Minerals

20 pages, 5116 KB

Open AccessEditor’s ChoiceArticle

Phase Guard: A False Positive Filter for Automatic Rietveld Quantitative Phase Analysis Based on Counting Statistics in HighScore Plus

by Matteo Pernechele and Sheida Makvandi

Minerals 2025, 15(10), 1041; https://doi.org/10.3390/min15101041 - 30 Sep 2025

Viewed by 515

Abstract

Accurate quantification of minor mineral phases is important in Powder X-Ray Diffraction (PXRD) and Rietveld phase quantification. The precise limit of quantification for the various phases is rarely considered but rather approximated to 0.2–2 wt% by applying a global minimum weight percentage threshold. [...] Read more.

Accurate quantification of minor mineral phases is important in Powder X-Ray Diffraction (PXRD) and Rietveld phase quantification. The precise limit of quantification for the various phases is rarely considered but rather approximated to 0.2–2 wt% by applying a global minimum weight percentage threshold. This approximation often leads to false positive or false negative phase quantity, jeopardizing the trustworthiness of the analytic method in general. In this work (1) we propose a dynamic and adaptable false positive filtering method for Rietveld Quantitative X-ray diffraction (QXRD) based on a phase-specific signal-to-noise ratio referred to as “Phase-SNR”; (2) we introduce the method baptized “Phase Guard” which is implemented in the software HighScore Plus. Phase Guard is based on peaks counting statistics and it automatically adapts to different mineral scattering powers, different mineral crystallinity, instrumental configuration and measurement time. Its applicability and benefits are demonstrated with several examples in cement and mining applications. The adoption of Phase Guard is especially beneficial for industrial black-box solutions, where all “probable” phases are included in the model, even when they are absent from the sample. Phase Guard eliminates false positives, it reduces the likelihood of false negatives, and it is an essential tool to answer the question “what is the limit of quantification for Rietveld analysis?” Full article

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

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23 pages, 13715 KB

Open AccessEditor’s ChoiceArticle

Sedimentary Environment, Tectonic Setting, and Paleogeographic Reconstruction of the Late Jurassic Weimei Formation in Dingri, Southern Tibet

by Jie Wang, Songtao Yan, Hao Huang, Tao Liu, Chongyang Xin and Song Chen

Minerals 2025, 15(10), 1040; https://doi.org/10.3390/min15101040 - 30 Sep 2025

Viewed by 395

Abstract

The Weimei Formation, the most complete Upper Jurassic sedimentary sequence in the Tethyan Himalaya, is crucial for understanding the tectono-sedimentary evolution of the northern Indian margin. However, its depositional environment remains debated, with conflicting shallow- and deep-water interpretations. This study integrates sedimentary facies, [...] Read more.

The Weimei Formation, the most complete Upper Jurassic sedimentary sequence in the Tethyan Himalaya, is crucial for understanding the tectono-sedimentary evolution of the northern Indian margin. However, its depositional environment remains debated, with conflicting shallow- and deep-water interpretations. This study integrates sedimentary facies, petrography, zircon geochronology, and geochemical analyses to constrain the provenance, depositional environment, and tectonic setting of the Weimei Formation. The results reveal that the sedimentary system primarily consists of shoreface, delta, and shelf facies, with locally developed slope-incised valleys. Detrital zircon ages are concentrated at ~468 Ma and ~964 Ma, indicating a provenance mainly derived from the Indian continent. Geochemical characteristics, such as high SiO₂, low Na₂O–CaO–TiO₂ contents, right-leaning REE patterns, and significant negative Eu anomalies, suggest the derivation of sediments from felsic upper crustal recycling within a passive continental margin. Stratigraphic comparison between southern and northern Tethyan Himalayan sub-zones reveals a paleogeographic “uplift–depression” pattern, characterized by the coexistence of shoreface–shelf deposits and slope-incised valleys. This study provides key evidence for reconstructing the Late Jurassic paleogeography of the northern Indian margin and the tectonic evolution of the Neo-Tethys Ocean. Full article

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

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16 pages, 3586 KB

Open AccessEditor’s ChoiceArticle

Preparation of High-Purity Quartz by Roasting–Water Quenching and Ultrasound-Assisted Acid Leaching Process

by Liran Jiao, Yong Huang, Yingshuang Zhang, Sining Li, Yubin Liu, Guirong Wei and Linlong Wei

Minerals 2025, 15(10), 1028; https://doi.org/10.3390/min15101028 - 28 Sep 2025

Cited by 1 | Viewed by 399

Abstract

High-purity quartz is a key material for photovoltaics, semiconductors, and optical fibers. The raw material for high-purity quartz mainly comes from natural crystal and pegmatite. It is an attractive research field to excavate alternative feedstocks for traditional materials. Quartz conglomerate is a coarse-grained, [...] Read more.

High-purity quartz is a key material for photovoltaics, semiconductors, and optical fibers. The raw material for high-purity quartz mainly comes from natural crystal and pegmatite. It is an attractive research field to excavate alternative feedstocks for traditional materials. Quartz conglomerate is a coarse-grained, clastic sedimentary rock that is cemented by a secondary silica or siliceous matrix. Economically, quartz conglomerate is gaining attention as a strategic alternative to depleting high-grade quartz veins and pegmatites. In this study, high-purity quartz was prepared by purifying quartz conglomerate from Jimunai, Altay, Xinjiang. The method combined high-temperature roasting, water quenching, and ultrasonic-assisted acid leaching. The effects of process parameters on purification efficiency were systematically investigated with the aid of XRD, SEM-EDS, and ICP-OES quantitative element detection. Many cracks formed on the quartz during roasting and quenching. These cracks exposed gap-filling impurities. Gas–liquid inclusions were removed, improving acid leaching. Under optimal ultrasonic-assisted acid leaching conditions (80 °C, 4 h, 10% oxalic acid + 12% hydrochloric acid, 180 W), the Fe content decreased to 6.95 mg/kg, with an 85.6% removal rate. The total impurity content decreased to 210.43 mg/kg. The SiO₂ grade increased from 99.77% to 99.98%. Compared to traditional acid leaching, ultrasonic-assisted acid leaching improved Fe removal and reduced environmental pollution. Full article

(This article belongs to the Collection Ultrasound-Assisted Technologies in Mineral Processing and Metallurgy)

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29 pages, 47976 KB

Open AccessEditor’s ChoiceArticle

An Occurrence of Pyroxmangite in the NYF Granitic Pegmatite of the Gabal El-Bakriya Intrusion, Arabian–Nubian Shield

by Danial M. Fathy, Faris A. Abanumay, Shehata Ali, Esam S. Farahat, Andrey Bekker and Mokhles K. Azer

Minerals 2025, 15(10), 1027; https://doi.org/10.3390/min15101027 - 28 Sep 2025

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Abstract

We report here, for the first time on the Nubian Shield, the western half of the Arabian–Nubian Shield (ANS), pegmatite-hosted pockets with a unique mineralogy, including pyroxmangite. It represents the second discovery on the ANS, where the first one was at Jabal Aja [...] Read more.

We report here, for the first time on the Nubian Shield, the western half of the Arabian–Nubian Shield (ANS), pegmatite-hosted pockets with a unique mineralogy, including pyroxmangite. It represents the second discovery on the ANS, where the first one was at Jabal Aja on the Arabian Shield, the eastern half of the ANS. One of the most remarkable aspects of pyroxmangite is its rarity and the potential economic value of its use in jewelry and decorative applications. Pegmatites are associated with A-type granites of the Gabal El-Bakriya intrusion (GEBI), Eastern Desert, Egypt. Mineralized pegmatites occur at the margin of the alkali-feldspar granite and exhibit gradational contacts with the host rocks. The pegmatites were emplaced as plugs and dikes within the intrusion and along its periphery. Pyroxmangite appears as coarse-grained, massive black aggregates or as disseminated crystals. The pegmatites are composed of K-feldspars and quartz, with subordinate amounts of albite, micas, and mafic minerals. Accessory phases include monazite-(Ce), zircon, fergusonite, xenotime, fluorite, pyrochlore, allanite, thorite, bastnäsite, samarskite, cassiterite, beryl, and pyrochlore. Pyroxmangite-bearing assemblages consist essentially of pyroxmangite and garnet, with accessory pyrochroite, quartz, zircon, magnetite, and fluorite. Geochemically, the pegmatites are highly evolved, with elevated SiO₂ content (76.51–80.69 wt.%) and variable concentrations of trace elements. They show significant enrichment in Nb (Nb > Ta), Y, REE, Zr, Th, U, and F, consistent with NYF-type pegmatites. REE contents range from 173.94 to 518.21 ppm, reflecting diverse accessory mineral assemblages. Tectonically, the pegmatites crystallized in a post-collisional setting, representing a late-stage differentiate of the A-type GEBI magma. Mineralization is concentrated in the apical and marginal zones of the granitic cupola and is dominated by barite, fluorite, Nb-Ta oxides, REE minerals, and uranium-bearing phases. The highly evolved granites, greisens, pegmatites, and quartz-fluorite veins of the GEBI have a high economic potential, deserving further exploration. Full article

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

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16 pages, 1274 KB

Open AccessEditor’s ChoiceArticle

Study on the Effect of Grinding Media Material and Proportion on the Cyanide Gold Extraction Process

by Guiqiang Niu, Yunfeng Shao, Qingfei Xiao, Mengtao Wang, Saizhen Jin, Guobin Wang and Yijun Cao

Minerals 2025, 15(10), 1031; https://doi.org/10.3390/min15101031 - 28 Sep 2025

Viewed by 387

Abstract

Laboratory and industrial tests were conducted to study the impact of grinding media material on key indicators such as grinding product particle size, sodium cyanide consumption, gold recovery rate, unit power consumption, and ball consumption. Laboratory test results indicate that the reasonable mixing [...] Read more.

Laboratory and industrial tests were conducted to study the impact of grinding media material on key indicators such as grinding product particle size, sodium cyanide consumption, gold recovery rate, unit power consumption, and ball consumption. Laboratory test results indicate that the reasonable mixing of ceramic and steel balls can achieve an increase of more than 2.8% in the fineness of the grinding product (−0.038 mm), an increase of 0.3% in the gold recovery rate, and a decrease of 1.3 kg/t in the consumption of sodium cyanide. Industrial trial studies indicate that, compared to the traditional steel ball scheme, using a ceramic ball to steel ball mass ratio of 3:1 under conditions of processing 50,000 tons of gold concentrate annually can save a total of 1.31 million yuan in annual ball consumption, electricity consumption, and cyanide consumption costs. Additionally, the improved recovery rate generates an additional economic benefit of 3.63 million yuan, resulting in an annual comprehensive economic benefit increase of 4.94 million yuan. In summary, in gold cyanide leaching grinding, the mixture ratio between ceramic balls and steel balls demonstrates significant potential for energy conservation, cost reduction, and efficiency enhancement, providing a theoretical basis and technical support for subsequent process optimization and green gold extraction. Full article

(This article belongs to the Collection Advances in Comminution: From Crushing to Grinding Optimization)

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18 pages, 5103 KB

Open AccessEditor’s ChoiceArticle

Geochemical Characterisation of Strategic Elements (Li, Co, Ni, Cu, Ga, Ge, and REEs) in Bottom Ash from the Thermal Power Plant (Afşin–Elbistan, Türkiye)

by Leyla Kalender, Hatice Kara, Mehmet Ali Ertürk, Cihan Yalçın, Mehmet Deniz Turan and Emine Cicioğlu Sütçü

Minerals 2025, 15(10), 1026; https://doi.org/10.3390/min15101026 - 28 Sep 2025

Viewed by 386

Abstract

This study investigates the concentrations and geochemical behaviour of strategic elements—including Li, Co, Ni, Cu, Ga, Ge, rare earth elements (REEs), and yttrium (Y)—in bottom ash samples from the Afşin–Elbistan thermal power plant, Türkiye. Thirty bottom ash samples were analysed, revealing average ∑LREE [...] Read more.

This study investigates the concentrations and geochemical behaviour of strategic elements—including Li, Co, Ni, Cu, Ga, Ge, rare earth elements (REEs), and yttrium (Y)—in bottom ash samples from the Afşin–Elbistan thermal power plant, Türkiye. Thirty bottom ash samples were analysed, revealing average ∑LREE and ∑HREE concentrations of 86.3 µg/g and 3.3 µg/g, respectively, resulting in an L/H ratio of 24.9, indicating pronounced enrichment in light REEs. The total ∑REE + Y concentration (111 µg/g) is comparable to the background value for coal but approximately 1.5 times lower than those reported for average Chinese coals and the upper continental crust (UCC). REE contents significantly exceed those of sedimentary (5.36 µg/g), mafic (16.77 µg/g), and felsic (3.60 µg/g) rocks. Elevated Li (30.5 µg/g) and Ni (114.4 µg/g) concentrations point to a mafic magmatic source, whereas Cu (28.7 µg/g) likely originates from basic volcanic rocks such as those of the Dağlıca Complex and the Kemaliye Formation. Chondrite-normalised REE patterns show Dy depletion relative to mafic rocks and Ho depletion compared to sedimentary rocks. Positive δEu anomalies (>1) support a mafic or UCC provenance, while slightly positive δCe values indicate hydrothermal leaching influences. The co-precipitation of Ce with Ca–Mg hydroxides and clay minerals in coal-bearing lacustrine sediments is suggested. Ga enrichment is attributed to aluminium-rich clay minerals and organic matter. Overall, these geochemical signatures reflect combined inputs from hydrothermal leaching and volcanic weathering within a coal-bearing lacustrine environment. Full article

(This article belongs to the Special Issue Mineralogical and Geochemical Characteristics of Coal and Coal-Bearing Strata)

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25 pages, 46515 KB

Open AccessEditor’s ChoiceArticle

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

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

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

Viewed by 645

Abstract

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

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

{Al}_{2}

O_{3}

,

{Fe}_{2}

O_{3}

,

{SiO}_{2}

, and

{TiO}_{2}

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

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

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14 pages, 1544 KB

Open AccessEditor’s ChoiceArticle

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

by Anastassia Borisova

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

Viewed by 397

Abstract

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

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

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

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41 pages, 5058 KB

Open AccessEditor’s ChoiceReview

Review of Enargite Flotation—Part I: Surface Characterization and Advances in Selective Flotation

by Pablo Miranda-Villagrán, Rodrigo Yepsen, Andrés Ramírez-Madrid, Jorge H. Saavedra and Leopoldo Gutiérrez

Minerals 2025, 15(9), 971; https://doi.org/10.3390/min15090971 - 13 Sep 2025

Viewed by 680

Abstract

Enargite (Cu₃AsS₄), a copper–arsenic sulfosalt, represents a critical challenge in copper mineral processing due to its high arsenic content, which poses significant environmental, metallurgical, and economic issues. Its flotation behavior closely resembles that of other copper sulfides such as [...] Read more.

