Minerals

26 pages, 5245 KB

Open AccessArticle

Sedimentary Environment and Organic Matter Enrichment of the First Member in the Upper Triassic Xujiahe Formation, Southeastern Sichuan Basin

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

Minerals 2025, 15(10), 1071; https://doi.org/10.3390/min15101071 - 13 Oct 2025

Abstract

The Xujiahe Formation (FM) is a significant source rock layer in the Sichuan Basin. In recent years, a growing number of scholars believe that the shale gas potential of the Xujiahe Formation is equally substantial, with the first member of the formation being [...] Read more.

The Xujiahe Formation (FM) is a significant source rock layer in the Sichuan Basin. In recent years, a growing number of scholars believe that the shale gas potential of the Xujiahe Formation is equally substantial, with the first member of the formation being the richest resource. The deposition of Member (Mbr) 1 of Xujiahe FM represents the first and most extensive transgression event within the entire Xujiahe Formation. This study investigates the sedimentary environment and organic matter (OM) enrichment mechanisms of the dark mud shales in the Mbr1 of Xujiahe FM on the southeastern margin of the Sichuan Basin, utilizing methods such as elemental geochemistry and organic geochemistry analyses. The results indicate that these dark mud shales possess a relatively high OM abundance, averaging 2.20% and reaching a maximum of 6.22%. The OM is primarily Type II₂ to Type III. Furthermore, the paleoclimate during the Mbr1 period in the study area was warm and humid with lush aquatic vegetation. Intense weathering and ample precipitation transported large amounts of nutrients into the lacustrine/marine basin, promoting the growth and reproduction of algae and terrestrial plants. Correlation analysis between the Total Organic Carbon (TOC) content and various geochemical proxies in the Mbr1 mud shales suggests that OM enrichment in the study area was primarily controlled by the climate and sedimentation rate; substantial OM accumulation occurred only with abundant terrigenous OM input and a relatively high sedimentation rate. Redox conditions, primarily productivity, and terrigenous detrital input acted as secondary factors, collectively modulating OM enrichment. Event-driven transgressions also played an important role in creating conditions favorable for OM preservation. Synthesizing the influence of these multiple factors on OM enrichment, this study proposes two distinct composite models for OM enrichment, dominated by climate and sedimentation rate. Full article

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

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25 pages, 3220 KB

Open AccessArticle

Industrial-Based Comprehension on the Ceramic Body Composition by Continuous/Batch Grinding Methods

by Emrah Durgut

Minerals 2025, 15(10), 1070; https://doi.org/10.3390/min15101070 - 12 Oct 2025

Abstract

In this study, the effects of batch and continuous grinding on the ceramic floor tile body were investigated in terms of cost, capacity, and technical aspects. In batch milling, a changing speed during grinding was more efficient than a constant speed. Capacity and [...] Read more.

In this study, the effects of batch and continuous grinding on the ceramic floor tile body were investigated in terms of cost, capacity, and technical aspects. In batch milling, a changing speed during grinding was more efficient than a constant speed. Capacity and energy consumption increased as the mill rotation speed increased in continuous grinding. Specific energy consumptions were measured as 36 kW/ton and 43.1 kW/ton, with 1.6 ton/h and 8.375 t/h capacities. Additionally, d₁₀, d₅₀, and d₉₀ values for ground ceramic floor tile bodies were determined to be 2.5, 9.5, and 47.2 µm and 2.5, 9.4, and 48.1 µm for batch and continuous grinding, respectively. No significant difference was observed in the color and shrinkage values, while water absorptions were calculated to be 1.1% and 0.3% as sintering properties for batch and continuous methods, respectively. In the phase analysis of a sintered body prepared using the continuous method, mullite and quartz were observed, while microcline was also analyzed differently from such minerals for the batch one. Structural changes, surface morphology, and roughness were also interpreted by DTA/TG, SEM, and AFM analysis. The presence of plastic clay minerals during the grinding process in batch milling caused non-plastic raw materials not to be ground sufficiently, and sintering characteristics changed. Full article

(This article belongs to the Special Issue From Clay Minerals to Ceramics: Progress and Challenges)

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18 pages, 91562 KB

Open AccessArticle

Mineralogy and Critical Metal Distribution in Upper Carboniferous Aluminum-Bearing Strata from the Yangquan Mining Area, Northeastern Qinshui Basin: Insights from TIMA

by Ning Wang, Yingxia Xu, Jun Zhao, Shangqing Zhang, Zhiyi Liu and Menghuai Hou

Minerals 2025, 15(10), 1069; https://doi.org/10.3390/min15101069 - 12 Oct 2025

Abstract

Critical metals associated with aluminum-bearing strata have garnered increasing attention due to their considerable economic potential. Recent investigations have identified notable enrichment of Li, Ga, Zr, Nb, REEs (rare earth elements), etc., within the Upper Carboniferous Benxi Formation in the Yangquan mining area, [...] Read more.

Critical metals associated with aluminum-bearing strata have garnered increasing attention due to their considerable economic potential. Recent investigations have identified notable enrichment of Li, Ga, Zr, Nb, REEs (rare earth elements), etc., within the Upper Carboniferous Benxi Formation in the Yangquan mining area, the Northeastern Qinshui Basin, Northern China. However, their mineralogical characteristics and micro-scale modes of occurrence remain insufficiently constrained. In this study, we employed the TESCAN Integrated Mineral Analyzer (TIMA) in combination with X-ray diffraction (XRD) and clay-separation experiments to provide direct mineralogical evidence for the occurrence of Ti, Li, Ga, Zr, and REEs in claystone and aluminous claystone from the Benxi Formation, Yangquan mining area, Northeastern Qinshui Basin. Our results indicate that both lithologies are primarily composed of kaolinite and diaspore, with minor amounts of anatase and cookeite; illite is additionally present in the claystone. Titanium predominantly occurs as anatase in both lithologies, though a portion in aluminous claystone may be incorporated into kaolinite and other Ti-bearing minerals such as rutile and leucoxene. Lithium is primarily hosted by cookeite in both rock types. Mineral assemblage variations further suggest that kaolinite may have partially transformed into Li-rich chlorite (i.e., cookeite) during the transformation from aluminous claystone to claystone. Gallium is chiefly associated with diaspore and kaolinite, with a stronger correlation with diaspore in the aluminous claystone. Zircon is the sole carrier of Zr in both lithologies. Importantly, La and Ce show a consistent spatial association with O–Al–Si–Ti–P mixed aggregates in TIMA maps, particularly in aluminous claystone. Based on these spatial patterns, textural relationships, and comparisons with previous studies, phosphate minerals are inferred to be the dominant REE hosts, although minor contributions from other phases cannot be completely excluded. These findings highlight a previously underexplored mode of critical-metal enrichment in Northern Chinese bauxite-bearing strata and provide a mineralogical basis for future extraction and utilization. Full article

(This article belongs to the Special Issue Bauxite: Mineralogy, Geochemistry and Potential Industrial Application)

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19 pages, 3575 KB

Open AccessArticle

Attenuation of Acid Mine Drainage in a Coal Waste Deposit in Southern Brazil and the Prospect of Transitioning from Active to Passive Treatment

by Felipe Santin Keller, Cláudio Boff, Daniela Silva, Alexandre Grigorieff, Cristiano Corrêa Weber, Jéssica Weiler and Ivo André Homrich Schneider

Minerals 2025, 15(10), 1068; https://doi.org/10.3390/min15101068 - 11 Oct 2025

Abstract

Capão da Roça, located in the municipality of Charqueadas, is one of the few areas of coal tailing deposits at the surface within the State of Rio Grande do Sul, Brazil that generates acid mine drainage (AMD). Over the course of 2007, the [...] Read more.

