Minerals

28 pages, 1013 KiB

Open AccessReview

Review of Interfacial Regulation of Apatite Flotation

by Zhe Liu, Lixia Li, Zhuguo Li, Meng Wang, Feifei Liu and Hongcheng Mi

Minerals 2025, 15(6), 558; https://doi.org/10.3390/min15060558 (registering DOI) - 23 May 2025

Phosphate ores, which are regarded as critical mineral resources, play an important role in various industrial fields. Apatite is the main source of phosphate mineral resources and must be concentrated before it is processed into industrial products. Flotation is the most commonly employed [...] Read more.

Phosphate ores, which are regarded as critical mineral resources, play an important role in various industrial fields. Apatite is the main source of phosphate mineral resources and must be concentrated before it is processed into industrial products. Flotation is the most commonly employed method for apatite concentration. However, as the proportion of fine apatite increases, the challenge of separating it from gangue minerals intensifies, due to the resemblance in surface characteristics between apatite and gangue. Interfacial regulation during flotation is fundamental to the process, including the regulation of the mineral/water interface wettability by flotation reagents (collectors and modifiers), the control of interactions between mineral particles, and the regulation of interactions between mineral particles and bubbles. This article introduces the surface characteristics of apatite and its main gangue minerals. It discusses innovative work on flotation reagents (primarily collectors and depressants) and their action mechanisms on mineral surfaces. It reviews the current development of theories on the regulation of interactions between interparticles and between particles and bubbles. Finally, the study outlook the future research on interfacial regulation in apatite flotation. This study is intended to offer references for the continued advancement of apatite flotation. Full article

(This article belongs to the Special Issue Industrial Minerals Flotation—Fundamentals and Applications)

17 pages, 2944 KiB

Open AccessArticle

Gemological Characteristics and Coloration Mechanism of Vanadium-Bearing Beryl from Nigeria

by Yunlong Hong, Yu Zhang, Xinyi Shao, Yanyi Mu and Yuemiao Yu

Minerals 2025, 15(6), 557; https://doi.org/10.3390/min15060557 - 23 May 2025

Abstract

Vanadium-bearing beryl is a vanadium-bearing variety of green beryl (distinct from emerald) that exhibits an “electro-optical” green (blue-green) color, which has led to its commercial popularity. However, the underlying coloration mechanism remains unclear. The present study adopted standard gemological tests and non-destructive spectroscopic [...] Read more.

Vanadium-bearing beryl is a vanadium-bearing variety of green beryl (distinct from emerald) that exhibits an “electro-optical” green (blue-green) color, which has led to its commercial popularity. However, the underlying coloration mechanism remains unclear. The present study adopted standard gemological tests and non-destructive spectroscopic tests, such as X-ray fluorescence, UV-visible-near infrared (UV-Vis-NIR), infrared and Raman spectroscopy, to analyze the vanadium-bearing beryl from Nigeria. The results of these tests indicated the presence of Fe as the predominant chromogenic element of vanadium-bearing beryl, followed by V, at a level exceeding that of Cr. Furthermore, the samples displayed lower levels of alkali and magnesium when compared to other beryls, accompanied by lower refractive indices and specific gravities. Spectroscopic analysis indicates that the structural channels are dominated by type I H₂O, with CO₂, HDO, and D₂O molecules also present. The inclusions observed in vanadium-bearing beryl bear a resemblance to those found in typical aquamarines, which are raindrop-shaped inclusions, and to those found in emeralds of various origins, which are irregular, jagged, gas–liquid two-phase/three-phase inclusions. The broad UV-Vis-NIR absorption bands at 427 and 610 nm are characteristic of V³⁺ (and a minor amount of Cr³⁺). Charge transfer between Fe²⁺ and Fe³⁺ may also contribute to the 610 nm band, which is superimposed on the absorption bands of V³⁺ and Cr³⁺. These factors primarily contribute to the blue-green coloration of beryl. The absorption induced by V³⁺ in the visible violet-blue region exhibits stronger intensity and a greater tendency towards the blue region compared to Cr³⁺. Consequently, the resultant vanadium-bearing beryl acquires the yellow-green hue (induced by V) overlaid with the light blue (induced by charge transfer between Fe²⁺-Fe³⁺ pairs), resulting in the so-called “electro-optical” green (blue-green) beryl. Full article