Enargite (Cu₃AsS₄), a copper–arsenic sulfosalt, represents a critical challenge in copper mineral processing due to its high arsenic content, which poses significant environmental, metallurgical, and economic issues. Its flotation behavior closely resembles that of other copper sulfides such as chalcopyrite and chalcocite, complicating selective separation at early beneficiation stages. This review presents a comprehensive examination of enargite’s surface chemistry and electrochemical behavior, focusing on the influence of oxidation, pH, and pulp potential on surface reactivity, charge distribution (zeta potential), and hydrophobicity. Detailed insights into the formation of surface oxidation layers, passivation mechanisms, and contact angle variations are provided to elucidate collector-mineral interactions. Advances in selective flotation techniques are also discussed, including the use of depressant reagents, controlled redox environments, and reagent conditioning strategies. Special attention is given to flotation in seawater, where ionic strength and multivalent ions significantly influence mineral-reagent interactions and flotation outcomes. Galvanic interactions between enargite and other sulfide minerals are identified as critical factors affecting floatability and selectivity. The review consolidates findings from recent experimental and electrochemical studies, highlighting promising approaches to enhance enargite rejection and copper concentrate purity. It concludes with perspectives on future research aimed at optimizing flotation processes and developing sustainable solutions for processing arsenic-bearing copper ores. Full article

(This article belongs to the Special Issue Mineral Processing and Extractive Metallurgy of Sulfide Ores, 2nd Edition)

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17 pages, 7660 KB

Open AccessEditor’s ChoiceArticle

Subresolution Porosity Estimation of Porous Rocks from CT Images: Incorporating X-Ray Mass Attenuation Coefficients

by Jianhuang Chen, Zhongjian Zhang, Zhenyu Long, Qiong Zhang and Zhongqi Yue

Minerals 2025, 15(9), 966; https://doi.org/10.3390/min15090966 - 12 Sep 2025

Viewed by 462

Abstract

Rock porosity is a key parameter for quantifying fluid flow properties and predicting mechanical behaviour. Although X-ray CT imaging has been widely used to estimate porosity, the accuracy of such methods is still hindered by beam energy and mineralogical heterogeneity. In this study, [...] Read more.

Rock porosity is a key parameter for quantifying fluid flow properties and predicting mechanical behaviour. Although X-ray CT imaging has been widely used to estimate porosity, the accuracy of such methods is still hindered by beam energy and mineralogical heterogeneity. In this study, a methodology for the estimation of subresolution porosity is proposed, taking into account the relative relationship of X-ray mass attenuation coefficients (MACs) among minerals. The approach segments macroparticles, matrix, and macropores and calibrates their relative X-ray MAC relationships to establish the upper and lower bounds of the matrix LAC. Subresolution porosity is then estimated based on these calibrated limits. Taking Belgian Fieldstone and Bentheimer Sandstone as examples, the method described in this paper has stronger connectivity than does the binarised porosity estimation method and higher estimation accuracy than does the subresolution porosity calculation method, which does not consider the MAC. The proposed method is intended to refine the rationality of the subresolution porosity calculation and to broaden its theoretical scope of application. Full article

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

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28 pages, 4033 KB

Open AccessEditor’s ChoiceArticle

Assessing Jarosite Kinetic Dissolution Rates at Acidic Conditions and Different Temperatures

by Mateus De Souza Buriti, Marie Poulain, Pierre Cézac and Lidia Casás

Minerals 2025, 15(9), 965; https://doi.org/10.3390/min15090965 - 11 Sep 2025

Viewed by 688

Abstract

K-jarosite (KFe₃(SO₄)₂(OH)₆), the most common jarosite-type mineral in natural and industrial settings, has been widely studied to understand its dissolution behavior in both environmental and industrial contexts. However, reported kinetic data remain inconsistent due to [...] Read more.

K-jarosite (KFe₃(SO₄)₂(OH)₆), the most common jarosite-type mineral in natural and industrial settings, has been widely studied to understand its dissolution behavior in both environmental and industrial contexts. However, reported kinetic data remain inconsistent due to the combined influence of kinetic factors, despite the importance of such data for optimizing system conditions and improving process control and environmental management. The present work aims to help elucidate K-jarosite dissolution by carrying out new experiments in sulfuric acid medium (pH 1 and 2) at different temperatures (296, 323 and 343 K) and using two initial concentrations (0.4 and 1 g of K-jarosite/kg of solution). K-jarosite was synthesized and characterized by analytical techniques (XRD, SEM and BET), and the composition was determined by induction-coupled plasma optical emission spectroscopy (ICP-OES). Derivative (DVKM), Noyes–Whitney (NWKM) and Shrinking Core (SCKM) kinetic models previously used in the literature of jarosite-type compounds were adjusted to the data obtained here and compared. The results showed that higher temperatures and lower pH led to faster dissolution rates. Smaller initial concentrations decreased the rates slightly but had less impact than the other variables. Experiments at pH 1 led to the dissolution of all jarosite solids, while at pH 2 they led to incomplete dissolution. Remarkably, at pH 2 and at higher temperatures (mainly at 343 K), there was slight reprecipitation of the iron. XRD analysis identified no peak other than K-jarosite peaks after dissolution. DVKM and NWKM represented the effect of the studied parameters well. However, only using SCKM was a kinetic equation describing the dissolution process obtained. While the behavior of the kinetic curve is well established, the model fails to correctly describe the induction period. Under extreme conditions (>323 K, pH 1), dissolution is described by a chemical reaction controlling stage and it changes to mass transport in mild conditions. As theoretically expected, the results obtained in this work give important information about the prediction of the behavior of jarosite dissolution in terrestrial environments (acid mine and acid rock drainages) and hydrometallurgical process in mild acidic conditions and high temperatures. Full article

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

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20 pages, 11423 KB

Open AccessEditor’s ChoiceArticle

Clay Mineral Characteristics and Smectite-to-Illite Transformation in the Chang-7 Shale, Ordos Basin: Processes and Controlling Factors

by Kun Ling, Ziyi Wang, Yaqi Cao, Yifei Liu and Lin Dong

Minerals 2025, 15(9), 951; https://doi.org/10.3390/min15090951 - 5 Sep 2025

Cited by 1 | Viewed by 1066

Abstract

As critical components in continental shale systems, the composition and evolution of clay minerals are fundamental to their diagenetic processes and petrophysical properties. The Chang-7 shales in the Ordos Basin exhibit abundant clay mineral content, offering a valuable case study for clay mineral [...] Read more.

As critical components in continental shale systems, the composition and evolution of clay minerals are fundamental to their diagenetic processes and petrophysical properties. The Chang-7 shales in the Ordos Basin exhibit abundant clay mineral content, offering a valuable case study for clay mineral research under moderate diagenetic conditions. This study employed XRD analysis to determine the whole-rock mineralogy, clay mineral composition, and the evolution characteristics of illite-smectite mixed-layer minerals (I/S). Comprehensive clay mineral datasets compiled from 13 newly analyzed wells and existing literature revealed distinct lateral distribution patterns. Total Organic Carbon (TOC) analysis and vitrinite reflectance (R_o) measurements provided systematic quantification of organic matter abundance and thermal maturation parameters in the studied samples. The results reveal that the Chang-7 shale exhibits a characteristic clay mineral assemblage, with I/S (average 44.2%) predominating over illite (34.7%), followed by chlorite (15.6%) and limited kaolinite (5.4%). Frequent volcanic activities provided substantial precursor materials for smectite formation, which actively participated in subsequent illitization processes, while chlorite and kaolinite distributions were predominantly controlled by provenance inputs and sedimentary facies, respectively. Inconsistencies exist between diagenetic stages inferred from I/S mixed-layer ratios and R_o values, particularly in low-maturity samples exhibiting accelerated illitization. The observed negative correlation between TOC content and mixed-layer ratios in Well YY1 and YSC Section samples demonstrates the catalytic role of organic matter in facilitating smectite-to-illite transformation. These results systematically clarify the coupled effects of sedimentary-diagenetic processes, offering new insights into the mutual interactions between inorganic and organic phases during illitization under natural geological conditions. The findings advance the understanding of Chang-7 shale oil and gas systems and offer practical guidance for future exploration. Full article

(This article belongs to the Special Issue Reservoir and Geochemistry Characteristics of Black Shale, 2nd Edition)

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40 pages, 3732 KB

Open AccessEditor’s ChoiceReview

Applications and Prospects of Muography in Strategic Deposits

by Xingwen Zhou, Juntao Liu, Baopeng Su, Kaiqiang Yao, Xinyu Cai, Rongqing Zhang, Ting Li, Hengliang Deng, Jiangkun Li, Shi Yan and Zhiyi Liu

Minerals 2025, 15(9), 945; https://doi.org/10.3390/min15090945 - 4 Sep 2025

Viewed by 1271

Abstract

With strategic mineral exploration extending to deep and complex geological settings, traditional methods increasingly struggle to dissect metallogenic systems and locate ore bodies precisely. This synthesis of current progress in muon imaging (a technology leveraging cosmic ray muons’ high penetration) aims to address [...] Read more.

With strategic mineral exploration extending to deep and complex geological settings, traditional methods increasingly struggle to dissect metallogenic systems and locate ore bodies precisely. This synthesis of current progress in muon imaging (a technology leveraging cosmic ray muons’ high penetration) aims to address these exploration challenges. Muon imaging operates by exploiting the energy attenuation of cosmic ray muons when penetrating earth media. It records muon transmission trajectories via high-precision detector arrays and constructs detailed subsurface density distribution images through advanced 3D inversion algorithms, enabling non-invasive detection of deep ore bodies. This review is organized into four thematic sections: (1) technical principles of muon imaging; (2) practical applications and advantages in ore exploration; (3) current challenges in deployment; (4) optimization strategies and future prospects. In practical applications, muon imaging has demonstrated unique advantages: it penetrates thick overburden and high-resistance rock masses to delineate blind ore bodies, with simultaneous gains in exploration efficiency and cost reduction. Optimized data acquisition and processing further allow it to capture dynamic changes in rock mass structure over hours to days, supporting proactive mine safety management. However, challenges remain, including complex muon event analysis, long data acquisition cycles, and limited distinguishability for low-density-contrast formations. It discusses solutions via multi-source geophysical data integration, optimized acquisition strategies, detector performance improvements, and intelligent data processing algorithms to enhance practicality and reliability. Future advancements in muon imaging are expected to drive breakthroughs in ultra-deep ore-forming system exploration, positioning it as a key force in innovating strategic mineral resource exploration technologies. Full article

(This article belongs to the Special Issue 3D Mineral Prospectivity Modeling Applied to Mineral Deposits)

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32 pages, 2165 KB

Open AccessEditor’s ChoiceReview

Biogeochemical Interactions and Their Role in European Underground Hydrogen Storage

by Frank E. Viveros, Na Liu and Martin A. Fernø

Minerals 2025, 15(9), 929; https://doi.org/10.3390/min15090929 - 1 Sep 2025

Viewed by 1115

Abstract

Integrating renewable energy requires robust, large-scale storage solutions to balance intermittent supply. Underground hydrogen storage (UHS) in geological formations, such as salt caverns, depleted hydrocarbon reservoirs, or aquifers, offers a promising way to store large volumes of energy for seasonal periods. This review [...] Read more.

Integrating renewable energy requires robust, large-scale storage solutions to balance intermittent supply. Underground hydrogen storage (UHS) in geological formations, such as salt caverns, depleted hydrocarbon reservoirs, or aquifers, offers a promising way to store large volumes of energy for seasonal periods. This review focuses on the biological aspects of UHS, examining the biogeochemical interactions between H₂, reservoir minerals, and key hydrogenotrophic microorganisms such as sulfate-reducing bacteria, methanogens, acetogens, and iron-reducing bacteria within the gas–liquid–rock–microorganism system. These microbial groups use H₂ as an electron donor, triggering biogeochemical reactions that can affect storage efficiency through gas loss and mineral dissolution–precipitation cycles. This review discusses their metabolic pathways and the geochemical interactions driven by microbial byproducts such as H₂S, CH₄, acetate, and Fe²⁺ and considers biofilm formation by microbial consortia, which can further change the petrophysical reservoir properties. In addition, the review maps 76 ongoing European projects focused on UHS, showing 71% target salt caverns, 22% depleted hydrocarbon reservoirs, and 7% aquifers, with emphasis on potential biogeochemical interactions. It also identifies key knowledge gaps, including the lack of in situ kinetic data, limited field-scale monitoring of microbial activity, and insufficient understanding of mineral–microbe interactions that may affect gas purity. Finally, the review highlights the need to study microbial adaptation over time and the influence of mineralogy on tolerance thresholds. By analyzing these processes across different geological settings and integrating findings from European research initiatives, this work evaluates the impact of microbial and geochemical factors on the safety, efficiency, and long-term performance of UHS. Full article

(This article belongs to the Special Issue Mineral Dissolution and Precipitation in Geologic Porous Media)

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22 pages, 5306 KB

Open AccessEditor’s ChoiceArticle

Geochemical Signatures and Element Interactions of Volcanic-Hosted Agates: Insights from Interpretable Machine Learning

by Peng Zhang, Xi Xi and Bo-Chao Wang

Minerals 2025, 15(9), 923; https://doi.org/10.3390/min15090923 - 29 Aug 2025

Viewed by 507

Abstract

To unravel the link between agate geochemistry, host volcanic rocks, and ore-forming processes, this study integrated elemental correlation analysis, interaction interpretation, and interpretable machine learning (LightGBM-SHAP framework with SMOTE and 5-fold cross-validation) using 203 in-situ element datasets from 16 global deposits. The framework [...] Read more.