Capão da Roça, located in the municipality of Charqueadas, is one of the few areas of coal tailing deposits at the surface within the State of Rio Grande do Sul, Brazil that generates acid mine drainage (AMD). Over the course of 2007, the landfill was characterised in detail, and an active treatment plant involving pH neutralisation and metal precipitation operations was implemented to meet emission standards for mine water. In that year, based on the sulphur mass balance, it was estimated that the process of AMD generation would last for approximately two decades. The objective of this work was to study the temporal evolution of the parameters of the raw AMD. The effluent was analysed for 17 years on a monthly basis in regard to pH, acidity, metals (Fe, Al, and Mn), and sulphates. The results indicated an increase in pH (from 2.1 to 4.7), a decay in the concentration of metals (from 177.8 to 0.1 mg L⁻¹ for iron, 29.0 to 0.1 mg L⁻¹ for aluminium, and 3.1 to 0.6 mg L⁻¹ for manganese), sulphates (from 2023 to 307 mg L⁻¹), and acidity (from 539.5 mg CaCO₃ L⁻¹ to 3.96 mg CaCO₃ L⁻¹), which were adjusted to a first-order kinetic model in agreement with observations at some other mining sites. Over the years, the active lime neutralisation–precipitation treatment system has been efficient in treating the effluent. Today, most water quality parameters already meet emissions standards; however, the AMD treatment plant is still necessary to prevent pH fluctuations and to reduce the concentrations of manganese. For this reason, a transition from an active to a passive treatment system was considered. Pilot scale studies confirmed that channels filled with gravel-size limestone or slag enable the neutralisation/increase in the pH of the effluent and remove residual amounts of some metals, resulting in an effluent with no level of toxicity to the microcrustacean Daphnia magna. Full article

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

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26 pages, 15886 KB

Open AccessReview

Coal-Based Direct Reduction for Dephosphorization of High-Phosphorus Iron Ore: A Critical Review

by Hongda Xu, Rui Li, Jue Kou, Xiaojin Wen, Jiawei Lin, Jiawen Yin, Chunbao Sun and Tichang Sun

Minerals 2025, 15(10), 1067; https://doi.org/10.3390/min15101067 - 11 Oct 2025

Abstract

Conventional separation methods often prove ineffective for complex, refractory high-phosphorus iron ores. Recent advances propose a coal-based direct reduction dephosphorization-magnetic separation process, achieving significant dephosphorization efficiency. This review systematically analyzes phosphorus occurrence states in high-phosphorus oolitic iron ores across global deposits, particularly within [...] Read more.

Conventional separation methods often prove ineffective for complex, refractory high-phosphorus iron ores. Recent advances propose a coal-based direct reduction dephosphorization-magnetic separation process, achieving significant dephosphorization efficiency. This review systematically analyzes phosphorus occurrence states in high-phosphorus oolitic iron ores across global deposits, particularly within iron minerals. We categorize contemporary research and elucidate dephosphorization mechanisms during coal-based direct reduction. Key factors influencing iron mineral phase transformation, iron enrichment, and phosphorus removal are comprehensively evaluated. Phosphorus primarily exists as apatite and collophane gangue m horization agents function by: (1) inhibiting phosphorus-bearing mineral reactions or binding phosphorus into soluble salts to prevent incorporation into metallic iron; (2) enhancing iron oxide reduction and coal gasification; (3) disrupting oolitic structures, promoting metallic iron particle growth, and improving the intergrowth relationship between metallic iron and gangue. Iron mineral phase transformations follow the sequence: Fe₂O₃ → Fe₃O₄ → FeO (FeAl₂O₄, Fe₂SiO₄) → Fe. Critical parameters for effective dephosphorization under non-reductive phosphorus conditions include reduction temperature, duration, reductant/dephosphorization agent types/dosages. Future research should focus on: (1) investigating phosphorus forms in iron minerals for targeted ore utilization; (2) reducing dephosphorization agent consumption and developing sustainable alternatives; (3) refining models for metallic iron growth and improving energy efficiency; (4) optimizing reduction atmosphere control; (5) implementing low-carbon emission strategies. Full article

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

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25 pages, 4831 KB

Open AccessArticle

Comparative Evaluation of Flow Rate Distribution Methods for Uranium In-Situ Leaching via Reactive Transport Modeling

by Maksat Kurmanseiit, Nurlan Shayakhmetov, Daniar Aizhulov, Aray Tleuberdy, Banu Abdullayeva and Madina Tungatarova

Minerals 2025, 15(10), 1066; https://doi.org/10.3390/min15101066 - 11 Oct 2025

Viewed by 37

Abstract

In situ leaching represents an efficient and safe method for uranium mining, where a suboptimal well flow rate distribution leads to solution imbalances between wells, forming stagnant zones that increase operational costs. This study examines a real technological block from the Budenovskoye deposit, [...] Read more.

In situ leaching represents an efficient and safe method for uranium mining, where a suboptimal well flow rate distribution leads to solution imbalances between wells, forming stagnant zones that increase operational costs. This study examines a real technological block from the Budenovskoye deposit, applying reactive transport modeling to optimize well flow rates and reduce operational time and reagent consumption. A reactive transport model was developed based on mass conservation and Darcy’s laws coupled with chemical kinetics describing sulfuric acid interactions with uranium minerals (

U O_{2}

and

U O_{3}

). The model simulated a technological block with 4 production and 18 injection wells arranged in hexagonal cells over 511–542 days to achieve 90% uranium recovery. Six approaches for well flow rate redistribution were compared, based on different weighting factor calculation methods: advanced traditional, linear distance, squared distance, quadrilateral area, and two streamline-based approaches utilizing the minimum and average time of flight. The squared distance method achieved the highest efficiency, reducing operational costs by 5.7% through improved flow redistribution. The streamline-based methods performed comparably and offer potential advantages for heterogeneous conditions by automatically identifying hydraulic connections. The reactive transport modeling approach successfully demonstrated that multi-criteria optimization methods can improve ISL efficiency by 3.9%–5.7% while reducing operational costs. Full article

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

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18 pages, 5594 KB

Open AccessArticle

Optimization of High-Pressure Grinding Roll (HPGR) Performance in an Industrial-Scale HPGR/Tower Mill Comminution Circuit

by Bo Wei, Zhitao Yuan, Quan Feng, Qiang Zhang, Xinyang Xu, Qingyou Meng, Bern Klein and Lixia Li

Minerals 2025, 15(10), 1065; https://doi.org/10.3390/min15101065 - 11 Oct 2025

Viewed by 165

Abstract

The integration of high-pressure grinding roller (HPGR) with pre-concentration techniques and stirred mills is recognized for its energy efficiency. Studies have suggested that the feed with a P₈₀ around 1 mm is acceptable for stirred mills or coarse particle flotation. Nonetheless, published [...] Read more.

The integration of high-pressure grinding roller (HPGR) with pre-concentration techniques and stirred mills is recognized for its energy efficiency. Studies have suggested that the feed with a P₈₀ around 1 mm is acceptable for stirred mills or coarse particle flotation. Nonetheless, published experimental data characterizing the comminution behavior of single-stage HPGR circuits configured with a 1 mm screen aperture remain scarce. Moreover, extant research remains confined to laboratory scale. Consequently, critical performance metrics, including production capacity, screening efficiency, and process continuity, have not been substantively documented in the literature. In this paper, the HPGR performance in an industrial-scale HPGR/tower mill comminution circuit was assessed and optimized by laboratory and industrial tests. The research meticulously analyzed the impact of feed rate on the industrial-scale flip-flow screen and HPGR performance and found that the HPGR featuring two studded rolls with a diameter of 800 mm and a width of 400 mm, operating in a reverse classification circuit with a scalped feed by a 14.64 m² flip-flow screen while running continuously 24 h per day, is capable of producing a −1 mm comminution product suitable for tower mill feed. Under the optimal operating conditions identified, it achieved a specific energy consumption of 4.57 kWh/t with a feed rate of 27.08 t/h. Full article

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

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16 pages, 3467 KB

Open AccessArticle

Coordination-Driven Rare Earth Fractionation in Kuliokite-(Y), (Y,HREE)₄Al(SiO₄)₂(OH)₂F₅: A Crystal–Chemical Study

by Sergey V. Krivovichev, Victor N. Yakovenchuk, Olga F. Goychuk and Yakov A. Pakhomovsky

Minerals 2025, 15(10), 1064; https://doi.org/10.3390/min15101064 - 10 Oct 2025

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Abstract

The crystal structure of kuliokite-(Y), Y₄Al(SiO₄)₂(OH)₂F₅, has been re-investigated using the material from the type locality the Ploskaya Mt, Kola peninsula, Russian Arctic. It has been shown that in contrast to previous studies, [...] Read more.

