Minerals

39 pages, 28889 KiB

Open AccessFeature PaperArticle

Pyrochlore-Supergroup Minerals and Their Relation to Columbite-Group Minerals in Peralkaline to Subaluminous A-Type Rare-Metal Granites with Special Emphasis on the Madeira Pluton, Amazonas, Brazil

by Karel Breiter, Hilton Tulio Costi and Zuzana Korbelová

Minerals 2024, 14(12), 1302; https://doi.org/10.3390/min14121302 - 23 Dec 2024

Viewed by 569

Abstract

Niobium (Nb) and tantalum (Ta) are quoted as “strategic” or “critical” elements for contemporaneous society. The main sources of Nb and Ta are minerals of the pyrochlore supergroup (PSGM) and the columbite group (CGM) mined from different magmatic lithologies. Textures and chemical compositions [...] Read more.

Niobium (Nb) and tantalum (Ta) are quoted as “strategic” or “critical” elements for contemporaneous society. The main sources of Nb and Ta are minerals of the pyrochlore supergroup (PSGM) and the columbite group (CGM) mined from different magmatic lithologies. Textures and chemical compositions of PSGM and CGM often provide key information about the origin of NbTa mineralization. Therefore, we decided to carry out a detailed study of the relations between the PSGM and CGM and their post-magmatic transformations, and the Madeira peralkaline pluton (Brazil) is an ideal object for such a study. Textures of the PSGM and CGM were studied using BSE imaging and SEM mapping, and their chemical compositions were determined using 325 electron microprobe analyses. Pyrochlore from the Madeira granite can be chemically characterized as Na, Ca-poor, U- and Pb-dominant, and Sn- and Zn-enriched; REE are enriched only during alteration. Two stages of alteration are present: (i) introduction of Fe + Mn, with the majority of them consumed by columbitization; (ii) introduction of Si and Fe, and in lesser amounts also Pb and U: Si, Pb, and U incorporated into pyrochlore, iron forming Fe-oxide halos around pyrochlore. During both stages, F and Na decreased. In the case of a (nearly) complete pyrochlore columbitization, U and Th were exsolved to form inclusions of a thorite/coffinite-like phase. In contrast to altered pyrochlores from other localities, pyrochlore from Madeira shows a relatively high occupancy of the A-site. Although Madeira melt was Na-, F-rich, contemporaneous crystallization of cryolite consumed both elements and pyrochlore was, from the beginning, relatively Na-, F-poor. Full article

(This article belongs to the Special Issue Rare-Metal Granites)

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12 pages, 4421 KiB

Open AccessArticle

The Crystal Chemistry and Structure of V-Bearing Silicocarnotite from Andradite–Gehlenite–Pseudowollastonite Paralava of the Hatrurim Complex, Israel

by Evgeny V. Galuskin, Irina O. Galuskina, Maria Książek, Joachim Kusz, Yevgeny Vapnik and Grzegorz Zieliński

Minerals 2024, 14(12), 1301; https://doi.org/10.3390/min14121301 - 23 Dec 2024

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Abstract

Silicocarnotite, Ca₅[(PO₄)(SiO₄)](PO₄), was first described from slag over 140 years ago. In 2013, it was officially recognised as a mineral after being discovered in the larnite–gehlenite hornfels of the pyrometamorphic Hatrurim Complex. This paper describes [...] Read more.

Silicocarnotite, Ca₅[(PO₄)(SiO₄)](PO₄), was first described from slag over 140 years ago. In 2013, it was officially recognised as a mineral after being discovered in the larnite–gehlenite hornfels of the pyrometamorphic Hatrurim Complex. This paper describes the composition and structure of V-bearing silicocarnotite, crystals of which were found in a thin paralava vein cutting through the gehlenite hornfels. A network of thin paralava veins a few centimetres thick is widespread in the gehlenite hornfels of the Hatrurim Basin, Negev Desert, Israel. These veins, typically coarse crystalline rock and traditionally referred to as paralava, have a symmetrical structure and do not contain glass. Silicocarnotite in the paralava, whose primary rock-forming minerals are gehlenite, flamite, Ti-bearing andradite, rankinite and pseudowollastonite, was a relatively late-stage high-temperature mineral, crystallising at temperatures above 1100 °C. It formed from the reaction of a Si-rich residual melt with pre-existing fluorapatite. A single-crystal structural study of silicocarnotite (Pnma, a = 6.72970(12) Å, b = 15.5109(3) Å, c = 10.1147(2) Å) suggests that the phenomenon of Ca1 position splitting observed in this mineral is most likely related to the partial ordering of Si and P in the T2O₄ tetrahedrons. Raman studies of silicocarnotite with varying vanadium content have shown that phases with V₂O₅ content of 3–5 wt.% exhibit additional bands at approximately 864 cm⁻¹, corresponding to vibrations of ν₁(VO₄)³⁻. Full article

(This article belongs to the Special Issue Isomorphism, Chemical Variability, and Solid Solutions of Minerals and Related Compounds, 2nd Edition)

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12 pages, 4751 KiB

Open AccessArticle

Investigation of Appropriate Collector Selection for Hematite Removal from Pyrolusite and the Adsorption Mechanism on the Crystal Surface

by Yuhang Shi, Nan Nan, Baoxu Song, Fangyuan Ma, Jiquan Han, Enming Huang, Shuai Wang, Guang Yang and Lan Zhou

Minerals 2024, 14(12), 1300; https://doi.org/10.3390/min14121300 - 23 Dec 2024

Viewed by 554

Abstract

This study examined the appropriate hematite (Fe₂O₃) collector for the concentration of pyrolusite (MnO₂) in a reverse flotation. Actual ore flotation studies were performed to determine how sodium oleate, sodium dodecyl sulfonate, and oxidized paraffin soap affect [...] Read more.

This study examined the appropriate hematite (Fe₂O₃) collector for the concentration of pyrolusite (MnO₂) in a reverse flotation. Actual ore flotation studies were performed to determine how sodium oleate, sodium dodecyl sulfonate, and oxidized paraffin soap affect hematite removal during reverse flotation of pyrolusite ore. In order to explore the flotation mechanism, simulation experiments were carried out. Firstly, the crystal models of pyrolusite and hematite were established. Then, in order to verify the reliability of the simulation results, the simulated XRD spectra of the crystal model were compared with the measured spectra. Finally, density functional theory and molecular dynamics modeling were used to study the interaction between collector molecules and mineral surfaces. The flotation test results show that oxidized paraffin soap is the best hematite collector and promotes its flotation, removing iron from pyrolusite. Molecular dynamics simulations and density functional theory show that the three collectors (oxidized paraffin soap, sodium oleate, and sodium dodecyl sulfonate) have a much stronger interaction with hematite than with pyrolusite. Therefore, it is possible to separate pyrolusite and hematite through flotation. The simulation results also show that oxidized paraffin soap has the highest adsorption strength and selectivity for hematite. This characteristic makes oxidized paraffin soap an excellent collector for effectively removing hematite from pyrolusite in the reverse flotation process. Full article

(This article belongs to the Special Issue Desorption and/or Reuse of Collectors in Mineral Flotation)

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18 pages, 2383 KiB

Open AccessArticle

Retention of Nickel and Cobalt in Boda Claystone Formation

by Ottó Czömpöly, Fruzsina Szabó, Margit Fábián, Tamás Kolonits, Zsolt Fogarassy, Dániel Zámbó, Marc Aertsens and János Osán

Minerals 2024, 14(12), 1299; https://doi.org/10.3390/min14121299 - 22 Dec 2024

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Abstract

The Boda Claystone Formation (BCF) is considered to serve as a natural barrier to the potential high-level radioactive waste repository in Hungary. In order to evaluate the radionuclide retention capacity of the albitic claystone of the BCF, the adsorption and diffusion properties of [...] Read more.