To unravel the link between agate geochemistry, host volcanic rocks, and ore-forming processes, this study integrated elemental correlation analysis, interaction interpretation, and interpretable machine learning (LightGBM-SHAP framework with SMOTE and 5-fold cross-validation) using 203 in-situ element datasets from 16 global deposits. The framework achieved 99.01% test accuracy and 97.4% independent prediction accuracy in discriminating host volcanic rock types. Key findings reveal divergence between statistical elemental correlations and geological interactions. Synergies reflect co-migration/co-precipitation, while antagonisms stem from source competition or precipitation inhibition, unraveling processes like stepwise crystallization. Rhyolite-hosted agates form via a “crust-derived magmatic hydrothermal fluid—medium-low salinity complexation—multi-stage precipitation” model, driven by high-silica fluids enriching Sb/Zn. Andesite-hosted agates follow a “contaminated fluid—hydrothermal alteration—precipitation window differentiation” model, controlled by crustal contamination. Basalt-hosted agates form through a “low-temperature hydrothermal fluid—basic alteration—progressive mineral decomposition” model, with meteoric water regulating Na-Zn relationships. Zn acts as a cross-lithology indicator, tracing crust-derived fluid processes in rhyolites, feldspar alteration intensity in andesites, and alteration timing in basalts. This work advances volcanic-agate genetic studies via “correlation—interaction—mineralization model” coupling, with future directions focusing on large-scale micro-area elemental analysis. Full article

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

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29 pages, 5957 KB

Open AccessEditor’s ChoiceArticle

Multistage Fluid Evolution and P-T Path at Ity Gold Deposit and Dahapleu Prospect (Western Ivory Coast)

by Yacouba Coulibaly, Michel Cathelineau and Marie-Christine Boiron

Minerals 2025, 15(9), 918; https://doi.org/10.3390/min15090918 - 28 Aug 2025

Viewed by 862

Abstract

Gold mineralisation at Ity (Ivory Coast) is spatially associated with skarns formed at contacts between carbonate-rich Birimian volcano-sedimentary rocks and felsic intrusions, whereas at Dahapleu, a nearby skarn-free prospect, gold occurs in structurally controlled shear zones. Gold occurs as native gold in pyrite [...] Read more.

Gold mineralisation at Ity (Ivory Coast) is spatially associated with skarns formed at contacts between carbonate-rich Birimian volcano-sedimentary rocks and felsic intrusions, whereas at Dahapleu, a nearby skarn-free prospect, gold occurs in structurally controlled shear zones. Gold occurs as native gold in pyrite or as a Bi–Te–Au–Ag telluride assemblage. Fluid inclusion data indicate that Ity formed through a hybrid model: a mesothermal orogenic gold system dominated by CO₂–CH₄ fluids at >350 °C, superimposed on earlier skarn mineralisation characterised by saline fluids. At Dahapleu, no skarn fluids were identified, but volatile-rich inclusions with more variable signatures (CO₂, CO₂–CH₄, CO₂–N₂) indicate metamorphic fluids circulating in convective, fault-related systems and recording distinct fluid–rock interactions. The Ity–Dahapleu mineralising system thus displays fluid inclusion characteristics typical of mesothermal orogenic gold systems, likely at higher temperatures than most West African Birimian deposits. Overall, the Ity system reflects a long-lived thermal anomaly driving fluid circulation and metal deposition, with successive favourable events: rapid exhumation of hot lithospheric crust, granite intrusion, and skarn formation, followed by shear deformation and hydrothermal activity. 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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42 pages, 1483 KB

Open AccessEditor’s ChoiceReview

An Overview of Applications, Toxicology and Separation Methods of Lithium

by Ma. del Rosario Moreno-Virgen, Blanca Paloma Escalera-Velasco, Hilda Elizabeth Reynel-Ávila, Herson Antonio González-Ponce, Alvaro Rodrigo Videla-Leiva, Arturo Ignacio Morandé-Thompson, Marco Ludovico-Marques, Noemi Sogari and Adrián Bonilla-Petriciolet

Minerals 2025, 15(9), 917; https://doi.org/10.3390/min15090917 - 28 Aug 2025

Viewed by 1475

Abstract

Lithium has emerged as a critical element in contemporary society. It has been classified as an indispensable feedstock in the manufacture of lithium-ion batteries for electric mobility, portable electronics, and stationary energy storage systems, which are essential for the integration of intermittent renewable [...] Read more.

Lithium has emerged as a critical element in contemporary society. It has been classified as an indispensable feedstock in the manufacture of lithium-ion batteries for electric mobility, portable electronics, and stationary energy storage systems, which are essential for the integration of intermittent renewable energy sources. This metal also has other industrial applications and is projected to support future developments in semiconductor and aerospace technology. However, the exponential growth in global Li demand driven by energy transition and technological innovation requires a resilient and sustainable supply chain where both technological and environmental challenges should be addressed. This review discusses and analyzes some of current challenges associated with the Li supply chain given a particular emphasis on its separation methods. First, statistics of the Li market and its applications are provided, including the main sources from which to recover Li and the environmental impact associated with conventional Li extraction techniques from mineral ores and salar brines. Different separation methods (e.g., solvent extraction, adsorption, ion exchange, membrane technology) to recover Li from different sources are reviewed. Recent advances and developments in these separation strategies are described, including a brief analysis of their main limitations and capabilities. The importance and potential of recycling strategies for end-of-life batteries and industrial residues are also highlighted. A perspective on the gaps to be resolved with the aim of consolidating the Li supply chain to support the energy transition agenda is provided in this review. Full article

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

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13 pages, 3828 KB

Open AccessEditor’s ChoiceArticle

Effects of Fluid Inclusion Component Release on Flotation Behavior of Fluorite Minerals

by Renji Zheng, Shilin Hong, Sheng Wang, Honghu Tang and Zhiyong Gao

Minerals 2025, 15(9), 912; https://doi.org/10.3390/min15090912 - 27 Aug 2025

Viewed by 561

Abstract

Fluid inclusions, ubiquitously present within fluorite during diagenesis and mineralization, are released as inevitable ionic components in the pulp during mineral crushing and grinding. This study, grounded in geochemistry, combined microstructural analysis, spectroscopy, and X-ray computed tomography (X-CT) to investigate the morphology and [...] Read more.

Fluid inclusions, ubiquitously present within fluorite during diagenesis and mineralization, are released as inevitable ionic components in the pulp during mineral crushing and grinding. This study, grounded in geochemistry, combined microstructural analysis, spectroscopy, and X-ray computed tomography (X-CT) to investigate the morphology and petrographic characteristics of fluid inclusions in fluorite minerals. Building on this foundation, inductively coupled plasma optical emission spectrometry (ICP-OES) and ion chromatography (IC) were employed to analyze the release patterns of fluid inclusion components and their impact on fluorite flotation. The results reveal that fluid inclusions within fluorite are predominantly liquid-rich, two-phase (vapor-liquid) inclusions, exhibiting a spatial distribution density as high as 14.1%. Furthermore, fluid components are released during fluorite grinding, particularly homonymous Ca²⁺ ions, which significantly influence fluorite flotation behavior. Low concentrations of Ca²⁺ can activate fluorite flotation, whereas high concentrations of Ca²⁺ consume the collector (sodium oleate) in solution through competitive adsorption. This competition inhibits the adsorption of sodium oleate onto the fluorite mineral surface. The findings of this research provide theoretical support for in-depth studies on fluid inclusions in minerals and their effects on mineral flotation behavior, thereby facilitating the clean and efficient recovery of strategic fluorite mineral resources. Full article

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

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15 pages, 7780 KB

Open AccessEditor’s ChoiceArticle

Geochronological Constraints on the Genesis of the Changshitougounao Gold Deposit, Qinling Orogen

by Xian-Fa Xue, Sheng-Xiang Lu, Shou-Xu Wang, Da-Hu Yuan, Zheng-Wang Zeng, Jin-Hong Qiu and Jie Wang

Minerals 2025, 15(9), 903; https://doi.org/10.3390/min15090903 - 26 Aug 2025

Viewed by 1017

Abstract

The Western Qinling Orogenic Belt, China’s second-largest Au-metallogenic province, hosts numerous polymetallic deposits, with gold resources particularly concentrated in the northwestern Xiahe–Hezuo area. The Changshitougounao gold deposit, located south of the Xiahe Fault, comprises disseminated ores controlled by near E–W-trending faults and is [...] Read more.

The Western Qinling Orogenic Belt, China’s second-largest Au-metallogenic province, hosts numerous polymetallic deposits, with gold resources particularly concentrated in the northwestern Xiahe–Hezuo area. The Changshitougounao gold deposit, located south of the Xiahe Fault, comprises disseminated ores controlled by near E–W-trending faults and is primarily hosted in quartz diorite and the Lower Triassic Longwuhe Formation. Zircon LA–ICP–MS U–Pb dating of fresh quartz diorite yields an age of 241.8 ± 2.6 Ma. Two generations of monazite were identified: type I magmatic monazite and type II hydrothermal monazite. Type I monazite is intergrown with feldspar, quartz, and biotite, and in situ LA–ICP–MS U–Pb analysis gives an age of 239.2 ± 2.2 Ma. Type II monazite occurs as irregular granular aggregates associated with Au-bearing sulfides and hydrothermal sericite, with an in situ U–Pb age of 230 ± 3.5 Ma. Apatite, also coeval with Au-bearing sulfides and type II monazite, yields an LA–ICP–MS U–Pb age of 230.9 ± 2.5 Ma and 230.7 ± 3.0 Ma. Zircon and type I monazite thus constrain the emplacement of the ore-bearing quartz diorite to ca. 240 Ma, whereas hydrothermal type II monazite and apatite constrain the timing of mineralization to ca. 230 Ma. The ~10 Ma interval between magmatism and mineralization indicates that goldmineralization in the Changshitougounao deposit is decoupled from Early Triassic magmatic activity. Integrating previous studies of the West Qinling geodynamic evolution, we infer that the Changshitougounao deposit formed during collisional orogenesis, in response to the closure of the Paleo-Tethys Ocean. Consequently, the Changshitougounao gold deposit is best classified as an orogenic gold system. Pyrite–arsenopyrite and sericite alteration serve as effective exploration vectors, and the contact zone between quartz diorite veins and slate represents a favorable structural setting for ore prospecting. Full article

(This article belongs to the Special Issue Gold–Polymetallic Deposits in Convergent Margins)

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13 pages, 5817 KB

Open AccessEditor’s ChoiceArticle

Dissolution of Diamond in Water–Chloride Fluids at Mantle P-T Conditions

by Alexander Khokhryakov, Alexey Kruk, Alexander Sokol and Denis Nechaev

Minerals 2025, 15(9), 897; https://doi.org/10.3390/min15090897 - 24 Aug 2025

Viewed by 763

Abstract

Syngenetic fluid inclusions in natural diamonds are indicators of the composition of fluids responsible for growth and crystallization conditions. The chloride concentration in saline fluid inclusions of natural diamonds reaches 50 wt%. We study the dissolution of diamonds in the H₂O-KCl-NaCl [...] Read more.

Syngenetic fluid inclusions in natural diamonds are indicators of the composition of fluids responsible for growth and crystallization conditions. The chloride concentration in saline fluid inclusions of natural diamonds reaches 50 wt%. We study the dissolution of diamonds in the H₂O-KCl-NaCl system at temperatures of 1200 °C and 1400 °C and a pressure of 5.5 GPa using a BARS high-pressure multi-anvil apparatus. Two scenarios of diamond dissolution were experimentally investigated: (i) metasomatism by saline brines at high oxygen fugacity of the magnetite–hematite buffer; (ii) interaction with reduced carbon-unsaturated water–chloride fluid at low fO₂ imposed by the iron–wüstite buffer. It is found that the presence of alkaline chlorides in the aqueous fluid significantly accelerates diamond dissolution at high oxygen fugacity but inhibits the process under reduced conditions. The morphology of diamond dissolution features is controlled by the presence of water in the fluid over the entire range of the studied P-T-fO₂ conditions. Experimental results indicate that the interaction with oxidizing highly saline fluids during metasomatic events could negatively affect diamond preservation in mantle rocks and eventually lead to the formation of uneconomic kimberlites. Under reducing conditions, water–chloride fluids favor diamond preservation. Full article

(This article belongs to the Special Issue Unveiling the Depths: Advances in Kimberlite Research as Windows into Earth’s Evolution and Resource Potential)

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33 pages, 8102 KB

Open AccessEditor’s ChoiceArticle

Fluid Components in Cordierites from Granulite- and Amphibolite-Facies Rocks of the Aldan Shield and Yenisei Ridge, Russia: Evidence from Pyrolysis-Free GC-MS, Raman, and IR Spectroscopy

by Ksenia Zatolokina, Anatoly Tomilenko, Taras Bul’bak and Nikolay Popov

Minerals 2025, 15(9), 890; https://doi.org/10.3390/min15090890 - 22 Aug 2025

Viewed by 808

Abstract

This study provides the first comprehensive characterization of fluid components in cordierites from both moderate- to high-pressure granulite facies of the Aldan Shield (Sutam and Nimnyr blocks), and granulite–amphibolite facies of the Yenisei Ridge (Kan and Yenisei series of the Angara–Kan complex), Russia, [...] Read more.

