Minerals

18 pages, 7190 KB

Open AccessArticle

Lithofacies Characteristics and Sedimentary Evolution of the Lianggaoshan Formation in the Southeastern Sichuan Basin

by Qingshao Liang, Qianglu Chen, Yunfei Lu, Yanji Li, Jianxin Tu, Guang Yang and Longhui Gao

Minerals 2025, 15(9), 1003; https://doi.org/10.3390/min15091003 - 22 Sep 2025

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Abstract

The Lower Submember of the Second Member of the Lianggaoshan Formation (LGS2-LS) in the Fuling area, southeastern Sichuan Basin, represents the deepest lacustrine depositional stage of the formation and constitutes an important target for shale oil and gas exploration. Based on core observations, [...] Read more.

The Lower Submember of the Second Member of the Lianggaoshan Formation (LGS2-LS) in the Fuling area, southeastern Sichuan Basin, represents the deepest lacustrine depositional stage of the formation and constitutes an important target for shale oil and gas exploration. Based on core observations, thin-section petrography, X-ray diffraction, geochemical analyses, and sedimentary facies interpretation from representative wells, this study characterizes the lithofacies types, sedimentary environments, and depositional evolution of the LGS2-LS. Results show that the LGS2-LS is dominated by clay–quartz assemblages, with average clay mineral and quartz contents of 44.6% and 38.8%, respectively, and can be subdivided into shallow and semi-deep lacustrine subfacies comprising eight microfacies. Geochemical proxies indicate alternating warm-humid and hot-arid paleoclimatic phases, predominantly freshwater conditions, variable redox states, and fluctuations in paleoproductivity. Sedimentary evolution reveals multiple transgressive–regressive cycles, with Sub-layer 6 recording the maximum water depth and deposition of thick organic-rich shales under strongly reducing conditions. The proposed sedimentary model outlines a terrigenous clastic lacustrine system controlled by lake-level fluctuations, transitioning from littoral to shallow-lake to semi-deep-lake environments. The distribution of high-quality organic-rich shales interbedded with sandstones highlights the LGS2-LS as a favorable interval for shale oil and gas accumulation, providing a geological basis for further hydrocarbon exploration in the southeastern Sichuan Basin. Full article

(This article belongs to the Special Issue Sedimentary Basins and Minerals)

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18 pages, 2069 KB

Open AccessArticle

Colour Stability of Light-Sensitive Minerals Under UVA_340nm Irradiation: Implications for the Conservation of Cultural Heritage and Museum Display Conditions

by Fabio Sitzia, Patricia Moita, Silvia Bottura-Scardina and Carla Lisci

Minerals 2025, 15(9), 999; https://doi.org/10.3390/min15090999 - 20 Sep 2025

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Abstract

Several minerals are known to undergo chromatic variations when exposed to sunlight, particularly ultraviolet (UV) radiation. These phases, defined as photosensitive, exhibit colour change due to photochemical reactions. To understand this phenomenon, this study investigates the colour alteration in 26 common mineral phases, [...] Read more.

Several minerals are known to undergo chromatic variations when exposed to sunlight, particularly ultraviolet (UV) radiation. These phases, defined as photosensitive, exhibit colour change due to photochemical reactions. To understand this phenomenon, this study investigates the colour alteration in 26 common mineral phases, aiming to better understand their behaviour under artificial ageing conditions. Each mineral was firstly chemically characterised by SEM-EDS to identify common chromophoric impurities. Subsequently, samples were exposed to UV radiation in the climatic chamber. The colour shifts were semi-quantitatively assessed in the CIEL*a*b* colour space after ageing. The results indicate that just 4 minerals out of 26 display negligible colour variation, whereas 22 show evident colour changes. These findings highlight the vulnerability of photosensitive minerals to UV-induced colour changes and raise concerns regarding their behaviour in artworks, historical surfaces, and cultural heritage objects. As such minerals are frequently found in the heritage field, understanding their photochemical responses is essential for developing informed preventive conservation strategies, particularly concerning light exposure in both museum and outdoor contexts. Full article

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

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24 pages, 5437 KB

Open AccessArticle

Geochemical Characteristics and Hydrocarbon Generation Potential of Source Rock in the Baorao Trough, Jiergalangtu Sag, Erlian Basin

by Jieqiong Zhu, Yongbin Quan, Ruichang Yan, Xin Xiang, Yawen Xing, Yiming Hu, Yulei Shi, Hengrui Li, Huili Yang, Jianping Wu, Hao Zhang and Ning Tian

Minerals 2025, 15(9), 1002; https://doi.org/10.3390/min15091002 - 20 Sep 2025

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Abstract

The Baorao Trough of the Jiergalangtu Sag, located in the central Erlian Basin, is rich in petroleum resources. However, due to a lack of systematic geochemical characterization and comparative studies with other source rocks, the hydrocarbon generation potential of its Jurassic strata remains [...] Read more.

The Baorao Trough of the Jiergalangtu Sag, located in the central Erlian Basin, is rich in petroleum resources. However, due to a lack of systematic geochemical characterization and comparative studies with other source rocks, the hydrocarbon generation potential of its Jurassic strata remains unclear. In this study, 125 samples from the Baorao Trough were analyzed to evaluate their hydrocarbon generation potential, identify organic matter sources and depositional environments, and characterize hydrocarbon generation and expulsion. Results show that source rocks from the first member of the Tengge’er (K₁bt₁) Formation and the Aershan (K₁ba) Formation have high organic matter content, favorable kerogen types, and have reached low to medium maturity. In contrast, Jurassic source rocks are predominantly Type III kerogen and highly mature. K₁bt₁ was deposited in a weakly oxidizing to reducing, brackish environment, while K₁ba formed under weakly reducing, saline conditions. Jurassic source rocks also developed in weakly reducing, brackish to saline settings. Notably, saline and reducing environments promote the development of high-quality source rocks. The lower total organic carbon (TOC) threshold for effective source rocks in the study area is 0.8%, and the hydrocarbon expulsion threshold for vitrinite reflectance ratio (R_o) is approximately 0.8%. Accordingly, K₁bt₁ and K₁ba have undergone partial hydrocarbon expulsion but remain within the oil-generating window, indicating strong oil-generating potential. Jurassic source rocks likely experienced early thermal cracking of Type III kerogen, with generated oil migrating or escaping during early geological activity. However, some gas-generating potential remains. These findings provide significant evidence for assessing resource potential, predicting the distribution of high-quality source rocks and favorable exploration areas. Full article

(This article belongs to the Special Issue Organic Petrology and Geochemistry: Exploring the Organic-Rich Facies)

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17 pages, 6008 KB

Open AccessArticle

Small-Scale Porphyry Cu (Au) Systems in Collisional Orogens: A Case Study of the Xifanping Deposit with Implications for Mineralization Potential in Western Yangtze Craton, SW China

by Yunhai Hu, Mimi Yang, Xingyuan Li, Guoxiang Chi and Fufeng Zhao

Minerals 2025, 15(9), 1001; https://doi.org/10.3390/min15091001 - 20 Sep 2025

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Abstract

The Xifanping Cu–(Au) deposit, a small-scale porphyry system in the central Jinshajiang–Red River tectonic belt (JSRR), formed in a Cenozoic collisional setting. This study integrates zircon U–Pb geochronology, Lu–Hf isotopes, whole-rock geochemistry, and zircon trace element analyses of ore-bearing and barren porphyries, combined [...] Read more.

