemical data from New Brunswick, Canada. It emphasizes that not all intrusive units, including adakites, are inherently fertile and should not be directly used as the heat source evidence layer in mineral prospectivity mapping without prior analysis. Adakites play a crucial role in mineral exploration by helping distinguish between fertile and barren intrusive units, which significantly influence ore-forming processes. A dataset of 99 fertile and 66 barren adakites was analyzed using seven ML models: support vector machine (SVM), neural network, random forest (RF), decision tree, AdaBoost, gradient boosting, and logistic regression. These models were applied to classify 829 adakite samples from around the world into fertile and barren categories, with performance evaluated using area under the curve (AUC), classification accuracy, F1 score, precision, recall, and Matthews correlation coefficient (MCC). SVM achieved the highest performance (AUC = 0.91), followed by gradient boosting (0.90) and RF (0.89). For model validation, 160 globally recognized fertile adakites were selected from the dataset based on well-documented fertility characteristics. Among the tested models, SVM demonstrated the highest classification accuracy (93.75%), underscoring its effectiveness in distinguishing fertile from barren adakites for mineral prospectivity mapping. Statistical analysis and feature selection identified middle rare earth elements (REEs), including Gd and Dy, with Hf, as key indicators of fertility. A comprehensive analysis of 1596 scatter plots, generated from 57 geochemical variables, was conducted using linear discriminant analysis (LDA) to determine the most effective variable pairs for distinguishing fertile and barren adakites. The most informative scatter plots featured element vs. element combinations (e.g., Ga vs. Dy, Ga vs. Gd, and Pr vs. Gd), followed by element vs. major oxide (e.g., Fe₂O₃T vs. Gd and Al₂O₃ vs. Hf) and ratio vs. element (e.g., La/Sm vs. Gd, Rb/Sr vs. Hf) plots, whereas major oxide vs. major oxide, ratio vs. ratio, and major oxide vs. ratio plots had limited discriminatory power. 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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41 pages, 12142 KiB

Open AccessArticle

Geometallurgical Sampling and Testwork for Gold Mineralisation: General Considerations and a Case Study

by Simon C. Dominy and Hylke J. Glass

Minerals 2025, 15(4), 370; https://doi.org/10.3390/min15040370 - 2 Apr 2025

Abstract

Geometallurgy seeks to derisk the extraction of primary resources by developing optimal strategies across resource/reserve evaluation, mine planning, mineral processing, environmental management (including waste management), and energy use. Predictive geometallurgy is the crux of modern geometallurgical practice, which leads to a data-rich 3D [...] Read more.

Geometallurgy seeks to derisk the extraction of primary resources by developing optimal strategies across resource/reserve evaluation, mine planning, mineral processing, environmental management (including waste management), and energy use. Predictive geometallurgy is the crux of modern geometallurgical practice, which leads to a data-rich 3D block model(s). The geometallurgical approach aims to quantify variability through different sample types, including in situ and direct measurements; physical samples; process samples within the plant; and in-line sensor-based measurements. Sampling considerations across sample type, representativity, number of samples required, sample integrity, Quality Assurance/Quality Control, and reporting results in the context of international codes are emphasised. A geometallurgical protocol was developed to obtain multivariate data for highly heterogeneous gold-bearing conglomerate mineralisation. The protocol emphasises the importance of collecting high-quality samples through the use of diamond drill core and early implementation. The programme aimed to acquire an accurate head grade of each core intersection prior to destruction by metallurgical testwork. Core scanning and comminution test work was undertaken prior to the head assay. The protocol was developed so as to allow each core interval to be submitted for comminution testwork, recombined for head grade determination by PhotonAssay™, and subsequently submitted for gold recovery testwork. All core was scanned prior to testwork and assay, which collected digital imagery, geochemistry, and bulk density data. A comprehensive quality assurance and quality control system was implemented for the programme. This paper presents an overview of geometallurgical sampling and the development and implementation of the Beatons Creek testwork programme in support of a Pre-Feasibility Study. Full article

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

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17 pages, 33992 KiB

Open AccessArticle

Constructive Effect of Tuffaceous Filling Dissolution in Clastic Reservoir—A Case Study from Kuishan Sandstone in Permian of Gaoqing Buried Hill in Jiyang Depression, Bohai Bay Basin

by Xinghua Ci, Yelei Wang, Huanfu Du, Longwei Qiu, Zhifeng Wang and Zhen Yang

Minerals 2025, 15(4), 371; https://doi.org/10.3390/min15040371 - 1 Apr 2025

Abstract

Tuffaceous fillings are a significant component of the Permian Kuishan sandstone in the North China Platform, and their complex diagenetic processes have a notable impact on the development of clastic rock reservoirs. This study, based on microscopic analysis of reservoirs and combined with [...] Read more.