The Boda Claystone Formation (BCF) is considered to serve as a natural barrier to the potential high-level radioactive waste repository in Hungary. In order to evaluate the radionuclide retention capacity of the albitic claystone of the BCF, the adsorption and diffusion properties of the rock for Ni²⁺ and Co²⁺ cations (activation products) were investigated separately and in competitive conditions when the two ions were simultaneously added. Batch sorption experiments were performed with powdered and conditioned albitic claystone samples in synthetic pore water to obtain adsorption isotherms. In addition, adsorption tests were performed on petrographic thin sections to check the transferability between dispersed and compact systems. Correlation analysis of microscopic X-ray fluorescence elemental maps recorded on thin sections suggested that nickel is primarily bound to clay minerals (mainly illite and chlorite), which was confirmed by (scanning) transmission electron microscopy measurements. Around illite particles, a newly formed nickel-rich few atomic layer thick phyllosilicate phase was identified. The discrepancy between the experimental and modeled adsorption isotherm at high concentrations could be explained with this nickel-rich new phase. Apart from C_in = 10⁻³ M and only Ni²⁺ or Co²⁺ in the source, the apparent diffusion coefficients of Ni²⁺ and Co²⁺ (C_in = 10⁻³–10⁻² M) were found to be similar. Overall, the BCF shows promising capabilities to retain the studied radionuclides. Full article

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

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21 pages, 5031 KiB

Open AccessArticle

Interaction Between Nonionic Surfactants and Alkyl Amidoamine Cationic Collector in the Reverse Flotation of Iron Ore

by José Tadeu Gouvêa Junior, Flávia Paulucci Cianga Silvas, Christian Lariguet Taques Bittencourt, Vantuir Jorge de Morais, Ali Asimi Neisiani and Laurindo de Salles Leal Filho

Minerals 2024, 14(12), 1298; https://doi.org/10.3390/min14121298 - 22 Dec 2024

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Abstract

This paper evaluates the performance of four ethoxylated nonionic surfactants (nonyl phenol vs. C₁₃ alcohols) to act as ancillary collectors with Alkyl Amidoamine (AAA) in the reverse flotation of quartz at pH8 to concentrate iron ores. Compared to 100% AAA, the blend [...] Read more.

This paper evaluates the performance of four ethoxylated nonionic surfactants (nonyl phenol vs. C₁₃ alcohols) to act as ancillary collectors with Alkyl Amidoamine (AAA) in the reverse flotation of quartz at pH8 to concentrate iron ores. Compared to 100% AAA, the blend composed of 80% AAA (Flotinor^®5530) plus 20% of isotridecyl alcohol ethoxylated with five groups of ethylene oxide (DP-210 RO) improved quartz recovery (from 54% to 63%, p < 0.05) by increasing contact angle (from 55° to 56°, p < 0.05) and decreasing induction time (26 ms to 23 ms, p < 0.05). Compared to 100% AAA (200 g/t), the blend (160 g/t of AAA + 40 g/t of DP-210 RO) improved the flotation performance of iron ore, yielding richer hematite concentrate (65.3% Fe × 61.4% Fe) and less contaminated with quartz (4% SiO₂ × 10.2% SiO₂), coupled with an increase in Fe recovery from 79.8% × 81.6% in the sunken product as well as SiO₂ recovery from 91.7% to 96.9% in the froth. Results from zeta potential, the hydrodynamic diameter of reagent droplets, and the surface tension of the solution provide insights into the synergism between AAA and DP-210 RO. Full article

(This article belongs to the Special Issue An Overview of Applications and Types of Flotation Reagents: Performance, Efficiency and Optimization)

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11 pages, 25539 KiB

Open AccessArticle

Generation of Pre-Caldera Qixiangzhan and Syn-Caldera Millennium Rhyolites from Changbaishan Volcano by Shallow Remelting: Evidence from Zircon Hf–O Isotopes

by Haibo Zou and Jie Tong

Minerals 2024, 14(12), 1297; https://doi.org/10.3390/min14121297 - 22 Dec 2024

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Abstract

The Changbaishan volcano is well known for its major caldera-forming Millennium Eruption (ME) in 946 CE (Common Era). We report Hf–O isotopes of zircon grains from pre-caldera Qixiangzhan (QXZ) and syn-caldera eruptions of the Changbaishan (Baitoushan) volcano to constrain magma chamber processes. Zircon [...] Read more.

The Changbaishan volcano is well known for its major caldera-forming Millennium Eruption (ME) in 946 CE (Common Era). We report Hf–O isotopes of zircon grains from pre-caldera Qixiangzhan (QXZ) and syn-caldera eruptions of the Changbaishan (Baitoushan) volcano to constrain magma chamber processes. Zircon grains from the pre-caldera QXZ comendite lavas have δ¹⁸O ranging from 4.46 to 5.16 (lower than mantle values) and ε_Hf ranging from −4.47 to +4.37. Zircon grains from the syn-caldera ME1 charcoal-bearing non-welded comendite pyroclastic flow deposits have δ¹⁸O ranging from 2.25 (lower than mantle values) to 5.51 and ε_Hf from −3.75 to +3.31. By comparison, zircon grains from the ME2 welded trachytes have δ¹⁸O ranging from 5.66 to 6.20 (higher than mantle zircon values) and ε_Hf from −1.97 to +6.23. There are no correlations between O and Hf isotopes for all zircon grains in QXZ and ME1 comendites and ME2 trachyte. The ubiquitous occurrence of low-δ¹⁸O zircon grains in QXZ and ME1 comendites indicates shallow remelting of hydrothermally altered low-δ¹⁸O juvenile rocks. By contrast, ME2 trachyte zircons (except for two zircon grains) have normal δ¹⁸O (5.66 to 6.10) values, indicating a lack of remelting processes. Similar zircon Hf–O isotopes between pre-caldera QXZ comendites and syn-caldera ME1 comendites indicate tapping of the upper portion of a zoned magma chamber. Higher δ¹⁸O in ME2 trachyte zircons indicate tapping of the deeper portion of a zoned magma chamber free from shallow remelting. The lack of significant correlations between zircon O and Hf isotopes, and the relatively high εHf values for all Changbai zircon grains, argue against partial melting of ancient continental crust or significant contaminations by ancient crustal rocks as an origin for these felsic magmas. The QXZ and ME1 comendites were formed by shallow remelting of hydrothermally altered juvenile volcanic rocks, and ME2 trachytes were formed by evolution of mantle-derived basaltic magmas free of hydrothermal assimilations. A proto-caldera likely formed prior to the generation of QXZ lavas at 10 ka. Full article

(This article belongs to the Special Issue Magmatic Evolution through Time of Volcanic Zones: Evidence from Isotopic, Geochemical and Geochronological Data of Eruption Products)

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25 pages, 4754 KiB

Open AccessArticle

A “Pipeline”-Based Approach for Automated Construction of Geoscience Knowledge Graphs

by Qiurui Feng, Ting Zhao and Chao Liu

Minerals 2024, 14(12), 1296; https://doi.org/10.3390/min14121296 - 21 Dec 2024

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Abstract

With the development of technology, Earth Science has entered a new era. Continuous research has generated a large amount of Earth Science data, including a significant amount of semi-structured and unstructured data, which contain information about locations, geographical concepts, geological characteristics of mineral [...] Read more.

With the development of technology, Earth Science has entered a new era. Continuous research has generated a large amount of Earth Science data, including a significant amount of semi-structured and unstructured data, which contain information about locations, geographical concepts, geological characteristics of mineral deposits, and relationships. Efficient management of these Earth Science data is crucial for the development of digital earth systems, rational planning of resource industries, and resource security. By representing entities, relationships, and attributes through graph structures, knowledge graphs capture and present concepts and facts about the real world, facilitating efficient data management. However, due to the highly specialized and complex nature of Earth Science data and disciplinary differences, the methods used to construct general-purpose knowledge graphs cannot be directly applied to building knowledge graphs in the field of geological science. Therefore, this paper summarizes a “pipeline” approach to constructing an Earth Science knowledge graph in order to clarify the complete construction process and reduce barriers between data and technology. This approach divides the construction of the Earth Science knowledge graph into two parts and designs functional modules under each part to specify the construction process of the knowledge graph. In addition to proposing this approach, a knowledge graph of iron ore deposits is automatically constructed by integrating geographic and geological data related to iron ore deposits using deep learning techniques. The systematic approach presented in this paper reduces the threshold for constructing geological science knowledge graphs, provides methodological support for specific disciplines or research objects in Earth Science, and also lays the foundation for the construction of large-scale Earth Science knowledge graphs that combine crowdsourcing and expert decision-making, as well as the development of intelligent question-answering systems and intelligent decision-making systems covering the entire field of Earth Science. Full article

(This article belongs to the Special Issue Application of Big Data Mining, Machine Learning and Artificial Intelligence in Geoscience, 2nd Edition)

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20 pages, 6573 KiB

Open AccessArticle

Three-Dimensional Prospective Modeling and Deep Metallogenic Prediction of the Lintan Gold Deposit in Guizhou Province, China

by Shenghong Cheng, Xiaolong Wang, Qinping Tan, Peng Liu and Lujing Zheng

Minerals 2024, 14(12), 1295; https://doi.org/10.3390/min14121295 - 20 Dec 2024

Viewed by 716

Abstract

The Lintan gold deposit, located in the “gold triangle” of Qianxinan, Guizhou Province, has become a focal point for implementing the “exploring near existing deposits” strategy, aiming to identify another large-scale gold deposit within the region. This study addresses the challenges of deep-edge [...] Read more.

