Minerals

29 pages, 9622 KiB

Open AccessArticle

Provenance of the Upper Paleozoic Shihezi Formation in the Luonan Region of the Qinling Orogenic Belt and Its Tectonic Implications

by Yuliang Duan, Wenqi Pan, Xi Zhang, Zhengtao Zhang, Yi Ding, Ziwen Jiang, Zhichao Li, Lamao Meiduo, Weiran Zhao and Wenhou Li

Minerals 2025, 15(5), 549; https://doi.org/10.3390/min15050549 - 21 May 2025

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Abstract

This study investigates the provenance of the Permian Shihezi Formation (Fm) siliciclastic sediments in the Luonan area, southern margin of the North China Block, which constrain the sediment sources and tectonic evolution of the basin. Our research investigates the heavy mineral characteristics, geochemical [...] Read more.

This study investigates the provenance of the Permian Shihezi Formation (Fm) siliciclastic sediments in the Luonan area, southern margin of the North China Block, which constrain the sediment sources and tectonic evolution of the basin. Our research investigates the heavy mineral characteristics, geochemical features, detrital zircon U-Pb geochronology, and Lu-Hf isotope tracing the provenance characteristics of the Shihezi Fm in this region. Zircon yielded three distinct U-Pb age groups as follows: 320–300 Ma, 1950–1850 Ma, and 2550–2450 Ma. The ε_Hf(t) values of zircons ranged from −41 to 50, and the two–stage Hf model’s ages (T_DM2) values are concentrated between 3940 Ma and 409 Ma, suggesting that magmatic sources likely derive from Early Archaean–Devonian crustal materials. The heavy mineral assemblages are primarily composed of zircon, leucoxene, and magnetite. Further geochemical analyses of the rocks indicate a diverse provenance area and a complex tectonic evolution. Taken together, these results suggest that the provenance of the Shihezi Fm is from the North China Block, with secondary contributions from the Qinling Orogenic Belt and the North Qilian Orogenic Belt. The provenance of Luonan shares similarities with the southern Ordos Basin. Investigating the provenance of the Luonan area along the southern margin of the North China Craton provides critical supplementary constraints for shedding light on the Late Paleozoic tectonothermal events in the Qinling Orogenic Belt. Full article

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

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20 pages, 6159 KiB

Open AccessArticle

Isotopic and Geochemical Signatures of Dolostones and Their Implications for Carbonate Incipient Weathering Processes in the Datangpo Region, Guizhou, China

by Xin Yang, Qiuhua Shen and Xiaoming Sun

Minerals 2025, 15(5), 548; https://doi.org/10.3390/min15050548 - 21 May 2025

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Abstract

Determining carbon sources and sinks is crucial for understanding the global carbon cycle; however, the enigma of the ‘missing’ sinks remains unresolved. Recent studies have proposed carbonate weathering as a potential carbon sink, underscoring the need to clarify its mechanisms. Previous investigations of [...] Read more.

Determining carbon sources and sinks is crucial for understanding the global carbon cycle; however, the enigma of the ‘missing’ sinks remains unresolved. Recent studies have proposed carbonate weathering as a potential carbon sink, underscoring the need to clarify its mechanisms. Previous investigations of carbonate weathering largely relied on soil profiles, which were limited by the rarity of incipient weathering layers. Therefore, we have little knowledge about carbonate incipient weathering processes. To address this gap, spheroidal weathered dolostones were collected from Neoproterozoic Liangjiehe Formation (Nanhua System) in Guizhou, China. The pristine dolostone exhibits δ¹³C values ranging from −5.26 to −3.35‰ and δ¹⁸O values from −13.79 to −12.83‰. These isotopic signatures suggest that the dolostone formed under the high-latitude, cold climatic conditions that were prevalent during the Nanhua Period. Comprehensive petrographic and geochemical analyses of the spheroidal weathered dolostones revealed two distinct stages of incipient weathering. In Stage I, nickel (Ni) and cobalt (Co) contents decrease. The δ¹³C values fluctuate between −7.61 and −2.52‰, while the δ¹⁸O values range from −12.22 to −8.06‰. These observations indicate a weakly acidic microenvironment. In Stage II, there is an enrichment in manganese (Mn), with the δ¹³C values extending from −16.56 to −12.43‰ and the δ¹⁸O values from −8.46 to −7.03‰. These clues suggest a transition to a neutral microenvironment, with the isotopic compositions of carbon and oxygen in the dolomite influenced by atmospheric carbon dioxide (CO₂) and atmospheric precipitation. This study presents a pioneering investigation into the mineralogical and geochemical variations associated with carbonate incipient weathering processes. The variation in C-O isotopes during carbonate incipient weathering may indicate the re-precipitation of HCO₃⁻, suggesting that the carbon sink contribution of carbonate weathering to the global carbon cycle could be overestimated. Full article

(This article belongs to the Special Issue Carbonate Petrology and Geochemistry, 2nd Edition)

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21 pages, 3455 KiB

Open AccessArticle

Pore Structure Characterization of Jurassic Sandstones in the Northeastern Ordos Basin: An Integrated Experimental and Inversion Approach

by Haiyang Yin, Tongjun Chen, Yueyue Li, Haicheng Xu and Wan Li

Minerals 2025, 15(5), 547; https://doi.org/10.3390/min15050547 - 20 May 2025

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Abstract

Although Mercury Intrusion Porosimetry (MIP) and Nuclear Magnetic Resonance (NMR) are widely used for pore characterization, their effectiveness is fundamentally constrained by theoretical limitations. This study investigated the pore structure characteristics of coal-bearing sandstones from the northeastern Ordos Basin using an integrated approach [...] Read more.

Although Mercury Intrusion Porosimetry (MIP) and Nuclear Magnetic Resonance (NMR) are widely used for pore characterization, their effectiveness is fundamentally constrained by theoretical limitations. This study investigated the pore structure characteristics of coal-bearing sandstones from the northeastern Ordos Basin using an integrated approach combining experimental measurements and model-based inversion. The experimental measurements comprised a stress-dependent acoustic velocity test (P- and S-wave velocities), X-ray diffraction (XRD) mineralogical analysis, and NMR relaxation T₂ spectra characterization. For model-based inversion, we developed an improved Mori-Tanaka (M-T) theoretical framework incorporating stress-sensitive pore geometry parameters and dual-porosity (stiff/soft) microstructure representation. Systematic analysis revealed four key findings: (1) excellent agreement between model-inverted and NMR-derived total porosity, with a maximum absolute error of 1.09%; (2) strong correlation between soft porosity and the third peak of T₂ relaxation spectra; (3) stiff porosity governed by brittle mineral content (quartz and calcite), while soft porosity showing significant correlation with clay mineral abundance and Poisson’s ratio; and (4) markedly lower elastic moduli (28.78%–51.85%) in Zhiluo Formation sandstone compared to Yan’an Formation equivalents, resulting from differential diagenetic alteration despite comparable depositional settings. The proposed methodology advances conventional NMR analysis by simultaneously quantifying both pore geometry parameters (e.g., aspect ratios) and the stiff-to-soft pore distribution spectra. This established framework provides a robust characterization of the pore architecture in Jurassic sandstones, yielding deeper insights into sandstone pore evolution within the Ordos Basin. These findings provide actionable insights for water hazard mitigation and geological CO₂ storage practices. Full article

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

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73 pages, 8905 KiB

Open AccessReview

State-of-the-Art Lithium-Ion Battery Pretreatment Methods for the Recovery of Critical Metals

by Muammer Kaya and Hossein Delavandani

Minerals 2025, 15(5), 546; https://doi.org/10.3390/min15050546 - 20 May 2025

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Abstract

Today, lithium-ion batteries (LIBs) are widespread and play a vital role in advancing portable electronics (laptops and mobile phones), green energy technology (electrical vehicles), and renewable energy systems. There is about 30% off-spec scrap LIB production during manufacturing. This trend has caused the [...] Read more.