Tuffaceous fillings are a significant component of the Permian Kuishan sandstone in the North China Platform, and their complex diagenetic processes have a notable impact on the development of clastic rock reservoirs. This study, based on microscopic analysis of reservoirs and combined with quantitative analytical techniques such as electron probe microanalysis, homogenization temperatures of fluid inclusions, micro-area carbon-oxygen isotope analysis, and laser Raman spectroscopy, investigates the influence of tuffaceous interstitial material dissolution on reservoir development in the Permian Kuishan sandstone of the Gaoqing buried hill in the Jiyang Depression, Bohai Bay Basin. The results indicate that the dissolution intensity of tuffaceous interstitial materials can be classified into three levels: strong, moderate, and weak. In the strong dissolution zone, associated fractures and dissolution pores significantly contribute to reservoir porosity, with a positive correlation between dissolution plane porosity and total plane porosity. The reservoir space is characterized by a network of dissolution pores and fractures. The moderate dissolution zone is marked by the development of authigenic quartz, feldspar, and clay minerals, which do not effectively enhance porosity and permeability. The weak dissolution zone contains well-preserved volcanic glass shards, crystal fragments, and clay minerals, representing non-reservoir development sections. Lithology, sedimentary facies, diagenesis, and fractures collectively control the quality of the Permian Kuishan sandstone reservoir in the Gaoqing buried hill of the Jiyang Depression, Bohai Bay Basin. The advantageous zones for reservoir development in this area can be effectively predicted using thickness maps of the Kuishan sandstone, planar distribution maps of sedimentary facies, and fracture prediction maps derived from ant-tracking and coherence algorithms. Full article

(This article belongs to the Special Issue Petrological and Geochemical Characteristics of Reservoirs)

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24 pages, 15632 KiB

Open AccessArticle

Mineral Chemistry and Iron Isotope Characteristics of Magnetites in Pertek Fe-Skarn Deposit (Türkiye)

by Hatice Kara, Cihan Yalçın, Mehmet Ali Ertürk and Leyla Kalender

Minerals 2025, 15(4), 369; https://doi.org/10.3390/min15040369 - 1 Apr 2025

Abstract

This study investigates the mineral chemistry and iron isotope composition of the Pertek Fe-skarn deposit in the Eastern Taurides, Turkey, to elucidate skarn formation and ore genesis through chemical and isotopic parameters. The deposit consists of substantial and dispersed magnetite ores formed by [...] Read more.

This study investigates the mineral chemistry and iron isotope composition of the Pertek Fe-skarn deposit in the Eastern Taurides, Turkey, to elucidate skarn formation and ore genesis through chemical and isotopic parameters. The deposit consists of substantial and dispersed magnetite ores formed by the intrusion of a dioritic suite into marbles. Mineral assemblages, including hematite, goethite, andradite garnet, hedenbergite pyroxene, calcite, and quartz, exhibit compositional variations at different depths within the ore body. Magnetite is commonly associated with hematite, goethite, garnet, pyroxene, calcite, and quartz. Extensive LA–ICP–MS analysis of magnetite chemistry reveals elevated trace element concentrations of titanium (Ti), aluminum (Al), vanadium (V), and magnesium (Mg), distinguishing Pertek magnetite from low-temperature hydrothermal deposits. The enrichment of Ti (>300 ppm) and V (>200 ppm), along with the presence of Al and Mg, suggests formation from high-temperature hydrothermal fluids exceeding 300 °C. Discriminant diagrams, such as Al+Mn versus Ti+V, classify Pertek magnetite within the skarn deposit domain, affirming its medium- to high-temperature hydrothermal origin (200–500 °C), characteristic of skarn-type deposits. Magnetite thermometry calculations yield an average formation temperature of 414.53 °C. Geochemical classification diagrams, including Ni/(Cr+Mn) versus Ti+V and TiO₂-Al₂O₃-MgO+MnO, further support the skarn-type genesis of the deposit, distinguishing Pertek magnetite from other iron oxide deposits. The Fe-skarn ore samples display low total REE concentrations, variable Eu anomalies, enrichment in LREEs, and depletion in HREEs, consistent with fluid–rock interactions in a magmatic–hydrothermal system. The δ⁵⁶Fe values of magnetite range from 0.272‰ to 0.361‰, while the calculated δ⁵⁶Fe_aq values (0.479‰ to 0.568‰) suggest a magmatic–hydrothermal origin. The δ⁵⁷Fe values (0.419‰ to 0.530‰) and the calculated 10³lnβ value of 0.006397 indicate re-equilibration of the magmatic–hydrothermal fluid during ore formation. Full article

(This article belongs to the Section Mineral Deposits)

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