The Lintan gold deposit, located in the “gold triangle” of Qianxinan, Guizhou Province, has become a focal point for implementing the “exploring near existing deposits” strategy, aiming to identify another large-scale gold deposit within the region. This study addresses the challenges of deep-edge mineral exploration in the Lintan gold deposit by adopting a metallogenic system perspective. Using a multidisciplinary approach, it integrates geological, geophysical, and geochemical datasets to construct various three-dimensional (3D) visualization and prospectivity models. The research leverages geostatistical theories and methods, multisource digital information analysis, and advanced 3D modeling and visualization techniques to verify mineralization anomalies. These efforts expand the scope of prospectivity evaluation for the deep-edge regions of the Lintan gold deposit into 3D space. In the 3D spatial framework, this study elucidates the metallogenic geological characteristics, geophysical anomalies, and geochemical signatures within the study area. Building upon this foundation, it conducts a comprehensive analysis and evaluation of geological, geochemical, and geophysical prospecting indicators under multisource geoscience datasets. This approach transitions from known to unknown domains, effectively reducing the ambiguities and uncertainties associated with single-source data interpretations. The findings demonstrate that, under the guidance of geological prospectivity models, the effective integration and synthesis of geological, geophysical, and geochemical data can reveal the interrelationships between metallogenic geological bodies and the contributing factors of the metallogenic system. This enables the identification of anomalous information associated with metallogenic geological bodies and facilitates the spatial localization and prediction of target areas for deep-edge mineral resources. The proposed methodology provides novel insights and techniques for deep-edge mineral exploration. Comprehensive analysis indicates significant prospectivity for mineral resource exploration in the deep-edge regions of the Lintan gold deposit. Full article

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

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16 pages, 5835 KiB

Open AccessArticle

LA-ICP-MS Trace Element Characteristics and Geological Significance of Stibnite in the Zhaxikang Pb–Zn–Ag–Sb Deposit, Southern Tibet, SW China

by Zijun Qiu, Jinchao Wu, Panagiotis Voudouris, Stylianos Tombros, Jiajun Liu and Degao Zhai

Minerals 2024, 14(12), 1294; https://doi.org/10.3390/min14121294 - 20 Dec 2024

Viewed by 634

Abstract

Discovered within the North Himalayan Metallogenic Belt (NHMB), the Zhaxikang Pb–Zn–Ag–Sb deposit stands as the sole super-large scale ore deposit in the region. This deposit holds significant quantities of Pb and Zn (2.066 million tons at 6.38% average grade), Ag (2661 tons at [...] Read more.

Discovered within the North Himalayan Metallogenic Belt (NHMB), the Zhaxikang Pb–Zn–Ag–Sb deposit stands as the sole super-large scale ore deposit in the region. This deposit holds significant quantities of Pb and Zn (2.066 million tons at 6.38% average grade), Ag (2661 tons at an average of 101.64 g/t), and Sb (0.235 million tons at 1.14% average grade), making it one of China’s foremost Sb–polymetallic deposits. Stibnite represents the main carrier of Sb in this deposit and has been of great attention since its initial discovery. However, the trace element composition of stibnite in the Zhaxikang deposit has not yet been determined. This study carried out an analysis of the distribution patterns and substitution processes of trace elements within stibnite gathered from the Zhaxikang deposit, aiming to provide crucial information on ore-forming processes. Utilizing high-precision laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), we discovered that the studied stibnite is notably enriched in arsenic (~100 ppm) and lead (~10 ppm). Furthermore, the notably consistent time-resolved profiles suggest that elements such as Fe, Cu, As, In, Sn, Hg, and Pb predominantly exist as solid solutions within stibnite. Consequently, it is probable that the enrichment of Cu, Pb, and Sn in stibnite is due to isomorphic substitution reactions, including 3Pb²⁺↔2Sb³⁺, Cu⁺ + Pb²⁺↔Sb³⁺, and In³⁺ + Sn³⁺↔2Sb³⁺. Apart from that, Mn, Pb, and Hg with the spiky signals indicate their existence within stibnite as micro-inclusions. Overall, we found that the trace element substitutions in stibnite from the Zhaxikang Pb–Zn–Ag–Sb deposit are complicated. Incorporations of trace elements such as Pb, Cu, and In into stibnite are largely influenced by a variety of factors. The simple lattice structure and constant trace elements in studied stibnite indicate a low-temperature hydrothermal system and a relatively stable process for stibnite formation. Full article

(This article belongs to the Special Issue Ag-Pb-Zn Deposits: Geology and Geochemistry)

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40 pages, 20569 KiB

Open AccessFeature PaperArticle

An Archean Porphyry-Type Deposit: Cu-Au Mineralization Associated with the Chibougamau Tonalite–Diorite Pluton, Abitibi Greenstone Belt, Canada

by Alexandre Crépon, Lucie Mathieu, Daniel J. Kontak, Jeffrey Marsh and Michael A. Hamilton

Minerals 2024, 14(12), 1293; https://doi.org/10.3390/min14121293 - 20 Dec 2024

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Abstract

The Neoarchean diorite- and tonalite-dominated Chibougamau pluton (Canada) is ideal for case studies dedicated to the petrogenesis and timing of emplacement of fertile magmatic systems and associated Cu-Au porphyry systems. Using whole-rock analyses, geochronology, and zircon chemistry, it is determined that an early [...] Read more.

The Neoarchean diorite- and tonalite-dominated Chibougamau pluton (Canada) is ideal for case studies dedicated to the petrogenesis and timing of emplacement of fertile magmatic systems and associated Cu-Au porphyry systems. Using whole-rock analyses, geochronology, and zircon chemistry, it is determined that an early magmatic phase (pre-2714 Ma) is derived from a dioritic magma with a moderate ƒO₂ (ΔFMQ 0 to +1), which is optimal for transporting Au and Cu, and that diorite is a potentially fertile magma. Field descriptions indicate that the main mineralizing style consists of sulfide-filled hairline fractures and quartz–carbonate veins. This is likely the consequence of fluid circulation facilitated by a well-developed diaclase network formed following the intrusion of magma at about 4–7 km depth in a competent hosting material. The petrographic features of fluid inclusions (FIs), considered with their microthermometric data and evaporate mound chemistry, suggest the exsolution of early CO₂-rich fluids followed by the unmixing of later aqueous saline fluids characterized by a magmatic signature (i.e., Na-, Ca-, Fe-, Mn-, Ba-, and Cl-F). The type of magmatism and its oxidation state, age relationships, the nature of mineralization, and fluid chemistry together support a model whereby metalliferous fluids are derived from an intermediate hydrous magma. This therefore enforces a porphyry-type metallogenic model for this Archean setting. Full article

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

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19 pages, 7027 KiB

Open AccessArticle

The Northernmost Effects of the Neo-Tethys Oceanic Slab Subduction Under the Lhasa Terrane: Evidence from the Mazin Rhyolite Porphyry

by Zhuosheng Wang, Nan Wang, Zhibo Liu and Xudong Ma

Minerals 2024, 14(12), 1292; https://doi.org/10.3390/min14121292 - 20 Dec 2024

Viewed by 562

Abstract

The India–Asia collision represents the most significant geological event in the formation of the Tibetan plateau. The subsidence of the Neo-Tethys oceanic slab and the closure of the ocean basin were precursors of the India–Asia collision. The Linzizong volcanic formations, which range in [...] Read more.