Today, lithium-ion batteries (LIBs) are widespread and play a vital role in advancing portable electronics (laptops and mobile phones), green energy technology (electrical vehicles), and renewable energy systems. There is about 30% off-spec scrap LIB production during manufacturing. This trend has caused the accumulation of a huge number of spent LIBs. In addition to containing chemicals that are harmful to the environment, these batteries also contain critical metals; their recycling will greatly help to maintain a green and sustainable economic transition. Therefore, this issue has forced researchers to seek cost-effective and eco-friendly strategies for recycling LIBs. The pretreatment of waste batteries is an essential part of LIB recycling. This article aims to comprehensively review the basic structure of LIBS and existing pretreatment methods in recycling critical metals from LIBs, with a special focus on recent innovations. This manuscript has been prepared to help researchers conduct cutting-edge and novel research in LIB pretreatment and recycling. This approach not only helps researchers to understand the concepts, but also helps to identify and evaluate the strengths and weaknesses of different pretreatment methods. Also, in addition to mentioning the existing research limitations, suggestions for future research perspectives and less investigated areas that need further research have been presented. Full article

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

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28 pages, 12692 KiB

Open AccessArticle

Genesis of the Aït Abdellah Copper Deposit, Bou Azzer-El Graara Inlier, Anti-Atlas, Morocco

by Marieme Jabbour, Said Ilmen, Moha Ikenne, Basem Zoheir, Mustapha Souhassou, Ismail Bouskri, Ali El-Masoudy, Ilya Prokopyev, Mohamed Oulhaj, Mohamed Ait Addi and Lhou Maacha

Minerals 2025, 15(5), 545; https://doi.org/10.3390/min15050545 - 20 May 2025

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Abstract

The Aït Abdellah copper deposit in the Bou Azzer-El Graara inlier of the Moroccan Anti-Atlas provides key insights into structurally and lithologically controlled mineralization in Precambrian terranes. The deposit is hosted in feldspathic sandstones of the Tiddiline Group, which unconformably overlie the Bou [...] Read more.

The Aït Abdellah copper deposit in the Bou Azzer-El Graara inlier of the Moroccan Anti-Atlas provides key insights into structurally and lithologically controlled mineralization in Precambrian terranes. The deposit is hosted in feldspathic sandstones of the Tiddiline Group, which unconformably overlie the Bou Azzer ophiolite, and is spatially associated with a NE–SW-trending shear zone. This zone is characterized by mylonitic fabrics, calcite veining, and an extensive network of fractures, reflecting a two-stage deformation history involving early ductile shearing followed by brittle faulting and brecciation. These structural features enhanced rock permeability, enabling fluid flow and metal precipitation. Copper mineralization includes primary sulfides such as chalcopyrite, bornite, pyrite, chalcocite, digenite, and covellite, as well as supergene minerals like malachite, azurite, and chrysocolla. Sulfur isotope values (δ³⁴S = +5.9% to +22.8%) indicate a mixed sulfur source, likely derived from both ophiolitic rocks and volcano-sedimentary sequences. Carbon and oxygen isotope data suggest fluid interaction with marine carbonates and meteoric waters, potentially linked to post-Snowball Earth deglaciation processes. Fluid inclusion studies reveal homogenization temperatures ranging from 195 °C to 310 °C and salinities between 5.7 and 23.2 wt.% NaCl equivalent, supporting a model of fluid mixing between magmatic-hydrothermal and volcano-sedimentary sources. The paragenetic evolution of the deposit comprises three stages: (1) early hydrothermal precipitation of quartz, dolomite, sericite, pyrite, and early chalcopyrite and bornite; (2) a main mineralizing stage characterized by fracturing and deposition of bornite, chalcopyrite, and Ag-bearing sulfosalts; and (3) a late supergene phase with oxidation and secondary enrichment. The Aït Abdellah deposit is best classified as a shear zone-hosted copper system with a complex, multistage mineralization history. The integrated analysis of structural features, mineral assemblages, isotopic signatures, and fluid inclusion data reveals a dynamic interplay between deformation processes, hydrothermal alteration, and evolving fluid sources. Full article

(This article belongs to the Section Mineral Deposits)

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20 pages, 5717 KiB

Open AccessArticle

Differential Diagenesis and Hydrocarbon Charge of the Tight-Sandstone Reservoir: A Case Study from Low-Permeable Sandstone Reservoirs in the Ninth Member of the Upper Triassic Yanchang Formation, Ordos Basin, China

by Caizhi Hu, Likuan Zhang, Yuhong Lei, Lan Yu, Jing Qin and Xiaotao Zhang

Minerals 2025, 15(5), 544; https://doi.org/10.3390/min15050544 - 20 May 2025

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Abstract

Studies of hydrocarbon migration and enhanced oil recovery focus on the effects of reservoir heterogeneity on subsurface fluid flow and distribution. Differential diagenesis in clastic rock reservoirs is an important factor of internal-reservoir heterogeneity and its relationship to hydrocarbon charges is a key [...] Read more.

Studies of hydrocarbon migration and enhanced oil recovery focus on the effects of reservoir heterogeneity on subsurface fluid flow and distribution. Differential diagenesis in clastic rock reservoirs is an important factor of internal-reservoir heterogeneity and its relationship to hydrocarbon charges is a key scientific issue for understanding hydrocarbon accumulation mechanisms in tight-sandstone reservoirs. This paper focuses on the ninth member of the Upper Triassic Yanchang Formation (Chang 9), located in the central and western Ordos Basin, China. The aims of the paper are to examine the differential diagenesis of sandstone reservoirs and to illustrate the process of organic/inorganic fluid–rock interaction using an integrated method of petrography, UV fluorescence spectra, fluid inclusion, and basin modeling analyses. The Chang 9 reservoir comprises four sandstone types: mechanically compacted sandstone, calcite-cemented sandstone, water-bearing sandstone, and oil-bearing sandstone. These four types of sandstone experience contrasting diagenetic evolutions. During early diagenesis, mechanically compacted sandstone and calcite-cemented sandstone undergo strong deformation and cementation, respectively. The water-bearing and oil-bearing sandstones experience similar diagenetic evolutions, but significantly different from those two tight sandstones in fluid activity and diagenesis magnitude. Three types of porous bitumen were identified in the oil-bearing sandstone, whereas no bitumen was identified in the water-bearing sandstone. According to the contact relationship between bitumen, cements, and dissolution pores, the related diagenesis sequence of the oil-bearing sandstones of Chang 9 was reconstructed. Three phases of fluid flow occurred in turn, with hydrocarbon charging in the process, but no hydrocarbon charging occurred in the water-bearing sandstones. The research findings, in terms of organic and/or inorganic fluid–rock interaction, can be used as a reference for the differential diagenesis and process of fluid–rock interaction in low-permeability sandstone reservoirs with a highly heterogeneous internal reservoir framework. Furthermore, this study could help in understanding the internal heterogeneity characteristics of a fluvial sandstone reservoir and its relationship with hydrocarbon charging. Full article

(This article belongs to the Topic Recent Advances in Diagenesis and Reservoir 3D Modeling)

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16 pages, 2742 KiB

Open AccessReview

Urease-Driven Microbially Induced Carbonate Precipitation (MICP) for the Circular Valorization of Reverse Osmosis Brine Waste: A Perspective Review

by Dayana Arias, Karem Gallardo, Manuel Saldana and Felipe Galleguillos-Madrid

Minerals 2025, 15(5), 543; https://doi.org/10.3390/min15050543 - 20 May 2025

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Abstract

The growing scarcity of freshwater has accelerated the global deployment of desalination technologies, especially reverse osmosis (RO), as an alternative to meet increasing water demands. However, this process generates substantial quantities of brine—a hypersaline waste stream that can severely impact marine ecosystems if [...] Read more.