The crystal structure of kuliokite-(Y), Y₄Al(SiO₄)₂(OH)₂F₅, has been re-investigated using the material from the type locality the Ploskaya Mt, Kola peninsula, Russian Arctic. It has been shown that in contrast to previous studies, the mineral is monoclinic, Im, with a = 4.3213(1), b = 14.8123(6), c = 8.6857(3) Å, β = 102.872(4)°, and V = 541.99(3) Å³. The crystal structure was solved and refined to R₁ = 0.030 on the basis of 3202 unique observed reflections. The average chemical composition determined by electron microprobe analysis is (Y_2.96Yb_0.49Er_0.27Dy_0.13Tm_0.07Lu_0.05Ho_0.05Gd_0.01Ca_0.01)_Σ4.04Al_0.92Si_2.04O₈-[(OH)_2.61F_4.42]_Σ7.03; the idealized formula is (Y,Yb,Er)₄Al[SiO₄]₂(OH)_2.5F_4.5. The crystal structure of kuliokite-(Y) contains two symmetrically independent Y sites, Y1 and Y2, coordinated by eight and seven X anions, respectively (X = O, F). The coordination polyhedra can be described as a distorted square antiprism and a distorted pentagonal bipyramid, respectively. The refinement of site occupancies indicated that the mineral represents a rare case of HREE fractionation among two cation sites driven by their coordination numbers and geometry. In agreement with the lanthanide contraction, HREEs are selectively incorporated into the Y2 site with a smaller coordination number and tighter coordination environment. The strongest building unit of the structure is the [AlX₂(SiO₄)₂] chain of corner-sharing AlX₆ octahedra and SiO₄ tetrahedra running along the a axis. The chains have their planes oriented parallel to (001). The Y atoms are located in between the chains, along with the F⁻ and (OH)⁻ anions, providing the three-dimensional integrity of the crystal structure. Each F⁻ anion is coordinated by three Y³⁺ cations to form planar (FY₃)⁸⁺ triangles parallel to the (010) plane. The triangles share common edges to form [F₂Y₂]⁴⁺ chains parallel to the a axis. The analysis of second-neighbor coordination of Y sites allowed us to identify the structural topology of kuliokite-(Y) as the only case of the skd network in inorganic compounds, previously known in molecular structures only. The variety of anionic content in the mineral allows us to identify the potential existence of two other mineral species that can tentatively be named ‘fluorokuliokite-(Y)’ and ‘hydroxykuliokite-(Y)’. Full article

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

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13 pages, 2455 KB

Open AccessArticle

Spatial Distribution of Uranium and Thorium in the Soils of North Macedonia

by Trajče Stafilov and Robert Šajn

Minerals 2025, 15(10), 1063; https://doi.org/10.3390/min15101063 - 9 Oct 2025

Viewed by 223

Abstract

The aim of the study was to determine the spatial distribution and assess uranium and thorium contamination in the soils of North Macedonia. Topsoil samples (0–30 cm) were collected from 995 locations across the country on a 5 × 5 km grid. The [...] Read more.

The aim of the study was to determine the spatial distribution and assess uranium and thorium contamination in the soils of North Macedonia. Topsoil samples (0–30 cm) were collected from 995 locations across the country on a 5 × 5 km grid. The soil samples were analysed by inductively coupled plasma–mass spectrometry (ICP-MS) using the total digestion method. The distribution of uranium and thorium in the soils is discussed according to the country’s 8 statistical regions, 15 major geological formations and 13 pedological units. The average uranium content is 2.1 mg/kg, ranging from <0.1 to 13 mg/kg (median 2.0 mg/kg), while the average thorium content is 9.3 mg/kg, ranging from 0.20 to 92 mg/kg (median 9.5 mg/kg). The spatial distribution patterns of U and Th in the soils of North Macedonia are very similar and are determined by geology (parent material and mineralisation). High uranium (2.9–13 mg/kg) and thorium (42–92 mg/kg) contents were found mainly in soils in the areas of Neogene and Palaeozoic igneous rocks and Neogene clastites (Pelagonian, East Macedonian zone), as well as in the Kratovo-Zletovo Massif in the north-eastern part of the country and in the Kožuf Mountains in the central and southern parts, where Neogene igneous rocks predominate. According to the pedological units, the hydromorphic soils (mean content of 2.9 mg/kg U and 12 mg/kg Th) in the valleys of the country’s main rivers, which predominate in the western part, were the richest for these elements. Full article

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

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16 pages, 4007 KB

Open AccessArticle

Influence of Humic Acid on the Swelling Inhibition of Clay Minerals and Process Optimization

by Ying Cheng, Dandan Zhang, Xing Gao, Junxia Yu, Ruan Chi, Bona Deng and Fang Zhou

Minerals 2025, 15(10), 1062; https://doi.org/10.3390/min15101062 - 9 Oct 2025

Viewed by 148

Abstract

Medium and heavy rare earths (REEs) are mainly from weathered crust elution-deposited rare earth ores (WREOs), where REEs are adsorbed in ionic form on the surface of clay minerals such as kaolinite, illite, halloysite, etc. REEs in WREOs are extracted through the in [...] Read more.

Medium and heavy rare earths (REEs) are mainly from weathered crust elution-deposited rare earth ores (WREOs), where REEs are adsorbed in ionic form on the surface of clay minerals such as kaolinite, illite, halloysite, etc. REEs in WREOs are extracted through the in situ leaching process with (NH₄)₂SO₄ solution via ion exchange. However, this process often results in the swelling of clay minerals, subsequently destroying the ore body structure and causing landslides. This study investigated the inhibitory effects of humic acid (HA) on the swelling of primary clay minerals. An optimal inhibition on the swelling of clay minerals was demonstrated at 0.2 g/L. HA was mixed with 0.1 mol/L (NH₄)₂SO₄ solution at the solution pH of 6.8 and temperature of 25 °C. The swelling efficiency of kaolinite, illite, and halloysite in presence of HA decreased by 0.29%, 1.19%, and 0.19%, respectively, compared to using (NH₄)₂SO₄ alone. The surface hydration parameter of clay minerals was further calculated through viscosity theory. It was demonstrated that the surface hydration parameter of kaolinite and halloysite decreased nearly threefold, while that of illite decreased fivefold, demonstrating a desirable inhibition on clay swelling with HA. Viscosity theory offers valuable theoretical support for the development of anti-swelling agents. Full article

(This article belongs to the Special Issue Recent Progress in the Processing of Rare-Earth Ore)

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33 pages, 77489 KB

Open AccessArticle

Chemistry and Fe Isotopes of Magnetites in the Orbicular Bodies in the Tanling Diorite and Implications for the Skarn Iron Mineralization in the North China Craton

by Ruipeng Li, Shangguo Su and Peng Wang

Minerals 2025, 15(10), 1061; https://doi.org/10.3390/min15101061 - 9 Oct 2025

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Abstract

Skarn-type iron ore is economically significant, and numerous skarn ore deposits have been identified in the North China Craton. The newly discovered orbicular diorite in this region is distinguished from other analogous rocks due to the accumulation of large magnetite particles, which may [...] Read more.

Skarn-type iron ore is economically significant, and numerous skarn ore deposits have been identified in the North China Craton. The newly discovered orbicular diorite in this region is distinguished from other analogous rocks due to the accumulation of large magnetite particles, which may shed new light on the genesis of this ore type. The magnetite in different parts of the orbicular structure exhibits distinct compositional differences. For example, magnetite at the edge has a small particle size (200 μm) and is associated with the minerals plagioclase and hornblende, indicating that it crystallized from normal diorite magma. By contrast, magnetite in the core has a relatively large particle size (>1000 μm), is associated with apatite and actinolite, and contains apatite inclusions as well as numerous pores. The size of magnetite in the mantle falls between that of the edge and the core. The syngenetic minerals of magnetite in the mantle include epidote and plagioclase. The magnetites in the cores of orbicules have a higher content of Ti, Al, Ni, Cr, Sc, Zn, Co, Ga, and Nb than those in the rim. The δ⁵⁶Fe value of the core magnetite (0.46‰–0.78‰) is much higher than that of the mantle and rim magnetite in orbicules. Moreover, the δ⁵⁶Fe value of magnetite increases as the V content of magnetite gradually decreases. This large iron isotope fractionation is likely driven by liquid immiscibility that forms iron-rich melts under high oxygen fugacity. The reaction between magma and carbonate xenoliths (Ca, Mg)CO₃ during magma migration generates abundant CO₂, which significantly increases the oxygen fugacity of the magmatic system. Under the action of CO₂ and other volatile components, liquid immiscibility occurs in the magma chamber, and Fe-rich oxide melts are formed by the melting of carbonate xenoliths. Iron oxides (Fe₃O₄/Fe₂O₃₎ will crystallize close to the liquidus due to high oxygen fugacity. These characteristics of magnetite in the Tanling orbicular diorite (Wuan, China) indicate that diorite magma reacts with carbonate xenoliths to form “Fe-rich melts”, and skarn iron deposits are probably formed by the reaction of intermediate-basic magma with carbonate rocks that generate such “Fe-rich melts”. A possible reaction is as follows: diorite magma + carbonate → (magnetite-actinolite-apatite) + garnet + epidote + feldspar + hornblende + CO₂↑. Full article