The India–Asia collision represents the most significant geological event in the formation of the Tibetan plateau. The subsidence of the Neo-Tethys oceanic slab and the closure of the ocean basin were precursors of the India–Asia collision. The Linzizong volcanic formations, which range in age from the late Cretaceous to early Cenozoic (70–40 Ma), are widely distributed across the Lhasa terrane and are considered products of the closure of the Neo-Tethys oceanic basin and the India–Asia collision. Here, we report a newly identified series of rhyolite porphyries, which share similar age and geochemical features with typical Linzizong volcanic formations. These porphyries are the northernmost extension of Linzizong volcanic formations discovered to date. Zircon U-Pb dating suggests that they formed between 58.8 and 56.1 Ma. These porphyries are characterized by high SiO₂ (75.04%–77.82%), total alkali (K₂O: 4.71%–5.03%), and Na₂O (2.54%–3.63%) values; relatively low Al₂O₃ (12.30%–13.62%) and MgO (0.13%–0.33%) values; and low Mg# values (15.8–25.7). They also exhibit strong enrichment in light rare earth elements ([La/Yb]_N = 3.76–11.08); negative Eu anomalies (Eu/Eu* = 0.10–0.32); Rb, Ba, Th, U, and Pb enrichments; as well as Nb and Ta depletions. The samples have relatively low εNd(t) values (−6.0 to −3.8) and variable zircon εHf(t) values (−6.3 to +3.6). These features suggest they originated from the remelting of the juvenile lower crust of the North Lhasa terrane under high-temperature and extensional conditions. We propose that the Mazin rhyolite porphyries resulted from mantle-derived magma diapirism, triggering juvenile lower crust remelting during Neo-Tethys oceanic slab rollback at the onset of the India–Asia collision. These findings provide new insights into the magmatic processes associated with early collisional tectonics. Full article

(This article belongs to the Special Issue Tectonic Evolution of the Tethys Ocean in the Qinghai–Tibet Plateau)

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17 pages, 5629 KiB

Open AccessArticle

Evolutionary Ensembles of Artificial Agents for Enhanced Mineralogical Analysis

by Paolo Dell’Aversana

Minerals 2024, 14(12), 1291; https://doi.org/10.3390/min14121291 - 20 Dec 2024

Viewed by 649

Abstract

This paper presents a novel machine learning framework that applies evolutionary ensembles of artificial agents to mineralogical analysis and classification. The approach is based on hybridization techniques that combine diverse machine learning algorithms, creating large and effective communities of agents. These progressively mute [...] Read more.

This paper presents a novel machine learning framework that applies evolutionary ensembles of artificial agents to mineralogical analysis and classification. The approach is based on hybridization techniques that combine diverse machine learning algorithms, creating large and effective communities of agents. These progressively mute and improve through crossover, hybridization, and selection, addressing the challenges of mineral recognition and classification from thin section images. By combining multiple machine learning techniques, the ensemble of agents autonomously improves by evolving to adapt, enhancing its ability to identify mineral species and classify different types of alterations. We detail the method, provide examples using synthetic and real data, and explore the potential to improve mineralogical analysis workflows through this dynamic, self-improving system. Full article

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

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21 pages, 23925 KiB

Open AccessArticle

Detrital Zircon Dating, Deformation Stages, and Tectonics of the Pane Chaung Formation and Surrounding Units in the Western Indo-Burma Range, Southeast Asia

by Ji’en Zhang, Wenjiao Xiao, John Wakabayashi, Fulong Cai and Kyaing Sein

Minerals 2024, 14(12), 1290; https://doi.org/10.3390/min14121290 - 19 Dec 2024

Viewed by 638

Abstract

The Indo-Burma Range (IBR), as one of the youngest accreted units in the Eastern Neotethys, plays a crucial role in understanding the interactive relationships between the Gondwana supercontinent and its rifted microcontinents in SE Asia. However, its basement nature and tectonic evolution remain [...] Read more.

The Indo-Burma Range (IBR), as one of the youngest accreted units in the Eastern Neotethys, plays a crucial role in understanding the interactive relationships between the Gondwana supercontinent and its rifted microcontinents in SE Asia. However, its basement nature and tectonic evolution remain debated. Here, we conducted a comprehensive structural analysis across six sections within the IBR and correlated Late Triassic flysch units between the Western IBR (Pane Chaung Formation) and the Tethyan Himalaya. Within the Mindat section, the eastern segment of the Pane Chaung Formation unit displays top-to-east vergent overturned folds, indicating eastward backthrusting, in contrast to the prevailing top-to-west vergence structures in Kalemyo, Natchaung, Magwe and the western segment of the Mindat flysch unit. By reconstruction of this backthrust sheet, a megathrust separates the Pane Chaung Formation unit in the footwall to the west from schist units in the hanging wall to the east. The Pane Chaung Formation unit in the Western IBR and its counterparts in the Tethyan Himalaya share common characteristics, including herringbone cross-beddings, Carnian–Norian Halobia fossils, and dominant detrital zircons of 220–280, 500–620, 900–1000, and 1100–1140 Ma. Alongside the Paleozoic strata and Precambrian one-stage model ages of Mesozoic dikes, as evidenced by ɛ_Nd (t) (−13.4 to −0.1) and ɛ_Hf (t) (−24.2 to −0.1) in the Tethyan Himalaya, these facts suggest that the major tectonic units of the Western IBR–Tethyan Himalaya are the result of the amalgamation of a microcontinent with the West Burma Block. The transition from OIB to E-MORB and N-MORB, the rapid deepening of sedimentary waters, and the presence of the 155–152 Ma Indian ocean crust collectively indicate that the microcontinent rifted from the host East Gondwana as a fragment of the Argoland archipelago in the Late Jurassic. This identification sheds light on the orogenic processes of the doublet subduction zones in the Indo-Myanmar orogenic belt. Full article

(This article belongs to the Special Issue Multi-Method (Geo-) Thermochronology and Trace Elements Tracing Magmatism, Mineralization and Tectonic Evolution)

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19 pages, 24243 KiB

Open AccessFeature PaperArticle

Water Redistribution in Vein Quartz Under Progressive Deformation (During Plastic Deformation): μFTIR and EBSD Study (Western Transbaikalia, Russia)

by Elvira N. Kungulova, Artem A. Bibko, Roman Y. Shendrik, Evgeny N. Moskvichev, Dmitry V. Lychagin and Platon A. Tishin

Minerals 2024, 14(12), 1289; https://doi.org/10.3390/min14121289 - 19 Dec 2024

Viewed by 663

Abstract

Water distribution in the structure of vein quartz formed as a result of successive plastic deformations associated with dislocation slip and subsequent recrystallization was estimated using infrared microspectroscopic (μFTIR) mapping. Water contained in quartz demonstrates a broad absorption band in the IR range [...] Read more.

Water distribution in the structure of vein quartz formed as a result of successive plastic deformations associated with dislocation slip and subsequent recrystallization was estimated using infrared microspectroscopic (μFTIR) mapping. Water contained in quartz demonstrates a broad absorption band in the IR range at 2800–3750 cm⁻¹, which indicates its molecular state and suggests the presence of water bearing water inclusions. In addition to water, the presence of an absorption band located at 2341 cm⁻¹ seems to be due to the presence of carbon dioxide in a molecular state. A necessary step before assessing the distribution of volatile components in the quartz structure was to calibrate the boundaries obtained by calculating the intensity ratios of the peaks at 1118 and 1160 cm⁻¹ in the reflectance spectrum and using electron back scatter diffraction (EBSD). A variety of fluid distributions in different elements of the structure was observed. At medium temperatures and medium strain rates, dislocation mass transfer is effective during dislocation slip. At low strain rates and elevated temperatures, the contribution of diffusion creep gradually increases, which facilitates the interaction of volatile components with migrating boundaries. It was found that in the process of successive rearrangements, migration of fluid components occurs within the main elements of the structure due to the redistribution of dislocations between defects of different scale levels. Redistribution of fluid from fluid inclusions as a result of plastic deformations in the quartz structure is one of the ways of relaxing intracrystalline stresses during strengthening of the structure. Full article

(This article belongs to the Special Issue Physicochemical Properties and Purification of Quartz Minerals)

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22 pages, 7722 KiB

Open AccessArticle

Late Paleozoic Tectonics of the NW Tarim Block: Insights from Zircon Geochronology and Geochemistry in Xinjiang, China

by Baozhong Yang, Ao Lv, Xiangrong Zhang, Yejin Zhou, Wenxiao Zhou and Ernest Chi Fru

Minerals 2024, 14(12), 1288; https://doi.org/10.3390/min14121288 - 19 Dec 2024

Viewed by 632

Abstract

The Late Paleozoic strata on the northwestern margin of the Tarim Block provide valuable insights into the subduction and collision processes that formed the Southwest Tianshan Orogenic Belt. This study integrates detrital zircon U-Pb dating and sandstone geochemical analysis of the Balikelike and [...] Read more.