The growing scarcity of freshwater has accelerated the global deployment of desalination technologies, especially reverse osmosis (RO), as an alternative to meet increasing water demands. However, this process generates substantial quantities of brine—a hypersaline waste stream that can severely impact marine ecosystems if improperly managed. This perspective review explores the use of urease-driven Microbially Induced Carbonate Precipitation (MICP) as a biotechnological solution aligned with circular economy principles for the treatment and valorization of RO brines. Through the enzymatic activity of ureolytic microorganisms, MICP promotes the precipitation of calcium carbonate and other mineral phases, enabling the recovery of valuable elements and reducing environmental burdens. Beyond mineral capture, MICP shows promise in the stabilization of toxic metals and potential integration with microbial electrochemical systems for energy applications. This review summarizes current developments, identifies existing challenges, such as microbial performance in saline conditions and reliance on conventional urea sources, and proposes future directions focused on strain optimization, nutrient recycling, and process scalability for sustainable implementation. Full article

(This article belongs to the Special Issue Microbially Induced Carbonate Precipitation (MICP) in Non-Conventional Waters: Innovative Circular Economy Solutions for Mineral Formation, Environmental Remediation, and Sustainable Energy Production)

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27 pages, 9794 KiB

Open AccessArticle

Short-Term Climate Oscillations During the Messinian Salinity Crisis: New Insights from Gypsum Lithofacies of the Crati Basin (Lattarico, Calabria, Southern Italy)

by Rocco Dominici, Alessandra Costanzo, Adriano Guido, Giuseppe Maruca, Francesco Perri, Davide Molinaro and Mara Cipriani

Minerals 2025, 15(5), 542; https://doi.org/10.3390/min15050542 - 20 May 2025

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Abstract

This study presents the first detailed investigation of the petrography, mineralogy, and depositional environment of Messinian gypsum lithofacies outcropping on the western side of the Crati Basin (Calabria, Southern Italy), focusing on three sections: Castelluccio, Striscioli, and Piretto. The different localities preserve in [...] Read more.

This study presents the first detailed investigation of the petrography, mineralogy, and depositional environment of Messinian gypsum lithofacies outcropping on the western side of the Crati Basin (Calabria, Southern Italy), focusing on three sections: Castelluccio, Striscioli, and Piretto. The different localities preserve in situ gypsum accumulation (laminar gypsum and gypsiferous mudstone) and clastic gypsum deposits (nodular, gypsarenite and gypsrudite) formed during the second stage (5.60–5.55 Ma) of the Messinian Salinity Crisis (MSC). Observation and analyses of macro-, meso- and nanoscale reveal a complex climatic variability and depositional history that reflect different environmental conditions, from shallow-water evaporitic environments to deep basin settings affected by slope failures. The data highlights the influence of tectonic activity on facies distribution within the basin. Overall, this study emphasizes the importance of climatic and geological controls on gypsum deposition, offering a detailed interpretation of the Crati Basin’s evaporitic history and contributing to the broader understanding of Mediterranean Messinian evaporites. Full article

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

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12 pages, 2784 KiB

Open AccessArticle

Structural Distortion and Optoelectronic Signatures in Metal-Substituted Kaolinite: A First-Principles Investigation

by Qiuyu Zeng, Jun Xie, Jinbo Zhu, Jianqiang Yin and Wenliang Zhu

Minerals 2025, 15(5), 541; https://doi.org/10.3390/min15050541 - 20 May 2025

Viewed by 198

Abstract

This study employs density functional theory (DFT) simulations to systematically investigate the structural and optoelectronic modifications induced by the substitution of metal ions (Mg²⁺, Ca²⁺, Mn²⁺, Fe²⁺/³⁺, Co²⁺, and Ni²⁺ [...] Read more.

This study employs density functional theory (DFT) simulations to systematically investigate the structural and optoelectronic modifications induced by the substitution of metal ions (Mg²⁺, Ca²⁺, Mn²⁺, Fe²⁺/³⁺, Co²⁺, and Ni²⁺) in kaolinite. First-principles calculations reveal distinct substitution behaviors: Na-Ni (II)-1 exhibits the lowest cell energy, indicating superior structural stability, while Na-Mn (II)-1 demonstrates the most favorable substitution energy (−5.44 eV). XRD simulations of divalent substitutions show a positive correlation between atomic number and diffraction intensity at 8.778° and 9.774°, suggesting a spectral marker for substitution detection. Electronic structure analysis identifies significant bandgap reduction, with Na-Fe (II)-4 achieving an ultranarrow gap of 1.014 eV, attributed to spin-polarized d-orbital contributions. X-ray absorption fine-structure (XAFS) simulations further reveal metal-specific bond elongation, with Fe³⁺ substitutions preserving near-pristine coordination distances. These findings establish a comprehensive framework linking metal substitution to structural distortion and optoelectronic response, providing theoretical insights for optimizing kaolinite-based material properties through computational feature extraction. Full article

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

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27 pages, 23477 KiB

Open AccessArticle

The B-Zone 4611 Silver-Rich Pod—An Unusual Ag-Ge-Sb-As-Ni Assemblage Within the Irish-Type Zn-Pb Silvermines Deposit, County Tipperary, Ireland

by Colin J. Andrew and John H. Ashton

Minerals 2025, 15(5), 540; https://doi.org/10.3390/min15050540 - 19 May 2025

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Abstract

The Silvermines Pb-Zn-Ag-Ba orebodies comprise vein, replacement, cross-cutting and stratiform mineralization mostly hosted in Lower Carboniferous limestones in the vicinity of a major ENE and E-W trending normal fault array and represent a classic example of Irish-Type Zn-Pb mineralization. Historically the deposits have [...] Read more.

The Silvermines Pb-Zn-Ag-Ba orebodies comprise vein, replacement, cross-cutting and stratiform mineralization mostly hosted in Lower Carboniferous limestones in the vicinity of a major ENE and E-W trending normal fault array and represent a classic example of Irish-Type Zn-Pb mineralization. Historically the deposits have been exploited at various times, but the major limestone-hosted Zn-Pb-Ba mineralization was not discovered until the 1960s. Structurally controlled crosscutting vein and breccia mineralization represent pathways of hydrothermal fluids escaping from the Silvermines fault at depth that exhaled and replaced shallowly buried Waulsortian limestones creating the larger stratiform orebodies such as the Upper G and B-Zones. The B-Zone, comprising a pre-mining resource of 4.64 Mt of 4.53% Zn, 3.58% Pb, 30 g/t Ag has a locally highly variable host mineralogy dominated by pyrite, barite, siderite, within dolomitic and limestone breccias with local silica-haematite alteration. A small, highly unusual pod of very high-grade Ag-rich mineralization in the B-Zone, the 4611 Pod, discovered in 1978, has not been previously documented. Unpublished records, field notes, and mineralogical and chemical data from consultant reports have been assimilated to document this interesting and unusual occurrence. The pod, representing an irregular lens of mineralization ca 2 m thick and representing 500 t, occurs within the B-Zone orebody and comprises high grade Zn and Pb sulfides with significant patches of proustite-pyrargyrite (ruby silvers) and a host of associated Pb, Ag, Sb, As, Cu, Ge sulfide minerals, including significant argyrodite. Although evidence of any distinct feeder below the pod is lacking, the nature of the pod, its unusual mineralogy and its paragenesis suggests that it represents a small, possibly late source of exotic hydrothermal fluid where it entered the B-Zone stratiform mineralizing system. Full article

(This article belongs to the Special Issue Genesis and Evolution of Pb-Zn-Ag Polymetallic Deposits: 2nd Edition)

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23 pages, 22456 KiB

Open AccessArticle

Thermal Maturity of the Silurian “Hot” Shales and Correlation with the Present Geothermal Variations in West Lithuania, Baltic Basin

by Saulius Šliaupa, Jurga Lazauskienė and Rasa Šliaupienė

Minerals 2025, 15(5), 539; https://doi.org/10.3390/min15050539 - 19 May 2025

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Abstract

The most organic-rich shales are defined in the Dobele Fm. of the Aeronian Stage of about 10 m thick in west Lithuania. This particular layer is documented in the whole Baltic Basin. Compatible shales are widely distributed in other basins referred to as [...] Read more.