This study provides the first comprehensive characterization of fluid components in cordierites from both moderate- to high-pressure granulite facies of the Aldan Shield (Sutam and Nimnyr blocks), and granulite–amphibolite facies of the Yenisei Ridge (Kan and Yenisei series of the Angara–Kan complex), Russia, using integrated infrared and Raman spectroscopy coupled with pyrolysis-free gas chromatography–mass spectrometry (GC-MS). Granulite-facies cordierites record CO₂-dominated fluids (X_CO2 = CO₂/(H₂O + CO₂) = 0.74–0.99) with elevated values (X_CO2 = 0.89–0.99) in high-pressure, high-temperature (high-P-T) samples from the Sutam block and Kan series compared to moderate-P-T samples from the Nimnyr block (X_CO2 = 0.74–0.84). Amphibolite-facies cordierites (Yenisei series) show significantly lower CO₂ contents (X_CO2 = 0.51–0.57) and higher H₂O concentrations relative to high-pressure granulites. Critically, we report the first identification in cordierites of at least 12 homologous series of organic compounds and nitrogenated, sulfonated, and halogenated compounds. These results provide new constraints on fluid behavior across metamorphic facies transitions. Full article

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

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13 pages, 7481 KB

Open AccessEditor’s ChoiceArticle

Influence of Hydration on Shale Reservoirs: A Case Study of Gulong Shale Oil

by Feifei Fang, Ke Xu, Yu Zhang, Yu Wang, Zhimin Xu, Sijie He, Hui Huang, Hailong Wang, Weixiang Jin and Yue Gong

Minerals 2025, 15(8), 878; https://doi.org/10.3390/min15080878 - 21 Aug 2025

Viewed by 654

Abstract

In the process of the exploration and development of shale oil, the influence of hydration on shale reservoirs is complex, as it can not only improve porosity and permeability, but also lead to reservoir instability. At present, there is a lack of systematic [...] Read more.

In the process of the exploration and development of shale oil, the influence of hydration on shale reservoirs is complex, as it can not only improve porosity and permeability, but also lead to reservoir instability. At present, there is a lack of systematic understanding of the influence of hydration on the physical and chemical properties of shale oil reservoirs. Therefore, in this study, taking the Gulong shale oil reservoir in Songliao Basin as the research object, X-ray diffraction mineral composition analysis, electron microscope scanning, and micro-CT scanning were used to study the micro–macro-changes in shale caused by hydration, and the effects of different fracturing fluids on hydration were evaluated. The results show the following: (1) Hydration increases the porosity and permeability of Gulong shale through clay dispersion and dissolution pore formation, though these transient effects may compromise long-term reservoir stability due to pore-throat clogging. (2) Prolonged hydration significantly enhanced pore structure complexity, with tortuosity increasing by 64.7% (from 2.19 to 3.60) and the fractal dimension rising by 7.5% (from 1.99 to 2.14) with hydration time, and the proportion of larger pores (50–100 μm) increased significantly. (3) Hydration leads to crack propagation and new cracks, and the intersection of cracks reduces the core strength, which may eventually lead to macroscopic damage. (4) The influence of different fracturing fluids on the hydration reaction is obviously different. The higher the concentration, the stronger the hydration effect. Distilled water helps to increase porosity and permeability, but long-term effects may affect reservoir stability. The results of this paper reveal the changes in micro- and macro-characteristics of shale oil reservoirs under hydration, which is of great significance for analyzing the mechanism of hydration and provides theoretical support for improving shale oil recovery. Full article

(This article belongs to the Special Issue Clay Minerals: Roles in Oil and Gas Generation, Drilling, and Enhanced Recovery)

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33 pages, 7573 KB

Open AccessEditor’s ChoiceArticle

A Stochastic Framework for Mineral Resource Uncertainty Quantification and Management at Compañía Minera Doña Inés de Collahuasi

by Alejandro Cáceres, Xavier Emery, Felipe Ibarra, Jorge Pérez, Sebastián Seguel, Gonzalo Fuster, Andrés Pérez and Rodrigo Riquelme

Minerals 2025, 15(8), 855; https://doi.org/10.3390/min15080855 - 13 Aug 2025

Viewed by 21164

Abstract

Mineral resource classification plays a critical role in communicating confidence levels, yet supporting methodologies such as drill-hole spacing analysis and geostatistical simulations are not consistently applied in routine updates of deterministic resource models. As a result, both local and global uncertainty quantification remain [...] Read more.

Mineral resource classification plays a critical role in communicating confidence levels, yet supporting methodologies such as drill-hole spacing analysis and geostatistical simulations are not consistently applied in routine updates of deterministic resource models. As a result, both local and global uncertainty quantification remain underutilized, and drilling requirements are often defined without a clear link to uncertainty reduction. This paper introduces a mineral resource uncertainty and drilling policy framework developed and applied at Compañía Minera Doña Inés de Collahuasi (CMDIC). The framework quantifies the uncertainty of each mineral resource model update when new data are available and provides an initial approach to determining drilling requirements based on CMDIC’s risk acceptance policies for different project stages. The proposed approach is a stochastic workflow that uses the current deterministic mineral resource model and database to generate geostatistical simulations. These simulations account for data quality, quantity, geological variability, and copper-grade variability. They form the basis for mineral resource classification with an explicit uncertainty quantification and provide an optimized drilling campaign to achieve desired risk levels subject to budget constraints. Because stochastic modeling updates faster than deterministic modeling, it provides timely insights from new drilling campaigns and delivers valuable insights for subsequent deterministic geological and grade modeling updates. The implementation of this workflow demonstrates its feasibility as a standard step following deterministic modeling, leading to cost-effective mineral resource development and management by aligning technical practices with the organization’s strategic objectives and risk preferences. Full article

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

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39 pages, 13361 KB

Open AccessEditor’s ChoiceArticle

Mineralogical, Petrological, 3D Modeling Study and Geostatistical Mineral Resources Estimation of the Zone C Gold Prospect, Kofi (Mali)

by Jean-Jacques Royer and Niakalé Camara

Minerals 2025, 15(8), 843; https://doi.org/10.3390/min15080843 - 8 Aug 2025

Viewed by 1449

Abstract

A 3D model integrating mineralogical, petrological, and geostatistical resource estimation was developed for Zone C of the Kofi Birimian gold deposit in Western Mali. Petrographic analysis identified two forms of gold mineralization: (i) native gold or electrum inclusions within pyrite, and (ii) disseminated [...] Read more.

A 3D model integrating mineralogical, petrological, and geostatistical resource estimation was developed for Zone C of the Kofi Birimian gold deposit in Western Mali. Petrographic analysis identified two forms of gold mineralization: (i) native gold or electrum inclusions within pyrite, and (ii) disseminated native gold along pyrite fractures. Four types of hydrothermal alteration–epidotization, chloritization, carbonatization, and albitization were observed microscopically. Statistical analysis of geochemical data classified five lithologies: mafic dyke, felsic dyke, diabase, faulted breccia, and intermediate quartz diorite. Minerals identified petrographically were corroborated by multivariate correlations among elements (Cr, Fe, Ni, Al, Ti, Na, and Ca), as revealed by Principal Component Analysis (PCA). A 3D borehole-based model revealed spatial correlations between hydrothermal alteration zones and associated geochemical anomalies, notably tourmalinization (B) and albitization (Na), with the latter serving as a key indicator for new exploration targets. The spatial associations of anomalous Ag, B, Hg, As, and Na commonly linked to tourmalinization suggest favorable zones for gold and silver mineralization. Geostatistical analysis identified isotropic continuous mineralized structures for most elements, including gold. Spherical isotropic variograms with ranges from 35 to 75 m were fitted for in situ resource estimation (e.g., silver ≈ 40 m; gold ≈ 60 m). The resulting estimated resources (indicated + inferred), based on a 1.0 g/t Au cut-off, are 2.476 Mt at 3.5 g/t Au indicated (0.278 Moz or 8.67 t), and 1.254 Mt at 2.78 g/t Au inferred (0.112 Moz or 3.49 t). This study provides a framework for identifying new mineralized zones, and the multidisciplinary approach demonstrates the connections between mineralogy and the information embedded in geochemical datasets, which are revealed through appropriate tools and an understanding of the underlying processes. Full article

(This article belongs to the Special Issue Advancements in Mineral Resource Characterization Using Machine Learning)

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35 pages, 8847 KB

Open AccessEditor’s ChoiceArticle

From Pulp to Froth: Decoding the Role of Nanoparticle Colloidal Silica in Scheelite Flotation as a Calcite Depressant

by Borhane Ben Said, Suvarna Patil, Martin Rudolph, Daniel Goldmann and Lucas Pereira

Minerals 2025, 15(8), 834; https://doi.org/10.3390/min15080834 - 6 Aug 2025

Viewed by 3072

Abstract

Colloidal silica acts as a multifunctional reagent in the froth flotation process of semi-soluble salt-type minerals, enabling the selective depression of calcite. This study investigates its effect on four key minerals—calcite, scheelite, apatite, and fluorite—using a comprehensive suite of techniques to identify the [...] Read more.

Colloidal silica acts as a multifunctional reagent in the froth flotation process of semi-soluble salt-type minerals, enabling the selective depression of calcite. This study investigates its effect on four key minerals—calcite, scheelite, apatite, and fluorite—using a comprehensive suite of techniques to identify the flotation subprocesses modulated by colloidal silica. This work also aims to determine the specific flotation zones affected by colloidal silica, assessing the influence of its dosage, surface modification, and specific surface area on metallurgical outcomes. Atomic force microscopy revealed mineral-specific surface responses to colloidal silica conditioning: calcite exhibited localized nanoparticle adsorption, whereas apatite underwent a dissolution–reprecipitation mechanism. Scheelite and fluorite, in contrast, showed minimal surface modifications. These differences are attributed to variations in surface reactivity, hydration behavior, and crystallographic structure, with calcite offering a uniquely favorable environment for colloidal silica attachment. Mechanistic insights show that colloidal silica—especially the aluminate-modified type with high specific surface area—influences both the pulp and froth zones by producing small, stable bubbles, enhancing fine scheelite recovery, stabilizing froth, and effectively depressing calcite. In contrast, non-functionalized colloidal silica resulted in poor bubble control and unstable froth. These findings elucidate the subprocess-specific mechanisms by which colloidal silica operates and highlight its potential as a tunable, multifunctional reagent for improving selectivity in the flotation of semi-soluble salt-type minerals. Full article

(This article belongs to the Special Issue Application of Nanomaterials in Mineral Processing)

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22 pages, 5351 KB

Open AccessEditor’s ChoiceArticle

Hydrometallurgical Leaching of Copper and Cobalt from a Copper–Cobalt Ore by Aqueous Choline Chloride-Based Deep Eutectic Solvent Solutions

by Emmanuel Anuoluwapo Oke, Yorkabel Fedai and Johannes Hermanus Potgieter

Minerals 2025, 15(8), 815; https://doi.org/10.3390/min15080815 - 31 Jul 2025

Cited by 2 | Viewed by 1499

Abstract

The sustainable recovery of valuable metals such as Cu and Co from ores is a pressing need considering environmental and economic challenges. Therefore, this study evaluates the effectiveness of deep eutectic solvents (DESs) as alternative leaching agents for Cu and Co extraction. Four [...] Read more.

The sustainable recovery of valuable metals such as Cu and Co from ores is a pressing need considering environmental and economic challenges. Therefore, this study evaluates the effectiveness of deep eutectic solvents (DESs) as alternative leaching agents for Cu and Co extraction. Four DESs were prepared using choline chloride (ChCl) as a hydrogen bond acceptor (HBA) and oxalic acid (OA), ethylene glycol (EG), urea (U) and thiourea (TU) as hydrogen bond donors (HBDs). Leaching experiments were conducted with DESs supplemented with 30 wt.% water at varying temperatures, various solid-to-liquid ratios, and time durations. The ChCl:OA DES demonstrated the highest leaching efficiencies among the DESs tested on pure CuO and CoO, achieving 89.2% for Cu and 92.4% for Co (60 °C, 400 rpm, 6 h, −75 + 53 µm particle size, and 1:10 solid-to-liquid ratio). In addition, the dissolution kinetics, analysed using the shrinking core model (SCM), showed that the leaching process was mainly controlled by surface chemical reactions. The activation energy values for Cu and Co leaching were 46.8 kJ mol⁻¹ and 51.4 kJ mol⁻¹, respectively, supporting a surface chemical control mechanism. The results highlight the potential of ChCl:OA as a sustainable alternative for metal recovery. Full article

(This article belongs to the Special Issue Innovations in Hydrometallurgy: Traditional and Emerging Approaches for Sustainable Metal Recovery)

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31 pages, 29045 KB

Open AccessEditor’s ChoiceArticle

Earliest Cambrian Carbonate Platform Evolution, Environmental Change, and Organic Matter Accumulation in the Northwestern Yangtze Block, South China

by Jincheng Liu, Qingchun Jiang, Yan Zhang, Jingjiang Liu, Yifei Ai, Pengzhen Duan and Guangyou Zhu

Minerals 2025, 15(8), 812; https://doi.org/10.3390/min15080812 - 31 Jul 2025

Viewed by 542

Abstract

The earliest Cambrian (ca., 538.8–524.8 Ma) was an important period in geological history witnessing significant environmental change, during which organic-rich facies were developed in the Yangtze Platform, South China. However, the contemporaneous paleogeographic and stratigraphic framework within which the environmental change and organic [...] Read more.