The Xifanping Cu–(Au) deposit, a small-scale porphyry system in the central Jinshajiang–Red River tectonic belt (JSRR), formed in a Cenozoic collisional setting. This study integrates zircon U–Pb geochronology, Lu–Hf isotopes, whole-rock geochemistry, and zircon trace element analyses of ore-bearing and barren porphyries, combined with regional comparisons, to constrain magma sources, metallogenic controls, and genetic processes. Ore-bearing biotite quartz monzonite porphyries were emplaced at 32.15 ± 0.43 Ma and 32.49 ± 0.57 Ma, post-dating barren quartz monzonite porphyry (33.15 ± 0.51 Ma). These ages are consistent with molybdenite Re–Os ages (32.1 ± 1.6 Ma), indicating near-synchronous magmatism and mineralization. Both porphyry types belong to the shoshonitic, peraluminous series, enriched in LILE, depleted in HFSE, enriched in LREE, and lacking significant Eu anomalies. Their εHf (t) values (–2.94 to +3.68) and crustal model ages (TDM2 = 0.88–1.30 Ga) indicate derivation from Neoproterozoic subduction-modified lower crust. Ore-bearing porphyries, however, exhibit higher zircon Ce⁴⁺/Ce³⁺ ratios (average = 584 vs. 228 for barren porphyries) and elevated hydrous mineral contents (>10 vol.% amphibole + biotite), indicating more oxidized and water-rich parental magmas. Compared with large-scale porphyry systems (e.g., Dexing, northern Chile), the absence of adakitic signatures and only moderate oxidation limited the scale of mineralization. Overall, the Xifanping deposit formed through partial melting of Neoproterozoic subduction-modified lower crust in a post-collisional extensional regime: at ~33.2 Ma, melting of metasomatized ancient lower crust generated barren porphyries; at ~32 Ma, further evolution and differentiation of this lower crust magmas led to the extraction and enrichment of ore-forming materials from the thicken lower crust, producing hydrated, oxidized, ore-bearing magmas that intruded at shallow levels to form base and precious metal mineralizations. These results underscore the distinctive metallogenic characteristics of small-scale porphyry systems in collisional settings and provide new insights into how source composition and magma oxidation state constrain mineralization potential. Full article

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

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18 pages, 2248 KB

Open AccessArticle

Activation of Mineral Composition via Thermochemical Disintegration

by Nazym Akhmadiyeva, Sergey Gladyshev, Rinat Abdulvaliyev, Yerkezhan Abikak, Leila Imangaliyeva, Asiya Kasymzhanova and Galiya Ruzakhunova

Minerals 2025, 15(9), 1000; https://doi.org/10.3390/min15091000 - 20 Sep 2025

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Abstract

This study investigates the use of preliminary thermochemical activation in a NaHCO₃ solution under elevated pressure and temperature to modify the chemically stable and hard-to-process phase composition of various mineral raw materials and improve the recovery of valuable components. The method was [...] Read more.

This study investigates the use of preliminary thermochemical activation in a NaHCO₃ solution under elevated pressure and temperature to modify the chemically stable and hard-to-process phase composition of various mineral raw materials and improve the recovery of valuable components. The method was tested on various types of mineral raw materials, including slag from the reductive smelting of red mud from alumina production prior to acid leaching, ash before chemical beneficiation, gibbsite–kaolinite bauxite prior to gravity separation, and nephelines, for which the sintering process was replaced with chemical beneficiation. The slag from the reductive smelting of red mud was also tested before acid leaching. The activation of slag enhanced tricalcium silicate formation lead to leaching recoveries of ~96% for rare earth elements, ~92% for TiO₂, ~98% for CaO and Al₂O₃, and 50% for Fe₂O₃, compared to much lower values without activation. With ash, activation eliminated the sillimanite and hedenbergite phases, increased mullite and free silica, and formed calcite, resulting in a 15–20% higher silica recovery. With gibbsite–kaolinite bauxite, activation altered kaolinite, siderite, quartz, and hematite contents; eliminated calcium silicate; and improved the silicon modulus of the sand fraction by 35.9% during gravity beneficiation. For nepheline ore, activation promoted the formation of albite and hydrosodalite, eliminated corundum and andradite, and increased silica recovery from 33.58% to 59.6%. These results demonstrate that thermochemical activation effectively transforms mineral structures and significantly improves the efficiency of subsequent beneficiation processes. Full article

(This article belongs to the Special Issue Alkali Activation of Clay-Based Materials)

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15 pages, 2376 KB

Open AccessArticle

Dry Iron Ore Fluidization, Flowability, and Handling: Supporting Dry Processing of Iron Ores and Guiding Industrial Designing

by Benito Barbabela e Silva, Anderson de Araújo Soares, Monica Guimarães Vieira, Rogério Ruiz, Arthur Pinto Chaves and Maurício Guimarães Bergerman

Minerals 2025, 15(9), 998; https://doi.org/10.3390/min15090998 - 19 Sep 2025

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Abstract

Renewed interest in dry processing has arisen due to challenges in water management. In dry iron ore beneficiation, flowability of bulk solids is a key concern, leading to issues like plugging and clogging in bins and chutes. Handling also faces challenges from environmental [...] Read more.

Renewed interest in dry processing has arisen due to challenges in water management. In dry iron ore beneficiation, flowability of bulk solids is a key concern, leading to issues like plugging and clogging in bins and chutes. Handling also faces challenges from environmental regulations, particularly regarding dust emissions. Enclosed conveyor technologies, such as air-assisted conveyors that use fluidization, offer effective solutions, though the maximum particle size that can be conveyed is a limitation that needs consideration. This paper examines how the size and chemical composition of bulk iron ore materials affect their handling behavior. By employing Geldart’s and Jenike’s methods, this document provides technical parameters and recommendations, which are lacking in the current literature, for the designing of dry processing plants. Findings indicate that ultrafines can have a flow function as low as 2.05, indicating cohesive behavior even when dried, while fluidization tests support these characteristics. In contrast, coarser fractions are easy for free-flowing materials. Samples with a top size of 0.5 mm fall between sand-like and spoutable groups in Geldart’s classification. Denser materials did not fluidize, while less dense ones did. Thus, air slides should avoid handling materials at this threshold and focus on finer materials. This paper offers guidance for designing dry processing plants to address handling bottlenecks. Full article

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

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48 pages, 12749 KB

Open AccessArticle

Comparative Analysis of CO₂ Sequestration Potential in Shale Reservoirs: Insights from the Longmaxi and Qiongzhusi Formations

by Bo Li, Bingsong Yu, Paul W. J. Glover, Piroska Lorinczi, Kejian Wu, Ciprian-Teodor Panaitescu, Wei Wei, Jingwei Cui and Miao Shi

Minerals 2025, 15(9), 997; https://doi.org/10.3390/min15090997 - 19 Sep 2025

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Abstract

Shale reservoirs offer significant potential for CO₂ geological sequestration due to their extensive nanopore networks and heterogeneous pore systems. This study comparatively assessed the CO₂ storage potential of the Lower Silurian Longmaxi and Lower Cambrian Qiongzhusi shales through an integrated approach [...] Read more.

Shale reservoirs offer significant potential for CO₂ geological sequestration due to their extensive nanopore networks and heterogeneous pore systems. This study comparatively assessed the CO₂ storage potential of the Lower Silurian Longmaxi and Lower Cambrian Qiongzhusi shales through an integrated approach involving organic geochemical analysis, mineralogical characterization through X-ray diffraction (XRD), mercury intrusion capillary pressure (MICP), low-pressure nitrogen and carbon dioxide physisorption, field-emission scanning electron microscopy (FE-SEM), stochastic 3D microstructure reconstruction, multifractal analysis, and three-dimensional succolarity computation. The results demonstrate that mineral assemblages and diagenetic history govern pore preservation: Longmaxi shales, with moderate maturity and shallower burial, retain abundant organic-hosted mesopores, whereas overmature and deeply buried Qiongzhusi shales are strongly compacted and mineralized, reducing pore availability. Multifractal spectra and 3D reconstructions reveal that Longmaxi develops broader singularity spectra and higher succolarity values, reflecting more isotropic meso-/macropore connectivity at the SEM scale, while Qiongzhusi exhibits narrower spectra and lower succolarity, indicating micropore-dominated and anisotropic networks. Longmaxi has nanometer-scale throats (D₅₀ ≈ 10–25 nm) with high CO₂ breakthrough pressures (P₁₀ ≈ 0.57 MPa) and ultra-low RGPZ permeability (mean ≈ 1.5 × 10⁻² nD); Qiongzhusi has micrometer-scale throats (D₅₀ ≈ 1–3 μm), very low breakthrough pressures (P₁₀ ≈ 0.018 MPa), and much higher permeability (mean ≈ 4.63 × 10³ nD). Storage partitioning further differs: Longmaxi’s median total capacity is ≈15.6 kg m⁻³ with adsorption ≈ 93%, whereas Qiongzhusi’s median is ≈12.8 kg m⁻³ with adsorption ≈ 70%. We infer Longmaxi favors secure adsorption-dominated retention but suffers from injectivity limits; Qiongzhusi favors injectivity but requires reliable seals. Full article

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

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26 pages, 7813 KB

Open AccessArticle

Fe–Si–O Isotope Characteristics and Ore Formation Mechanisms of the Hugushan Area BIF-Type Iron Deposits in the Central North China Craton

by Ende Wang, Deqing Zhang, Jinpeng Luan, Yekai Men, Ran Wang, Jianming Xia and Suibo Zhang

Minerals 2025, 15(9), 996; https://doi.org/10.3390/min15090996 - 19 Sep 2025

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Abstract

The Hugushan banded iron formation (BIF) is one of the most representative iron ore deposits in the central part of the North China Craton, and its ore formation mechanism remains highly controversial. This study presents whole-rock and Fe–Si–O isotope geochemical evidence, offering a [...] Read more.