(This article belongs to the Special Issue Formation Study of Gem Deposits)

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19 pages, 34681 KiB

Open AccessArticle

Provenance and Geological Significance of Cenozoic Sandstones in the Nankang Basin, Southern Cathaysia Block, China

by Bing Zhao, Guojun Huang, Xiangke Wu, Shangyu Guo, Xijun Liu, Huoying Li, Hailin Huang and Hao Wu

Minerals 2025, 15(6), 556; https://doi.org/10.3390/min15060556 - 23 May 2025

Abstract

The Cenozoic Nankang Basin in China records a complex series of tectonic, magmatic, metamorphic, and sedimentary events associated with the surrounding Shiwanshan, Liuwanshan, and Yunkaishan orogenic systems. The Nankang Basin is a critical location for studying the Cenozoic tectono–sedimentary evolution and strategic mineral [...] Read more.

The Cenozoic Nankang Basin in China records a complex series of tectonic, magmatic, metamorphic, and sedimentary events associated with the surrounding Shiwanshan, Liuwanshan, and Yunkaishan orogenic systems. The Nankang Basin is a critical location for studying the Cenozoic tectono–sedimentary evolution and strategic mineral resources of the southern Cathaysia Block. We used core samples from multiple boreholes and regional geological survey data to analyze the rock assemblages, sediment types, and sedimentary facies of the Nankang Basin. In addition, we analyzed the detrital zircon U–Pb geochronology, sandstone detrital compositions, heavy mineral assemblages, and major element geochemistry. The detrital zircon grains from Cenozoic sandstones in the Nankang Basin have age peaks at 2500–2000, 1100–900, 500–400, and 300–200 Ma, with most grains having ages of 500–400 or 300–200 Ma. The provenance analysis indicates that the 300–200 Ma zircon grains originated mainly from the Liuwanshan pluton; the 500–400 Ma zircon grains originated from the Ningtan pluton; and the 2500–2000 and 1100–900 Ma zircon grains originated from the Lower Silurian Liantan Formation and Middle Devonian Xindu Formation. This indicates that the provenance of Cenozoic sandstones in the Nankang Basin primarily originates from Paleozoic–Early Mesozoic igneous in the surrounding area, while the regional old sedimentary rocks possibly serve as intermediate sedimentary reservoirs. The detrital compositions of the sandstones and heavy mineral assemblages indicate a change in the tectonic setting during the deposition of the Nankang and Zhanjiang Formations, with a change in the source of the sediments due to the uplift of the Shizishan. During the deposition of the Nankang Formation, the sediment transport direction was to the NNW, whereas during the deposition of the Zhanjiang Formation, it was to the NNE. The uplift of the Shizishan most probably occurred during the late Neogene and early Quaternary, separating the Hepu and Nankang Basins. Full article

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

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20 pages, 6256 KiB

Open AccessArticle

Optimizing Technological Parameters for Chromium Extraction from Chromite Ore Beneficiation Tailings

by Nazym Akhmadiyeva, Rinat Abdulvaliyev, Sergey Gladyshev, Bulat Sukurov, Yerkezhan Abikak, Alfiyam Manapova and Nauryzbek Bakhytuly

Minerals 2025, 15(6), 555; https://doi.org/10.3390/min15060555 - 22 May 2025

Abstract

This study focuses on optimizing the alkali roasting conditions for chromite beneficiation tailings with the goal of enhancing chromium oxide (Cr₂O₃) extraction. Within the experimental framework, the variables included roasting temperature, the amount of added Na₂CO₃ [...] Read more.