The earliest Cambrian (ca., 538.8–524.8 Ma) was an important period in geological history witnessing significant environmental change, during which organic-rich facies were developed in the Yangtze Platform, South China. However, the contemporaneous paleogeographic and stratigraphic framework within which the environmental change and organic matter accumulation took place remains poorly understood. We investigate this based on facies, sequence stratigraphic, and geochemical analyses of the lowermost Cambrian Maidiping and Zhujiaqing formations in the northwestern Yangtze Block. The results show that the terminal Ediacaran rimmed platform changed into a foredeep carbonate ramp and backbulge basin after the onset of the earliest Cambrian transgression. Across the Ediacaran–Cambrian boundary, the shallow-marine redox condition rapidly transitioned from relative euxinia to an oxygen-rich state. During the late transgression to highstand normal regression, the foredeep carbonate ramp expanded to the cratonic interior, and nutrients brought by intensified continental weathering and upwelling promoted significant phytoplankton proliferation, an increase in oxygen level and primary productivity, and then organic matter enrichment. During the forced regression, the carbonate ramp gradually changed into a rimmed platform. The weakening continental weathering and expanding anoxic area during the forced to lowstand normal regression led to the significant organic carbon burial in the foredeep basin. Full article

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

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26 pages, 8845 KB

Open AccessEditor’s ChoiceArticle

Occurrence State and Genesis of Large Particle Marcasite in a Thick Coal Seam of the Zhundong Coalfield in Xinjiang

by Xue Wu, Ning Lü, Shuo Feng, Wenfeng Wang, Jijun Tian, Xin Li and Hayerhan Xadethan

Minerals 2025, 15(8), 816; https://doi.org/10.3390/min15080816 - 31 Jul 2025

Viewed by 547

Abstract

The Junggar Basin contains a large amount of coal resources and is an important coal production base in China. The coal seam in Zhundong coalfield has a large single-layer thickness and high content of inertinite, but large particle Fe-sulphide minerals are associated with [...] Read more.

The Junggar Basin contains a large amount of coal resources and is an important coal production base in China. The coal seam in Zhundong coalfield has a large single-layer thickness and high content of inertinite, but large particle Fe-sulphide minerals are associated with coal seams in some mining areas. A series of economic and environmental problems caused by the combustion of large-grained Fe-sulphide minerals in coal have seriously affected the economic, clean and efficient utilization of coal. In this paper, the ultra-thick coal seam of the Xishanyao formation in the Yihua open-pit mine of the Zhundong coalfield is taken as the research object. Through the analysis of coal quality, X-ray fluorescence spectrometer test of major elements in coal, inductively coupled plasma mass spectrometry test of trace elements, SEM-Raman identification of Fe-sulphide minerals in coal and LA-MC-ICP-MS test of sulfur isotope of marcasite, the coal quality characteristics, main and trace element characteristics, macro and micro occurrence characteristics of Fe-sulphide minerals and sulfur isotope characteristics of marcasite in the ultra-thick coal seam of the Xishanyao formation are tested. On this basis, the occurrence state and genesis of large particle Fe-sulphide minerals in the ultra-thick coal seam of the Xishanyao formation are clarified. The main results and understandings are as follows: (1) the occurrence state of Fe-sulphide minerals in extremely thick coal seams is clarified. The Fe-sulphide minerals in the extremely thick coal seam are mainly marcasite, and concentrated in the YH-2, YH-3, YH-8, YH-9, YH-14, YH-15 and YH-16 horizons. Macroscopically, Fe-sulphide minerals mainly occur in three forms: thin film Fe-sulphide minerals, nodular Fe-sulphide minerals, and disseminated Fe-sulphide minerals. Microscopically, they mainly occur in four forms: flake, block, spearhead, and crack filling. (2) The difference in sulfur isotope of marcasite was discussed, and the formation period of marcasite was preliminarily divided. The overall variation range of the δ³⁴S value of marcasite is wide, and the extreme values are quite different. The polyflake marcasite was formed in the early stage of diagenesis and the δ³⁴S value was negative, while the fissure filling marcasite was formed in the late stage of diagenesis and the δ³⁴S value was positive. (3) The coal quality characteristics of the thick coal seam were analyzed. The organic components in the thick coal seam are mainly inertinite, and the inorganic components are mainly clay minerals and marcasite. (4) The difference between the element content in the thick coal seam of the Zhundong coalfield and the average element content of Chinese coal was compared. The major element oxides in the thick coal seam are mainly CaO and MgO, followed by SiO₂, Al₂O₃, Fe₂O₃ and Na₂O. Li, Ga, Ba, U and Th are enriched in trace elements. (5) The coal-accumulating environment characteristics of the extremely thick coal seam are revealed. The whole thick coal seam is formed in an acidic oxidation environment, and the horizon with Fe-sulphide minerals is in an acidic reduction environment. The acidic reduction environment is conducive to the formation of marcasite and is not conducive to the formation of pyrite. (6) There are many matrix vitrinite, inertinite content, clay content, and terrigenous debris in the extremely thick coal seam. The good supply of peat swamp, suitable reduction environment and pH value, as well as groundwater leaching and infiltration, together cause the occurrence of large-grained Fe-sulphide minerals in the extremely thick coal seam of the Xishanyao formation in the Zhundong coalfield. Full article

(This article belongs to the Special Issue Mineralogical and Geochemical Characteristics of Coal and Coal-Bearing Strata)

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20 pages, 6964 KB

Open AccessEditor’s ChoiceArticle

Mineralogical Analysis of Factors Affecting the Grade of High-Gradient Magnetic Separation Concentrates and Experimental Study on TiO₂ Enrichment Using ARC

by Yifei Liu, Zhenqiang Liu, Yuhua Wang, Yuxin Zhang and Dongfang Lu

Minerals 2025, 15(8), 799; https://doi.org/10.3390/min15080799 - 30 Jul 2025

Viewed by 670

Abstract

High-gradient magnetic separation is a key step in the pre-concentration of ilmenite before flotation, particularly in the gravity separation process. However, as the amount of weakly magnetic gangue minerals increases, the grade of the coarse concentrate from high-gradient magnetic separation decreases. This paper [...] Read more.

High-gradient magnetic separation is a key step in the pre-concentration of ilmenite before flotation, particularly in the gravity separation process. However, as the amount of weakly magnetic gangue minerals increases, the grade of the coarse concentrate from high-gradient magnetic separation decreases. This paper investigates the mineralogical factors affecting the enrichment efficiency of high-gradient magnetic separation. Additionally, a newly developed stirred fluidized bed device, an agitated reflux classifier (ARC), was successfully applied to remove weakly magnetic gangue minerals that are difficult to separate by high-gradient magnetic separation (HGMS). For low-grade ilmenite with a feed grade of 3.97%, a combined process of magnetic separation and gravity separation was employed, achieving a concentrate with a grade of 16.50% and a recovery rate of 54.11%. This concentrate meets the requirements for flotation feed. This study provides a new approach for the beneficiation of low-grade ilmenite. Full article

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

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31 pages, 10410 KB

Open AccessEditor’s ChoiceArticle

Integrated Prospectivity Mapping for Copper Mineralization in the Koldar Massif, Kazakhstan

by Dinara Talgarbayeva, Andrey Vilayev, Elmira Serikbayeva, Elmira Orynbassarova, Hemayatullah Ahmadi, Zhanibek Saurykov, Nurmakhambet Sydyk, Aigerim Bermukhanova and Berik Iskakov

Minerals 2025, 15(8), 805; https://doi.org/10.3390/min15080805 - 30 Jul 2025

Viewed by 1221

Abstract

This study developed a copper mineral prospectivity map for the Koldar massif, Kazakhstan, using an integrated approach combining geophysical and satellite methods. A strong spatialgenetic link was identified between faults and hydrothermal mineralization, with faults acting as key conduits for ore-bearing fluids. Lineament [...] Read more.

This study developed a copper mineral prospectivity map for the Koldar massif, Kazakhstan, using an integrated approach combining geophysical and satellite methods. A strong spatialgenetic link was identified between faults and hydrothermal mineralization, with faults acting as key conduits for ore-bearing fluids. Lineament analysis and density mapping confirmed the high permeability of the Koldar massif, indicating its structural prospectivity. Hyperspectral and multispectral data (ASTER, PRISMA, WorldView-3) were applied for detailed mapping of hydrothermal alteration (phyllic, propylitic, argillic zones), which are critical for discovering porphyry copper deposits. In particular, WorldView-3 imagery facilitated the identification of new prospective zones. The transformation of magnetic and gravity data successfully delineated geological features and structural boundaries, confirming the fractured nature of the massif, a key structural factor for mineralization. The resulting map of prospective zones, created by normalizing and integrating four evidential layers (lineament density, PRISMA-derived hydrothermal alteration, magnetic, and gravity anomalies), is thoroughly validated, successfully outlining the known Aktogay, Aidarly, and Kyzylkiya deposits. Furthermore, new, previously underestimated prospective areas were identified. This work fills a significant knowledge gap concerning the Koldar massif, which had not been extensively studied using satellite methods previously. The key advantage of this research lies in its comprehensive approach and the successful application of high-quality hyperspectral imagery for mapping new prospective zones, offering a cost-effective and efficient alternative to traditional ground-based investigations. Full article

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

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10 pages, 1262 KB

Open AccessEditor’s ChoiceCommunication

Gold as Pollution Tracer in Holocene Sediments of the Doñana National Park, the Largest Biological Reserve in Europe

by Verónica Romero, Francisco Ruiz, María Luz González-Regalado, María Isabel Carretero, Manuel Pozo, Guadalupe Monge, Luis Miguel Cáceres, Joaquín Rodríguez Vidal, Manuel Abad, Tatiana Izquierdo, Antonio Toscano, Paula Gómez and Gabriel Gómez

Minerals 2025, 15(8), 801; https://doi.org/10.3390/min15080801 - 30 Jul 2025

Viewed by 650

Abstract

Estuaries are excellent containers for the prehistorical and historical pollution that develops in their river basins. This paper studies the Au contents obtained by inductively coupled plasma spectrometry of two cores extracted from the Doñana National Park (Guadalquivir Estuary, SW Spain). Concentrations of [...] Read more.

Estuaries are excellent containers for the prehistorical and historical pollution that develops in their river basins. This paper studies the Au contents obtained by inductively coupled plasma spectrometry of two cores extracted from the Doñana National Park (Guadalquivir Estuary, SW Spain). Concentrations of this precious metal have been associated with the different prehistoric and historical stages of exploitation of the Iberian Pyritic Belt. The three detected peaks correspond to the first mining operations in the area around the park, the first systematic Tartessian mining and strong exploitation during the Roman period. Consequently, Au is an appropriate marker of the contamination phases prior to its current extraordinary biological diversity. Full article

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

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25 pages, 15689 KB

Open AccessEditor’s ChoiceArticle

Mineralogical and Chemical Properties and REE Content of Bauxites in the Seydişehir (Konya, Türkiye) Region

by Muazzez Çelik Karakaya and Necati Karakaya

Minerals 2025, 15(8), 798; https://doi.org/10.3390/min15080798 - 29 Jul 2025

Viewed by 1070

Abstract

The most important bauxite deposits in Türkiye are located in the Seydişehir (Konya) and Akseki (Antalya) regions, situated along the western Taurus Mountain, with a total reserve of approximately 44 million tons. Some of the bauxite deposits have been exploited for alumina since [...] Read more.

The most important bauxite deposits in Türkiye are located in the Seydişehir (Konya) and Akseki (Antalya) regions, situated along the western Taurus Mountain, with a total reserve of approximately 44 million tons. Some of the bauxite deposits have been exploited for alumina since the 1970s. In this study, bauxite samples, collected from six different deposits were examined to determine their mineralogical and chemical composition, as well as their REE content, with the aim of identifying which bauxite types are enriched in REEs and assessing their economic potential. The samples included massive, oolitic, and brecciated bauxite types, which were analyzed using optical microscopy, X-ray diffraction (XRD), X-ray fluorescence (XRF) and inductive coupled plasma-mass spectrometry (ICP-MS), field emission scanning electron microscopy (FESEM-EDX), and electron probe micro-analysis (EPMA). Massive bauxites were found to be more homogeneous in both mineralogical and chemical composition, predominantly composed of diaspore, boehmite, and rare gibbsite. Hematite is the most abundant iron oxide mineral in all bauxites, while goethite, rutile, and anatase occur in smaller quantities. Quartz, feldspar, kaolinite, dolomite, and pyrite were specifically determined in brecciated bauxites. Average oxide contents were determined as 52.94% Al₂O₃, 18.21% Fe₂O₃, 7.04% TiO₂, and 2.69% SiO₂. Na₂O, K₂O, and MgO values are typically below 0.5%, while CaO averages 3.54%. The total REE content of the bauxites ranged from 161 to 4072 ppm, with an average of 723 ppm. Oolitic-massive bauxites exhibit the highest REE enrichment. Cerium (Ce) was the most abundant REE, ranging from 87 to 453 ppm (avg. 218 ppm), followed by lanthanum (La), which reached up to 2561 ppm in some of the massive bauxite samples. LREEs such as La, Ce, Pr, and Nd were notably enriched compared to HREEs. The lack of a positive correlation between REEs and major element oxides, as well as with their occurrences in distinct association with Al- and Fe-oxides-hydroxides based on FESEM-EDS and EPMA analyses, suggests that the REEs are present as discrete mineral phases. Furthermore, these findings indicate that the REEs are not incorporated into the crystal structures of other minerals through isomorphic substitution or adsorption. Full article

(This article belongs to the Special Issue Critical Metal Minerals, 2nd Edition)

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39 pages, 8119 KB

Open AccessEditor’s ChoiceArticle

Magmatic Redox Evolution and Porphyry–Skarn Transition in Multiphase Cu-Mo-W-Au Systems of the Eocene Tavşanlı Belt, NW Türkiye

by Hüseyin Kocatürk, Mustafa Kumral, Hüseyin Sendir, Mustafa Kaya, Robert A. Creaser and Amr Abdelnasser

Minerals 2025, 15(8), 792; https://doi.org/10.3390/min15080792 - 28 Jul 2025

Viewed by 873

Abstract

This study explores the magmatic and hydrothermal evolution of porphyry–skarn–transitional Cu-Mo-W-Au systems within the Nilüfer Mineralization Complex (NMC), located in the westernmost segment of the Eocene Tavşanlı Metallogenic Belt, NW Türkiye. Through integration of field data, whole-rock geochemistry, Re–Os molybdenite dating, and amphibole–biotite [...] Read more.