The Hugushan banded iron formation (BIF) is one of the most representative iron ore deposits in the central part of the North China Craton, and its ore formation mechanism remains highly controversial. This study presents whole-rock and Fe–Si–O isotope geochemical evidence, offering a new perspective on the ore formation mechanism of the Hugushan BIFs. The samples from the upper and lower parts of the Hugushan BIFs are characterized by slight enrichment of heavy and light Fe isotopes, respectively. Additionally, the samples from the upper part of the Hugushan BIFs show characteristics of slightly positive Ce anomalies and negative La anomalies, suggesting that the shallow ancient seawater was in a partially oxidized state, whereas the deep seawater remained in a reductive environment during the depositional period. The low Al₂O₃ and TiO₂ concentrations, as well as the depletion of Zr and Hf in the Hugushan BIFs, suggest that the contribution of terrestrial detrital materials to deposition is extremely limited. The BIFs all exhibit positive Eu anomalies, and the quartz in the BIFs is depleted in ³⁰Si, a characteristic similar to that observed in siliceous rocks formed in hydrothermal vent environments and during hydrothermal plume activity. Additionally, the δ¹⁸O values of quartz in Hugushan BIFs are similar to the O isotope compositions of hydrothermal sedimentary siliceous rocks, further suggesting that the silicon in BIFs originates primarily from seafloor hydrothermal activity. The combination of Eu/Sm, Sm/Yb, and Y/Ho ratios indicates that the major components (iron and silica) of the Hugushan Iron Ore Deposit originated from the mixing of high-temperature hydrothermal fluids with seawater, with the hydrothermal fluid contributing slightly less than 0.1%. The magnetite and quartz bands in the BIFs exhibit inhomogeneous and covariant δ⁵⁶Fe and δ³⁰Si isotope characteristics, suggesting that the alternating siliceous and ferruginous layers are products of original chemical deposition in the ocean. Periodic hydrothermal activity and ocean transgression caused the recurring deposition of siliceous and ferruginous layers, resulting in the characteristic banded structure of the Hugushan Iron Ore Deposit. Full article

(This article belongs to the Special Issue Selected Papers from the 7th National Youth Geological Congress)

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23 pages, 6649 KB

Open AccessArticle

Mechanical and Microstructural Behavior of Mine Gold Tailings Stabilized with Non-Conventional Binders

by Bruna Zakharia Hoch, Mariana Tonini de Araújo, Lucas Festugato, Nilo Cesar Consoli and Krishna R. Reddy

Minerals 2025, 15(9), 995; https://doi.org/10.3390/min15090995 - 19 Sep 2025

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Abstract

Recent tailing dam failures in Brazil have been attributed to liquefaction. Chemical stabilization offers a promising solution to enhance the strength and stiffness of tailings and mitigate liquefaction potential. This study investigated the mechanical and microstructural behavior of gold mine tailings (GMTs) stabilized [...] Read more.

Recent tailing dam failures in Brazil have been attributed to liquefaction. Chemical stabilization offers a promising solution to enhance the strength and stiffness of tailings and mitigate liquefaction potential. This study investigated the mechanical and microstructural behavior of gold mine tailings (GMTs) stabilized using (i) an alkali-activated binder composed of sugar cane bagasse ash (SCBA), hydrated eggshell lime (HEL), and sodium hydroxide (NaOH) and (ii) Portland cement (PC). Drained and undrained triaxial shear tests and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) analyses were performed. Specimens stabilized with Portland cement exhibited a strong strain-softening behavior and the highest strength, with 5.3 MPa under 200 kPa confining pressure compared to 2.3 MPa for alkali-activated samples and 740 kPa for untreated GMTs. The addition of either binder also increased both the peak effective friction angle and the critical state stress ratio, confirming an enhanced shear strength. SEM-EDS analyses confirmed the formation of cementitious reaction products, explaining these improvements. This research validates both binders as viable solutions for tailing stabilization, with the novel alkali-activated binder offering a sustainable alternative for large-scale applications. Full article

(This article belongs to the Special Issue Alkali Activation of Clay-Based Materials)

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25 pages, 3607 KB

Open AccessArticle

Dry Concentration of Phosphate Ore by Using a Triboelectrostatic Belt Separator in Pilot Scale

by Brenda Sedlmaier Costa Coelho, Ricardo Neves de Oliveira, Gleison Elias da Silva and Laurindo de Salles Leal Filho

Minerals 2025, 15(9), 994; https://doi.org/10.3390/min15090994 - 19 Sep 2025

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Abstract

This study investigates the feasibility of using a triboelectrostatic belt separator (TBS) as a dry alternative to conventional magnetic separation for concentrating apatite from a phyllosilicate-rich phosphate ore from the Unidade de Mineração de Angico, Brazil. The testing material contained 22.9% P₂ [...] Read more.

This study investigates the feasibility of using a triboelectrostatic belt separator (TBS) as a dry alternative to conventional magnetic separation for concentrating apatite from a phyllosilicate-rich phosphate ore from the Unidade de Mineração de Angico, Brazil. The testing material contained 22.9% P₂O₅ and exhibited over 90% mineral liberation even at coarse fractions (+0.6 mm), being mainly composed of apatite and Mg/Al-bearing phyllosilicates. Pilot-scale experiments were carried out in an M6c TBS, evaluating operational parameters such as electrode polarity, belt speed, feed rate, and electrode gap. In the rougher stage, apatite’s positive charging behavior enabled separation from negatively charged gangue, with optimal conditions (run 4) producing a concentrate of 25.3% P₂O₅ at 85.1% recovery. Cleaner experiments further upgraded product quality, with runs 15 and 18 yielding concentrates of 29.0% and 28.9% P₂O₅ and overall P₂O₅ recoveries of 69.3% and 74.5%, respectively. Compared to high-intensity magnetic separation currently applied at the industrial plant, the TBS achieved superior mass and P₂O₅ recoveries and more effective MgO removal, although Fe₂O₃ and Al₂O₃ contents remained slightly above market thresholds. These results confirm the technical feasibility of triboelectrostatic separation for phosphate beneficiation, offering environmental benefits through reduced water consumption and tailings generation. Further research should focus on finer particle sizes (−0.3 mm), electrode design, and surface charge modifiers to enhance industrial performance. Full article

(This article belongs to the Special Issue Process Mineralogy, Plant Practice and Developments in Mineral Processing, 2nd Edition)

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25 pages, 46515 KB

Open AccessArticle

Parental Affinities and Environments of Bauxite Genesis in the Salt Range, Northwestern Himalayas, Pakistan

by Muhammad Khubab, Michael Wagreich, Andrea Mindszenty, Shahid Iqbal, Katerina Schöpfer and Matee Ullah

Minerals 2025, 15(9), 993; https://doi.org/10.3390/min15090993 - 19 Sep 2025

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Abstract

As the residual products of severe chemical weathering, bauxite deposits serve both as essential economic Al-Fe resources and geochemical archives that reveal information about the parent rocks’ composition, paleoenvironments and paleoclimates, and the tectonic settings responsible for their genesis. The well-developed Early Paleocene [...] Read more.