This study focuses on optimizing the alkali roasting conditions for chromite beneficiation tailings with the goal of enhancing chromium oxide (Cr₂O₃) extraction. Within the experimental framework, the variables included roasting temperature, the amount of added Na₂CO₃, and reaction time. The results revealed that temperature is the most critical factor directly affecting the extraction efficiency. Increasing the amount of Na₂CO₃ contributed to an increase in Cr₂O₃ recovery, although excessive addition may not be economically justified. The optimal conditions—1000 °C, 120%–130% Na₂CO₃ (relative to tailings mass), and 120 min—enabled a Cr₂O₃ extraction rate of up to 98.6% through aqueous leaching. The phase transformation analysis confirmed the breakdown of the spinel structure and formation of water-soluble sodium chromate. Microanalysis observations and measurements validated the progressive destruction of chromite grains and sodium enrichment in the reaction zones. The remaining leaching residue consisted of inert Na₂Mg₂Si₂O₇ and MgO, suitable for further metal recovery. The proposed approach enables efficient detoxification of hazardous tailings and serves as a basis for integrated utilization of Cr-bearing industrial waste. Full article

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

16 pages, 3793 KiB

Open AccessReview

Using Brazilian Nepheline Syenite Waste as an Alternative Mineral Resource for Various Applications

by Diego Haltiery Santos, Laura Pereira Rosa, Cleidson Rosa Alves, Lisandro Simão, Alexandre Zaccaron, Sabrina Arcaro, Oscar Rubem Klegues Montedo and Fabiano Raupp-Pereira

Minerals 2025, 15(6), 554; https://doi.org/10.3390/min15060554 - 22 May 2025

Abstract

The high extraction of natural resources and the limited use of mining waste as alternative mineral resources are intensifying the depletion of natural reserves. The linear economic structure used by industrial sectors needs to be replaced with more sustainable models, such as the [...] Read more.

The high extraction of natural resources and the limited use of mining waste as alternative mineral resources are intensifying the depletion of natural reserves. The linear economic structure used by industrial sectors needs to be replaced with more sustainable models, such as the one proposed in the circular economy. This study aimed to evaluate strategies for the valorization of nepheline syenite waste (NSW) as an alternative mineral resource to natural and conventional ones. To this end, a set of criteria was adopted, consisting of a systematic approach for waste valorization, namely classification, potentiality, quantity/viability, and applicability (CPQvA). This involved investigating the properties of NSW, including its environmental, physical, chemical, morphological, and durability characteristics. The findings provide evidence of several potential applications for NSW, including the civil construction (fine aggregate and supplementary cementitious material), metallurgical (segregation of the iron fraction), and agricultural (segregation of the alkaline fraction) sectors. Methodologies for the beneficiation of NSW are suggested for each of the investigated applications. The valorization of NSW not only reduces the environmental impact of mining but also contributes to sustainable development by creating new products and economic opportunities, thereby promoting industrial symbiosis and advancement in the circular economy. Full article

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

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24 pages, 2999 KiB

Open AccessArticle

Research on Prediction Method of Ferrous Oxide Content in Sinter Based on Optimized Neural Network

by Shaohui Li, Yuanyuan Cao, Zhenjie Zhou, Xinghua Li and Yanlong Zhu

Minerals 2025, 15(6), 553; https://doi.org/10.3390/min15060553 - 22 May 2025

Abstract

As a key parameter in the sintering process, the ferrous oxide content of sinter can reflect the working condition, energy consumption level, and quality level of the final sintered products in the sintering process. It has become a key problem to realize the [...] Read more.

As a key parameter in the sintering process, the ferrous oxide content of sinter can reflect the working condition, energy consumption level, and quality level of the final sintered products in the sintering process. It has become a key problem to realize the prediction of ferrous oxide content in sinter and feedback control of sinter quality accordingly. The two commonly used methods for detecting ferrous oxide content in industrial production currently do not meet real-time requirements and cannot provide timely feedback for production regulation. Therefore, research on real-time prediction technology of ferrous oxide content in sinter was carried out, and an optimized back propagation neural network model was established to realize the mapping between characteristic parameters and the FeO content in sinter. The characteristic parameters include image parameters and process parameters. Through the research on the brightness change trend of the machine tail cross-section image, the best cross-section image acquisition method based on brightness difference is realized, and image parameters are obtained by image processing technology. The process parameters were selected using correlation analysis. Through data processing techniques such as data cleaning, normalization, and feature fusion, feature parameters were obtained as input vectors for the neural network. To improve prediction accuracy and system stability, an adaptive learning rate and genetic algorithm were used to optimize the traditional BP neural network. The average test error of the optimized prediction model was 0.32%. Taking actual data production as an example, test data on the FeO content of sinter were extracted from the laboratory. Compared with the FeO content predicted by the system, the prediction time of the system was about 2 h earlier than the test time. In terms of prediction accuracy, the average absolute error was 0.25%, and the absolute prediction error was not more than ±1%. Full article