This study explores the magmatic and hydrothermal evolution of porphyry–skarn–transitional Cu-Mo-W-Au systems within the Nilüfer Mineralization Complex (NMC), located in the westernmost segment of the Eocene Tavşanlı Metallogenic Belt, NW Türkiye. Through integration of field data, whole-rock geochemistry, Re–Os molybdenite dating, and amphibole–biotite mineral chemistry, the petrogenetic controls on mineralization across four spatially associated mineralized regions (Kirazgedik, Güneybudaklar, Kozbudaklar, and Delice) were examined. The earliest and thermally most distinct phase is represented by the Kirazgedik porphyry system, characterized by high temperature (~930 °C), oxidized quartz monzodioritic intrusions emplaced at ~2.7 kbar. Rising fO₂ and volatile enrichment during magma ascent facilitated structurally focused Cu-Mo mineralization. At Güneybudaklar, Re–Os geochronology yields an age of ~49.9 Ma, linking Mo- and W-rich mineralization to a transitional porphyry–skarn environment developed under moderately oxidized (ΔFMQ + 1.8 to +0.5) and hydrous (up to 7 wt.% H₂O) magmatic conditions. Kozbudaklar represents a more reduced, volatile-poor skarn system, leading to Mo-enriched scheelite mineralization typical of late-stage W-skarns. The Delice system, developed at the contact of felsic cupolas and carbonates, records the broadest range of redox and fluid compositions. Mixed oxidized–reduced fluid signatures and intense fluid–rock interaction reflect complex, multistage fluid evolution involving both magmatic and external inputs. Geochemical and mineralogical trends—from increasing silica and Rb to decreasing Sr and V—trace a systematic evolution from mantle-derived to felsic, volatile-rich magmas. Structurally, mineralization is controlled by oblique fault zones that localize magma emplacement and hydrothermal flow. These findings support a unified genetic model in which porphyry and skarn mineralization styles evolved continuously from multiphase magmatic systems during syn-to-post-subduction processes, offering implications for exploration models in the Western Tethyan domain. Full article

(This article belongs to the Special Issue New Discovery and Exploration Methods of Porphyry and Epithermal Mineral Deposits)

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24 pages, 7393 KB

Open AccessEditor’s ChoiceArticle

Thermodynamic Modeling Constrains the Alteration and Mineralization Patterns of the Pulang Porphyry Cu-Au Deposits in Eastern Tibet

by Shaoying Zhang, Wenyan He, Huaqing Wang and Yiwu Xiao

Minerals 2025, 15(8), 780; https://doi.org/10.3390/min15080780 - 25 Jul 2025

Viewed by 722

Abstract

Thermodynamic simulations of fluid–rock interactions provide valuable insights into mineral deposit formation mechanisms. This study investigates the Pulang porphyry Cu-Au deposit in the Sanjiang Tethys Orogen, employing both Gibbs energy minimization (GEM) and the Law of mass action (LMA) method to understand alteration [...] Read more.

Thermodynamic simulations of fluid–rock interactions provide valuable insights into mineral deposit formation mechanisms. This study investigates the Pulang porphyry Cu-Au deposit in the Sanjiang Tethys Orogen, employing both Gibbs energy minimization (GEM) and the Law of mass action (LMA) method to understand alteration overprinting and metal precipitation. The modeling results suggest that the ore-forming fluid related to potassic alteration was initially oxidized (ΔFMQ = +3.54~+3.26) with a near-neutral pH (pH = 5.0~7.0). Continued fluid–rock interactions, combined with the input of reduced groundwater, resulted in a decrease in both pH (4.8~6.1) and redox potential (ΔFMQ~+1), leading to the precipitation of propylitic alteration minerals and pyrrhotite. As temperature further decreased, fluids associated with phyllic alteration showed a slight increase in pH (5.8~6.0) and redox potential (ΔFMQ = +2). The intense superposition of propylitic and phyllic alteration on the potassic alteration zone is attributed to the rapid temperature decline in the magmatic–hydrothermal system, triggering fluid collapse and reflux. Mo, mainly transported as HMoO₄⁻ and MoO₄⁻², precipitated in the high-temperature range; Cu, carried primarily by CuCl complexes (CuCl₄⁻³, CuCl₂⁻, CuCl), precipitated over intermediate to high temperatures; and Au, transported as Au-S complexes (Au(HS)₂⁻, AuHS), precipitated from intermediate to low temperatures. This study demonstrates that fluid–rock interactions alone can account for the observed sequence of alteration and mineralization in porphyry systems. Full article

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

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32 pages, 32586 KB

Open AccessEditor’s ChoiceArticle

Magmatic Evolution at the Saindak Cu-Au Deposit: Implications for the Formation of Giant Porphyry Deposits

by Jun Hong, Yasir Shaheen Khalil, Asad Ali Narejo, Xiaoyong Yang, Tahseenullah Khan, Zhihua Wang, Huan Tang, Haidi Zhang, Bo Yang and Wenyuan Li

Minerals 2025, 15(8), 768; https://doi.org/10.3390/min15080768 - 22 Jul 2025

Viewed by 2402

Abstract

The Chagai porphyry copper belt is a major component of the Tethyan metallogenic domain, which spans approximately 300 km and hosts several giant porphyry copper deposits. The tectonic setting, whether subduction-related or post-collisional, and the deep dynamic processes governing the formation of these [...] Read more.

The Chagai porphyry copper belt is a major component of the Tethyan metallogenic domain, which spans approximately 300 km and hosts several giant porphyry copper deposits. The tectonic setting, whether subduction-related or post-collisional, and the deep dynamic processes governing the formation of these giant deposits remain poorly understood. Mafic microgranular enclaves (MMEs), mafic dikes, and multiple porphyries have been documented in the Saindak mining area. This work examines both the ore-rich and non-ore intrusions in the Saindak porphyry Cu-Au deposit, using methods like molybdenite Re-Os dating, U-Pb zircon ages, Hf isotopes, and bulk-rock geochemical data. Geochronological results indicate that ore-fertile and barren porphyries yield ages of 22.15 ± 0.22 Ma and 22.21 ± 0.33 Ma, respectively. Both MMEs and mafic dikes have zircons with nearly identical ²⁰⁶Pb/²³⁸U weighted mean ages (21.21 ± 0.18 Ma and 21.21 ± 0.16 Ma, respectively), corresponding to the age of the host rock. Geochemical and Sr–Nd–Hf isotopic evidence indicates that the Saindak adakites were generated by the subduction of the Arabian oceanic lithosphere under the Eurasian plate, rather than through continental collision. The adakites were mainly formed by the partial melting of a metasomatized mantle wedge, induced by fluids from the dehydrating subducting slab, with minor input from subducted sediments and later crust–mantle interactions during magma ascent. We conclude that shallow subduction of the Arabian plate during the Oligocene–Miocene may have increased the flow of subducted fluids into the sub-arc mantle source of the Chagai arc. This process may have facilitated the widespread deposition of porphyry copper and copper–gold mineralization in the region. Full article

(This article belongs to the Section Mineral Deposits)

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20 pages, 1677 KB

Open AccessEditor’s ChoiceReview

Froth Flotation of Lepidolite—A Review

by Xusheng Yang, Bo Feng and Longxia Jiang

Minerals 2025, 15(7), 750; https://doi.org/10.3390/min15070750 - 17 Jul 2025

Cited by 2 | Viewed by 1058

Abstract

As one of the important lithium resource sources, lepidolite has become a new energy strategic resource research hot spot. The efficient flotation of lepidolite directly affects the recovery and economic value of lithium resources. This paper systematically reviews the flotation research progress of [...] Read more.

As one of the important lithium resource sources, lepidolite has become a new energy strategic resource research hot spot. The efficient flotation of lepidolite directly affects the recovery and economic value of lithium resources. This paper systematically reviews the flotation research progress of lepidolite, focusing on the influence of the type of capture agent and process parameters (pH, activator, and depressant) on flotation. In view of the separation problems caused by the similarity of the surface properties of lepidolite and its associated gangue minerals (albite, feldspar, and quartz), the strategies for regulating the crystal structure of the minerals and their surface properties are analyzed. In addition, the lepidolite flotation process and its challenges are summarized, including poor selectivity of chemicals, fine mineral embedded size, easy to form sludge, and insufficient environmental friendliness, etc. The future development direction of lepidolite flotation technology is also prospected, which provides theoretical support and reference for the efficient recovery of lepidolite. Full article

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

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21 pages, 8925 KB

Open AccessEditor’s ChoiceArticle

Zr-Th-REE Mineralization Associated with Albite–Aegirine-Bearing Rocks of the Burpala Alkaline Intrusion (North Baikal Region, South Margin of the Siberian Craton)

by Ivan Aleksandrovich Izbrodin, Anna Gennadievna Doroshkevich, Anastasia Evgenyevna Starikova, Alexandra Vladislavovna Malyutina, Tatyana Nikolaevna Moroz and Igor Sergeevich Sharygin

Minerals 2025, 15(7), 742; https://doi.org/10.3390/min15070742 - 16 Jul 2025

Viewed by 499

Abstract

The rocks of the Burpala alkaline intrusion contain a wide range of rare minerals that concentrate rare earth elements (REEs), Nb, Th, Li, and other incompatible elements. One of the examples of the occurrence of such mineralization is albite–aegirine rocks located at the [...] Read more.

The rocks of the Burpala alkaline intrusion contain a wide range of rare minerals that concentrate rare earth elements (REEs), Nb, Th, Li, and other incompatible elements. One of the examples of the occurrence of such mineralization is albite–aegirine rocks located at the contact zone between the intrusion and the host terrigenous–sedimentary rock. In albite–aegirine rocks, cubic crystals of “metaloparite”, partially or completely substituted by bastnäsite-(Ce) and polymorphic TiO₂ phases (anatase and rutile) mainly represent the rare metal minerals. In albite–aegirine rocks, trace element minerals are predominantly represented by cubic crystals of “metaloparite”, which are partially or completely replaced by bastnäsite-(Ce) and polymorphic TiO₂ phases such as anatase and rutile. Additionally, Th-bearing zircon (up to 17.7 wt% ThO₂) and a variety of unidentified minerals containing REEs, Th, and Nb were detected. The obtained data indicate that bastnäsite-(Ce) is the result of the recrystallization of “metaloparite” accompanied by the formation of Th-bearing zircon and Nb-bearing rutile (up to 9.9 wt% Nb₂O₅) and the separation of various undiagnosed, unidentified LREE phases. Our studies show that remobilization of LREEs, HFSEs, and local enrichment of rocks in these elements occurred due to the effects of residual fluid enriched in fluorine and carbon dioxide. Full article

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

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23 pages, 1663 KB

Open AccessEditor’s ChoiceReview

Adsorption of Antibiotics by Natural Clay Minerals

by Leonid Perelomov, Maria Gertsen, Saglara Mandzhieva, Vadim Sychev, Tamara Dudnikova, Ilya Khaidanov, Irina Perelomova, Tatiana Minkina and Yurii Atroshchenko

Minerals 2025, 15(7), 733; https://doi.org/10.3390/min15070733 - 14 Jul 2025

Cited by 1 | Viewed by 1860

Abstract

The use of widespread and inexpensive clay minerals as adsorptive agents, as well as materials obtained by their chemical modification, can contribute to the solution of the problem of environmental pollution with antibiotics. This review considers the structural features of various natural clay [...] Read more.

The use of widespread and inexpensive clay minerals as adsorptive agents, as well as materials obtained by their chemical modification, can contribute to the solution of the problem of environmental pollution with antibiotics. This review considers the structural features of various natural clay minerals and the effect of these features on their sorption capacity. Based on the analysis of available papers (over the last 15 years, also including some fundamental basics over the last 20–30 years), it has been established that the main property of an antibiotic molecule affecting the ability to be adsorbed by a clay mineral is the hydrophilicity of the organic substance molecule. The leading properties that determine the ability of clays to adsorb antibiotics are the charge and area of their surfaces. The ability of antibiotic molecules to protonate and a partial change in the edge charge of mineral layers is determined by the acidity of the sorption solution. In addition, empirical evidence is provided that the most important factors affecting adsorption are the ionic strength of the sorption solution, the concentration of the adsorbent and adsorbate, and the interaction temperature. The diversity of the composition, structure, and properties of clay minerals allows them to be effective sorbents for a wide range of antibiotics. Full article

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

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26 pages, 2032 KB

Open AccessEditor’s ChoiceReview

A Cross-Disciplinary Review of Rare Earth Elements: Deposit Types, Mineralogy, Machine Learning, Environmental Impact, and Recycling

by Mustafa Rezaei, Gabriela Sanchez-Lecuona and Omid Abdolazimi

Minerals 2025, 15(7), 720; https://doi.org/10.3390/min15070720 - 9 Jul 2025

Cited by 1 | Viewed by 4328

Abstract

Rare-earth elements (REEs), including lanthanides, scandium, and yttrium, are important for advanced technologies such as renewable energy systems, electronics, medical diagnostics, and precision agriculture. Despite their relative crustal abundance, REE extraction is impeded by complex geochemical behavior, dispersed distribution, and environmental challenges. This [...] Read more.