As the residual products of severe chemical weathering, bauxite deposits serve both as essential economic Al-Fe resources and geochemical archives that reveal information about the parent rocks’ composition, paleoenvironments and paleoclimates, and the tectonic settings responsible for their genesis. The well-developed Early Paleocene bauxite deposits of the Salt Range, Pakistan, provide an opportunity for deciphering their ore genesis and parental affinities. The deposits occur as lenticular bodies and are typically composed of three consecutive stratigraphic facies from base to top: (1) massive dark-red facies (L-1), (2) composite conglomeratic–pisolitic facies (L-2), and (3) Kaolinite-rich clayey facies (L-3). Results from optical microscopy, X-ray powder diffraction (XRPD), and scanning electron microscopy with Energy-Dispersive X-Ray Spectroscopy (SEM-EDS) reveal that facies L-1 contains kaolinite, hematite, and goethite as major minerals, with minor amounts of muscovite, quartz, anatase, and rutile. In contrast, facies L-2 primarily consists of kaolinite, boehmite, hematite, gibbsite, goethite, alunite/natroalunite, and zaherite, with anatase, rutile, and quartz as minor constituents. L-3 is dominated by kaolinite, quartz, and anatase, while hematite and goethite exist in minor concentrations. Geochemical analysis reveals elevated concentrations of

{Al}_{2}

O_{3}

,

{Fe}_{2}

O_{3}

,

{SiO}_{2}

, and

{TiO}_{2}

. Trace elements, including Th, U, Ga, Y, Zr, Nb, Hf, V, and Cr, exhibit a positive trend across all sections when normalized to Upper Continental Crust (UCC) values. Field observations and analytical data suggest a polygenetic origin of these deposits. L-1 suggests in situ lateritization of some sort of precursor materials, with enrichment in stable and ultra-stable heavy minerals such as zircon, tourmaline, rutile, and monazite. This facies is mineralogically mature with bauxitic components, but lacks the typical bauxitic textures. In contrast, L-2 is texturally and mineralogically mature, characterized by various-sized pisoids and ooids within a microgranular-to-microclastic matrix. The L-3 mineralogy and texture suggest that the conditions were still favorable for bauxite formation. However, the ongoing tectonic activities and wet–dry climate cycles post-depositionally disrupted the bauxitization process. The accumulation of highly stable detrital minerals, such as zircon, rutile, tourmaline, and monazite, indicates prolonged weathering and multiple cycles of sedimentary reworking. These deposits have parental affinity with acidic-to-intermediate/-argillaceous rocks, resulting from the weathering of sediments derived from UCC sources, including cratonic sandstone and shale. Full article

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

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18 pages, 8718 KB

Open AccessArticle

Distribution of Metals in Soils Surrounding Tailing Flotation Storages in Copper-Bearing Areas in Lower Silesia

by Agata Duczmal-Czernikiewicz, Natalia Hoska, Maciej Swęd and Marcin Siepak

Minerals 2025, 15(9), 992; https://doi.org/10.3390/min15090992 - 18 Sep 2025

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Abstract

One of the most critical issues in soil science is the content of metals and their environmental toxicity. This is especially relevant to soil contamination by metals in industrial and postindustrial areas. The region of Lower Silesia, known for exploitation of Cu and [...] Read more.

One of the most critical issues in soil science is the content of metals and their environmental toxicity. This is especially relevant to soil contamination by metals in industrial and postindustrial areas. The region of Lower Silesia, known for exploitation of Cu and Ag deposits, along with Zn and Pb, is significantly affected by metal contamination near post-flotation waste facilities in both old and new copper districts. Metal concentrations in soils adjacent to abandoned tailings storage facilities in the copper district were measured to identify factors influencing contamination in agricultural and technogenic soils. Concentrations of copper, lead, and zinc were determined in 111 samples taken from nine soil profiles down to a depth of 1.60 m. Significant variation was observed in metal content: in agricultural soils, copper reached up to 2800 mg/kg, lead up to 150 mg/kg, and zinc up to 65 mg/kg. In forest soils, concentrations reached as high as 1700 mg/kg for copper, 1800 mg/kg for lead, and up to 1100 mg/kg for zinc. The metal content increased with proximity to the tailings storage. Soil profiles closest to the emission source showed the highest metal concentrations, while concentrations of Cu, Pb, and Zn decreased with distance. Full article

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

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17 pages, 2381 KB

Open AccessArticle

Fibrous Minerals and Naturally Occurring Asbestos (NOA) in the Metacarbonate Hosted Fe Oxide-Cu-Au-Co Mineralized Rocks from the Guelb Moghrein Mine, Akjoujt, Mauritania: Implications for In Situ Hazard Assessment and Mitigation Protocols

by Jessica Shaye Schapira and Robert Bolhar

Minerals 2025, 15(9), 991; https://doi.org/10.3390/min15090991 - 18 Sep 2025

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Abstract

The awareness of the potential risks associated with the environmental exposition of asbestos is on the rise and has facilitated a new interest in in situ identification and assessment of the hazards of fibrous minerals. The mineralised metacarbonate rocks of the Guelb Moghrein [...] Read more.

The awareness of the potential risks associated with the environmental exposition of asbestos is on the rise and has facilitated a new interest in in situ identification and assessment of the hazards of fibrous minerals. The mineralised metacarbonate rocks of the Guelb Moghrein deposit have not been studied regarding the identification and characterisation of fibrous minerals occurrences. Thus, the aim of this study was to collect samples from different lithotypes with visually identifiable fibrous minerals and to examine the geological–structural features pertaining to their mode of occurrence and formation. The mineral fibre components of the rock samples demonstrate that fibrous and asbestiform mineralisation occurred via several modes, including fracture fill, slip-fibre recrystallisation and replacement. The geological diversity of fibrous amphibole mineralisation points to the chemistry of the rocks in this area and open space being the major factors controlling the presence of NOA in this deposit. The variability of NOA due to different fibrous mineral intergrowths is investigated by determining the bulk mineralogical and geochemical properties of the fibrous mineral content of each sample. A novel observation was pointed out in this study, showing the coexistence of fibrous siderite and anthophyllite. The identification of the asbestiform features exhibited by siderite, anthophyllite and talc in the mineralised metacarbonate of the Guelb Moghrein deposit underlines the necessity for further mineralogical research to enhance our understanding of fibrous minerals and how we assess their potential hazards to health. Full article

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

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19 pages, 10464 KB

Open AccessArticle

Callovian-Oxfordian Ironstones at the Northwestern Margin of the Neo-Tethys Ocean, with Mineralogically Diverse Iron Ooids: Example from Kutch Basin, India

by Arpita Chakraborty, Santanu Banerjee, Suraj Arjun Bhosale and Sabyasachi Mandal

Minerals 2025, 15(9), 990; https://doi.org/10.3390/min15090990 - 18 Sep 2025

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Abstract

Multiple ironstone beds formed during the Callovian-Oxfordian times as a consequence of intense continental weathering, upwelling, and hydrothermal activity. This study examines the compositional differences between core and rim, and the origin of iron ooids along the northwestern margin of the Neo-Tethys Ocean [...] Read more.

Multiple ironstone beds formed during the Callovian-Oxfordian times as a consequence of intense continental weathering, upwelling, and hydrothermal activity. This study examines the compositional differences between core and rim, and the origin of iron ooids along the northwestern margin of the Neo-Tethys Ocean to highlight sea-level fluctuations, redox conditions, and elemental influx. An integrated sedimentological study, including petrography, mineralogy, micro-texture, and mineral chemistry, was carried out to explain the origin and implications of ironstones. The ~14 m thick Callovian-Oxfordian, marginal marine deposits in the Kutch Basin, in western India, exhibit iron ooids, predominantly formed in oolitic shoals during transgression, associated with lagoonal siliciclastics. Callovian shoals interbedded with lagoonal facies record minor sea-level fluctuations, whereas the Oxfordian deposit records a major transgression and condensation, resulting in extensive ironstone deposits. The ooid cortices and nuclei exhibit distinctive mineralogy and micro-textures: glauconitic smectite exhibits poorly-developed rosettes, chamosite displays flower-like, and goethite shows rod-like features. Three types of ooids are formed: (i) monomineralic ooids are entirely of chamosite or goethite, (ii) quartz-nucleated ooids, and (iii) composite ooids with either chamosite core and goethite rim, or chamosite core and glauconitic smectite rim. The assemblages within iron ooids reflect variation in depositional redox conditions: glauconitic smectite develops under suboxic lagoonal flank, chamosite forms in anoxic central lagoon, and goethite precipitates on oxic shoals. Full article

(This article belongs to the Special Issue Tectonic Setting and Provenance of Sedimentary Rocks)

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14 pages, 1544 KB

Open AccessArticle

Kinetics of Sulfide Dissolution Controlled by Sulfur Radical Diffusion: Implications for Sulfur Transport and Triggering of Volcanic Eruptions

by Anastassia Borisova

Minerals 2025, 15(9), 989; https://doi.org/10.3390/min15090989 - 17 Sep 2025

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Abstract

Chemical mixing of different types of magma, such as basaltic magma and silica-rich, hydrous magma, often triggers volcanic eruptions. However, the kinetics, mechanisms, and rates of sulfide dissolution reactions in hydrous melts are currently unknown, despite the fact that these reactions can influence [...] Read more.