(This article belongs to the Special Issue Using Mineral Chemistry to Characterize Ore-Forming Processes)

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21 pages, 11164 KB

Open AccessArticle

Morphology and Chemical Composition of Newly Discovered Alluvial Gold from Baia, Eastern Carpathians, Romania

by Sergiu Drăguşanu and Călin Gabriel Tămaş

Minerals 2025, 15(10), 1060; https://doi.org/10.3390/min15101060 - 8 Oct 2025

Viewed by 255

Abstract

This study documents the first-ever recorded occurrence of alluvial gold in the foreland region of the Eastern Carpathians, specifically within the Moldavian Platform, Romania, and presents the morphological analysis and the chemical composition of the newly discovered alluvial gold. A total of 115 [...] Read more.

This study documents the first-ever recorded occurrence of alluvial gold in the foreland region of the Eastern Carpathians, specifically within the Moldavian Platform, Romania, and presents the morphological analysis and the chemical composition of the newly discovered alluvial gold. A total of 115 gold particles, with a combined weight of approximately 0.50 g, were collected from three distinct sites within the Baia region, near Falticeni town. The native gold grains exhibit average length and width ranging from 3.93 mm to 2.50 mm in location #1, 0.43 mm to 0.30 mm in location #2, and 1.01 mm to 0.56 mm in location #3, respectively. The gold grains are rounded to sub-rounded and display discoidal to subdiscoidal shapes. Traces of the original quartz gangue are occasionally retained on their surfaces. The morphological analysis and the presence of quartz attached to the gold grains suggest a short transportation distance. Quantitative electron probe microanalysis conducted on 16 gold grains yields a silver (Ag) content between 0.56 wt% to 6.19 wt%. The primary source of the alluvial gold remains unidentified. We suggest that this could be orogenic gold type deposit. Full article

(This article belongs to the Special Issue Native Gold as a Specific Indicator Mineral for Gold Deposits, 2nd Edition)

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15 pages, 6333 KB

Open AccessArticle

Design of New Eco-Cementitious Material Based on Foundry Slag and Lime Sludge

by Camila Lopes Eckert, Lucio Rosso Neto, Carlos Henrique Borgert, Júlio Preve Machado, Felipe Fardin Grillo, José Roberto de Oliveira, Matheus Vinicius Gregory Zimmermann, Mateus Milanez, Tchesare Andreas Keller, Tiago Elias Allievi Frizon, Bernardo Araldi da Silva, Agenor De Noni Junior and Eduardo Junca

Minerals 2025, 15(10), 1059; https://doi.org/10.3390/min15101059 - 8 Oct 2025

Viewed by 191

Abstract

Foundry slag has different characteristics from blast furnace slag, such as its high SiO₂ content and low basicity (CaO/SiO₂ < 1), which prevent it from being used as a cementitious component. Lime slurry is a waste product with a high CaO [...] Read more.

Foundry slag has different characteristics from blast furnace slag, such as its high SiO₂ content and low basicity (CaO/SiO₂ < 1), which prevent it from being used as a cementitious component. Lime slurry is a waste product with a high CaO content and can be used to increase the basicity of the mixture. The aim of this study is to obtain new supplementary, eco-cementitious material composed of foundry slag and lime sludge. The compositions were designed with binary basicity (molar ratio of CaO/SiO₂) ranging from 1.0 to 1.4. Clinker was replaced with the proposed material in the range of 6–34 wt% and the performance of the different cement compositions was tested. The results showed that replacing 20 wt% of clinker with the new eco-cementitious material with binary basicity of 1.2 resulted in cement with the same mechanical strength as the reference cement. The new material reacted with free CaO to generate additional calcium silicate hydrate. The initial setting time of the cement containing the new eco-cementitious material was 240 min, acting as hydration reaction retardant. The technical feature of the new eco-cementitious material allows the use of both wastes in cement composition, contributing to the requirements of circular economy. Full article

(This article belongs to the Special Issue Characterization and Reuse of Slag)

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22 pages, 6163 KB

Open AccessArticle

Provenance and Evolution of Heavy Minerals in Feldspar-Rich Sands from Wadi El Tuleia: A Mineralogical and Geochemical Approach

by Taher M. Shahin, Hatem M. El-Desoky, Sherif A. Taalab, Osama R. Elshahat, Assem M. El-Bery, Antoaneta Ene and Hamdy A. Awad

Minerals 2025, 15(10), 1058; https://doi.org/10.3390/min15101058 - 5 Oct 2025

Viewed by 342

Abstract

The heavy mineral-rich wadi deposits sourced from various wadis close to Gabal Homret Waggat in the central eastern Desert of Egypt are being analyzed to assess their genesis and paleoenvironment. This study integrates remote sensing (ALOS/PALSAR DEM and ASTER imagery), mineralogical, and geochemical [...] Read more.

The heavy mineral-rich wadi deposits sourced from various wadis close to Gabal Homret Waggat in the central eastern Desert of Egypt are being analyzed to assess their genesis and paleoenvironment. This study integrates remote sensing (ALOS/PALSAR DEM and ASTER imagery), mineralogical, and geochemical analyses (XRF and SEM-EDX). Remote sensing analysis (ASTER and ALOS/PALSAR) delineated three main watersheds and identified granitic plutons as the primary source rocks. Mineralogical analysis revealed a diverse heavy mineral assemblage, including zircon, rutile, ilmenite, magnetite, staurolite, and sillimanite, indicative of a provenance dominated by granitic and metamorphic rocks. Grain size analysis shows that the samples range from very platykurtic to extremely leptokurtic (Kg: 0.598–5.350 φ), indicating deposition in predominantly fluvial environments. Geochemical data show enrichment in SiO₂, Al₂O₃, K₂O, and Na₂O, indicating a felsic (granitic) source with low Chemical Index of Alteration (CIA: 41.89–51.83) and Plagioclase Index of Alteration (PIA: 37.97–52.78) values, and indicating that the source rocks show low to moderate chemical weathering. Tectonic discrimination diagrams suggest that the source rocks were formed in a continental island arc or active continental margin, consistent with the Arabian–Nubian Shield. The presence of economically valuable minerals like zircon and rare-earth-element-bearing monazite and columbite highlights the significant resource potential of these placer deposits. Full article

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

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20 pages, 4643 KB

Open AccessArticle

Paleoproterozoic Mafic and Ultramafic Rocks from the Mako Belt, Senegal: Implications for Back-Arc Basin Origin

by Ibrahima Dia, Tanya Furman, Kaan Sayit, Shelby Bowden, Mamadou Gueye, Cheikh Ibrahima Faye and Olivier Vanderhaeghe

Minerals 2025, 15(10), 1057; https://doi.org/10.3390/min15101057 - 5 Oct 2025

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Abstract

The Mako Belt in the Kédougou-Kéniéba Inlier (eastern Senegal) preserves Paleoproterozoic (2.3–1.9 Ga) mafic and ultramafic rocks that record early crustal growth processes within the southern West African Craton (WAC). Basalt bulk rock compositions preserve primary melt signatures, whereas the associated ultramafic cumulates [...] Read more.