The most organic-rich shales are defined in the Dobele Fm. of the Aeronian Stage of about 10 m thick in west Lithuania. This particular layer is documented in the whole Baltic Basin. Compatible shales are widely distributed in other basins referred to as similar Silurian “hot” shales. The average TOC was estimated at 6.67 wt.% (good and excellent source rock). The thermal maturity of shales was evaluated through organic geochemical techniques, including TOC determination, Rock–Eval pyrolysis, and organic petrography studies. The thermal maturity varies from T_max = 431 °C and eq.VR_o = 0.65% (early oil) to T_max = 468 °C and VR_o = 1.38% (locally up to 1.94%) (late oil and wet to dry gas generation). It is notable, most of the study area is confined to regional-scale West Lithuanian Geothermal Anomaly. Most of the geothermal features, both palaeo- and recent, recorded in lateral variation in thermal maturity of shales unravel persistence of heat flow. Locally, the Variscan tectonic activity was imprinted in thermal maturity of organic matter-rich shales (Žemaičių Naumiestis anomaly). Full article

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

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31 pages, 5464 KiB

Open AccessReview

The Utilization of Slag, Steel Slag, and Desulfurization Gypsum as Binder Systems in UHPC with Iron Tailings and Steel Fibers—A Review

by Hocine Heraiz, Jiajie Li, Ziping Pan, Dongdong Zhang, Yingxi Hu, Xinli Mu, Amer Baras, Jinhai Liu, Wen Ni and Michael Hitch

Minerals 2025, 15(5), 538; https://doi.org/10.3390/min15050538 - 18 May 2025

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Abstract

Ultra-high-performance concrete (UHPC) is known for its outstanding strength and durability but is often limited by the high cost of traditional materials, like cement, fine aggregates, and silica fume. This review examines the use of industrial by-products—specifically, iron tailings, steel slag, and desulfurization [...] Read more.

Ultra-high-performance concrete (UHPC) is known for its outstanding strength and durability but is often limited by the high cost of traditional materials, like cement, fine aggregates, and silica fume. This review examines the use of industrial by-products—specifically, iron tailings, steel slag, and desulfurization gypsum—as sustainable alternatives in UHPC mix design. These materials serve as supplementary cementitious components and fine aggregates, helping reduce environmental impacts and production costs. This study highlights the synergistic hydration mechanisms between Portland cement and waste-based materials, leading to improved microstructure and long-term strength. The role of steel fibers in enhancing crack resistance is also discussed. Challenges related to workability, cost, and lack of standardization are addressed, along with opportunities for innovative mix designs, low-carbon binders, and 3D printing. Overall, this paper underscores the potential of industrial by-products to advance sustainable, high-performance UHPC solutions. Full article

(This article belongs to the Special Issue Recycling of Industrial Waste for the Development of Sustainable Materials)

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13 pages, 1341 KiB

Open AccessArticle

Zircon Systematics of the Shionomisaki Volcano–Plutonic Complex (Kii Peninsula, Japan): A Potential Tool for the Study of the Source Region of Silicic Magmas

by Ulrich Knittel, Monika Walia and Shigeyuki Suzuki

Minerals 2025, 15(5), 537; https://doi.org/10.3390/min15050537 - 18 May 2025

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Abstract

The Shionomisaki Igneous Complex is part of the Mid Miocene igneous province developed within the Shimanto Accretionary Complex in front of the volcanic front in SW Japan. The igneous rocks in this province mostly have silicic compositions. New U-Pb ages obtained for two [...] Read more.

The Shionomisaki Igneous Complex is part of the Mid Miocene igneous province developed within the Shimanto Accretionary Complex in front of the volcanic front in SW Japan. The igneous rocks in this province mostly have silicic compositions. New U-Pb ages obtained for two samples from the Shionomisaki Complex at the southern tip of the Kii Peninsula (14.6 ± 0.4 Ma and 14.9 ± 0.4 Ma) fall into the range of previous age determinations (14.6 ± 0.2 to 15.4 ± 0.3 Ma). Hf isotopic compositions obtained for co-magmatic zircon (εHf(t) = −0.7 to +4.8) lie between typical values obtained for mantle-derived magmas and values obtained for old crustal rocks. They are thus consistent with previous interpretations that the magmas are mixtures of mantle and crustally derived magmas. In the modelling of the isotopic characteristics of the magmas, the sediments of the Shimanto belt are taken as the protolith of the silicic magmas. Xenocrystal zircon (i.e., zircon picked up during ascent and emplacement of the magma) found in the silicic igneous rocks exhibits a similar age pattern as detrital zircon of the Shimanto sediments. However, the age pattern obtained in this study for zircon cores, which are considered to be restitic zircon (i.e., zircon derived from the source of the anatectic melt), shows little semblance with the age pattern of Shimanto sediments. It is, therefore, tentatively suggested that the source area of the silicic magmas may not be identical with the sediments of the Shimanto Accretionary Complex. Full article

(This article belongs to the Special Issue Igneous Rocks as Archives of Earth's Geological History: Magma Processes and Continental Crust Evolution)

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15 pages, 5879 KiB

Open AccessArticle

The Mineralization Mechanism of the Axi Gold Deposit in West Tianshan, NW China: Insights from Fluid Inclusion and Multi-Isotope Analyses

by Fang Xia, Chuan Chen and Weidong Sun

Minerals 2025, 15(5), 536; https://doi.org/10.3390/min15050536 - 18 May 2025

Viewed by 282

Abstract

The Axi gold deposit, which is located in the Tulasu Basin of the West Tianshan orogenic belt in Northwest China, features vein-type ore bodies hosted in radial structural fractures formed due to volcanic activity. The deposit experienced three distinct mineralization stages: Stage I, [...] Read more.

The Axi gold deposit, which is located in the Tulasu Basin of the West Tianshan orogenic belt in Northwest China, features vein-type ore bodies hosted in radial structural fractures formed due to volcanic activity. The deposit experienced three distinct mineralization stages: Stage I, characterized by the microcrystalline quartz–pyrite crust; Stage II, characterized by quartz–sulfide–native gold veins; and Stage III, characterized by quartz–carbonate veins. Fluid inclusion studies have identified four types of inclusions: pure vapor, vapor-rich, liquid-rich, and pure liquid. The number of vapor-rich inclusions decreases when moving from Stage I to Stage III, whereas the number of liquid-rich inclusions increases. The fluid temperature gradually decreases from 178–225 °C in Stage I to 151–193 °C in Stage II and further to 123–161 °C in Stage III, whereas the fluid salinity decreases slightly from 2.1%–5.1% wt.% NaCl eqv to 1.4%–4.6% wt.% NaCl eqv and finally to 0.5%–3.7% wt.% NaCl eqv. As suggested by the results of the oxygen, hydrogen, and carbon isotope analyses, the ore-forming fluids were primarily meteoric water. Sulfur isotopic compositions indicate a single deep mantle source. The lead isotopic compositions closely resemble those of Dahalajunshan Formation volcanic rocks, indicating that these rocks were the primary source of the ore-forming material. In addition, gold mineralization formed in a Devonian–Early Carboniferous volcanic arc environment. Element enrichment was mainly caused by the circulation of heated meteoric water through the volcanic strata, while fluid boiling and water–rock interactions were the main mechanisms driving element precipitation. The integrated model developed in this study underscores the intricate interplay between volcanic processes and meteoric fluids during the formation of the Axi gold deposit, offering a robust framework for an understanding of the formation processes and enhancing the predictive exploration models in analogous geological settings. Full article

(This article belongs to the Special Issue Mineralogy, Geochemistry and Fluid Inclusion Study of Gold Deposits Endowed in Critical Metals)

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31 pages, 54013 KiB

Open AccessArticle

Ore-Forming Fluid Evolution and Ore Genesis of the Cuyu Gold Deposit in Central Jilin Province, NE China: Constraints from Geology, Fluid Inclusions, and H–O–S–Pb Isotope Studies

by Haozhe Li, Qun Yang, Leigang Zhang, Yunsheng Ren, Mingtao Li, Chan Li, Bin Wang, Sitong Chen and Xiaolei Peng

Minerals 2025, 15(5), 535; https://doi.org/10.3390/min15050535 - 17 May 2025

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Abstract

The Cuyu gold deposit in central Jilin Province in Northeast China is located in the eastern segment of the northern margin of the North China Craton (NCC), as well as the eastern segment of the Xing’an–Mongolian Orogenic Belt (XMOB). Gold ore-bodies are controlled [...] Read more.