Chemical mixing of different types of magma, such as basaltic magma and silica-rich, hydrous magma, often triggers volcanic eruptions. However, the kinetics, mechanisms, and rates of sulfide dissolution reactions in hydrous melts are currently unknown, despite the fact that these reactions can influence the sulfur budget in the crust and mantle. I experimentally model dissolution of pyrrhotite minerals in hydrous rhyolite melt at conditions corresponding to the sulfate–sulfide transition field at 1 GPa pressure. The reaction results in the production of FeO, SO₄²⁻, H₂, H₂S and di- and tri-sulfur radical ions, (S₂⁻ or S₃⁻) in fluid/melt. The calculated sulfur diffusion coefficient implies extremely fast sulfur diffusion in the hydrous hybrid melt. The production of S-rich magma is controlled by the fastest-ever-recorded chemical diffusion of sulfur in the form of S₂⁻ or S₃⁻ in hybrid magma under sulfate-sulfide transition conditions. I demonstrate that such dissolution reactions can be responsible for triggering explosive volcanic eruptions (e.g., the 1991 Mount Pinatubo eruption) in volcanic arc settings. The sulfide dissolution reaction can also promote the production of chalcophile metal (sulfur-loving Au, Cu and Pt) ore deposits associated with the formation of volcanic arcs. Full article

(This article belongs to the Special Issue Advances in Mantle–Crust Interactions for Petrogenesis and Ore-Forming Processes)

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27 pages, 3998 KB

Open AccessArticle

Geochemical Features and Mobility of Trace Elements in Technosols from Historical Mining and Metallurgical Sites, Tatra Mountains, Poland

by Magdalena Tarnawczyk, Łukasz Uzarowicz, Wojciech Kwasowski, Artur Pędziwiatr and Francisco José Martín-Peinado

Minerals 2025, 15(9), 988; https://doi.org/10.3390/min15090988 - 17 Sep 2025

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Abstract

Ore mining and smelting are often related to environmental pollution. This study provides information about the geochemical features of Technosols at historical mining and metallurgical sites in the Tatra Mountains, southern Poland, evaluating the contents of potentially toxic trace elements (PTTE) and their [...] Read more.

Ore mining and smelting are often related to environmental pollution. This study provides information about the geochemical features of Technosols at historical mining and metallurgical sites in the Tatra Mountains, southern Poland, evaluating the contents of potentially toxic trace elements (PTTE) and their behaviours in soils, as well as the influence of soil properties on PTTE mobility. Thirteen soil profiles were studied in eight abandoned mining and smelting sites. PTTE concentrations, including rare earth elements (REE), were measured using ICP-MS and ICP-OES. Selected elements (Cu, Zn, Pb, Cd, As, Sb, Ba, Sr, Co, Ni, Mn and Cr) were fractionated using the modified European Community Bureau of Reference (BCR) four-step sequential extraction. Contamination of soils with PTTE was compared against Polish regulatory limits, which were exceeded for Cu, Zn, Pb, Mo, Hg, As, Co, Ni and Ba, with concentrations exceeding limits by 16, 18, 34 and 160 times for Cu, Hg, As and Ba, respectively, in some profiles. Based on geochemical features depending on parent material properties, the soils examined were divided into three groups. Group I Technosols (near-neutral soils developed from Fe/Mn-ore and carbonate-bearing mining waste) were particularly enriched in Co, Ni, Mn and REE. Group II Technosols (acidic soils developed from polymetallic ore-bearing aluminosilicate mining waste) contained elevated concentrations of Cu, Zn, Hg, As, Sb, Bi, Co, Ag, Ba, Sr, U and Th; they contained lower contents of REE than Group I Technosols. Group III Technosols (soils developed in smelting-affected areas and containing metallurgical waste) were rich in Cu, As, Sb, Ba, Hg, Co and Ag and contained the lowest REE contents among the studied soils. Sequential BCR extraction revealed that PTTE mobility varied strongly according to soil group, with higher mobility of Mn, Cu and Zn in acidic polymetallic ore-derived soils (Group II), while carbonate-rich soils (Group I) showed mainly immobile forms. Metallurgical slag-derived soils (Group III) exhibited complex PTTE behaviour controlled by organic matter and Fe/Mn oxides. Soil properties (pH, carbonates and TOC) seem to control PTTE mobility. Full article

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

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23 pages, 12095 KB

Open AccessArticle

Multi-Objective Parameter Optimisation of High-Pressure Grinding Rolls Based on Grey Relational Theory

by Ruijie Gu, Zhenzhong Qin, Shuaifeng Zhao, Yan Wang, Zhenguo An and Wenzhe Wu

Minerals 2025, 15(9), 987; https://doi.org/10.3390/min15090987 - 17 Sep 2025

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Abstract

The roller press crushing of ore is a complex process involving the interplay of multiple factors. Roller dimensions, gap settings, and rotational speed all influence this process, which in turn affects the comprehensive crushing performance of the high-pressure grinding rolls (HPGR). Therefore, to [...] Read more.

The roller press crushing of ore is a complex process involving the interplay of multiple factors. Roller dimensions, gap settings, and rotational speed all influence this process, which in turn affects the comprehensive crushing performance of the high-pressure grinding rolls (HPGR). Therefore, to simultaneously enhance the HPGR’s size reduction effectiveness (SRE) and throughput while controlling its energy consumption, wear, and edge effect, multi-objective parameter optimization of the HPGR is required. This study utilizes the Discrete Element Method (DEM) to simulate ore comminution within an HPGR. By first dividing the release zone into segments, the particle size distribution of the crushed product at different locations within this zone is investigated. Then, the influence of various factors on the SRE at different locations within HPGR is examined through single-factor experiments. Subsequently, the relative influence of roller diameter, roller width, roller speed, and roll gap on the comprehensive crushing performance of the HPGR is determined through signal-to-noise ratio (SNR) analysis and analysis of variance (ANOVA). Finally, multi-objective parameter optimization of the roller press crushing is conducted based on grey relational analysis (GRA), incorporating the weights assigned to different response target. The results indicate that the proportion of unbroken ore particles is relatively significant, primarily due to the edge effect. Further analysis reveals that along the horizontal diameter of the rollers, regions closer to the roller surface exhibit better SRE. Additionally, roller speed is identified as the most influential factor affecting the uniformity of SRE in the HPGR. The application of GRA to the multi-objective optimization of roller press crushing enables effective balancing of the comprehensive crushing performance in HPGR. Full article

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

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18 pages, 2425 KB

Open AccessArticle

Impact of Mining Methods and Mine Types on Heavy Metal (Loid) Contamination in Mine Soils: A Multi-Index Assessment

by Keyan Guo, Zizhao Zhang, Gensheng Li, Honglin Liu, Zhuo Wang, Yaokun Fu and Wenjuan Wang

Minerals 2025, 15(9), 986; https://doi.org/10.3390/min15090986 - 16 Sep 2025

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Abstract

Mining activities caused heavy metal enrichment in mine soils. Sixty-six soil samplings of 26 mines in the central Tianshan Mountains of China were conducted to reveal heavy metal pollution for the single-factor (P_i), Nemerow comprehensive pollution (P_N), [...] Read more.