(This article belongs to the Special Issue Mineralogy of Iron Ore Sinters, 3rd Edition)

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20 pages, 43321 KiB

Open AccessArticle

Volcano–Sedimentary Processes on an Ancient Oceanic Seafloor: Insights from the Gimigliano Metaophiolite Succession (Calabria, Southern Italy)

by Federica Barilaro, Andrea Di Capua, Giuseppe Cianflone, Giovanni Turano, Gianluca Robertelli, Fabrizio Brutto, Giuseppe Ciccone, Alessandro Foti, Vincenzo Festa and Rocco Dominici

Minerals 2025, 15(6), 552; https://doi.org/10.3390/min15060552 - 22 May 2025

Abstract

This study investigates the volcano–sedimentary processes that occurred in an oceanic branch of the Western Tethys, now part of the Gimigliano–Monte-Reventino metaophiolite Unit, exposed at the southeastern termination of the Sila Piccola Massif, within the northern sector of the Calabria–Peloritani terrane (Calabria, southern [...] Read more.

This study investigates the volcano–sedimentary processes that occurred in an oceanic branch of the Western Tethys, now part of the Gimigliano–Monte-Reventino metaophiolite Unit, exposed at the southeastern termination of the Sila Piccola Massif, within the northern sector of the Calabria–Peloritani terrane (Calabria, southern Italy). Fieldwork, petrography, and mineralogical analyses on the Gimigliano metaophiolite succession have identified five distinct volcano–sedimentary lithofacies. These lithofacies are characterized by mineral assemblages of epidote, chlorite, quartz, and albite, with minor amounts of muscovite and calcite, resulting from high-pressure–low-temperature (HP-LT) metamorphism followed by low-grade greenschist metamorphism of mid-oceanic ridge basalt (MORB)-type volcanic products. Based on their stratigraphic and textural features, these lithofacies have been interpreted as metabasaltic flow layers emplaced during effusive volcanic eruptions and metahyaloclastic and metavolcaniclastic deposits formed by explosion-driven processes. This lithofacies assemblage suggests that the Gimigliano area likely represented an oceanic sector with high rates of magmatic outflows, where interactions between magma and water facilitated explosive activity and the dispersion of primary volcaniclastic deposits, mainly from the water column, in addition to the emplacement of basaltic lava flow. In contrast, other metaophiolite complexes in the Calabria region, characterized by the presence of pillow basalts, were areas with low effusive rates. The coexistence of these differences, along with the extensive presence of metaultramafites, portrays the Calabrian branch of the Tethys as a slow-spreading oceanic ridge where variations in surficial volcanic processes were controlled by differences in the effusion rates across its structure. This study is a valuable example of how a volcano–sedimentary approach to reconstructing the emplacement mechanisms of metaophiolite successions can provide geodynamic insights into ancient oceanic ridges. Full article

(This article belongs to the Special Issue Volcaniclastic Sedimentation in Deep-Water Basins)

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17 pages, 7715 KiB

Open AccessArticle

Petrogenesis and Tectonic Implications of the Early–Middle Ordovician Granodiorites in the Yaogou Area of the North Qilian Orogenic Belt

by Dechao Li, Yang Yang, Yao Xiao, Pengde Liu, Xijun Liu, Gang Chen, Xiao Liu, Rongguo Hu, Hao Tian and Yande Liu

Minerals 2025, 15(6), 551; https://doi.org/10.3390/min15060551 - 22 May 2025

Abstract

A diverse range of granitoids in the North Qilian Orogenic Belt (NQOB) offers valuable insights into the region’s tectonomagmatic evolution. In this study, we undertook a geochronological, mineralogical, geochemical, and zircon Hf isotopic analysis of granodiorites from the Yaogou area of the NQOB. [...] Read more.