The Cuyu gold deposit in central Jilin Province in Northeast China is located in the eastern segment of the northern margin of the North China Craton (NCC), as well as the eastern segment of the Xing’an–Mongolian Orogenic Belt (XMOB). Gold ore-bodies are controlled by NW-trending faults and mainly occur in late Hercynian granodiorite. The mineralization process in the Cuyu deposit can be divided into three stages: quartz + coarse grained arsenopyrite + pyrite (stage I), quartz + sericite + pyrite + arsenopyrite + electrum + chalcopyrite + sphalerite (stage II), and quartz + calcite ± pyrite (stage III). Stage II is the most important for gold mineralization. We conducted analyses including petrography, microthermometry, laser Raman spectroscopy of fluid inclusions, and H–O–S–Pb isotopic analysis to elucidate the mineralization processes in the Cuyu deposit. Five types of primary fluid inclusions (FIs) are present in the hydrothermal quartz and calcite grains of the ore: liquid-rich two-phase aqueous fluid inclusions (L-type), vapor-rich two-phase aqueous fluid inclusions (V-type), CO₂-bearing two- or three-phase inclusions (C1-type), CO₂-rich two- or three-phase inclusions (C2-type), and pure CO₂ mono-phase inclusions (C3-type). From stages I to III, the fluid inclusion assemblages changed from L-, C2-, and C3-types to L-, V-, C1-, C2-, and C3-types and, finally, to L-types only. The corresponding homogenization temperatures for stages I to III were 242–326 °C, 202–298 °C, and 106–188 °C, and the salinities were 4.69–9.73, 1.63–7.30, and 1.39–3.53 wt.% NaCl equiv., respectively. The ore-forming fluid system evolved from a NaCl-H₂O-CO₂ ± CH₄ ± H₂S fluid system in stage I and II with immiscible characteristics to a homogeneous NaC-H₂O fluid system in stage III. Microthermometric data for stages I to III show a decreasing trend in homogenization temperatures and salinities. The mineral assemblages, fluid inclusions, and H–O–S–Pb isotopes indicate that the initial ore-forming fluids of stage I were exsolved from diorite porphyrite and characterized by a high temperature and low salinity. The addition of meteoric water in large quantities led to decreases in temperature and pressure, resulting in a NaCl-H₂O-CO₂ ± CH₄ ± H₂S fluid system with significant immiscibility in stage II, facilitating the deposition of gold and associated polymetallic sulfides. The Cuyu gold deposit has a similar ore genesis to those of gold deposits in the Jiapigou–Haigou gold belt (JHGB) of southeastern Jilin Province indicating potential for gold prospecting in the northwest-trending seam of the JHGB. Full article

(This article belongs to the Special Issue Genesis and Metallogeny of Non-ferrous and Precious Metal Deposits, 2nd Edition)

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25 pages, 4251 KiB

Open AccessArticle

Testing Pyrrhotite Trace Element Chemistry as a Vector Towards the Mineralization in the Sullivan Deposit, B.C.

by Naci Sertug Senol, Daniel David Gregory, Indrani Mukherjee, Nelson Román, Roisin Kyne and Kaleb S. Boucher

Minerals 2025, 15(5), 534; https://doi.org/10.3390/min15050534 - 17 May 2025

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Abstract

Mineral exploration methods are expensive and time-consuming, especially in recent times, where many near-surface deposits have been found and exploited. To overcome these challenges, new strategies must be developed. Here, we test whether the trace element chemistry of pyrrhotite changes systematically with distance [...] Read more.

Mineral exploration methods are expensive and time-consuming, especially in recent times, where many near-surface deposits have been found and exploited. To overcome these challenges, new strategies must be developed. Here, we test whether the trace element chemistry of pyrrhotite changes systematically with distance from mineralization at the Sullivan deposit, British Columbia. If so, this could provide an additional tool to search for new ore bodies. Forty samples of the hanging wall, footwall, and mineralization hosting stratigraphy (host horizon) were collected from seven drill holes, both proximal and distal to the Sullivan deposit. These samples were analyzed using reflected light microscopy, an electron microprobe, and LA-ICPMS (laser ablation, inductively coupled plasma mass spectrometry). A total of three hundred and ninety LA-ICPMS analyses were used to build machine learning classifiers (cluster analysis and random forests) to determine whether an unknown pyrrhotite sample was from the mineralized horizon and, if so, whether it was proximal or distal to the mineralization. Our study found that the trace element abundance in pyrrhotite was higher in the footwall and hanging wall compared to the host horizon, and within the host horizon, was higher distal to the mineralization. Full article

(This article belongs to the Special Issue Mineral Chemistry: Tool for Vectoring towards Mineral Deposits)

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42 pages, 2446 KiB

Open AccessReview

A Mineralogical Perspective on Rare Earth Elements (REEs) Extraction from Drill Cuttings: A Review

by Muhammad Hammad Rasool, Syahrir Ridha, Maqsood Ahmad, Raba’atun Adawiyah Bt Shamsuddun, Muhammad Khurram Zahoor and Azam Khan

Minerals 2025, 15(5), 533; https://doi.org/10.3390/min15050533 - 17 May 2025

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Abstract

The growing demand for rare earth elements (REEs) in high-tech and green energy sectors has prompted renewed exploration of unconventional sources. Drill cuttings, which are commonly discarded during subsurface drilling, are increasingly recognized as a potentially valuable, underutilized secondary REE reservoir. This review [...] Read more.

The growing demand for rare earth elements (REEs) in high-tech and green energy sectors has prompted renewed exploration of unconventional sources. Drill cuttings, which are commonly discarded during subsurface drilling, are increasingly recognized as a potentially valuable, underutilized secondary REE reservoir. This review adopts a mineral-first lens to assess REE occurrence, extractability, and recovery strategies from drill cuttings across various lithologies. Emphasis is placed on how REEs associate with specific mineral host phases ranging from ion-adsorbed clays and organically bound forms to structurally integrated phosphates, each dictating distinct leaching pathways. The impact of drilling fluids on REE surface chemistry and mineral integrity is critically examined, alongside an evaluation of analytical and extraction methods tailored to different host phases. A scenario-based qualitative techno-economic assessment and a novel decision-tree framework are introduced to align mineralogy with optimal recovery strategies. Limitations in prior studies, particularly in characterization workflows and mineralogical misalignment in leaching protocols, are highlighted. This review redefines drill cuttings from industrial waste to a strategic resource, advocating for mineralogically guided extraction approaches to enhance sustainability in the critical mineral supply chain. Full article

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

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27 pages, 15247 KiB

Open AccessArticle

Geochronological Evolution of the Safaga–Qena Transect, Northern Eastern Desert, Egypt: Implications of Zircon U-Pb Dating

by Sherif Mansour, Abdelghafar M. Abu-Elsaoud, Faouzi Haouala, Mohamed Zaki Khedr, Akihiro Tamura and Noriko Hasebe

Minerals 2025, 15(5), 532; https://doi.org/10.3390/min15050532 - 17 May 2025

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Abstract

The granitic rocks and the Dokhan Volcanics at the transect between Safaga and Qena, the Egyptian Northern Eastern Desert represent the northern termination of the Arabian–Nubian Shield (ANS), which, in turn, represents the northern part of the East African Orogeny (EAO). The geochronological [...] Read more.

The granitic rocks and the Dokhan Volcanics at the transect between Safaga and Qena, the Egyptian Northern Eastern Desert represent the northern termination of the Arabian–Nubian Shield (ANS), which, in turn, represents the northern part of the East African Orogeny (EAO). The geochronological development of the magmatic activities that constructed the ANS is critical in understanding these orogenies. The ANS was constructed through pre-collisional, syn-collisional, and post-collisional magmatic phases. The transition between these magmatic phases marks tectonic shifting from subduction to compressional and extensional tectonic settings, respectively. The chronological constraints of these tectonic–magmatic phases are still questionable. Our study aims to refine these chronological constraints through the dating of four calc-alkaline granitic rocks (722 ± 5 Ma–561 ± 4 Ma), five alkaline granitic rocks (758 ± 5 Ma–555 ± 4 Ma), and three Dokhan Volcanic rocks (618 ± 5 Ma–606 ± 5 Ma). Our results suggest the absence of any pre-collisional rocks. The syn-collisional magmatism extended here from 758 ± 5 Ma to 653 ± 7 Ma, demonstrating the chronological domination of the syn-orogenic compressional regime in the NED. The Dokhan Volcanic activity marked the shifting of the tectonic setting from a compressional to an extensional regime at 618 ± 5 Ma. Post-collisional plutonism dominated between 583 ± 5 Ma and 555 ± 4 Ma in the studied region, suggesting that ANS magmatic activity was extended to the Phanerozoic edge. These findings refute the classical interpretations of older magmatism as calc-alkaline granitoids and younger magmatism as alkaline granitoids. Pre-Neoproterozoic (pre-ANS) xenocrysts with ages of 1879 ± 22, 1401 ± 25, 1385 ± 12, 1232 ± 27, 1210 ± 18, and 1130 ± 15 Ma were yielded, which might support a local reworked ancient magmatic source. Full article

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

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27 pages, 21759 KiB

Open AccessArticle

Origin and Tectonic Implication of Cenozoic Alkali-Rich Porphyry in the Beiya Au-Polymetallic Deposit, Western Yunnan, China

by Yun Zhong, Yajuan Yuan, Ye Lu and Bin Xia

Minerals 2025, 15(5), 531; https://doi.org/10.3390/min15050531 - 16 May 2025

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Abstract

Cenozoic alkali-rich porphyries are widely distributed in the junction zone between the Sanjiang Orogenic belt and the Yangtze Plate. They are of great significance for understanding the regional geodynamics, tectonic evolution, and metallogenesis. However, the origin of these porphyries remains controversial. In this [...] Read more.