Mining activities caused heavy metal enrichment in mine soils. Sixty-six soil samplings of 26 mines in the central Tianshan Mountains of China were conducted to reveal heavy metal pollution for the single-factor (P_i), Nemerow comprehensive pollution (P_N), geo-accumulation (I_geo), potential ecological risk (E_i), and health risks. The results indicate that mines in Bayingolin and Aksu exhibit the most severe pollution (P_N = 26.64 and 25.28), characterized by Cd (P_i = 115.18) and As (P_i = 67.20), forming a Cd-As compound pattern. While Ili mines show Ni-Cu co-exceedance, and Turpan mines have lower overall pollution but localized Cd enrichment. Additionally, Cd is identified as the most severe by I_geo, with moderate or higher pollution levels observed in 61.00% of samplings. The E_i assessment revealed that Cd posed the greatest threat, with 100%, 53.80%, and 30.70% of samplings indicating slight, high, and extremely high ecological risk levels, respectively. Health risk assessment indicated that non-carcinogenic risks were dominated by Cr (affecting 19.20% of samplings), while carcinogenic risks were primarily from As (7.70%) and Cd (11.50% of samplings), with Cr exhibiting the highest carcinogenic risk. Furthermore, comparative analysis showed that underground mines led to higher pollution levels (I_geo) for Cd, Cu, Mn, Pb, and Zn compared to open-pit mines, and metal mines incurred greater heavy metal(loid) contamination than non-metal mines. These findings could provide data for mine soil pollution remediation in the central Tianshan Mountains. Full article

(This article belongs to the Special Issue Risks Assessment, Management and Control of Mining Contamination, 2nd Edition)

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13 pages, 5644 KB

Open AccessArticle

Technology Development and Industrial Practice of Distinct Low-Cost Heap Bioleaching at Monywa Copper Mine

by Zhentang Wang, Baojun Yang, Jun Wang, Keqi Guo, Xin Zhang, Rui Liao and Guanzhou Qiu

Minerals 2025, 15(9), 985; https://doi.org/10.3390/min15090985 - 16 Sep 2025

Viewed by 291

Abstract

This paper presents a case study on heap bioleaching at the Monywa copper mine in Myanmar. Through mineralogical characterization and leaching tests, specific heap bioleaching technologies were developed and implemented at the mine. These technologies include acidification and start-up of heap bioleaching without [...] Read more.

This paper presents a case study on heap bioleaching at the Monywa copper mine in Myanmar. Through mineralogical characterization and leaching tests, specific heap bioleaching technologies were developed and implemented at the mine. These technologies include acidification and start-up of heap bioleaching without external acid addition, ore classification with process optimization, and selective inhibition of pyrite oxidation for acid/iron balance during heap bioleaching. The optimized heap bioleaching technologies implemented at the Monywa copper mine have reduced both capital and operating costs. These advantages are specifically reflected in the use of multi-lift pads for both heap bioleaching and final residue storage, optimized processing based on ore characteristics, and the implementation of a solution closed cycle process without the need for additional acid or neutralization. These findings demonstrate a cost-effective approach to heap bioleaching and provide practical insights for operational optimization in similar copper mines. Full article

(This article belongs to the Special Issue Advances in the Theory and Technology of Biohydrometallurgy)

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18 pages, 15262 KB

Open AccessArticle

Thin-Section Petrography in the Use of Ancient Ceramic Studies

by David Ben-Shlomo

Minerals 2025, 15(9), 984; https://doi.org/10.3390/min15090984 - 16 Sep 2025

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Abstract

The potential of thin-section petrography for the analysis of ancient ceramic materials, such as pottery vessels, figurative objects and building materials made of fired clay, was already recognized during the 19th century, but its use has become more intensive during the past 80 [...] Read more.

The potential of thin-section petrography for the analysis of ancient ceramic materials, such as pottery vessels, figurative objects and building materials made of fired clay, was already recognized during the 19th century, but its use has become more intensive during the past 80 years. Since pottery is the most common and typologically datable artifact in archaeological excavations from the pottery Neolithic period onwards (some 7000–8000 years ago), the analysis of pottery, including its composition, is a central component of archaeological research. As ceramic materials are made of fired clay, which in turn is procured from soils, weathered rocks and geological formations, the mineralogical composition of the ceramic artifacts represents the clay sources. The study of the mineralogical and rock fragment composition of thin sections of ancient ceramic artifacts can yield the characterization of the clay and soil type and thus the geographic location or area of the clay source. Since in antiquity we assume clay was not precured from a distance of more than one day’s walk from the production site (‘site catchment area’), the production location can be detected as well. Thus, petrographic analysis can identify the trade of artifacts and commodities (if the ceramics are containers) in antiquity, which can shed light on political and cultural links and trade between ancient societies and their economic and social structure. In addition, since clay was often treated by ancient potters to improve its quality (levigation, clay mixing, addition of temper), technological aspects of the production sequence (chaîne opératoire) can also be acquired by petrographic analysis. Today, petrographic analysis is part of many standard studies of ancient pottery. While it is an old and relatively ‘low tech’ method, the accessibility of the equipment needed and its high analytic potential maintains its important and common position in archaeological research. This article describes the method and its analytical potential from the archaeological point of view and briefly mentions several archaeological case studies exemplifying its wide and diversified potential in the study of ancient ceramics in past decades. Full article

(This article belongs to the Special Issue Thin Sections: The Past Serving The Future)

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3 pages, 137 KB

Open AccessEditorial

Editorial for Special Issue “Footprints of Mineral Systems with IOCG, IOA and Affiliated Critical Metal Deposits: From Metasomatism to Metamorphism”

by Olivier Blein

Minerals 2025, 15(9), 983; https://doi.org/10.3390/min15090983 - 16 Sep 2025

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Abstract

Metasomatic iron and alkali–calcic (MIAC) systems can form iron oxide copper–gold (IOCG), rare-earth (REE) iron oxide–apatite (IOA), and affiliated critical and precious metal deposits [...] Full article

(This article belongs to the Special Issue Footprints of Mineral Systems with IOCG, IOA and Affiliated Critical Metal Deposits: From Metasomatism to Metamorphism)

18 pages, 4518 KB

Open AccessArticle

Nitric Acid Purification of Molybdenite Concentrate: Copper-Iron Removal and Development of a Comprehensive Dissolution Kinetics Model

by Hossein Shalchian, Payam Ghorbanpour, Behzad Nateq, Marco Passadoro, Pietro Romano, Francesco Vegliò and Nicolò Maria Ippolito

Minerals 2025, 15(9), 982; https://doi.org/10.3390/min15090982 - 16 Sep 2025

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Abstract

The selective removal of impurities from molybdenite concentrates is crucial for producing high-purity molybdenum products. In this study, the purification of molybdenite concentrate was investigated using nitric acid as both a leaching medium and oxidizing agent. Leaching experiments were carried out under various [...] Read more.

The selective removal of impurities from molybdenite concentrates is crucial for producing high-purity molybdenum products. In this study, the purification of molybdenite concentrate was investigated using nitric acid as both a leaching medium and oxidizing agent. Leaching experiments were carried out under various conditions of temperature (22–78 °C) and nitric acid concentration (0.12–0.48 M). The results demonstrated that while molybdenite remained mostly undissolved, copper and iron were effectively leached, with near-complete removal at 78 °C in 0.24 M HNO₃ after 6 h. Compared with other acid systems, nitric acid leaching experiments in this study demonstrated higher efficiency and selectivity under relatively moderate conditions of concentration and temperature. Kinetic analyses were performed based on the shrinking core model (SCM) and extended by developing a comprehensive rate equation that incorporates both nitric acid concentration and reactive surface effects. Fitting the developed model to experimental data revealed distinct kinetic regimes below and above 50 °C, suggesting a mechanism shift from surface chemical reaction control to diffusion through an ash layer. The purified molybdenite was characterized by SEM-EDS and ICP-OES, confirming almost complete elimination of Cu and Fe impurities. This work highlights nitric acid as a promising and efficient medium for selective leaching of molybdenite concentrates and provides a comprehensive kinetic model applicable across different leaching conditions. Full article

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

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17 pages, 1075 KB

Open AccessArticle

Contaminants Removal from Construction and Demolition Waste (CDW) with Water Jigs

by Hassan Barkat, Artur Bressanelli Teixeira, Carlos Hoffmann Sampaio and Josep Oliva Moncunill

Minerals 2025, 15(9), 981; https://doi.org/10.3390/min15090981 - 16 Sep 2025

Viewed by 234

Abstract

This study evaluates the viability of water jig for removing the impurities from CDW and the concentration of concrete aggregates from mixtures containing 10%, 20%, and 30% impurities (brick and gypsum), simulating the materials commonly found in CDW. Laboratory-scale jigging tests were conducted [...] Read more.