The Late Paleozoic strata on the northwestern margin of the Tarim Block provide valuable insights into the subduction and collision processes that formed the Southwest Tianshan Orogenic Belt. This study integrates detrital zircon U-Pb dating and sandstone geochemical analysis of the Balikelike and Kalundaer formations to examine sedimentary provenance and tectonic settings during the Cisuralian–Guadalupian Epoch in the Keping area on the northwestern margin of the Tarim Block. Three of five Precambrian detrital zircon U-Pb age populations, 2500–2300 and 2000–1800 Ma and 900–600 Ma, are likely related to the fragmentation of the Columbia supercontinent and Rodinia’s assembly, respectively. Two Paleozoic detrital zircons, 500–380 Ma, are associated with Paleozoic magmatism. Among them, ~295 Ma zircons are associated with post-collisional extension and emplacement of the Tarim Large Igneous Province. Geochemical analysis of sandstones, coupled with tectonic reconstruction, indicates a passive continental margin setting in the northwestern margin of the Tarim Block during the Silurian Period, later transitioned to a foreland basin from the Pennsylvanian to the Guadalupian Epochs. The crustal transformation from the Middle-late Devonian to Early Mississippian marked the closure of the South Tianshan Ocean (STO), involving a soft collision and significant uplift, with major orogenesis occurring in the Late Guadalupian. Five key stages are identified in the evolution of the foreland basin: (1) Middle-late Devonian to Early Mississippian initiation (remnant ocean basin stage); (2) Late Mississippian to Early Pennsylvanian early stage; (3) Late Pennsylvanian to Early Cisuralian middle stage; (4) the Late Cisuralian stage; and (5) the terminal Guadalupian stage. These findings provide new constraints on when STO closed and propose an innovative foreland basin evolution model during the late post-collisional phase from the Late Mississippian to Guadalupian. Collectively, the data advance our understanding of the tectonic processes that shaped the northwestern Tarim Block, with broader implications for Paleozoic geodynamics. Full article

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

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26 pages, 4405 KiB

Open AccessArticle

Removal of Diesel from Aqueous Solutions by a Combined Adsorption and Microbial Degradation Process

by Marija Lukić, Aleksandra Daković, Kristina Joksimović, Jelena Milić, Milena Obradović, Vladimir Beškoski and Jelena Avdalović

Minerals 2024, 14(12), 1287; https://doi.org/10.3390/min14121287 - 18 Dec 2024

Viewed by 567

Abstract

Diesel contamination in water bodies poses a significant environmental challenge due to the toxic effects of its water-soluble fraction (WSF) on aquatic ecosystems and human health. The aim of this work was the design of a new technological procedure for the purification of [...] Read more.

Diesel contamination in water bodies poses a significant environmental challenge due to the toxic effects of its water-soluble fraction (WSF) on aquatic ecosystems and human health. The aim of this work was the design of a new technological procedure for the purification of water contaminated with the WSF of diesel. The procedure is based on the adsorption of organic pollution on an organozeolite, after which the biodegradation of the adsorbed pollutant takes place. The material for obtaining organozeolite was a natural zeolite from the Zlatokop deposit (Vranje, Serbia). The zeolitic surface was modified with hexadecyltrimethylammonium bromide (HDTMA-Br), a cationic quaternary ammonium salt. The adsorption experiments, with initial WSF concentrations of 2.5–25 mg/L, at pH 6 and at 20 °C, were performed in a batch system using organozeolite, and the results showed that more than 90% of the WSF of diesel was removed, reaching equilibrium after 1 h. The maximum adsorbed capacity of organozeolite for the removal of the WSF of diesel fuel from water under the tested conditions was 22.2 mg/g. Equilibrium data were well fitted by a linear isotherm model, while a pseudo-second-order equation well fitted the kinetic data. After adsorption, a 15-day biodegradation experiment was carried out under batch conditions. The results showed that the examined consortium of microorganisms degraded 80% of the adsorbed contaminant. Additional respirometric analyses showed that, in parallel with the degradation of the contaminant, the degradation of the long-chain HDTMA ions at the surface of the organozeolite also occurred. To the best of our knowledge, this is the first study combining adsorption and biodegradation to remove the WSF of diesel from water. Full article

(This article belongs to the Special Issue Zeolite: From a Boiling Stone to the Applicable Minerals in Various Industrial Processes: 2nd Edition)

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25 pages, 6929 KiB

Open AccessReview

Case Studies of Magnetic and Electromagnetic Techniques Covering the Last Fifteen Years

by Marc A. Vallée, Mouhamed Moussaoui and Khorram Khan

Minerals 2024, 14(12), 1286; https://doi.org/10.3390/min14121286 - 18 Dec 2024

Viewed by 1184

Abstract

Magnetic and electromagnetic techniques have a long history of application in mineral exploration to detect deposits and their surroundings. Their implementation over the last fifteen years has been affected by strong variations in the mining market in parallel with important technological developments. During [...] Read more.

Magnetic and electromagnetic techniques have a long history of application in mineral exploration to detect deposits and their surroundings. Their implementation over the last fifteen years has been affected by strong variations in the mining market in parallel with important technological developments. During this period, both methods were the subject of numerous documented case studies all over the globe, which is a sign of popularity and longevity of these techniques. Through a review of case histories from the main geophysical journals, we analyze the principal usage of these methods when applied to mineral exploration, while the majority of documented cases originate from North America, Asia, and Australia. There are more case studies describing the use of the magnetic method and we attribute this popularity to direct and indirect use of this method for mineral exploration. In particular, there is an increasing number of magnetic surveys conducted with drones. Combining magnetic and electromagnetic techniques is also common. The number of magnetic and EM technique case histories range by descending order from gold, porphyry copper, polymetallic, massive sulfides, uranium, Ni-Cu-PGE, iron ore, kimberlite, and iron-oxide copper-gold, with a number of single continent-specific applications. Full article

(This article belongs to the Special Issue Advances in Magnetic and Electromagnetic Techniques for Mineral Exploration: Enhancing Resource Discovery)

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13 pages, 3958 KiB

Open AccessArticle

Effect of Recycling Chicken Eggshell Waste as a Pore-Forming Mineral Source in Low-Water-Absorption Bi-Layered Red Ceramic Tiles

by Thaís Queiroz Gomes Vigneron and José Nilson França Holanda

Minerals 2024, 14(12), 1285; https://doi.org/10.3390/min14121285 - 18 Dec 2024

Viewed by 581

Abstract

This work evaluated the effects of incorporating chicken eggshell waste in a low-water-absorption bi-layered red ceramic tile composition, focusing on its porosity. Red ceramic tile formulations were prepared with incorporations of 0, 5, 10, 15, 20 and 25 wt.% of chicken eggshell waste. [...] Read more.

This work evaluated the effects of incorporating chicken eggshell waste in a low-water-absorption bi-layered red ceramic tile composition, focusing on its porosity. Red ceramic tile formulations were prepared with incorporations of 0, 5, 10, 15, 20 and 25 wt.% of chicken eggshell waste. The bi-layered red floor tile processing method consisted of dry powder granulation, double uniaxial pressing and firing at 1220 °C using a fast-firing cycle. The physical properties and microstructural development of the tile specimens were investigated. It was found that chicken eggshell waste exhibited good chemical compatibility for use in red ceramic tile formulations, enabling its recycling. The novel bi-layered red ceramic tiles presented water absorption between 0.34 and 0.97% and apparent density between 2.09 and 2.14 g/cm³. The results demonstrated that chicken eggshell waste, when incorporated up to 15 wt.%, can be used as an efficient pore-forming carbonate source to manufacture low-water-absorption bi-layered red ceramic tiles (BIa and BIb groups—ISO 13006), which allows use in ventilated façades. It was concluded that the proposed approach is suitable for recycling chicken eggshell waste into red ceramic tile formulations, with relevant repercussions for the circular economy. Full article

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

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21 pages, 8572 KiB

Open AccessArticle

The Measurement of Metal Mineral Particle Size Under the Microscope Based on Gaussian Pyramids and Directional Maximum Intercept

by Chaoxi Luo, Feng Xie, Bo Li, Xiangwen Lv, Meiguang Jiang, Jing Zhang, Sheng Jian, Fang Yang and Yong Wang

Minerals 2024, 14(12), 1284; https://doi.org/10.3390/min14121284 - 17 Dec 2024

Viewed by 566

Abstract

With the development of mineral resources, minerals are becoming increasingly difficult to process. In order to utilize these resources more effectively, in-depth research into process mineralogy has become increasingly important in the field of mineralogy, and particle size measurement under the microscope is [...] Read more.