The Mako Belt in the Kédougou-Kéniéba Inlier (eastern Senegal) preserves Paleoproterozoic (2.3–1.9 Ga) mafic and ultramafic rocks that record early crustal growth processes within the southern West African Craton (WAC). Basalt bulk rock compositions preserve primary melt signatures, whereas the associated ultramafic cumulates are variably serpentinized and are better assessed through mineral chemistry. Basalts occur as massive and pillow lavas, with MgO contents of 5.9–9.1 wt.% and flat to slightly LREE-depleted patterns (La/Smₙ = 0.73–0.88). Primitive mantle-normalized diagrams show subduction-related signatures, including enrichment in Ba, Pb, and Rb and depletion in Nb and Ta. Most basalts and all ultramafic rocks display (Nb/La)_PM > 1, consistent with enriched mantle melting in a back-arc setting. Harzburgites and lherzolites have cumulate textures, high Cr and Ni contents, and spinel with chromian cores (Cr# > 0.6) zoned sharply to Cr-rich magnetite rims that overlap basalt spinel compositions. Integration of the petrographic, mineralogical, and whole-rock geochemical data indicates the presence of mafic melts derived from a subduction-modified mantle wedge and likely formed in a back-arc basin above a subducting slab, rather than from a plume or mid-ocean ridge setting. Regional comparisons with other greenstone belts across the WAC suggest that the Mako Belt was part of a broader arc–back-arc system accreted during the Eburnean orogeny (~2.20–2.00 Ga). This study supports the view that modern-style plate tectonics—including subduction and back-arc magmatism—was already active by the Paleoproterozoic, and highlights the Mako Belt as a key archive of early lithospheric evolution in the WAC. Full article

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

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12 pages, 5253 KB

Open AccessArticle

Beneficiation of Fine-Grained Bayan Obo Niobium Ore Using a Slime Vibrating Table

by Si Li and Wen Chen

Minerals 2025, 15(10), 1056; https://doi.org/10.3390/min15101056 - 5 Oct 2025

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Abstract

In order to enhance the separation efficiency of fine-grained Bayan Obo Niobium Ore, a novel gravity separation equipment named Slime Vibrating Table (SVT) was developed. The SVT employs an electromagnetic drive to generate a reciprocating motion for the table, with a lower stroke [...] Read more.

In order to enhance the separation efficiency of fine-grained Bayan Obo Niobium Ore, a novel gravity separation equipment named Slime Vibrating Table (SVT) was developed. The SVT employs an electromagnetic drive to generate a reciprocating motion for the table, with a lower stroke and higher frequency than a conventional Slime Shaking Table (SST). Key parameters of SVT, including table slope, wash-water flow rate, vibration voltage, and vibration frequency, were tested for a niobium ore assaying 0.19% Nb₂O₅ with a particle size below 74 um by 68.78%. Under the optimized condition, SVT was able to obtain a primary concentrate assaying 1.31% Nb₂O₅ with a recovery of 52.64%, which was 0.22% and 26.59% higher than that of SST, respectively. Size-by-size analysis indicated that the enhanced separation performance of SVT was mainly attributed to its superior recovery of Nb₂O₅ in the −38 μm fraction. The SVT introduced in this study shows great potential for efficient recovery of fine-grained strategic metals, including rare earths, tantalum, tungsten, tin, and antimony, etc. Full article

(This article belongs to the Special Issue Recent Advances in Separation Techniques for Critical Minerals/Metals, Circular Economy, and Sustainability)

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15 pages, 2535 KB

Open AccessArticle

Chemical Characterization of Red Pigments Used in Funerary Practices in Northeastern Patagonia (Chubut, Argentina) During the Late Holocene

by Celeste Gurin, Marcia Mazzuca, Julieta Gómez Otero and Marta S. Maier

Minerals 2025, 15(10), 1055; https://doi.org/10.3390/min15101055 - 5 Oct 2025

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Abstract

In this study, we present the chemical characterization of red pigment samples and their associated sediments that were collected from three human burial sites in Northeastern Patagonia. Regarding their chronology, the La Azucena 1 site (880 ¹⁴C years BP) corresponds to the [...] Read more.

In this study, we present the chemical characterization of red pigment samples and their associated sediments that were collected from three human burial sites in Northeastern Patagonia. Regarding their chronology, the La Azucena 1 site (880 ¹⁴C years BP) corresponds to the period prior to European contact while the Loma Torta and Rawson sites date to periods following contact. These burials were discovered fortuitously. In the case of the La Azucena 1 site it was due to the impact of environmental conditions typical of this region, such as sparse vegetation and the effects of rain and wind, while for the Rawson and Loma Torta sites the burials suffered severe anthropic impact. Analysis of the red pigments and their sediments by a combination of analytical techniques using XRF, XRD, and ATR-FTIR revealed hematite as the chromophore responsible for the red color, together with large amounts of quartz in all the samples. The diffractogram of the red pigment from the La Azucena I site showed notable differences compared to those from the Loma Torta and Rawson sites, with calcite (CaCO₃) and anorthite (Na_0.45Ca_0.56)(Al_1.55Si_21.5O₈) as accompanying minerals and the presence of cristobalite, a high-temperature polymorph of silica (SiO₂), which were not identified in the sediment sample. This suggests that minerals identified in this sample are characteristic of the pigment material rather than of the sediment where the bone remains were found. Full article

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

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3 pages, 152 KB

Open AccessEditorial

Gypsum Crystals: The Importance and the Role of Calcium Sulphate in Past and Modern Environments

by Alessandra Costanzo and Mara Cipriani

Minerals 2025, 15(10), 1054; https://doi.org/10.3390/min15101054 - 4 Oct 2025

Viewed by 156

Abstract

This Special Issue gathers together a diverse set of studies that collectively advance our understanding of gypsum (CaSO₄·2H₂O) and evaporite systems, encompassing sedimentology, mineralogy, geochemistry, experimental crystallography, and planetary mineralogy [...] Full article

(This article belongs to the Special Issue Gypsum Crystals: The Importance and the Role of Calcium Sulphate in Past and Modern Environments)

15 pages, 3727 KB

Open AccessArticle

In Situ High-Temperature and High-Pressure Spectroscopic Study of the Thermal and Pressure Behavior of Hydrous Fe-Rich Ringwoodite

by Jiayi Yu, Tianze Chen and Li Zhang

Minerals 2025, 15(10), 1053; https://doi.org/10.3390/min15101053 - 4 Oct 2025

Viewed by 178

Abstract

In situ high-temperature Raman spectroscopy (up to 550 °C) and infrared spectroscopy (up to 700 °C) were employed to analyze hydrous Fe-rich ringwoodite (Fo76 composition containing 0.69 wt% H₂O). The results demonstrate that the hydrous Fe-rich ringwoodite sample undergoes irreversible structural [...] Read more.

In situ high-temperature Raman spectroscopy (up to 550 °C) and infrared spectroscopy (up to 700 °C) were employed to analyze hydrous Fe-rich ringwoodite (Fo76 composition containing 0.69 wt% H₂O). The results demonstrate that the hydrous Fe-rich ringwoodite sample undergoes irreversible structural transformation above 300 °C at ambient pressure, converting to an amorphous phase. This indicates a lower thermal stability threshold compared to Fe-bearing ringwoodite (Fo90) with equivalent water content. Notably, identical infrared spectral evolution patterns were observed during heating (25–500 °C) for the studied Fo76 sample and previously reported Fo82/Fo90 specimens, suggesting minimal influence of iron content variation on hydroxyl group behavior. The material derived from Fe-rich ringwoodite through structural transformation at ~350 °C retains the capacity to preserve water within a defined temperature window (400–550 °C). In situ high-pressure Raman spectroscopy experiments conducted up to 20 GPa detected no notable structural modifications, suggesting that hydrous Fe-rich ringwoodite, hydrous Fe-bearing ringwoodite, and hydrous Mg-endmember ringwoodite exhibit comparable structural stability within this pressure range. Full article

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

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18 pages, 11049 KB

Open AccessArticle

Pore Diagenetic Evolution and Its Coupling Relationship with Natural Gas Accumulation in Tight Sandstone Reservoirs of the Second Member of the Xujiahe Formation, Xinchang Area, Western Sichuan

by Zongze Li, Sibing Liu, Youyi Bi, Junqi Li, Meizhou Deng, Jinxi Wang and Hengyi Gao

Minerals 2025, 15(10), 1052; https://doi.org/10.3390/min15101052 - 3 Oct 2025

Viewed by 241

Abstract

By employing thin section analysis, scanning electron microscopy (SEM), homogenization temperatures of fluid inclusions, and carbon–oxygen isotope analysis of carbonate cements, this study conducted a temporal-quantitative investigation into the porosity evolution of relatively high-quality reservoirs in the Second Member of the Xujiahe Formation [...] Read more.