This study evaluates the viability of water jig for removing the impurities from CDW and the concentration of concrete aggregates from mixtures containing 10%, 20%, and 30% impurities (brick and gypsum), simulating the materials commonly found in CDW. Laboratory-scale jigging tests were conducted in single-stage jigging, and the products were characterized based on density > 2.6 g/cm³, water absorption, shape factor, and bulk density to evaluate the separation performance. It was noted that dense fractions consistently achieved high purity with less than 1% impurities and a concrete content of more than 99% and that more than 80% of dense material was recovered. These results demonstrate that water jigging is a technically viable method for producing recycled aggregates of sufficient quality for reuse in concrete while also reducing CDW disposal by more than 40% and contributing to the sector’s carbon footprint reduction. The findings confirm that even a single-stage jigging process can provide high-quality recycled aggregates, offering a simple and effective route for CDW beneficiation. Full article

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

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21 pages, 8196 KB

Open AccessReview

A Review of Rare Earth Elements Resources in Africa

by Junping Ren, Alei Gu, Kai Sun, Hang Zhang, Jianwu Li, Hongwei Sun, Yiguan Lu, Xin Tong, Xingyuan Wu and Zuomin Zhou

Minerals 2025, 15(9), 980; https://doi.org/10.3390/min15090980 - 16 Sep 2025

Viewed by 647

Abstract

Rare earth elements (REEs) are essential for modern high-tech development and have been identified as key mineral resources by major economies worldwide. This paper presents a systematic review of REE deposits in Africa, covering their distribution, reserves and resources, deposit types, mineralization ages, [...] Read more.

Rare earth elements (REEs) are essential for modern high-tech development and have been identified as key mineral resources by major economies worldwide. This paper presents a systematic review of REE deposits in Africa, covering their distribution, reserves and resources, deposit types, mineralization ages, characteristics of typical deposits, and exploration investments. Africa hosts abundant REE resources, which are primarily concentrated in 12 countries. The continent’s reserves and advanced resources of rare earth oxides (REO) amount to 195.6 × 10⁴ t and 1014.4 × 10⁴ t, respectively. In recent years, exploration and development efforts have progressed rapidly. REE mineralization in Africa can be classified into eight categories, with carbonatite and ion-adsorption-type deposits currently being the primary focus of exploration and development. Exploration investment in African REE deposits peaked in 2012, followed by a decline to its lowest point in 2017. Since 2018, the exploration investment value has increased rapidly. Looking ahead, prices for light rare earth elements (LREEs) are projected to stabilize or experience a slight decrease, while prices for heavy rare earth elements (HREEs) are expected to gradually increase. Full article

(This article belongs to the Special Issue Recent Developments in Rare Metal Mineral Deposits)

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23 pages, 30956 KB

Open AccessArticle

Microstructures and Anisotropy of Slates from Northern China

by Jingyi Huang, Hans-Rudolf Wenk and Michelle Devoe

Minerals 2025, 15(9), 979; https://doi.org/10.3390/min15090979 - 15 Sep 2025

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Abstract

Slates transform from shales at relatively low-grade metamorphic conditions. They often reveal highly anisotropic microstructures and very strong crystal alignment that must be considered in seismic modeling and engineering construction. In this paper, we investigate nine slate samples from four regions in northern [...] Read more.

Slates transform from shales at relatively low-grade metamorphic conditions. They often reveal highly anisotropic microstructures and very strong crystal alignment that must be considered in seismic modeling and engineering construction. In this paper, we investigate nine slate samples from four regions in northern China: Fangshan, Beijing; Xushui, Hebei; Damao Qi, Inner Mongolia; and Zhengxiangbai Qi, Inner Mongolia. The microstructural characteristics were analyzed with scanning electron microscopy and explored with digital crystal size distribution analysis. Preferred crystal orientation characteristics of slate minerals were investigated with high-energy synchrotron X-ray diffraction and subsequent Rietveld refinement. This research shows that the main components of slates in this study are quartz, muscovite, chlorite, and minor orthoclase. In terms of morphology, muscovite, chlorite, and quartz are strongly elongated and oriented. The crystallographic orientation of sheet silicates is very strong, exceeding 100 multiples of random distribution for chlorite from Fangshan. However, quartz with a preferred strong shape orientation has a crystallographic preferred orientation close to random. The preferred orientation characteristics of minerals serve as a basis for calculating elastic properties and anisotropies of the Chinese slate samples that contribute significantly to seismic anisotropy documented in northern China. Full article

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

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21 pages, 11443 KB

Open AccessArticle

Formation Conditions of Early Cambrian Witherite (BaCO₃) Deposit in Chongqing: Implications for Differential Oceanic Changes

by Jie Jiang, Feng Liang, Chan Wang, Yaming Tian, Yunxi Hu, Hao Liu, Zhipeng Xia, Changjian Yuan, Kaibin Han and Susu Zhou

Minerals 2025, 15(9), 978; https://doi.org/10.3390/min15090978 - 15 Sep 2025

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Abstract

The discovery of extensive layered witherite (BaCO₃) deposits in the Early Cambrian strata in South China offers valuable insights into the unique paleo-marine environment of this region. Based on stratigraphy, petrography, geochemistry, fluid inclusions, and pervious published multi-isotope geochemical analysis, we [...] Read more.

The discovery of extensive layered witherite (BaCO₃) deposits in the Early Cambrian strata in South China offers valuable insights into the unique paleo-marine environment of this region. Based on stratigraphy, petrography, geochemistry, fluid inclusions, and pervious published multi-isotope geochemical analysis, we aim to explore the distinct genesis mechanism of the witherite deposits in the Chengkou area of South China and unveil the specific paleo-marine environment during their formation. This study concludes that the wide ⁸⁷Sr/⁸⁶Sr ratios (0.708266 to 0.708504) of witherite and barytocalcite (BaCa(CO₃)₂) support the seawater-derived barium. Negative δ¹³C values (−15.6 to −12.5‰) indicate the involvement of organic matter during the formation of witherite. The complex vapor-phase (including CH₄, H₂S, etc.) and HS⁻-containing liquid-phase compositions in the primary liquid–vapor inclusions of the witherite and barytocalcite imply that the two minerals are formed in sulfur-rich euxinic seawater. The broad homogenization temperatures are generated by thermal re-equilibration of the inclusions, rather than the actual temperatures of the trapped fluids. The salinity range of fluid inclusions in the Bashan witherite deposit (0.2 to 16.2 wt.%) records mixing between moderate-salinity basinal-derived fluids and low-salinity seawater-sourced fluids. We propose that the formation of Chengkou witherite deposits is linked to a sulfate-limited euxinic seawater environment, highlighting the spatiotemporal heterogeneity in Early Cambrian paleo-oceanic sulfate concentrations. Full article

(This article belongs to the Section Mineral Deposits)

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21 pages, 1571 KB

Open AccessArticle

Synergistic ZnO–CuO/Halloysite Nanocomposite for Photocatalytic Degradation of Ciprofloxacin with High Stability and Reusability

by Willams A. Albuquerque, Adilson J. Neres Filho, Yonny Romaguera-Barcelay, Santiago Medina-Carrasco, Maria del Mar Orta, Pollyana Trigueiro and Ramón Raudel Peña-Garcia

Minerals 2025, 15(9), 977; https://doi.org/10.3390/min15090977 - 15 Sep 2025

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Abstract

This study focused on creating a novel material by integrating ZnO and CuO nanoparticles into the structure of halloysite using a hydrothermal method. The formation of the nanocomposite was validated through X-ray diffraction and Raman analysis, which confirmed the presence of ZnO and [...] Read more.