With the development of mineral resources, minerals are becoming increasingly difficult to process. In order to utilize these resources more effectively, in-depth research into process mineralogy has become increasingly important in the field of mineralogy, and particle size measurement under the microscope is one of the critical aspects of process mineralogy. At present, the use of scanning electron microscopes and other equipment for measurement is very expensive, and manual measurement has problems such as poor accuracy and low efficiency. In addition, there is a lack of reference materials for the segmentation algorithm of mineral light images. This article proposes a Gaussian pyramid based on bilateral filtering combined with directional maximum intercept to measure mineral particle size under the microscope. In the experiments, different segmentation algorithms were studied, including Gaussian pyramid segmentation based on bilateral filtering, segmentation based on Fuzzy C-Means, and the rapidly developing deep learning segmentation algorithms in recent years. By comparing the segmentation effects of these three algorithms on various mineral thin-section images, the Gaussian pyramid segmentation algorithm based on bilateral filtering was selected as the optimal one. This was then combined with the directional maximum intercept method to measure the particle size of ilmenite and pyrite images. The experimental results show that the segmentation method based on the bilateral filtering Gaussian pyramid technique has higher segmentation accuracy than the other two algorithms, and can accurately measure the particle size of minerals under the microscope. Compared with manual measurement, this method can effectively and accurately measure the microscopic particle size of target minerals, greatly reducing the workload of measurement personnel and reducing the time spent on measurement. Full article

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

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44 pages, 42509 KiB

Open AccessReview

Gold and Platinum Group Element Occurrence Related to Black Shale Formations in the Southern Urals (Russia): A Review

by Alexander V. Snachev and Mikhail A. Rassomakhin

Minerals 2024, 14(12), 1283; https://doi.org/10.3390/min14121283 - 17 Dec 2024

Viewed by 752

Abstract

This paper gives a brief description of all structural–formational zones in the Southern Urals. Riphean and Paleozoic black shale sediments with strong positive anomalies of gold and a number of other elements are widely developed within this region. This paper reports that carbonaceous [...] Read more.

This paper gives a brief description of all structural–formational zones in the Southern Urals. Riphean and Paleozoic black shale sediments with strong positive anomalies of gold and a number of other elements are widely developed within this region. This paper reports that carbonaceous shales are a very favorable geochemical environment for the primary accumulation of many industrially important elements. Under certain conditions (in the areas of magmatism, zonal metamorphism, and tectonic activity), they can serve as a source of metals and concentrate deposits, and occurrences of gold, silver, and platinoids. Among these deposits, a new type of vein-embedded gold–sulfide mineralization with dispersed gold and platinum metals, localized in rocks rich in organic carbon, has been detected. In this study, we made an attempt to summarize and systematize research materials on this issue. The presented data indicate a high potential of carbonaceous sediments in the Southern Urals, providing a good basis for further prospecting works and analytical studies. Full article

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

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18 pages, 12205 KiB

Open AccessArticle

An Open-Pit Mines Land Use Classification Method Based on Random Forest Using UAV: A Case Study of a Ceramic Clay Mine

by Yuanrong He, Yangfeng Lai, Bingning Chen, Yuhang Chen, Zhiying Xie, Xiaolin Yu and Min Luo

Minerals 2024, 14(12), 1282; https://doi.org/10.3390/min14121282 - 17 Dec 2024

Viewed by 622

Abstract

Timely and accurate land use information in open-pit mines is essential for environmental monitoring, ecological restoration planning, and promoting sustainable progress in mining regions. This study used high-resolution unmanned aerial vehicle (UAV) imagery, combined with object-oriented methods, optimal segmentation algorithms, and machine learning [...] Read more.

Timely and accurate land use information in open-pit mines is essential for environmental monitoring, ecological restoration planning, and promoting sustainable progress in mining regions. This study used high-resolution unmanned aerial vehicle (UAV) imagery, combined with object-oriented methods, optimal segmentation algorithms, and machine learning algorithms, to develop an efficient and practical method for classifying land use in open-pit mines. First, six land use categories were identified: stope, restoration area, building, vegetation area, arterial road, and waters. To achieve optimal scale segmentation, an image segmentation quality evaluation index is developed, emphasizing both high intra-object homogeneity and high inter-object heterogeneity. Second, spectral, index, texture, and spatial features are identified through out-of-bag (OOB) error of random forest and recursive feature elimination (RFE) to create an optimal multi-feature fusion combination. Finally, the classification of open-pit mines was executed by leveraging the optimal feature combination, employing the random forest (RF), support vector machine (SVM), and k-nearest neighbor (KNN) classifiers in a comparative analysis. The experimental results indicated that classification of appropriate scale image segmentation can extract more accurate land use information. Feature selection effectively reduces model redundancy and improves classification accuracy, with spectral features having the most significant effect. The RF algorithm outperformed SVM and KNN, demonstrating superior handling of high-dimensional feature combinations. It achieves the highest overall accuracy (OA) of 90.77%, with the lowest misclassification and omission errors and the highest classification accuracy. The disaggregated data facilitate effective monitoring of ecological changes in open-pit mining areas, support the development of mining plans, and help predict the quality and heterogeneity of raw clay in some areas. Full article

(This article belongs to the Special Issue Application of UAV and GIS for Geosciences, 2nd Edition)

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20 pages, 10364 KiB

Open AccessArticle

Res-UNet Ensemble Learning for Semantic Segmentation of Mineral Optical Microscopy Images

by Chong Jiang, Alfian Abdul Halin, Baohua Yang, Lili Nurliyana Abdullah, Noridayu Manshor and Thinagaran Perumal

Minerals 2024, 14(12), 1281; https://doi.org/10.3390/min14121281 - 17 Dec 2024

Viewed by 612

Abstract

In geology and mineralogy, optical microscopic images have become a primary research focus for intelligent mineral recognition due to their low equipment cost, ease of use, and distinct mineral characteristics in imaging. However, due to their close reflectivity or transparency, some minerals are [...] Read more.

In geology and mineralogy, optical microscopic images have become a primary research focus for intelligent mineral recognition due to their low equipment cost, ease of use, and distinct mineral characteristics in imaging. However, due to their close reflectivity or transparency, some minerals are not easily distinguished from other minerals or background. Secondly, the number of background pixels often vastly exceeds the number of pixels for individual mineral particles, and the number of pixels of different mineral particles in the image also varies significantly. These have led to the issue of data imbalance. This imbalance results in lower recognition accuracy for categories with fewer samples. To address these issues, a flexible ensemble learning for semantic segmentation based on multiple optimized Res-UNet models is proposed, introducing dice loss and focal loss functions and incorporating a pre-positioned spatial transformer networks block. Twelve optimized Res-UNet models were used to construct multiple Res-UNet ensemble learnings using heterogeneous ensemble strategies. The results demonstrate that the system integrated with five learners using the weighted voting fusion method (RUEL-5-WV) achieved the best performance with a mean Intersection over Union (mIOU) of 91.65 across all nine categories and an IOU of 84.33 for the transparent mineral (gangue). The results indicate that this ensemble learning scheme outperforms individual optimized Res-UNet models. Compared to the classical Deeplabv3 and PSPNet, this scheme also exhibits significant advantages. Full article

(This article belongs to the Special Issue Application of Deep Learning and Computer Vision in Petrographic Images Analysis)

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11 pages, 2922 KiB

Open AccessArticle

The Trace-Element Characteristics of Chrysoberyl: Insights from Compositional and Spectroscopic Analyses

by Linling Dong, Yimiao Liu, Xinxin Gao and Ren Lu

Minerals 2024, 14(12), 1280; https://doi.org/10.3390/min14121280 - 17 Dec 2024

Viewed by 479

Abstract

To characterize the trace-element characteristics of chrysoberyl, we studied twenty-six chrysoberyl samples from various localities by using laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS), photoluminescence (PL), and ultraviolet–visible–near-infrared (UV–Vis–NIR) spectroscopy. Chemical analysis has confirmed the existence of trace elements, including Fe, Ti, [...] Read more.