A diverse range of granitoids in the North Qilian Orogenic Belt (NQOB) offers valuable insights into the region’s tectonomagmatic evolution. In this study, we undertook a geochronological, mineralogical, geochemical, and zircon Hf isotopic analysis of granodiorites from the Yaogou area of the NQOB. Zircon U-Pb dating reveals that the Yaogou granodiorites formed during the Early–Middle Ordovician (473–460 Ma). The Yaogou granodiorites have high SiO₂ (63.3–71.1 wt.%), high Al₂O₃ (13.9–15.8 wt.%) contents, and low Zr (96–244 ppm), Nb (2.9–18 ppm), as well as low Ga/Al ratios (10,000 × Ga/Al ratios of 1.7–2.9) and FeO^T/MgO ratios (1.9–3.2), and are characterized by elevated concentrations of light rare earth elements and large-ion lithophile elements such as Rb, Th, and U, coupled with significant depletion in heavy rare earth elements and high-field-strength elements including Nb, Ta, and Ti. Additionally, the presence of negative europium anomalies further reflects geochemical signatures typical of I-type granitic rocks. The zircon grains from these rocks display negative ε_Hf(t) values (−14.6 to −10.7), with two-stage Hf model ages (T_DM2) from 2129 to 1907 Ma. These characteristics suggest that the magmatic source of the Yaogou granodiorites likely originated from the partial melting of Paleoproterozoic basement-derived crustal materials within a tectonic environment associated with subduction in the North Qilian Ocean. Integrating regional geological data, we suggest that during the Early Paleozoic, the North Qilian Oceanic slab underwent double subduction: initially southward, followed by a northward shift. Due to the deep northward subduction of the Qaidam continental crust and oceanic crust along the southern margin of the Qilian Orogenic Belt, the southward subduction of the North Qilian ocean was obstructed, triggering a reversal in subduction polarity. This reversal likely decelerated the southward subduction and initiated northward subduction, ultimately leading to the formation of the Yaogou granodiorites. These findings enhance our understanding of the complex tectonic processes that shaped the North Qilian Orogenic Belt during the Early Paleozoic, emphasizing the role of subduction dynamics and continental interactions in the region’s geological evolution. Full article

(This article belongs to the Special Issue Geochronology and Geochemistry of Alkaline Rocks)

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18 pages, 3111 KiB

Open AccessArticle

Advances in the Development of Hydrometallurgical Processes in Acidic and Alkaline Environments for the Extraction of Copper from Tailings Deposit

by Diego Davoise and Ana Méndez

Minerals 2025, 15(6), 550; https://doi.org/10.3390/min15060550 - 22 May 2025

Abstract

The geopolitical and economic situation impacts raw materials demand. As principal ore deposits reach exhaustion, the study of new sources of raw materials becomes essential. Therefore, mining wastes emerge as alternative sources of raw materials. Their physicochemical properties, such as small particle size [...] Read more.

The geopolitical and economic situation impacts raw materials demand. As principal ore deposits reach exhaustion, the study of new sources of raw materials becomes essential. Therefore, mining wastes emerge as alternative sources of raw materials. Their physicochemical properties, such as small particle size or concentration of some metals of interest, enhance reprocessing. A number of critical raw materials (As, Co, Cu, Sb) and base metals (Pb, Zn), as well as precious metals (Ag), were found present in an abandoned tailing deposit composed by finely grounded washed roasted pyrites within the Iberian Pyrite Belt. Copper leaching from a sample of this deposit was investigated. Two hydrometallurgical approaches were studied: acidic leaching with and without activated carbon; and alkaline leaching with glycine solutions. Leaching tests were carried out during 24 h at ambient and moderate temperatures (60 °C). In acidic medium, the maximum copper extraction varied from 88 to 92.5%, while in alkaline medium, the maximum copper extraction was in the range of 71%–76%. Using activated carbon and H₂O₂ seemed to slightly promote the copper extraction with the maximum extraction (92.5%) after 2 h of leaching at 60 °C. Complementarily, above 50% of the zinc and cobalt contained were extracted. In contrast, temperature in alkaline conditions played a key role in reaction speed, but also in precipitation of copper insoluble compounds. In addition, the glycine solution at pH 10–10.5 showed high selectivity for copper over zinc, iron, lead, arsenic, and antimony. Two extra tests at pH above 12 showed arsenic dissolution (up to 51% at pH 12.5). Full article

(This article belongs to the Special Issue Hydrometallurgical Treatments of Copper Ores, By-Products and Waste)

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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

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

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

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

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

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

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

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

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

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

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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