Cenozoic alkali-rich porphyries are widely distributed in the junction zone between the Sanjiang Orogenic belt and the Yangtze Plate. They are of great significance for understanding the regional geodynamics, tectonic evolution, and metallogenesis. However, the origin of these porphyries remains controversial. In this study, new petrological, geochemical, and geochronological data are presented for Cenozoic syenite porphyry from the Beiya porphyry Au-polymetallic deposit in western Yunnan. Zircon U-Pb dating results show that the Beiya syenite porphyries formed around 36.3–35.0 Ma, coinciding with the magmatic peak in the Jinshajiang-Red River (JSJ-RR) alkali-rich porphyry belt. Geochemical analyses indicate that the Beiya porphyries have potassic characteristics and an arc-like geochemical affinity, with C-type adakite affinity, suggesting a post-collisional setting. The JSJ-RR fault zone is unlikely to be the primary mechanism responsible for the formation of this alkali-rich porphyry magmatism. Instead, the development of the Beiya alkali-rich porphyries is likely associated with the convective removal of the lower part of the overthickened lithospheric mantle and asthenospheric upwelling during the Eocene–Oligocene. Their magmas probably originated from the partial melting of Paleo–Mesoproterozoic garnet amphibolite facies rocks in the thickened lower continental crust, with the addition of shoshonitic mafic magmas produced by the partial melting of metasomatized lithospheric mantle triggered by asthenospheric upwelling. This study provides additional reliable evidence to further constrain the origin of Cenozoic alkali-rich porphyries in the JSJ-RR belt. Full article

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

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32 pages, 20045 KiB

Open AccessArticle

Mineralogy and Geochemistry of Early Triassic Granite in South China: Insights into Source Region Characteristics and REE Mineralization

by Liya Yang, Yongfeng Cai, Jieting Ouyang, Fang Xu, Yankun Chen and Yun Zhou

Minerals 2025, 15(5), 530; https://doi.org/10.3390/min15050530 - 16 May 2025

Viewed by 125

Abstract

Regolith-hosted rare-earth element (REE) deposits are some of the most important types of REE deposits. The relationship between Late Paleozoic and Early Mesozoic granite and regolith-hosted REE deposits is still poorly studied. Detailed geochronology, geochemistry, and rare-earth mineralogy analyses of Early Triassic granite [...] Read more.

Regolith-hosted rare-earth element (REE) deposits are some of the most important types of REE deposits. The relationship between Late Paleozoic and Early Mesozoic granite and regolith-hosted REE deposits is still poorly studied. Detailed geochronology, geochemistry, and rare-earth mineralogy analyses of Early Triassic granite in the South China Block were conducted. The geochronological results showed that four representative granite samples yielded formation ages of 245 ± 1 Ma, 244 ± 1 Ma, 244 ± 1 Ma, and 244 ± 2 Ma, respectively. The granites show geochemical affinity to A-type granite. They are characterized by enrichment in Rb, Th, and U, are depleted in Ba, Sr, P, and Ti, and show obvious negative Nb and Ta anomalies. They have high light rare-earth element (LREE) and low heavy rare-earth element (HREE) contents, with obvious negative Eu anomalies. They were derived from the partial melting of a sediment source and underwent intense fractional crystallization during the magma evolution process. They contain a certain number of rare-earth-element-bearing minerals, such as monazite, xenotime, apatite, and zircon. Their REE compositions and mineral associations are similar to those of the parent rocks from typical regolith-hosted REE deposits in South China. The highly weathered horizon at the ridge of the granite weathering crust profile has the highest REE content. A comprehensive analysis indicated that the degree of magma evolution, geomorphology, and weathering are important factors controlling the formation of regolith-hosted REE deposits in the area. Full article

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

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23 pages, 12331 KiB

Open AccessArticle

Optimization of Magnetization Roasting and Magnetic Separation for the Recovery of Iron from Low-Grade Iron Plant Tailings

by Anele Shamase and Willie Nheta

Minerals 2025, 15(5), 529; https://doi.org/10.3390/min15050529 - 16 May 2025

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Abstract

This study employs response surface methodology (RSM) with a custom optimal design to develop and optimize iron (Fe) grade and recovery through magnetization roasting followed by induced dry-roll magnetic separation. The relationships between the independent and dependent variables are investigated. The effect of [...] Read more.

This study employs response surface methodology (RSM) with a custom optimal design to develop and optimize iron (Fe) grade and recovery through magnetization roasting followed by induced dry-roll magnetic separation. The relationships between the independent and dependent variables are investigated. The effect of roasting temperature, magnetization roasting time, magnetic field intensity, rotor speed, and product splitter position for the induced dry-roll magnetic separator on Fe grade and recovery are studied. Suitable models are generated to predict the optimum operating conditions. An analysis of Variance (ANOVA) is employed to validate the developed regression models’ adequacy and assess the main and interaction-related effects on Fe grade and recovery. During magnetization roasting, a satisfactory Fe grade of 66.8% with a recovery of 16.7% was obtained under optimal conditions of 1050 °C for 97 min. Conversely, after the induced dry-roll magnetic separator optimization, an Fe grade of 66.1% with a recovery of 60.2% was achieved under optimum conditions of 0.105 T for magnetic field intensity, 70 Hz for rotor speed, and an 11 mm product splitter position. This study effectively illustrates how RSM can model the processes of magnetization roasting and induced dry-roll magnetic separation, particularly concerning the operating parameters used for treating iron ore plant tailings. Furthermore, it highlights the efficiency of this methodology in generating substantial insights in a short timeframe while minimizing the number of experiments conducted. Full article

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

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37 pages, 16597 KiB

Open AccessArticle

Geochemistry, Isotope Characteristics, and Evolution of the Kesikköprü Iron Deposit (Türkiye)

by Erkan Yılmazer and Mustafa Haydar Terzi

Minerals 2025, 15(5), 528; https://doi.org/10.3390/min15050528 - 15 May 2025

Viewed by 248

Abstract

The Kesikköprü iron deposit, located in the Central Anatolian Crystalline Complex, occurs in the triple contact of Kesikköprü granitoid, mafic–ultramafic rocks, and marble. The causative Kesikköprü granitoid, consisting of diorite, granodiorite, and granite, is classified as sub-alkaline, calc-alkaline, and shoshonitic, displaying metaluminous to [...] Read more.