To characterize the trace-element characteristics of chrysoberyl, we studied twenty-six chrysoberyl samples from various localities by using laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS), photoluminescence (PL), and ultraviolet–visible–near-infrared (UV–Vis–NIR) spectroscopy. Chemical analysis has confirmed the existence of trace elements, including Fe, Ti, Ga, Sn, B, Cr, and V. The phenomenon of ionic isomorphic substitution frequently occurs at lattice sites within chrysoberyl. Notably, the isomorphic substitution of Al³⁺ in octahedral sites is significant, with the primary substituting elements being Fe, Ti, Cr, V, Ga, and Sn. The PL spectra of chrysoberyl samples exhibit sharp peaks at 678 and 680 nm, which are attributed to Cr³⁺, even in samples in which the Cr concentration is below the detection limit of LA-ICP-MS. This demonstrates the high-sensitivity feature of PL spectroscopy. The UV–Vis–NIR spectra of chrysoberyl samples consistently exhibit a band at 440 nm, and strong double narrow bands near 367 nm and 375 nm are observed. These spectral features are associated with Fe³⁺ chromophores—specifically, Fe³⁺-Fe³⁺ pairs or clusters and Fe³⁺ ions, respectively. By combining LA–ICP–MS analysis and PL mapping on a sample exhibiting color zoning, it has been found that the darker sections contain a higher concentration of Cr compared to the lighter sections, while the concentrations of other elements remain largely consistent. In other words, subtle variations in Cr concentration may be the underlying cause of color zoning in chrysoberyl. Full article

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

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15 pages, 1824 KiB

Open AccessArticle

Assessment of Gravity Deportment of Gold-Bearing Ores: Gravity Recoverable Gold Test

by Oldřich Šigut, Tomáš Široký, Iva Janáková, Radek Střelecký and Vladimír Čablík

Minerals 2024, 14(12), 1279; https://doi.org/10.3390/min14121279 - 16 Dec 2024

Viewed by 666

Abstract

This study investigated the potential of low-grade gold deposits in modern mining, particularly in the context of declining high-grade resources. The primary method for processing these ores was gravity separation with the Knelson concentrator. A GRG test (gravity recoverable gold test) was conducted [...] Read more.

This study investigated the potential of low-grade gold deposits in modern mining, particularly in the context of declining high-grade resources. The primary method for processing these ores was gravity separation with the Knelson concentrator. A GRG test (gravity recoverable gold test) was conducted on two gold-bearing samples: a polymetallic Cu-Zn-Au ore from Zlaté Hory–Západ (Czech Republic) containing refractory gold and an ore with free gold from Kašperské Hory (Czech Republic). The study evaluated the effectiveness of the GRG test for gold recovery from these ores. The results showed that the Kašperské Hory sample predominantly contained relatively large gold grains, with recovery rates dropping significantly upon finer comminution. In the sample from the Zlaté Hory–Západ deposit, the greatest GRG release occurred in the first and last test stages, suggesting that larger sulfide grains with bound gold passed predominantly in the first stage, while fine gold with residual sulfides passed in the third. Both samples achieved high overall GRG recovery rates, with 64.2% for Kašperské Hory and more than 66% for Zlaté Hory–Západ, demonstrating the efficacy of centrifugal concentrators for both ores. Full article

(This article belongs to the Special Issue Unlocking Critical Elements in Base Metal Supply Chains: Challenges and Opportunities)

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20 pages, 28626 KiB

Open AccessArticle

The Evolution of Ore-Forming Fluids of the Halasheng Ag-Pb-Zn Deposit, Inner Mongolia: Evidence from Fluid Inclusions and Mineral Constitute

by Ri Han, Kezhang Qin, Fengming Xu, Junchao Lyu, Xinyuan Yang, Jing Zhang, Yuli Wang and Kaixuan Hui

Minerals 2024, 14(12), 1278; https://doi.org/10.3390/min14121278 - 16 Dec 2024

Viewed by 580

Abstract

The Early Cretaceous Halasheng deposit, located in the southern Erguna Block, is an intermediate sulfidation epithermal Ag-Pb-Zn deposit in the Derbugan metallogenic belt. The Halasheng deposit comprises both proximal skarn mineralization and distal hydrothermal vein-type Pb-Zn-Ag mineralization, which can be further divided into [...] Read more.

The Early Cretaceous Halasheng deposit, located in the southern Erguna Block, is an intermediate sulfidation epithermal Ag-Pb-Zn deposit in the Derbugan metallogenic belt. The Halasheng deposit comprises both proximal skarn mineralization and distal hydrothermal vein-type Pb-Zn-Ag mineralization, which can be further divided into three stages represented by Fe-As-S, Pb-Zn-Cu-Fe-S, and Ag-Pb-Zn-Sb-S element associations. The main ore minerals in the Halasheng deposit include galena, sphalerite, pyrite, arsenopyrite, chalcopyrite, bournonite, falkmanite, and argentiferous minerals. Visible silver in the form of independent argentiferous minerals, mainly including freibergite, polybasite, stromeyerite, pyrargyrite, acanthite, and native silver, is the major type of silver occurring in the Halasheng district. Fluid inclusion studies of sphalerite and quartz from different mineralization stages revealed that skarn mineralization has the relatively highest homogenization temperature (322~398 °C), while in the vein-type hydrothermal mineralization stage, the homogenization temperature has a declining trend from the early stage to late stage (from 300~350 °C to 145~236 °C). In the whole mineralization process, the salinity of ore-forming fluids is almost constant at a relatively high level (10.5~21.9 wt% NaCl). Fluid cooling, or fluid–wallrock reaction, is supposed to be the major cause of metal precipitation in the Halasheng deposit. Through an analogy with the typical Ag-Pb-Zn deposits in the Derbugan metallogenic belt, it is suggested that the discovered orebodies in the Halasheng deposit likely belong to the shallow part of the epithermal system, and there is high potential to discover Zn, Cu-Zn orebodies, and even porphyry Mo-Cu mineralization. In terms of regional ore prospecting, Early Cretaceous intermediate-acid intrusions have the potential to form related Ag-Pb-Zn deposits and should receive special attention. Furthermore, places where Lower Cambrian marbles are exposed or concealed are favorable settings for skarn mineralization. Full article

(This article belongs to the Special Issue Mineralogical and Geochemical Characterization of Zn-Pb Ore Deposits: Insights into Their Genesis, Implications for Exploration, and Environmental Issues)

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21 pages, 23597 KiB

Open AccessArticle

The Effect of Pre–Triassic Unconformity on a Hydrocarbon Reservoir: A Case Study from the Eastern Mahu Area, Northwestern Junggar Basin, China

by Yong Tang, Xiaosong Wei, Detian Yan, Menglin Zheng, Lei Zhang and Zhichao Yu

Minerals 2024, 14(12), 1277; https://doi.org/10.3390/min14121277 - 16 Dec 2024

Viewed by 516

Abstract

Unconformities are of significant interest to petroleum geologists because of their crucial roles in influencing reservoir quality and controlling oil and gas migration. This study investigates the impact of unconformities on a reservoir within a prolific oil–gas-bearing zone between the Middle Permian and [...] Read more.

Unconformities are of significant interest to petroleum geologists because of their crucial roles in influencing reservoir quality and controlling oil and gas migration. This study investigates the impact of unconformities on a reservoir within a prolific oil–gas-bearing zone between the Middle Permian and Lower Triassic strata in the northwestern Junggar Basin, utilizing thin sections, well logging data, seismic profiles, and geochemical analyses. The results reveal a well-developed three-layer unconformity structure characterized by a thick weathered clay layer, which acts as an effective caprock for hydrocarbons. The diagenetic evolution of the Lower Wuerhe Formation in the northwestern Junggar Basin consists of an initial stage of compaction followed by a subsequent stage of dissolution and cementation. Four key factors, including low argillaceous content in sandstone and conglomerate, diagenetic compaction, zeolite dissolution and cementation, and clay mineral infill, have played a crucial role in influencing the reservoir characteristics of the Lower Wuerhe Formation. In addition, the development of unconformities promotes atmospheric freshwater leaching, which enhances the dissolution of the underlying reservoir while developing an extensive network of strike-slip faults that improve connectivity within hydrocarbon reservoirs. This process facilitates both vertical and lateral migration of hydrocarbons along hard rock layers, which allows the unconformity to breach into the overlying conglomerate reservoirs. The results of this study suggest that the reservoir in proximity to the unconformity surface often exhibits high porosity and rich hydrocarbon content, offering valuable insights for future oil and gas exploration and development. Full article

(This article belongs to the Special Issue Volcanism and Oil–Gas Reservoirs—Geology and Geochemistry)

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14 pages, 3502 KiB

Open AccessArticle

Zheshengite, Pb₄ZnZn₂(AsO₄)₂(PO₄)₂(OH)₂: A New Mineral of the Dongchuanite Group and the Influence of As–P Isomorphic Substitution on Unit-Cell Parameters of Dongchuanite Group Minerals

by Ningyue Sun, Guowu Li, Yuan Xue, Hongtao Shen and Jinhua Hao

Minerals 2024, 14(12), 1276; https://doi.org/10.3390/min14121276 - 16 Dec 2024

Viewed by 594

Abstract

Zheshengite (IMA2022-011), Pb₄ZnZn₂(AsO₄)₂(PO₄)₂(OH)₂, is a new mineral from Sanguozhuang Village in the eastern Dongchuan Copper Ore Field, Yunnan Province, China. The new mineral is named after Zhesheng Ma (1937–). [...] Read more.