By employing thin section analysis, scanning electron microscopy (SEM), homogenization temperatures of fluid inclusions, and carbon–oxygen isotope analysis of carbonate cements, this study conducted a temporal-quantitative investigation into the porosity evolution of relatively high-quality reservoirs in the Second Member of the Xujiahe Formation (Xu-2 Member) in the Xinchang area of western Sichuan. The analysis focused on quantifying porosity loss due to compaction, cementation, and porosity enhancement from dissolution. Results indicate that compaction exerted the most significant impact on reservoir quality in the Xu-2 Member, causing over 70% of total porosity loss. Cementation processes, including carbonate cements, silica cements, and authigenic chlorite, further degraded reservoir properties. Authigenic chlorite precipitated earliest at burial depths of 600–800 m, while authigenic quartz and carbonate cements persistently affected the reservoir at depths of 2000–5000 m, reducing porosity by at least 10% (up to 21%). Dissolution processes initiated at approximately 3500 m burial depth, generating secondary porosity of ≥2%, with a maximum increase of 16%. Integrating these findings with the natural gas accumulation history, the coupling relationship between pore evolution and gas accumulation was elucidated. The study reveals that reservoir tightness in the Xu-2 Member developed at burial depths of 4050–5300 m, with large-scale gas accumulation predominantly occurring prior to reservoir densification. The findings provide critical guidance for identifying high-quality tight sandstone reservoirs and optimizing exploration targets in the Xu-2 Member of the Xinchang area, Western Sichuan Basin, thereby supporting efficient development of regional tight gas resources. Full article

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

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15 pages, 3041 KB

Open AccessArticle

Adsorption Characteristics of Praseodymium and Neodymium with Clay Minerals

by Zhuo Chen, Han Wang, Ruan Chi and Zhenyue Zhang

Minerals 2025, 15(10), 1051; https://doi.org/10.3390/min15101051 - 3 Oct 2025

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Abstract

As the production of electric vehicles grows, the rare earth elements Pr and Nd become increasingly significant, as they are key in magnetic materials production. In order to achieve the green and efficient recovery of Pr and Nd from the rare earth leachate, [...] Read more.

As the production of electric vehicles grows, the rare earth elements Pr and Nd become increasingly significant, as they are key in magnetic materials production. In order to achieve the green and efficient recovery of Pr and Nd from the rare earth leachate, this paper selected kaolinite and halloysite as adsorbents to conduct rare earth solution adsorption experiments for exploring the effects of the initial leachate concentration, the solution pH, and the adsorption temperature on the adsorption process. The adsorption characteristics of Pr and Nd by clay minerals were analyzed by quantum chemical calculation. The results showed that the adsorption effects of clay minerals on Pr and Nd decreased with the rise of leachate concentration. When leachate pH increased, the adsorption efficiency of kaolinite and halloysite for Pr firstly increased and then decreased, and the optimal adsorption efficiency was 13.33% and 24.778% at pH 6, respectively. The adsorption effects of kaolinite and halloysite on Nd enhanced gradually with the increase in pH, which increased to 15.925% and 30.482% at pH 7, respectively. With temperature increased, the adsorption of Pr and Nd by kaolinite and halloysite was positively correlated. The isothermal adsorption model was fitted to the experimental data, and it was found that the adsorption of Pr and Nd by kaolinite and halloysite was consistent with the Langmuir model, with R² above 0.96, indicating that the adsorption process was a single molecular layer adsorption. The results provide theoretical support for the effective recycling of Pr and Nd, which is of great significance for the utilization of rare earth resources in permanent magnets. Full article

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

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36 pages, 7458 KB

Open AccessArticle

Mineral Prospectivity Mapping for Exploration Targeting of Porphyry Cu-Polymetallic Deposits Based on Machine Learning Algorithms, Remote Sensing and Multi-Source Geo-Information

by Jialiang Tang, Hongwei Zhang, Ru Bai, Jingwei Zhang and Tao Sun

Minerals 2025, 15(10), 1050; https://doi.org/10.3390/min15101050 - 3 Oct 2025

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Abstract

Machine learning (ML) algorithms have promoted the development of predictive modeling of mineral prospectivity, enabling data-driven decision-making processes by integrating multi-source geological information, leading to efficient and accurate prediction of mineral exploration targets. However, it is challenging to conduct ML-based mineral prospectivity mapping [...] Read more.

Machine learning (ML) algorithms have promoted the development of predictive modeling of mineral prospectivity, enabling data-driven decision-making processes by integrating multi-source geological information, leading to efficient and accurate prediction of mineral exploration targets. However, it is challenging to conduct ML-based mineral prospectivity mapping (MPM) in under-explored areas where scarce data are available. In this study, the Narigongma district of the Qiangtang block in the Himalayan–Tibetan orogen was chosen as a case study. Five typical alterations related to porphyry mineralization in the study area, namely pyritization, sericitization, silicification, chloritization and propylitization, were extracted by remote sensing interpretation to enrich the data source for MPM. The extracted alteration evidences, combined with geological, geophysical and geochemical multi-source information, were employed to train the ML models. Four machine learning models, including artificial neural network (ANN), random forest (RF), support vector machine and logistic regression, were employed to map the Cu-polymetallic prospectivity in the study area. The predictive performances of the models were evaluated through confusion matrix-based indices and success-rate curves. The results show that the classification accuracy of the four models all exceed 85%, among which the ANN model achieves the highest accuracy of 96.43% and a leading Kappa value of 92.86%. In terms of predictive efficiency, the RF model outperforms the other models, which captures 75% of the mineralization sites within only 3.5% of the predicted area. A total of eight exploration targets were delineated upon a comprehensive assessment of all ML models, and these targets were further ranked based on the verification of high-resolution geochemical anomalies and evaluation of the transportation condition. The interpretability analyses emphasize the key roles of spatial proxies of porphyry intrusions and geochemical exploration in model prediction as well as significant influences everted by pyritization and chloritization, which accords well with the established knowledge about porphyry mineral systems in the study area. The findings of this study provide a robust ML-based framework for the exploration targeting in greenfield areas with good outcrops but low exploration extent, where fusion of a remote sensing technique and multi-source geo-information serve as an effective exploration strategy. 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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14 pages, 1641 KB

Open AccessArticle

The Effect of Electrochemical Surface Properties on Molybdenite Flotation in Seawater

by Yang Chen, Na Zhang and Haoran Cui

Minerals 2025, 15(10), 1049; https://doi.org/10.3390/min15101049 - 3 Oct 2025

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Abstract

Seawater has been widely used in copper–molybdenum flotation plants due to the shortage of fresh water and the high cost of seawater desalination, especially in arid regions. There have been many studies concerning the molybdenite flotation in seawater. Due to the complication of [...] Read more.

Seawater has been widely used in copper–molybdenum flotation plants due to the shortage of fresh water and the high cost of seawater desalination, especially in arid regions. There have been many studies concerning the molybdenite flotation in seawater. Due to the complication of seawater flotation, it is difficult to identify the key factors affecting molybdenite recoveries. It is known that the unique structure of molybdenite plays an important role in molybdenite flotation. The anisotropic property of molybdenite leads to the different surface properties of basal and edge plane surfaces. Electrochemical properties of sulfides have a significant effect on the surface properties which affect the flotation performance. Therefore, it is important to understand the surface electrochemical properties such as surface chemistry, redox processes, and reaction kinetics of molybdenite’s two different surfaces in seawater, and to determine what affects the molybdenite flotation behaviors in seawater. In this study, the surface properties of molybdenite basal and edge plane surfaces in both fresh water and seawater were investigated through various electrochemical techniques. Open circuit potential (OCP) measurement indicated that edge plane surfaces were easier to be oxidized than basal plane surfaces. Cyclic voltammetry (CV) studies showed that the basal plane surfaces were stable with a low electrochemical reactivity, while the edge plane surfaces had relatively high electrochemical reactivity. In addition, the redox property of the molybdenite surface was enhanced in seawater, which is a key to the improvement of fine molybdenite flotation in seawater. Electrochemical impedance spectroscopy (EIS) measurements further confirmed the stability of basal plane surfaces and indicated a greater charge transfer ability of edge plane surfaces in seawater. Different molybdenite particle sizes with different basal and edge ratios were applied in the flotation in both fresh water and seawater; the results illustrated that molybdenite flotation was enhanced in seawater especially to fine particles. The flotation and electrochemical studies reveal that the electrochemical reactivity of edge plane surface plays an important role in molybdenite seawater flotation. Full article

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

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14 pages, 2100 KB

Open AccessArticle

Recovery of Copper from Pregnant Leach Solutions of Copper Concentrate Using Aluminum Shavings

by Oscar Joaquín Solís Marcial, Alfonso Nájera-Bastida, Orlando Soriano-Vargas, José Pablo Ruelas Leyva, Alfonso Talavera-López, Horacio Inchaurregui and Roberto Zárate Gutiérrez

Minerals 2025, 15(10), 1048; https://doi.org/10.3390/min15101048 - 2 Oct 2025

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Abstract

Copper is one of the most used metals today due to its wide range of applications. Traditionally, this metal has been primarily extracted through pyrometallurgical methods, which presents several environmental and energy-related drawbacks. An alternative is hydrometallurgy, which has achieved acceptable copper extraction [...] Read more.