The Kesikköprü iron deposit, located in the Central Anatolian Crystalline Complex, occurs in the triple contact of Kesikköprü granitoid, mafic–ultramafic rocks, and marble. The causative Kesikköprü granitoid, consisting of diorite, granodiorite, and granite, is classified as sub-alkaline, calc-alkaline, and shoshonitic, displaying metaluminous to partially peraluminous properties. Sr-Nd isotope data and the geochemical characteristics of the Kesikköprü granitoid indicate a metasomatized mantle origin, with its ultimate composition arising from crustal contamination and magma mixing along with fractional crystallization in a post-collisional setting. The ⁴⁰Ar/³⁹Ar geochronology reveals a total fusion age of 73.41 ± 0.32 Ma for the biotite of the Kesikköprü granitoid. The alteration pattern in the deposit is characterized by an endoskarn zone comprising garnet–pyroxene (±phlogopite ± epidote) and an exoskarn zone displaying a zoning of garnet (±pyroxene ± phlogopite), pyroxene (±garnet ± phlogopite ± epidote), epidote–garnet, and epidote-rich subzones. Magnetite is extracted from massive lenses within the exoskarn zones and shows vein, disseminated, banded, massive, and brecciated textures. The low potassium content of phlogopites which are associated with magnetite mineralization prevents the determination of a reliable alteration age. δ¹⁸O thermometry reveals a temperature range between 462 and 528 °C for the magnetite mineralization. According to geochemical (trace and rare earth elements), stable (δ¹⁸O, δ²H, δ³⁴S, and δ¹³C), and radiogenic (⁸⁷Sr/⁸⁶Sr and ¹⁴³Nd/¹⁴⁴Nd) isotope data, the hydrothermal fluid responsible for the alteration and mineralization is related to the Kesikköprü granitoid, from which a significant magmatic component originates initially, followed by meteoric fluids at lower temperatures (123 °C) during the late-stage formation of calcite–quartz veins. Full article

(This article belongs to the Section Mineral Deposits)

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12 pages, 4511 KiB

Open AccessArticle

Assessment of Feldspars from Central Portugal Pegmatites for Sustainable Ceramic Applications

by Carla Candeias, Adga Gomes and Fernando Rocha

Minerals 2025, 15(5), 527; https://doi.org/10.3390/min15050527 - 15 May 2025

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Abstract

This study investigates the mineralogical, chemical, and fusibility characteristics of feldspar samples collected from eight pegmatitic bodies in central Portugal. The primary aim was to evaluate their suitability for use in ceramic applications, driven by the need to valorize local georesources, reduce dependence [...] Read more.

This study investigates the mineralogical, chemical, and fusibility characteristics of feldspar samples collected from eight pegmatitic bodies in central Portugal. The primary aim was to evaluate their suitability for use in ceramic applications, driven by the need to valorize local georesources, reduce dependence on imported raw materials, and contribute to the sustainability and competitiveness of the Portuguese ceramic sector. Samples were analyzed by X-Ray Diffraction (XRD), X-ray Fluorescence (XRF), inductively coupled plasma mass spectrometry (ICP-MS), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Firing tests were performed to assess fusibility, whiteness, and visible impurity behavior. Results indicate that seven of the eight samples were dominated by a combination of microcline and albite, with minor amounts of quartz and muscovite. Crystallinity indices varied across samples, reflecting differences in mineral order and thermal reactivity. Chemical compositions showed acceptable levels of SiO₂ and Al₂O₃, and total alkali contents (Na₂O + K₂O) between 10% and 16%, aligning with industrial standards for ceramic raw materials. The Fe₂O₃ contents were below 0.3% in most samples, suggesting favorable conditions for whiteness upon firing. Loss on ignition (LOI) values were generally low, except for one sample rich in muscovite. Fusibility behavior varied significantly between samples, with albite-rich samples showing lower melting points and better flow characteristics, while microcline-dominant samples required higher temperatures for vitrification but contributed to structural stability. The K₂O/Na₂O ratio presented values favoring earlier softening and fluxing. Whiteness revealed that samples with low Fe₂O₃ and TiO₂ content, particularly those with low mica content, achieved the best aesthetic outcomes post-firing. Full article

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

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19 pages, 7249 KiB

Open AccessArticle

Effect of Calcium Chloride on the Reinforcement of Uranium Tailings with Sodium Hydroxide–Sodium Silicate–Metakaolin

by Qianjin Niu and Xiujuan Feng

Minerals 2025, 15(5), 526; https://doi.org/10.3390/min15050526 - 15 May 2025

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Abstract

The uranium tailings mineral body is large and loose, and this could lead to radioactive contamination. Nuclides and heavy metals released from uranium tailings can be reduced through reinforcement treatment. The current study investigated the effect of CaCl₂ solutions with the same [...] Read more.

The uranium tailings mineral body is large and loose, and this could lead to radioactive contamination. Nuclides and heavy metals released from uranium tailings can be reduced through reinforcement treatment. The current study investigated the effect of CaCl₂ solutions with the same volume and different mass fractions on uranium tailing reinforcement under the premise of fixing the dosage of metakaolin, sodium hydroxide, sodium silicate, and the water reducer. It was found that, when 20.0% CaCl₂ was injected, the hydration reaction occurred more efficiently, and a more uniform gel polymer was produced. The degree of polymerization was higher, as well as the degree of aggregation near macropores. A large number of closed mesopores formed on the solidified surface. The pore structure of the solidified body was significantly improved; uranium ore particles had smaller gaps between them; the solidified body was better compacted; the leaching rates of uranium and its heavy metal ions were significantly reduced; and the compressive strength of the solidified body improved. In the triaxial test, the solidified body had a strength increase of 4.7 times. In addition to SEM, XPS, and XRD, the solidified samples were analyzed. In uranium slag solidified bodies, C-S-H and C-A-H gels and C-A-S-H and N-A-S-H polymers were formed. The gel polymers were wrapped around the uranium tailing particles, resulting in an 82.6% reduction in uranium leaching and a 57.2% reduction in radon exhalation. Full article

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

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18 pages, 4982 KiB

Open AccessArticle

Precipitating Rare Earth by NH₄HCO₃ from a Concentrated Rare Earth and Magnesium Sulfate Solution

by Qiang Wang, Tao Qi, Hongdong Yu, Limin Zhang, Dongjiang Sun, Yinliang Liu, Tongxiang Liang and Lue Huang

Minerals 2025, 15(5), 525; https://doi.org/10.3390/min15050525 - 15 May 2025

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Abstract

The ammonium bicarbonate precipitation method has become one of the main ways to extract rare earths from rare earth leaching solutions due to its advantages of simple operation, mature technology, and low cost. Therefore, the objective of this study was to explore the [...] Read more.

The ammonium bicarbonate precipitation method has become one of the main ways to extract rare earths from rare earth leaching solutions due to its advantages of simple operation, mature technology, and low cost. Therefore, the objective of this study was to explore the precipitation of rare earth carbonate (REC) from a concentrated rare earth and magnesium sulfate solution by ammonium bicarbonate. The terminal pH to precipitate rare earth was determined. The effects of factors including the feeding rate, temperature, ammonium bicarbonate concentration, seed dosage, and stirring rate on the rare earth precipitation efficiency, the Mg and SO₄²⁻ amounts in the obtained REC, and the median particle sizes of the REC were investigated. The effects of these factors on the Mg and SO₄²⁻ amounts in the REC and the median particle sizes of the REC were compared by one-way analysis of variance (ANOVA). The results showed that at a terminal pH of 6.8, a feeding rate of 0.5 mL/min, a temperature of 25 °C, an ammonium bicarbonate concentration of 0.6 mol/L, a crystal seed dosage of 7.5%, and a stirring speed of 300 r/min, without aging, the contents of rare earth oxide (REO), MgO, and SO₄²⁻ in the REC were 57.69%, 0.23%, and 1.68%, respectively, superior to the requirements of the current Chinese national standard (GB/T 16479-2020) for REC. The rare earth precipitation efficiency was 99.78%. Among the investigated factors, the pH was the main factor affecting the rare earth precipitation efficiency. The seed dosage significantly changed the median particle sizes of the REC and the Mg content of the REC. For SO₄²⁻, its content was fluctuant and could be controlled at a relatively low value by the seed dosage and specific stirring rate. Full article

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

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3 pages, 136 KiB

Open AccessEditorial

Editorial for Special Issue “Research on Ikaite—Natural Occurrences and Synthetic Mineral Precipitation”

by Gabrielle J. Stockmann and Juan Diego Rodríguez-Blanco

Minerals 2025, 15(5), 524; https://doi.org/10.3390/min15050524 - 15 May 2025

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Abstract

This Special Issue consists of five articles published in the period of 2022–2025, with a special focus on the metastable calcium carbonate mineral ikaite (CaCO₃·6H₂O) and the pseudomorph type known as glendonite [...] Full article

(This article belongs to the Special Issue Research on Ikaite—Natural Occurrences and Synthetic Mineral Precipitation)

12 pages, 5901 KiB

Open AccessArticle

Characteristics of Mineralization of Refractory Gold and Its Influence on Cyanide Gold Leaching Rates: A Case Study in Pituca II, Zamora Chinchipe, Ecuador

by Santiago Jose Navas Jaramillo and Renato Efren Gonzalez Zuñiga

Minerals 2025, 15(5), 523; https://doi.org/10.3390/min15050523 - 15 May 2025

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Abstract

The recovery of gold in metallurgical processes is significantly influenced by the presence of refractory minerals. This study investigates the mineralogical characteristics of refractory gold in the Pituca II ore deposit, with a focus on identifying the sulfide minerals that encapsulate gold particles [...] Read more.