Zheshengite (IMA2022-011), Pb₄ZnZn₂(AsO₄)₂(PO₄)₂(OH)₂, is a new mineral from Sanguozhuang Village in the eastern Dongchuan Copper Ore Field, Yunnan Province, China. The new mineral is named after Zhesheng Ma (1937–). Zheshengite occurs as prismatic single crystals with chisel-like terminations on hemimorphite, with crystal sizes ranging from 0.02 to 0.05 mm. It is a brittle mineral with irregular fractures, a Mohs hardness of 2½ to 3, perfect cleavage on {011}, and a calculated density of 6.26 g/cm³. The empirical formula of zheshengite, based on 18 O atoms per formula unit, is (Pb_4.12Ca_0.01)_∑4.13(Zn_0.83Cu_0.23Fe_0.04)_∑1.10Zn_2.00[(As_0.90P_0.10)_∑1.00O₄]₂[(P_0.94Si_0.01)_∑0.95O₄]₂(OH)₂. Zheshengite exhibits a triclinic structure (space group P−1, no. 2), with unit-cell parameters: a = 4.7746(4) Å, b = 8.4920 (7) Å, c = 10.4056 (8) Å, α = 97.087 (7)°, β = 101.060 (7)°, γ = 92.996 (7)°, V = 409.66 (6) Å³, and Z = 1. As a member of the dongchuanite group, zheshengite features a dongchuanite-type structure. This study reveals the impact of As–P isomorphic substitution on unit-cell parameters in the dongchuanite group, identifying correlations between As content and changes in parameters a and V, which may serve as diagnostic indicators for dongchuanite group minerals. In addition, the structure studies of zheshengite may have implications for environmental protection. Full article

(This article belongs to the Collection New Minerals)

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16 pages, 8666 KiB

Open AccessArticle

Sedimentological and Geochemical Evaluation of the Lower Cretaceous Yamama Formation, Riyadh, Saudi Arabia: An Integrated Tool for Paleoenvironmental Interpretation

by Rayan Khalil

Minerals 2024, 14(12), 1275; https://doi.org/10.3390/min14121275 - 16 Dec 2024

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Abstract

Geochemical proxies are a reliable tool in deciphering the paleoenvironment and diagenetic alteration in carbonate rock units. The Lower Cretaceous Yamama Formation (LCYF) is an important carbonate unit of the Saudi Arabia region which has been studied in detail to evaluate the paleoenvironment [...] Read more.

Geochemical proxies are a reliable tool in deciphering the paleoenvironment and diagenetic alteration in carbonate rock units. The Lower Cretaceous Yamama Formation (LCYF) is an important carbonate unit of the Saudi Arabia region which has been studied in detail to evaluate the paleoenvironment and diagenetic alteration through geochemical studies. This study presents new data on petrography, stable isotopes, and trace and rare-earth elements to enhance our understanding on paleoenvironments, redox conditions, and paleosalinity during the deposition of these carbonate units. Field studies show that the formation is composed of thick-to-thin-bedded limestone. Petrographic studies show that the formation is mostly composed of mudstone, wackestone, packstone, and grainstone facies. The stable isotopic values of carbon (δ¹³C V-PDB = +0.58‰ to +2.23‰) and oxygen (δ¹⁸O V-PDB = −6.38‰ to −4.48‰) are directly within the range of marine signatures. CaCO₃’s dominance over SiO₂ and Al₂O₃ indicates minimal detrital contribution during the LCYF precipitation. The REE pattern suggests coeval marine signatures which include (i) a slight LREE depletion compared to HREEs (av. Nd/Yb_N = 0.70), (ii) negative Ce anomalies (av. Ce/Ce* = 0.5), and (iii) a positive La anomaly (av. La/La* = 1.70). Micritic limestone has low Hf (bdl to 0.4 µg/g), Sc (bdl to 2.5 µg/g), and Th (bdl to 0.8 µg/g) content, which suggests negligible detrital influence. The Ce content of different facies (Ce = 1u.80 to 12.85 µg/g) suggests that their deposition took place under oxic to dysoxic conditions. However, there is moderate variation during the deposition of MF-I, with higher Ce values as compared to MF-II, MF-III, and MF-IV, which suggests that the deposition of MF-I mostly took place in anoxic to dysoxic conditions. Full article

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

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13 pages, 3858 KiB

Open AccessArticle

The Controlling Effect of CaCO₃ Supersaturation over Zn Carbonate Assemblages: Co-Crystallization in Silica Hydrogel

by André Jorge Pinto, Nuria Sánchez-Pastor and Angeles Fernández-González

Minerals 2024, 14(12), 1274; https://doi.org/10.3390/min14121274 - 15 Dec 2024

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Abstract

Weathering products of sphalerite-bearing ores play an important role in controlling the fate of Zn in the environment. In this framework, the relative stability of Zn carbonates is of special relevance for the common case of ore weathering by carbonated groundwater in the [...] Read more.

Weathering products of sphalerite-bearing ores play an important role in controlling the fate of Zn in the environment. In this framework, the relative stability of Zn carbonates is of special relevance for the common case of ore weathering by carbonated groundwater in the presence of calcium carbonates. We investigated the experimental (co)nucleation and growth of Zn and Ca carbonates at 25 °C in finite double diffusion silica hydrogel media with the purpose of deciphering the system’s reactive pathway and unraveling the major governing factors behind the obtained mineral assemblages. The crystallized solids were carefully extracted two months post-nucleation and studied with micro-Raman spectroscopy, micro X-ray diffraction (XRD), scanning electron microscopy, and electron microprobe (EMP) methods. The obtained results indicate that the grown Zn-bearing phases corresponded to smithsonite and/or Zn hydroxyl carbonate, while CaCO₃ polymorphs aragonite and calcite were also crystallized. Moreover, the observed mineral textural relationships reflected the interplay between supersaturation with respect to CaCO₃/pCO₂ and the grown Zn-bearing carbonate. Experiments conducted in more supersaturated conditions with respect to CaCO₃ polymorphs (higher pCO₂) favored the precipitation of smithsonite, while the opposite was true for the obtained Zn hydroxyl carbonate phase. The gathered Raman, XRD, and EMP data indicate that the latter phase corresponded to a non-stoichiometric, poorly crystalline solid. Full article

(This article belongs to the Special Issue Dissolution and Precipitation Dynamics at the Mineral–Fluid Interface)

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11 pages, 3845 KiB

Open AccessArticle

Comparative Analysis of Physico-Chemical and Potassium Sorption Properties of Sensitive Clays

by Marta Di Sante, Evelina Fratalocchi, Francesco Mazzieri, Bruno Di Buò and Tim Länsivaara

Minerals 2024, 14(12), 1273; https://doi.org/10.3390/min14121273 - 14 Dec 2024

Viewed by 1101

Abstract

The paper analyses physico-chemical and geotechnical characteristics of four Scandinavian sensitive soils formed under different environmental depositional conditions, with the main aims to contribute to the knowledge of sensitive soils and assess the potassium sorption capacity among the investigated soils, as a basic [...] Read more.

The paper analyses physico-chemical and geotechnical characteristics of four Scandinavian sensitive soils formed under different environmental depositional conditions, with the main aims to contribute to the knowledge of sensitive soils and assess the potassium sorption capacity among the investigated soils, as a basic characteristic to evaluate the effectiveness of treatment with KCl and to analyse potassium migration in such soils. The results show that, although the chemical composition of the four soils is very similar, their sensitivity is significantly different. The correlation from literature linking the specific surface, mineralogy, and plasticity in sensitive clays of Eastern Canada, was found to be qualitatively valid for the investigated Scandinavian sensitive clays, too. The highest value of the sensitivity index among the tested soils was found to be related to the lowest cation exchange capacity and to a limited amount of amorphous minerals. These characteristics contribute to explaining the highly sensitive behaviour of that soil affecting the structure formation during the deposition stage. The potassium sorption capacity has been experimentally investigated through batch tests specifically performed on the sensitive soils, as the first step to quantify the maximum sorption capacity and identify the main factors affecting it. The maximum potassium sorption capacity was always lower than that estimated by the cation exchange capacity, and it increased with the cation exchange capacity, plasticity index, and activity of the soils, as well as with the amount of phyllosilicates and amorphous minerals. Full article

(This article belongs to the Special Issue Adsorption Properties and Environmental Applications of Clay Minerals)

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Minerals, Volume 14, Issue 12 (December 2024) – 120 articles

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