This study focused on creating a novel material by integrating ZnO and CuO nanoparticles into the structure of halloysite using a hydrothermal method. The formation of the nanocomposite was validated through X-ray diffraction and Raman analysis, which confirmed the presence of ZnO and CuO phases without compromising the structure of halloysite. Microscopic analysis revealed a well-distributed presence of metallic oxide nanoparticles within the nanotubular structure of halloysite, which adhered to both the outer and inner surfaces of the clay mineral. Optical characterization identified a substantial density of defects, which played a key role in improving the performance of the supported semiconductors. Furthermore, the narrow band gap at 3.02 eV promoted the mobility of photogenerated charges. Photocatalytic tests yielded promising results, demonstrating a synergistic effect between photocatalysis and adsorption processes that positively influenced the removal of ciprofloxacin from solutions. The material achieved up to 76% removal of the antibiotic within 120 min, utilizing a catalyst concentration of 0.5 g L⁻¹ with a pollutant concentration of 20 mg L⁻¹. In reuse experiments, the material exhibited high recyclability even after multiple reaction cycles. Halloysite-based nanocomposites represent a strategic advancement in environmental remediation technologies, contributing to the development of clean, effective, and reusable materials. Full article

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

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18 pages, 4138 KB

Open AccessArticle

Classification of Thin-Section Rock Images Using a Combined CNN and SVM Approach

by İlhan Aydın, Taha Kubilay Şener, Ayşe Didem Kılıç and Hüseyin Derviş

Minerals 2025, 15(9), 976; https://doi.org/10.3390/min15090976 - 15 Sep 2025

Viewed by 421

Abstract

The accurate classification of rocks is crucial for applications such as earthquake prediction, resource exploration, and geological analysis. Traditional methods rely on expert examination of thin-section images under a microscope, making the process time-consuming and prone to errors. Recent advancements in deep learning [...] Read more.

The accurate classification of rocks is crucial for applications such as earthquake prediction, resource exploration, and geological analysis. Traditional methods rely on expert examination of thin-section images under a microscope, making the process time-consuming and prone to errors. Recent advancements in deep learning have emerged as a powerful tool for automated rock classification; however, distinguishing between similar rock types such as sedimentary, metamorphic, and magmatic rocks remains a challenge. This study proposes a novel hybrid convolutional neural network (CNN) approach that combines the strengths of VGG16 and EfficientNetV2 architectures for the classification of thin-section rock images. The model, developed using the Feature-Selected Hybrid Network (FSHNet), demonstrates significant improvements over individual models, achieving a 5% increase in accuracy compared to Efficient-NetV2B0 and a 9% increase compared to VGG16. By employing the ReliefF algorithm for feature selection and Support Vector Machines (SVMs) for classification, the model further reduces the dimensionality of the feature space, enhancing computational efficiency. The proposed model has been applied to two different rock datasets. The first dataset consists of 2634 images, categorized into sedimentary, metamorphic, and magmatic rock classes. Additionally, the approach was tested on a second dataset comprising petrographic microfacies images, demonstrating its effectiveness in multiclass geological structure classification. Validation on both datasets shows that the proposed method outperforms popular deep learning models and previous studies, achieving a 3% increase in accuracy. These results highlight that the proposed approach provides a robust and efficient solution for automated rock classification, offering significant advancements for geological research and real-world applications. Full article

(This article belongs to the Special Issue Thin Sections: The Past Serving The Future)

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19 pages, 6850 KB

Open AccessArticle

Geochronology and Geochemistry of the Galale Cu–Au Deposit in the Western Segment of the Bangong–Nujiang Suture Zone: Implications for Molybdenum Potential

by Chang Liu, Zhusen Yang, Xiaoyan Zhao and Jingtao Mao

Minerals 2025, 15(9), 975; https://doi.org/10.3390/min15090975 - 15 Sep 2025

Viewed by 271

Abstract

The Galale Cu–Au deposit lies on the northern margin of the western Gangdese metallogenic belt, near the western edge of the Gangdese arc within the Bangong–Nujiang suture zone. Unlike the well-studied Miocene Cu belt in southern Gangdese, this region remains insufficiently investigated, particularly [...] Read more.

The Galale Cu–Au deposit lies on the northern margin of the western Gangdese metallogenic belt, near the western edge of the Gangdese arc within the Bangong–Nujiang suture zone. Unlike the well-studied Miocene Cu belt in southern Gangdese, this region remains insufficiently investigated, particularly in terms of geochemical characterization, leading to an ambiguous metallogenic model and a debated tectonic setting—specifically, the unresolved issue of subduction polarity across the Bangong–Nujiang suture. This tectonic ambiguity has important implications for understanding magma sources, metal transport pathways, and, consequently, for guiding mineral exploration strategies in the area. To address this, we conducted zircon U–Pb dating on the ore-related quartz diorite and granodiorite, yielding crystallization ages of 84.05 ± 0.34 Ma and 77.20 ± 0.69 Ma, respectively. Integrated with previous data, these results constrain mineralization to 83–89 Ma, which includes both skarn-type Cu–polymetallic and porphyry-type Cu mineralization. Regional comparisons support a tectonic model involving slab rollback and southward subduction of the Bangong–Nujiang oceanic lithosphere. Geochemical analyses of quartz diorite, granodiorite, and monzonitic granite show high-K calc-alkaline, peraluminous I-type affinities, with enrichment in LREEs and LILEs, and depletion in HREEs and HFSEs. Notably, the monzonitic granite is marked by high SiO₂, Sr/Y, and Rb/Sr ratios, low Zr/Hf, strong LREE enrichment, weak Eu anomalies, and pronounced Nb–Ta depletion, indicating high oxygen fugacity and favorable conditions for Mo mineralization. The deposit formed through tectono-magmatic processes related to the closure of the Bangong–Nujiang Neo-Tethys Ocean. Subduction and subsequent lithospheric delamination induced partial melting of mantle and crustal sources, generating quartz diorite and granodiorite intrusions. Magmatic fluids interacted with carbonate wall rocks to form skarn assemblages, concentrating ore metals along structures. The mineralization formed within the contact zones between intrusions and surrounding country rocks. Late-stage granite porphyry intrusions (~77 Ma), inferred from major, trace, and rare earth element compositions to have the highest Mo potential, may represent an extension of earlier skarn mineralization in the area (83–89 Ma). This study presents the first comprehensive geochemical dataset for the Galale deposit, refines its metallogenic model, and identifies key geochemical indicators (e.g., Sr, Y, Nb, Rb, Zr, Hf) for Mo exploration. Full article

(This article belongs to the Special Issue Metallogenic Regularity and Metallographic Prediction of Strategic Deposits)

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Open AccessArticle

Composition, Properties, and Flotation Reagent Regimes of Carbonaceous Material

by Akim Yergeshev, Rustam Tokpayev, Marina Karmeeva, Tamina Khavaza, Mikhail Nauryzbayev and Vladislava Ignatkina

Minerals 2025, 15(9), 974; https://doi.org/10.3390/min15090974 - 14 Sep 2025

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Abstract

The novelty of this study lies in the first comparative characterisation of five carbonaceous materials: three monophase carbons (wood charcoal, carbon, graphite) and two ore-derived CM samples from polymetallic sulphide and oxidised lithium ores. The methodology included IR spectroscopy, XPS, acid–base adsorption centres [...] Read more.

The novelty of this study lies in the first comparative characterisation of five carbonaceous materials: three monophase carbons (wood charcoal, carbon, graphite) and two ore-derived CM samples from polymetallic sulphide and oxidised lithium ores. The methodology included IR spectroscopy, XPS, acid–base adsorption centres identified by colour indicators, chemical composition analysis, and kinetic flotation tests. Bulk and surface compositions differed significantly: although the ash content of ore-derived CM reached 84.4%, XPS revealed carbon-enriched surfaces with thin films of about 1–2 nm. IR spectra confirmed multiphase structures with carbonate, silica, and aluminosilicate bands, and showed an identical composition of CM from different industrial ore types. Flotation kinetics confirmed high floatability (recoveries 80%–99%, k up to 1.95 min⁻¹). Even with sodium lignosulphonate at 500 mg/L, recovery only decreased from 83.02% to 52.54%, showing the limited efficiency of depressants. These results provide a basis for the preliminary removal of CM prior to rough (bulk) flotation in the processing of different ore types, improving concentrate quality, reducing reagent consumption, and lowering metallurgical losses. Full article

(This article belongs to the Special Issue Mineral Processing and Recycling Technologies for Sustainable Future)

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Minerals, Volume 15, Issue 9 (September 2025) – 118 articles

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