Rare-earth elements (REEs), including lanthanides, scandium, and yttrium, are important for advanced technologies such as renewable energy systems, electronics, medical diagnostics, and precision agriculture. Despite their relative crustal abundance, REE extraction is impeded by complex geochemical behavior, dispersed distribution, and environmental challenges. This review presents a comprehensive overview of REE geochemistry, mineralogy, and major deposit types including carbonatites, alkaline igneous rocks, laterites, placer deposits, coal byproducts, and marine sediments. It also highlights the global distribution and economic potential of key REE projects. The integration of machine learning has further enhanced exploration by enabling deposit classification and geochemical modeling, especially in data-limited regions. Environmental and health challenges associated with REE mining, processing, and electronic waste (e-waste) recycling are studied, along with the expanding use of REEs in agriculture and medicine. Some recycling efforts offer promise for supply diversification, but significant technological and economic barriers remain. Ensuring a secure and sustainable REE supply will require integrated approaches combining advanced analytics, machine learning, responsible extraction, and coordinated policy efforts. The present review offers a general overview that can be useful for informing future studies and resource-related discussions. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series: "Critical and Strategic Minerals", 2nd Edition)

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21 pages, 12768 KB

Open AccessEditor’s ChoiceArticle

Applicability Analysis with the Improved Spectral Unmixing Models Based on the Measured Hyperspectral Data of Mixed Minerals

by Haonan Zhang, Lizeng Duan, Yang Zhang, Huayu Li, Donglin Li and Yan Li

Minerals 2025, 15(7), 715; https://doi.org/10.3390/min15070715 - 6 Jul 2025

Cited by 1 | Viewed by 921

Abstract

Hyperspectral technology can non-destructively identify and analyze minerals. However, the quantitative inversion of different components in mixed minerals remains difficult in mineral spectral analysis. A set of mineral samples was prepared from dolomite and gypsum, varying in their components. Three improved spectral decomposition [...] Read more.

Hyperspectral technology can non-destructively identify and analyze minerals. However, the quantitative inversion of different components in mixed minerals remains difficult in mineral spectral analysis. A set of mineral samples was prepared from dolomite and gypsum, varying in their components. Three improved spectral decomposition models were proposed: the Continuum Removal-Fully Constrained Linear Spectral Model (CR-FCLSM), the Natural Logarithm-Fully Constrained Linear Spectral Model (NL-FCLSM), and the Ratio Derivative Model (RDM). The unmixing Abundance Error (AE) was 0.161, 0.051, and 0.082 for CR-FCLSM, NL-FCLSM, and RDM. The results of the three improved linearized unmixing models are better than those of the traditional linear spectral unmixing model. The NL-FCLSM effectively enhanced the linear characteristics of the spectrum, making it more suitable for two mineral mixing scenarios. The systematic bias of CR-FCLSM may be due to its insufficient sensitivity to low-abundance signals. The stability of RDM depends on the selection of a strong linear band. The unmixing experiments of the measured spectra and the data from the USGS spectral library demonstrate that the improved linear unmixing model is more accurate than the traditional linear spectral model and simpler to calculate than the nonlinear spectral model, providing a new approach for demodulating hyperspectral images. Full article

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

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32 pages, 68153 KB

Open AccessEditor’s ChoiceReview

Barite Deposits of Türkiye: A Review

by Zeynep Cansu, Hüseyin Öztürk and Nurullah Hanilçi

Minerals 2025, 15(7), 692; https://doi.org/10.3390/min15070692 - 28 Jun 2025

Viewed by 1107

Abstract

Türkiye hosts a wide variety of barite deposits that can be broadly classified into two major groups based on their tectonic settings: magmatism-associated and passive margin-hosted deposits. The magmatism-associated deposits include Kızılcaören (F + Ba + REE + Th, Beylikova–Eskişehir), Kirazören (Bulancak–Giresun), and [...] Read more.

Türkiye hosts a wide variety of barite deposits that can be broadly classified into two major groups based on their tectonic settings: magmatism-associated and passive margin-hosted deposits. The magmatism-associated deposits include Kızılcaören (F + Ba + REE + Th, Beylikova–Eskişehir), Kirazören (Bulancak–Giresun), and Karacaören (Mesudiye–Ordu). The Kızılcaören deposit formed in relation to the emplacement of a late Oligocene carbonatitic sill, while the Kirazören and Karacaören deposits are associated with the Cretaceous Pontide magmatic arc. Passive margin-hosted deposits occur within various Paleozoic sedimentary lithologies—such as metasandstone, shale, schist, and limestone—and are found in the Taurides and the Arabian Platform. These deposits occur as either concordant or discordant veins. This barite belt extends from Şarkikaraağaç (Isparta), through Hüyük (Konya) and Alanya (Antalya), to Silifke (Mersin), Tordere (Adana), Önsen, Şekeroba (Kahramanmaraş), and Hasköy (Muş). The Paleozoic deposits represent the major barite resources of Türkiye, with an annual production of approximately 300,000 metric tons. Smaller deposits around Gazipaşa (Antalya) contain minor Pb-Zn sulfides. Mesozoic barite deposits are hosted in Triassic dolomites and are associated with Pb-Zn mineralization in the Hakkari region of the Arabian Platform. Pb and Sr isotope data indicate that the barium in these deposits was derived from ancient continental crust. The isotopic compositions of both concordant (stratabound) and discordant (vein-type) barites are generally homogeneous. In northwestern Türkiye, the Sr isotope compositions of the barite deposits align well with those of the Oligocene carbonatite host complex. The ⁸⁷Sr/⁸⁶Sr isotope ratio of the Kızılcaören deposit (0.706‰) is the least radiogenic among Turkish barite deposits, suggesting a mantle contribution. The Kirazören deposit in the Pontide magmatic arc follows with a slightly higher ratio (0.707‰). Triassic barites from the Hakkari region yield ⁸⁷Sr/⁸⁶Sr values around 0.709‰, slightly more radiogenic than coeval seawater. Paleozoic barite deposits show the most radiogenic ⁸⁷Sr/⁸⁶Sr values, including Aydıncık (0.718‰), Şarkikaraağaç (0.714‰), Hasköy (0.713‰), Kahramanmaraş (0.712‰), Tordere, and Hüyük (both 0.711‰), consistent with their respective host rocks. The elevated radiogenic Pb and Sr isotope values in the passive margin-hosted deposits suggest that the barium originated from deeper, barium-enriched rocks, whereas stable sulfur isotope data point to a marine sulfur source. Moreover, Sr and S isotopic signatures indicate that the Paleozoic sediment-hosted deposits formed in association with cold seeps on the seafloor, resembling modern analogs. In contrast, the Mesozoic Karakaya deposit (Hakkari) represents a typical vent-proximal, sediment-hosted deposit with no magmatic signature. Full article

(This article belongs to the Special Issue Stratabound Barite Deposits: Mineralogy, Isotope Geochemistry and Geochronology)

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32 pages, 21563 KB

Open AccessEditor’s ChoiceArticle

Diagenetic Classification—A New Concept in the Characterization of Heterogeneous Carbonate Reservoirs: Permian–Triassic Successions in the Persian Gulf

by Hamzeh Mehrabi, Saghar Sadat Ghoreyshi, Yasaman Hezarkhani and Kulthum Rostami

Minerals 2025, 15(7), 690; https://doi.org/10.3390/min15070690 - 27 Jun 2025

Viewed by 744

Abstract

Understanding diagenetic processes is fundamental to characterizing heterogeneous carbonate reservoirs, where variations in pore structures and mineralogy significantly influence reservoir quality and fluid flow behavior. This study presents an integrated diagenetic classification approach applied to the upper Dalan and Kangan formations in the [...] Read more.

Understanding diagenetic processes is fundamental to characterizing heterogeneous carbonate reservoirs, where variations in pore structures and mineralogy significantly influence reservoir quality and fluid flow behavior. This study presents an integrated diagenetic classification approach applied to the upper Dalan and Kangan formations in the Persian Gulf. Utilizing extensive core analyses, petrographic studies, scanning electron microscopy (SEM) imaging, and petrophysical data, six distinct diagenetic classes were identified based on the quantification of key processes such as dolomitization, dissolution, cementation, and compaction. The results reveal that dolomitization and dissolution enhance porosity and permeability, particularly in high-energy shoal facies, while cementation and compaction tend to reduce reservoir quality. A detailed petrographic examination and rock typing, including pore type classification and hydraulic flow unit analysis using flow zone indicator methods, allowed the subdivision of the reservoir into hydraulically meaningful units with consistent petrophysical characteristics. The application of the Stratigraphic Modified Lorenz Plot facilitated large-scale reservoir zonation, revealing the complex internal architecture and significant heterogeneity controlled by depositional environments and diagenetic overprints. This diagenetic classification framework improves predictive modeling of reservoir behavior and fluid distribution, supporting the optimization of exploitation strategies in heterogeneous carbonate systems. The approach demonstrated here offers a robust template for similar carbonate reservoirs worldwide, emphasizing the importance of integrating diagenetic quantification with multi-scale petrophysical and geological data to enhance reservoir characterization and management. Full article

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

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25 pages, 3819 KB

Open AccessEditor’s ChoiceArticle

Evolution of Mafic Tungnárhraun Lavas: Transcrustal Magma Storage and Ascent Beneath the Bárðarbunga Volcanic System

by Tanya Furman, Denali Kincaid and Collin Oborn Brady

Minerals 2025, 15(7), 687; https://doi.org/10.3390/min15070687 - 27 Jun 2025

Viewed by 779

Abstract

The Tungnárhraun basalts in southern Iceland record a transcrustal magma system formed during Holocene deglaciation. These large-volume (>1 km³) Early through Mid-Holocene lavas contain ubiquitous plagioclase feldspar macrocrysts that are too primitive to have grown from the host lavas. Thermobarometry based [...] Read more.

The Tungnárhraun basalts in southern Iceland record a transcrustal magma system formed during Holocene deglaciation. These large-volume (>1 km³) Early through Mid-Holocene lavas contain ubiquitous plagioclase feldspar macrocrysts that are too primitive to have grown from the host lavas. Thermobarometry based on plagioclase melt and clinopyroxene melt equilibrium reveals a transcrustal structure with at least three distinct storage regions. A lower-crustal mush zone at ~14–30 km is fed by primitive, low ⁸⁷Sr/⁸⁶Sr magmas with diverse Ti/K and Al/Ti signatures. Plagioclase feldspar growth is controlled by an experimentally determined pseudoazeotrope where crystals develop inversely correlated An and Mg contents. The rapid ascent of magmas to mid-crustal levels (~8–9 km) allows the feldspar system to revert to conventional thermodynamic phase constraints. Continued plagioclase growth releases heat, causing olivine and pyroxene to be resorbed and giving the magmas their characteristic high CaO/Al₂O₃ values (~0.8–1.0) and Sc contents (~52 ppm in matrix material). Mid-Holocene MgO-rich lavas with abundant plagioclase feldspar macrocrysts erupted directly from this depth, but both older and younger magmas ascended to a shallow-crustal storage chamber (~5 km) where they crystallized olivine, clinopyroxene, and plagioclase feldspar and evolved to lower MgO contents. The Sr isotope differences between the plagioclase macrocrysts and their carrier melts suggest that the fractionation involves the minor assimilation of country rock. This model does not require the physical disruption of an established and long-lived gabbroic cumulate mush. The transcrustal structures documented here existed in south Iceland at least throughout the Holocene and likely influenced much of Icelandic magmatism. Full article

(This article belongs to the Special Issue Trans-Crustal Evolution of Magmas: Clues from Thermodynamic and Geochemical Modelling, Thermo-Barometry and Experimental Petrology)

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31 pages, 34129 KB

Open AccessEditor’s ChoiceArticle

Prediction of Buried Cobalt-Bearing Arsenides Using Ionic Leach Geochemistry in the Bou Azzer-El Graara Inlier (Central Anti-Atlas, Morocco): Implications for Mineral Exploration

by Yassine Lmahfoudi, Houssa Ouali, Said Ilmen, Zaineb Hajjar, Ali El-Masoudy, Russell Birrell, Laurent Sapor, Mohamed Zouhair and Lhou Maacha

Minerals 2025, 15(7), 676; https://doi.org/10.3390/min15070676 - 24 Jun 2025

Cited by 1 | Viewed by 1552

Abstract

The Aghbar-Bou Azzer East mining district (ABED) is located between the Bou Azzer East and Aghbar deposits. It is an area of approximately 7 km long towards ENE–WSW and 2 km wide towards N–S. In this barren area, volcano-sedimentary rocks are attributed to [...] Read more.