Copper is one of the most used metals today due to its wide range of applications. Traditionally, this metal has been primarily extracted through pyrometallurgical methods, which presents several environmental and energy-related drawbacks. An alternative is hydrometallurgy, which has achieved acceptable copper extraction rates. However, this process has not found widespread industrial application due to operational challenges and the complexity associated with the selective recovery of copper ions from the Pregnant Leach Solution (PLS), especially due to the coexistence of copper and iron ions, complicating the efficient separation of both metals. In this work, the use of aluminum shavings as a cementation agent is proposed, analyzing variables such as the initial shaving concentration (2.5, 5, 10, 15, and 20 g/L), the agitation speed (0, 200, and 400 rpm), and a temperature of 20, 30, and 40 °C. The results demonstrated selective copper cementation, achieving a 100% recovery in 30 min under stirring conditions of 400 rpm. The analysis performed using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) revealed the formation of solid phases such as metallic copper (Cu), aluminum hydroxide [Al(OH)₃], and elemental sulfur (S). Additionally, it was observed that the iron ion concentration remained constant throughout the experiment, indicating a high selectivity in the process. The kinetic analysis revealed that the reaction follows a first-order model without stirring. An activation energy of 62.6 kJ/mol was determined within the experimental temperature range of 20–40 °C, confirming that the process fits the chemical reaction model. These findings provide a deeper understanding of the system’s behavior, highlighting its feasibility and potential for industrial-scale applications. Full article

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

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20 pages, 9509 KB

Open AccessArticle

Extraction of Remote Sensing Alteration Information Based on Integrated Spectral Mixture Analysis and Fractal Analysis

by Kai Qiao, Tao Luo, Shihao Ding, Licheng Quan, Jingui Kong, Yiwen Liu, Zhiwen Ren, Shisong Gong and Yong Huang

Minerals 2025, 15(10), 1047; https://doi.org/10.3390/min15101047 - 2 Oct 2025

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Abstract

As a key target area in China’s new round of strategic mineral exploration initiatives, Tibet possesses favorable metallogenic conditions shaped by its unique geological evolution and tectonic setting. In this paper, the Saga region of Tibet is the research object, and Level-2A Sentinel-2 [...] Read more.

As a key target area in China’s new round of strategic mineral exploration initiatives, Tibet possesses favorable metallogenic conditions shaped by its unique geological evolution and tectonic setting. In this paper, the Saga region of Tibet is the research object, and Level-2A Sentinel-2 imagery is utilized. By applying mixed pixel decomposition, interfering endmembers were identified, and spectral unmixing and reconstruction were performed, effectively avoiding the drawback of traditional methods that tend to remove mineral alteration signals and masking interference. Combined with band ratio analysis and principal component analysis (PCA), various types of remote sensing alteration anomalies in the region were extracted. Furthermore, the fractal box-counting method was employed to quantify the fractal dimensions of the different alteration anomalies, thereby delineating their spatial distribution and fractal structural characteristics. Based on these results, two prospective mineralization zones were identified. The results indicate the following: (1) In areas of Tibet with low vegetation cover, applying spectral mixture analysis (SMA) effectively removes substantial background interference, thereby enabling the extraction of subtle remote sensing alteration anomalies. (2) The fractal dimensions of various remote sensing alteration anomalies were calculated using the fractal box-counting method over a spatial scale range of 0.765 to 6.123 km. These values quantitatively characterize the spatial fractal properties of the anomalies, and the differences in fractal dimensions among alteration types reflect the spatiotemporal heterogeneity of the mineralization system. (3) The high-potential mineralization zones identified in the composite contour map of fractal dimensions of alteration anomalies show strong spatial agreement with known mineralization sites. Additionally, two new prospective mineralization zones were delineated in their periphery, providing theoretical support and exploration targets for future prospecting in the study area. Full article

(This article belongs to the Special Issue Global Mineral Resource Exploration Using Multi-Sensor Satellite Data and Machine Learning Algorithms)

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26 pages, 4017 KB

Open AccessArticle

Research on Multi-Source Information-Based Mineral Prospecting Prediction Using Machine Learning

by Jie Xu, Yongmei Li, Wei Liu, Shili Han, Kaixuan Tan, Yanshi Xie and Yi Zhao

Minerals 2025, 15(10), 1046; https://doi.org/10.3390/min15101046 - 1 Oct 2025

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Abstract

The Shizhuyuan polymetallic deposit in Hunan Province, China, is a world-class ore field rich in tungsten (W), tin (Sn), molybdenum (Mo), and bismuth (Bi), now facing resource depletion due to prolonged exploitation. This study addresses the limitations of traditional geological prediction methods in [...] Read more.

The Shizhuyuan polymetallic deposit in Hunan Province, China, is a world-class ore field rich in tungsten (W), tin (Sn), molybdenum (Mo), and bismuth (Bi), now facing resource depletion due to prolonged exploitation. This study addresses the limitations of traditional geological prediction methods in complex terrain by integrating multi-source datasets—including γ-ray spectrometry, high-precision magnetometry, induced polarization (IP), and soil radon measurements—across 5049 samples. Unsupervised factor analysis was employed to extract five key ore-indicating factors, explaining 82.78% of data variance. Based on these geological features, predictive models including Support Vector Machine (SVM), Random Forest (RF), and Extreme Gradient Boosting (XGBoost) were constructed and compared. SHAP values were employed to quantify the contribution of each geological feature to the prediction outcomes, thereby transforming the machine learning “black-box models” into an interpretable geological decision-making basis. The results demonstrate that machine learning, particularly when integrated with multi-source data, provides a powerful and interpretable approach for deep mineral prospectivity mapping in concealed terrains. Full article

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

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17 pages, 11781 KB

Open AccessArticle

Identifying New Copper Mineralization via Multispectral Remote Sensing (MSRS) and Short-Wave Infrared (SWIR) Spectral Analysis in Dingyang, Western Gangdese Belt, Xizang

by Zhibin Li, Zhaxi PuBu, Xian Che, Gen Chen, Jiangang Wei, Deng Pan and Xiaojia Jiang

Minerals 2025, 15(10), 1045; https://doi.org/10.3390/min15101045 - 1 Oct 2025

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Abstract

The Gangdese metallogenic belt (GMB), spanning nearly 2000 km across central Tibet, represents the primary copper–polymetallic metallogenic belt in Tibet and a world-class porphyry copper province. However, extreme high-altitude conditions, ecological fragility, and limited accessibility in western GMB have significantly constrained the efficacy [...] Read more.