The recovery of gold in metallurgical processes is significantly influenced by the presence of refractory minerals. This study investigates the mineralogical characteristics of refractory gold in the Pituca II ore deposit, with a focus on identifying the sulfide minerals that encapsulate gold particles and understanding their impact on gold recovery rates via cyanidation leaching. To establish a theoretical basis for optimizing gold recovery, a comprehensive suite of analytical techniques including electron microprobe analysis, petrographic analysis, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and X-ray diffraction was employed to characterize the ore’s composition and mineralogical properties. The primary ore minerals identified were pyrite, galena, chalcopyrite, and sphalerite, with hessite occurring as an accessory phase. Gold was observed as fine-grained particles (<40 µm), predominantly enclosed within pyrite and galena, contributing to its refractory nature. Cyanidation tests revealed a strong correlation between particle size and leaching efficiency: material ground to D₈₀ = 170 mesh (90 μm) achieved a recovery rate of 81.2%, compared to 72.2% for material at D₈₀ = 100 mesh (150 μm). These findings elucidate the mineralogical constraints on gold recovery and underscore the necessity of appropriate particle size reduction to enhance leaching performance. The study provides practical insights and targeted recommendations for pretreatment strategies, thereby contributing to more efficient exploitation of refractory gold ores in similar geological settings. Full article

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

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24 pages, 38314 KiB

Open AccessArticle

Multi-Analytical Characterization of Serpentinite Rocks Employed as Stone Material: An Example from Andalusia (Southern Spain), Basilicata, and Calabria (Southern Italy)

by Roberto Visalli, Rafael Navarro, Roberto Buccione, Valeria Indelicato, Giovanna Rizzo, Rosolino Cirrincione and Rosalda Punturo

Minerals 2025, 15(5), 522; https://doi.org/10.3390/min15050522 - 14 May 2025

Viewed by 319

Abstract

Serpentinites are metamorphic rocks constituted primarily by serpentine-group minerals (antigorite, chrysotile, lizardite) resulting from the transformation and low-temperature hydration of previous olivine-rich ultramafic rocks, such as dunite, lherzolite, wehrlite, and harzburgite. The peculiar features of the serpentinites such as the greenish color and [...] Read more.

Serpentinites are metamorphic rocks constituted primarily by serpentine-group minerals (antigorite, chrysotile, lizardite) resulting from the transformation and low-temperature hydration of previous olivine-rich ultramafic rocks, such as dunite, lherzolite, wehrlite, and harzburgite. The peculiar features of the serpentinites such as the greenish color and the intricate vein and mesh-like texture, as well as their role in CO₂ sequestration when carbonated, have hugely increased interest in studying these rocks over recent decades. Moreover, since antiquity, serpentinites have long been exploited, traded, and exported worldwide as daily tools, as well as in buildings and decorative stones in both internal and external architectural elements, because of their aesthetic appeal, attractiveness, and durability. In this work, we analyzed and compared petrographic features, geochemical signatures, and physical–mechanical properties of serpentinites from historical quarries from Andalusia (southern Spain), Basilicata, and Calabria (southern Italy) where they have been used as dimension stones in religious and civil buildings and as construction materials. We aim to evaluate and assess differences in petrographic, carbonation, uniaxial compressive strength, and seismic behavior, that could affect the efficiency when these serpentinites are used as either building and construction materials or for preservation/renovation purposes in cultural heritage. Results obtained from petrophysical investigations of serpentinites from these regions highlight that these materials are suitable for use in construction to various extents and are considered a valuable georesource, behind a detailed characterization carried out before their implementation in construction or conservation/restoration of architectural heritage. Full article

(This article belongs to the Special Issue Mineralogy, Chemistry, Weathering and Application of Serpentinite)

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26 pages, 5048 KiB

Open AccessArticle

Estimation of Copper Grade, Acid Consumption, and Moisture Content in Heap Leaching Using Extended and Unscented Kalman Filters

by Lisbel Bárzaga-Martell, Simón Diaz-Quezada, Humberto Estay and Javier Ruiz-del-Solar

Minerals 2025, 15(5), 521; https://doi.org/10.3390/min15050521 - 14 May 2025

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Abstract

The leaching process is essential in the mining industry, because it efficiently extracts valuable minerals, such as copper. However, monitoring and controlling the leaching process presents significant challenges due to material variability, uneven distribution of the leaching solution, and the effects of environmental [...] Read more.

The leaching process is essential in the mining industry, because it efficiently extracts valuable minerals, such as copper. However, monitoring and controlling the leaching process presents significant challenges due to material variability, uneven distribution of the leaching solution, and the effects of environmental factors like temperature and moisture content. One of the main technological challenges is measuring variables within the leaching heap. Implementing state observers or estimators (i.e., virtual sensors) offers a promising solution, allowing for a cost-effective estimation of non-measurable process variables. To validate this approach, this paper proposes and analyzes the use of two estimation methods, the Extended Kalman Filter (EKF) and the Unscented Kalman Filter (UKF), to estimate the moisture content, copper in the ore, and acid consumption based on measurements of acid and copper concentrations in the heap leaching process. The results obtained from simulations demonstrate accurate estimations from both state observers. The variable best estimated with EKF was the moisture content, achieving a 0.041% Integral Absolute Error (IAE) and a 0.069% Integral Square Error (ISE) in one of the analyzed scenarios. Utilizing these state estimators improves the understanding of the internal dynamics of heap leaching, often limited by the lack of field-level instrumentation, such as sensors and transmitters. This approach can enhance the operational efficiency of heap leaching plants by enabling the real-time estimation of unmeasurable variables, ultimately improving metal recovery and reducing acid consumption. Full article

(This article belongs to the Special Issue Application of Machine Learning in Mining, Mineral Processing and Extractive Metallurgy)

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Open AccessArticle

Characterization of Mineralogical Species in a Copper Concentrate After Acid Pretreatment

by Geraldine Villagrán Santana, Víctor Quezada, Oriol Rius-Ayra, Alisiya Biserova-Tahchieva and Nuria Llorca-Isern

Minerals 2025, 15(5), 520; https://doi.org/10.3390/min15050520 - 14 May 2025

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Abstract

In Chile, copper concentrate production through mineral flotation is increasing while production through hydrometallurgical processes is decreasing due to the depletion of oxidized ores. Using the idle capacity of hydrometallurgy plants for acid pretreatment of sulfate ores before the leaching stage is an [...] Read more.

In Chile, copper concentrate production through mineral flotation is increasing while production through hydrometallurgical processes is decreasing due to the depletion of oxidized ores. Using the idle capacity of hydrometallurgy plants for acid pretreatment of sulfate ores before the leaching stage is an attractive alternative; however, a deeper understanding of the process and the products of such treatment is required. In this study, the mineral species formed during acid pretreatment are characterized to identify new mineralogical species. Pretreatment was conducted at 50 °C with 210 kg/t H₂SO₄ over 15 days on a copper concentrate mainly composed of enargite (35.93%). The characterization techniques used were X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), and X-ray Photoelectron Spectroscopy (XPS). XRD identified copper sulfate (CuSO₄) formation and the disappearance of chalcocite/digenite (Cu₂S) and bornite (Cu₅FeS₄), indicating their transformation into sulfates. FESEM showed that enargite particles were oxidized, suggesting they did not form copper sulfates. The XPS results confirmed the presence of copper in species such as sulfides and sulfates. The results indicate that chalcocite and bornite transformed into copper sulfates, while chalcopyrite and enargite were only superficially oxidized. The combination of techniques allowed for a detailed identification of mineral transformations during pretreatment. Full article

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

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