The Aghbar-Bou Azzer East mining district (ABED) is located between the Bou Azzer East and Aghbar deposits. It is an area of approximately 7 km long towards ENE–WSW and 2 km wide towards N–S. In this barren area, volcano-sedimentary rocks are attributed to the Ouarzazate group outcrop (Ediacarian age): they are composed of volcanic rocks (ignimbrite, andesite, rhyolite, dacite, etc.) covered by the Adoudou detritic formation in angular unconformity. Given the absence of serpentinite outcrops, exploration investigation in this area has been very limited. This paper aims to use ionic leach geochemistry (on samples of soil) to detect the presence of Co-bearing arsenides above hidden ore deposits in this unexplored area of the Bou Azzer inlier. In addition, a detailed structural analysis allowed the identification of four families of faults and fractures with or without filling. Three directional major fault systems of several kilometers in length and variable orientation in both the Cryogenian basement and the Ediacaran cover have been identified: (i) ENE–WSW, (ii) NE–SW, and (iii) NW–SE. Several geochemical anomalies for Co, As, Ni, Ag, and Cu are aligned along three main directions, including NE–SW, NW–SE, and ENE–WSW. They are particularly well-defined in the western zone but are only minor in the central and eastern zones. Some of these anomalies correlate with the primary structural features observed in the studied area. These trends are consistent with those known under mining exploitation in nearby ore deposits, supporting the potential for similar mineralization in the ABED. Based on structural analysis and ionic leach geochemistry, drilling programs were conducted in the study area, confirming the continuity of serpentinites at depth beneath the Ediacaran cover and the presence of Co–Fe-bearing arsenide ores. This validates the ionic geochemistry technique as a reliable method for exploring buried ore deposits. Full article

(This article belongs to the Special Issue Novel Methods and Applications for Mineral Exploration, Volume III)

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18 pages, 6291 KB

Open AccessEditor’s ChoiceArticle

Petrological Exploration of Magma Storage and Evolution Conditions at the Eastern Virunga Volcanic Province (Rwanda, East African Rift System)

by Fabio Colle, Teresa Trua, Serena Giacomelli, Massimo D’Orazio and Roberto Valentino

Minerals 2025, 15(7), 666; https://doi.org/10.3390/min15070666 - 20 Jun 2025

Cited by 1 | Viewed by 588

Abstract

The Virunga Volcanic Province (VVP), located in the western branch of the East African Rift System, hosts a variety of alkaline lavas erupted from closely spaced volcanic centers. However, the magmatic system of this region, particularly in its eastern sector, remains insufficiently constrained. [...] Read more.

The Virunga Volcanic Province (VVP), located in the western branch of the East African Rift System, hosts a variety of alkaline lavas erupted from closely spaced volcanic centers. However, the magmatic system of this region, particularly in its eastern sector, remains insufficiently constrained. In this study, we present a petrological and geochemical investigation of basaltic to trachytic lavas from the eastern VVP. Thermobarometric analysis of mineral phases indicates that basalts originated from magma storage zones between 4 and 30 km deep, with crystallization temperatures of ~1200 °C and melt H₂O contents lower than 1 wt%. In contrast, more evolved magmas crystallized at similar depths, but at lower temperatures (~1050 °C) and higher H₂O contents, ranging from 2 to 4 wt%. Thermodynamic modelling suggests that extensive (up to 70%) fractional crystallization of an assemblage dominated by olivine, clinopyroxene, and plagioclase can produce the more evolved trachytic derivatives from basaltic parental melts. When integrated with previous studies from other VVP volcanoes, our findings deepen the understanding of the architecture of the magmatic system beneath the region, suggesting it resembles a well-developed multi-level plumbing system. Full article

(This article belongs to the Special Issue Trans-Crustal Evolution of Magmas: Clues from Thermodynamic and Geochemical Modelling, Thermo-Barometry and Experimental Petrology)

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24 pages, 4791 KB

Open AccessEditor’s ChoiceArticle

Zircon out, Elpidite in: Deformation-Driven Zirconosilicate Evolution in Peralkaline Granites: A Case Study of the Papanduva Pluton (Brazil)

by Larissa P. Grangeiro, Frederico C. J. Vilalva, Silvio R. F. Vlach and Armando L. S. de Oliveira

Minerals 2025, 15(7), 667; https://doi.org/10.3390/min15070667 - 20 Jun 2025

Viewed by 434

Abstract

The peralkaline granites of the Papanduva Pluton (South Brazil) display a remarkable facies dichotomy, with zircon dominant in massive facies and diverse zirconosilicates (Zr-Si) in foliated facies. This study employs petrography and mineral chemistry (major and trace elements) to elucidate the textural diversity [...] Read more.

The peralkaline granites of the Papanduva Pluton (South Brazil) display a remarkable facies dichotomy, with zircon dominant in massive facies and diverse zirconosilicates (Zr-Si) in foliated facies. This study employs petrography and mineral chemistry (major and trace elements) to elucidate the textural diversity and compositional evolution of these minerals. Three discrete zirconosilicate groups were identified: Na-rich elpidite (euhedral, vein-like, and granular varieties), Na-poor (Na,K)Zr-Si-I, and silica-rich (Na,K)Zr-Si-II. Contrary to the expected crystallization sequences, trace element data reveal that REE enrichment correlates with deformation intensity rather than paragenetic order, with vein-like aggregates along deformation features showing the highest REE concentrations. Statistical analysis demonstrates significant correlations between REE contents and alkali exchange patterns. We propose a three-stage evolutionary model involving magmatic crystallization, deformation-enhanced fluid interaction, and late-stage recrystallization, with a progressive evolution from Na-dominated to K-dominated conditions. This study provides new insights into closed-system fluid evolution in agpaitic environments and highlights deformation as a primary control on element mobility in peralkaline granitic systems. Full article

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

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34 pages, 12770 KB

Open AccessEditor’s ChoiceArticle

Immiscibility in Magma Conduits: Evidence from Granitic Enclaves

by Ya Tian, Guanglai Li, Yongle Yang, Chao Huang, Yinqiu Hu, Kai Xu and Ji Zhang

Minerals 2025, 15(7), 664; https://doi.org/10.3390/min15070664 - 20 Jun 2025

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Abstract

Many granitic enclaves are developed in the volcanic channel of the Xiangshan volcanic basin. To explore their genesis, this study examined the petrography, geochemistry, LA-ICP-MS zircon U–Pb chronology, and zircon Hf isotopes of the granitic enclaves and compared them with the porphyroclastic lavas. [...] Read more.

Many granitic enclaves are developed in the volcanic channel of the Xiangshan volcanic basin. To explore their genesis, this study examined the petrography, geochemistry, LA-ICP-MS zircon U–Pb chronology, and zircon Hf isotopes of the granitic enclaves and compared them with the porphyroclastic lavas. In general, the granitic enclaves and porphyroclastic lavas have similar structures, and the rock-forming minerals and accessory minerals have relatively close compositions. In terms of rock geochemical characteristics, the granitic enclaves are richer in silicon and alkalis but have lower abundances of aluminum, magnesium, iron, and calcium than the porphyroclastic lavas. Rb, Th, K, Sm, and other elements are more enriched, whereas Ba, Ti, Nb, P, and other elements are more depleted. The granitic enclaves have lower rare earth contents (195.53 × 10⁻⁶–271.06 × 10⁻⁶) than the porphyroclastic lavas (246.67 × 10⁻⁶–314.27 × 10⁻⁶). The rare earth element distribution curves of the two are generally consistent, both right-leaning, and enriched with light rare earth patterns. The weighted average zircon U–Pb ages of two granitic enclave samples were 135.45 ± 0.54 Ma (MSWD = 0.62, n = 17) and 135.81 ± 0.60 Ma (MSWD = 0.40, n = 20), respectively, which are consistent with the weighted average age of a single porphyroclastic lava sample of 134.01 ± 0.53 Ma (MSWD = 2.0, n = 20). The zircons of the two kinds of rocks crystallize at almost the same temperature. The consistent trend of the rare earth element distribution curve of zircons in the granitic enclaves and the porphyroclastic lava samples indicates that the zircons of the two samples were formed in the same stage. The formation process of granitic enclaves may be that the lower crustal melt is induced to rise, and the crystallization differentiation occurs in the magma reservoir and is stored in the form of crystal mush, forming a shallow crystal mush reservoir. The crystal mush reservoir is composed of a large number of rock-forming minerals such as quartz, feldspar, and biotite, as well as accessory mineral crystals such as zircon and flowable intergranular melt. In the later stage of magma high evolution, a small and short-time magmatic activity caused a large amount of crystalline granitic crystal mush to pour into the volcanic pipeline. In the closed system of volcanic pipeline, the pressure and temperature decreased rapidly, and the supercooling degree increased, and the immiscibility finally formed pale granitic enclaves. Full article

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

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23 pages, 11397 KB

Open AccessEditor’s ChoiceArticle

Tectonic Evolution of Wadi Hebran Area on the Suez Rift Eastern Flank, Sinai, Egypt

by Sherif Mansour, Amr Elkelish, Abdullah S. Alawam, Mohamed A. Gharib, Akihiro Tamura and Noriko Hasebe

Minerals 2025, 15(6), 655; https://doi.org/10.3390/min15060655 - 18 Jun 2025

Viewed by 1041

Abstract

Continental rifts represent one of the most important settings geologically and economically. The Suez Rift represents more than 74% of the Egyptian crude oil. It represents the northern end of the Red Sea, which understanding is vital to reconstructing the tectonics, dynamics, and [...] Read more.

Continental rifts represent one of the most important settings geologically and economically. The Suez Rift represents more than 74% of the Egyptian crude oil. It represents the northern end of the Red Sea, which understanding is vital to reconstructing the tectonics, dynamics, and time–temperature history of the whole region. An effective method to reveal rift-related history is by studying its flanks, which are represented here by the Arabian-Nubian Shield Neoproterozoic basement rocks. We applied an approach integrating new fission-track thermochronology data, new time–temperature modeling, stratigraphic information, and geological knowledge, which has proven its effectiveness in such geological settings. The collected samples from the Wadi Hebran area on the eastern flank of the Suez rift showed two differentiated cooling histories: The first has a Carboniferous zircon fission-track and a Cretaceous apatite fission-track age, and the second has a Triassic zircon fission-track and an Oligocene–Miocene apatite fission-track age. The time–temperature history modeling supported four distinct cooling events activated through the Neoproterozoic post-accretion erosional event, Variscan tectonic event, Gondwana disintegration, and the Suez Rift initiation. The rock uplift that accompanied the Suez Rift reaches up to 4 km, explaining the extraordinary elevations of the Catherina region, and supports an active rift component in the southern segment of the Suez Rift eastern flank. Full article

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

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11 pages, 1410 KB

Open AccessEditor’s ChoiceArticle

Theoretical Study on Impact of Chemical Composition and Water Content on Mechanical Properties of Stratlingite Mineral

by Daniel Tunega and Ali Zaoui

Minerals 2025, 15(6), 648; https://doi.org/10.3390/min15060648 - 16 Jun 2025

Viewed by 438

Abstract

Stratlingite is known as one of the hydration products of aluminum-rich cements. Its microstructure and, consequently, mechanical properties, depend on the Al/Si ratio and hydration conditions. The layered structure of stratlingite is characterized as defected, with vacancies in the aluminosilicate layer. This study [...] Read more.

Stratlingite is known as one of the hydration products of aluminum-rich cements. Its microstructure and, consequently, mechanical properties, depend on the Al/Si ratio and hydration conditions. The layered structure of stratlingite is characterized as defected, with vacancies in the aluminosilicate layer. This study uses density functional theory calculations on different stratlingite models to show how chemical composition, water content, and structural defects affect its mechanical properties. The developed models represent structures with full occupancy, with little or no content of structural water, and with vacancies in the aluminosilicate layer. It was shown that the full occupancy models have the highest toughness and are strongly anisotropic. The calculated bulk modulus (B_H) of the models with full occupancy was about 40 GPa, being in the typical range for calcium aluminosilicate minerals. The water loss led to an increase in B_H by approximately 40% compared to the models with full occupancy. In contrast, the models with vacancies exhibited a decrease in B_H of about 30%. In models with the high silicon content (Al/Si ratio of 1/4), B_H, Young’s (E_H), and shear (G_H) moduli decreased in a range 15%–30% compared to the models with an Al/Si ratio of 2/3 of Al/Si. Finally, according to Pugh’s ratio (B_H/G_H), which serves as a criterion for brittle–ductile transition (1.8), the models with full occupancy exhibit a brittle behavior, whereas the defected structures are closer to ductile. This could explain the elastic behavior of stratlingite binder in concretes. Generally, the calculations showed that all investigated parameters (chemical composition, water content, and structural defects) have a significant impact on the mechanical properties of stratlingite minerals. Full article

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

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19 pages, 11500 KB

Open AccessEditor’s ChoiceArticle

Continental Rift Driven by Asthenosphere Flow and Lithosphere Weakening by Flood Basalts: South America and Africa Cenozoic Rifting

by Ingo L. Stotz, Berta Vilacís, Jorge N. Hayek and Hans-Peter Bunge

Minerals 2025, 15(6), 644; https://doi.org/10.3390/min15060644 - 13 Jun 2025

Viewed by 806

Abstract

Continental rifting is the process by which land masses separate and create new ocean basins. The emplacement of large igneous provinces (LIPs) is thought to have played a key role in (super) continental rifting; however, this relationship remains controversial due to the lack [...] Read more.

Continental rifting is the process by which land masses separate and create new ocean basins. The emplacement of large igneous provinces (LIPs) is thought to have played a key role in (super) continental rifting; however, this relationship remains controversial due to the lack of a clearly established mechanism linking LIP emplacement to continental fragmentation. Here, we show that plume flow links LIP magmatism to continental rifting quantitatively. Our findings are further supported by the sedimentary record, as well as by the mineralogy and petrology of the rocks. This study analyzes the early Cretaceous separation of West Gondwana into South America and Africa. Prior to rifting, Jurassic hiatuses in the stratigraphic record of continental sediments from both continents indicate plume ascent and the resulting dynamic topography. Cretaceous mafic dyke swarms and sill intrusions are products of major magmatic events that coincided with continental rifting, leading to the formation of large igneous provinces in South America and Africa, including the Central Atlantic Magmatic Province, Equatorial Magmatic Province, Paraná–Etendeka, and Karoo. It has been suggested that dyke intrusions may weaken the lithosphere by reducing its mechanical strength, creating structural weaknesses that localize extensional deformation and facilitate rift initiation. The sedimentary analysis and petrological evidence from flood basalt magmas indicate that plumes may have migrated from the depths toward the surface during the Jurassic and erupted during the Cretaceous. It is thought that the resulting fast plume flow, induced by one or more mantle plumes, generated a dynamic force that, in combination with lithospheric weakening from dyke intrusion, eventually rifted the lithosphere of West Gondwana. Full article

(This article belongs to the Special Issue Large Igneous Provinces: Research Frontiers)

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