The Gangdese metallogenic belt (GMB), spanning nearly 2000 km across central Tibet, represents the primary copper–polymetallic metallogenic belt in Tibet and a world-class porphyry copper province. However, extreme high-altitude conditions, ecological fragility, and limited accessibility in western GMB have significantly constrained the efficacy of conventional exploration methods. Identifying effective mineralogical indicators and rapidly delineating mineralization–hydrothermal centers within this metallogenic system remain critical challenges for exploration geologists. This study integrates multispectral remote sensing (MSRS; Sentinel-2) with short-wave infrared (SWIR) spectral analysis to establish mineral spectroscopic exploration indicators for the periphery of the Zhunuo porphyry copper ore-concentrated area. Principal Component Analysis (PCA) and band ratio techniques were employed to delineate remote sensing alteration anomalies, followed by SWIR spectral features to identify mineralization–hydrothermal centers. Hydrothermal alteration in the study area is dominated by sericite, chlorite, and epidote, with subordinate carbonate and sulfate minerals. Multispectral anomalies (Al-OH, ferric contamination, and carbonate alterations) in the Dingyang area exhibit intensity and compositional patterns comparable to those of the Cimabanshuo, Beimulang, and Zhigunong deposits, indicating high mineralization potential. SWIR analysis identified sericite-based exploration indicators (Pos2200 < 2203 nm, Dep2200 > 0.3, SWIR-IC > 1.6). A Spectral Feature-Based Geological Content Method (SFGCM) model was developed to delineate mineralization–hydrothermal centers, revealing new malachite and azurite mineralization in the Dingyang area. The MSRS-SWIR provides a novel perspective for applying spectroscopy to rapidly identify porphyry copper mineralized hydrothermal centers in high-altitude, ecologically fragile areas. Full article

(This article belongs to the Special Issue Mineralogy of Porphyry Systems: Genesis, Exploration, and Applications)

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13 pages, 1471 KB

Open AccessArticle

Effect of Frother Type on Surface Properties and Flotation Performance of Galena: A Comparative Study of EH, PPG250, and MIBC

by Yunus Emre Cavdar, Ilayda Asil, Saleban Mohamed Muse, Feridun Boylu and Orhan Ozdemir

Minerals 2025, 15(10), 1044; https://doi.org/10.3390/min15101044 - 1 Oct 2025

Viewed by 362

Abstract

The selection of suitable frothers in flotation processes plays a crucial role in controlling bubble formation, foam stability, and ultimately mineral recovery. Therefore, understanding the interfacial behavior of frothers is important to optimize flotation efficiency, especially for valuable sulfide minerals such as galena [...] Read more.

The selection of suitable frothers in flotation processes plays a crucial role in controlling bubble formation, foam stability, and ultimately mineral recovery. Therefore, understanding the interfacial behavior of frothers is important to optimize flotation efficiency, especially for valuable sulfide minerals such as galena (PbS). In this study, the interfacial behavior and flotation performance of different frothers in PbS flotation were investigated with a particular focus on surface tension, bubble coalescence, foam stability, and flotation recovery. A high-purity crystalline PbS sample (≈96.65% PbS) obtained from Trabzon, Türkiye, was subjected to systematic experimental analyses including surface tension measurements, critical coalescence concentration (CCC) determination, dynamic foam stability (DFS) tests using the DFA100 analyzer, and micro-flotation experiments. 2-ethylhexanol (EH), polypropylene glycol 250 (PPG250), and methyl isobutyl carbinol (MIBC) were used as frothers, while potassium ethyl xanthate (PEX) was employed as a collector. The results revealed that EH had the highest surface activity (42.67 mN/m at 1000 ppm), and the lowest CCC value (~2 ppm) compared to PPG250 (~3 ppm) and MIBC (~8 ppm). According to the micro-flotation results, the flotation recovery gradually increased with increasing frother dosage; the highest recoveries were obtained with PPG250 (99.45%), EH (98.31%), and MIBC (95.17%). PPG250 and EH achieved higher flotation performance at lower dosages compared to MIBC. These findings highlight the critical role of molecular structure and interfacial properties in the effective selection of frothers for galena flotation. Full article

(This article belongs to the Special Issue Surface Chemistry and Reagents in Flotation)

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25 pages, 8488 KB

Open AccessArticle

Limestone-Based Hybrid Passive Treatment for Copper-Rich Acid Mine Drainage: From Laboratory to Field

by Joshua Pascual Pocaan, Brian Gerald Bueno, Jaica Mae Pagaduan, Johara Capingian, Michelle Airah N. Pablo, Jacob Louies Rohi W. Paulo, Arnel B. Beltran, Aileen H. Orbecido, Renan Ma. Tanhueco, Carlito Baltazar Tabelin, Mylah Villacorte-Tabelin, Vannie Joy T. Resabal, Irish Mae Dalona, Dennis Alonzo, Pablo Brito-Parada, Yves Plancherel, Robin Armstrong, Anne D. Jungblut, Ana Santos, Paul F. Schofield, Richard Herrington and Michael Angelo B. Promentilla Show full author list Hide full author list

Minerals 2025, 15(10), 1043; https://doi.org/10.3390/min15101043 - 1 Oct 2025

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Abstract

Acid mine drainage (AMD) is an environmental concern that needs to be addressed by some mining industries because of its high concentrations of metals and acidity that destroy affected ecosystems. Its formation typically persists beyond the operating life of a mine site. Its [...] Read more.

Acid mine drainage (AMD) is an environmental concern that needs to be addressed by some mining industries because of its high concentrations of metals and acidity that destroy affected ecosystems. Its formation typically persists beyond the operating life of a mine site. Its management is even more challenging for sites that are abandoned without rehabilitation. In this study, a legacy copper–gold mine located in Sto. Niño, Tublay, Benguet, Philippines, generating a copper- and manganese-rich AMD (Cu, maximum 17.2 mg/L; Mn, maximum 2.90 mg/L) at pH 4.59 (minimum) was investigated. With its remote location inhabited by the indigenous people local community (IPLC), a novel limestone-based hybrid passive treatment system that combines a limestone leach bed (LLB) and a controlled modular packed bed reactor (CMPB) has been developed from the laboratory and successfully deployed in the field while investigating the effective hydraulic retention time (HRT), particle size, and redox conditions (oxic and anoxic) in removing Cu and Mn and increasing pH. Laboratory-scale and pilot-scale systems using simulated and actual AMD, respectively, revealed that a 15 h HRT and both oxic and anoxic conditions were effective in treating the AMD. Considering these results and unsteady conditions of the stream in the legacy mine, a hybrid multi-stage limestone leach bed and packed bed were deployed having variable particle size (5 mm to 100 mm) and HRT. Regular monitoring of the system showed the effective removal of Cu (88.5%) and Mn (66.83%) as well as the increase of pH (6.26), addressing the threat of AMD in the area. Improvement of the lifespan of the system needs to be addressed, as issues of Cu-armoring were observed, resulting in reduced performance over time. Nonetheless, the study presents a novel technique in implementing passive treatment systems beyond the typical treatment trains reported in the literature. Full article

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

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36 pages, 1673 KB

Open AccessReview

The Evolution of Machine Learning in Large-Scale Mineral Prospectivity Prediction: A Decade of Innovation (2016–2025)

by Zekang Fu, Xiaojun Zheng, Yongfeng Yan, Xiaofei Xu, Fanchao Zhou, Xiao Li, Quantong Zhou and Weikun Mai

Minerals 2025, 15(10), 1042; https://doi.org/10.3390/min15101042 - 30 Sep 2025

Viewed by 212

Abstract

The continuous growth in global demand for mineral resources and the increasing difficulty of mineral exploration have created bottlenecks for traditional mineral prediction methods in handling complex geological information and large amounts of data. This review aims to explore the latest research progress [...] Read more.

The continuous growth in global demand for mineral resources and the increasing difficulty of mineral exploration have created bottlenecks for traditional mineral prediction methods in handling complex geological information and large amounts of data. This review aims to explore the latest research progress in machine learning technology in the field of large-scale mineral prediction from 2016 to 2025. By systematically searching the Web of Science core database, we have screened and analyzed 255 high-quality scientific studies. These studies cover key areas such as mineral information extraction, target area selection, mineral regularity modeling, and resource potential evaluation. The applied machine learning technologies include Random Forests, Support Vector Machines, Convolutional Neural Networks, Recurrent Neural Networks, etc., and have been widely used in the exploration and prediction of various mineral deposits such as porphyry copper, sandstone uranium, and tin. The findings indicate a substantial shift within the discipline towards the utilization of deep learning methodologies and the integration of multi-source geological data. There is a notable rise in the deployment of cutting-edge techniques, including automatic feature extraction, transfer learning, and few-shot learning. This review endeavors to synthesize the prevailing state and prospective developmental trajectory of machine learning within the domain of large-scale mineral prediction. It seeks to delineate the field’s progression, spotlight pivotal research dilemmas, and pinpoint innovative breakthroughs. 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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Minerals, Volume 15, Issue 10 (October 2025) – 68 articles

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