Minerals

22 pages, 4518 KiB

Open AccessArticle

Petrological, Textural, Compositional, and Economic Potential of Carbonatites from the Peshawar Plain Alkaline Igneous Province, Northwestern Himalaya

by Mehboob ur Rashid and Hafiz U. Rehman

Minerals 2025, 15(5), 439; https://doi.org/10.3390/min15050439 - 23 Apr 2025

Abstract

Carbonatites, which are rare mantle-derived igneous rocks that are mainly enriched in carbonate minerals and host relatively higher amounts of rare earth element (REE)-bearing phases, remain subjects of extensive geological research due to their enigmatic origin and potential economic importance. This study aims [...] Read more.

Carbonatites, which are rare mantle-derived igneous rocks that are mainly enriched in carbonate minerals and host relatively higher amounts of rare earth element (REE)-bearing phases, remain subjects of extensive geological research due to their enigmatic origin and potential economic importance. This study aims to describe the petrographic, mineralogical, and some rare-earth element (REE) abundances of four carbonatite bodies (known as Sillai Patti, Loe Shilman, Warsak, and Jambil) exposed in the Peshawar Plain Alkaline Igneous Province (PPAIP), northwestern Himalaya, Pakistan, to identify their economic potential. The observed petrographic, textural features, and chemical compositions of the constituent minerals of the carbonatites were utilized to elucidate the evolutionary processes through which the rocks evolved. The results indicate distinct mineralogical assemblages dominated by calcite, dolomite, apatite, pyroxene, biotite, and feldspar, with accessory opaque and REE-bearing phases, such as pyrochlore, monazite, and britholite. The apatite grains display compositional zoning reflecting their growth under magmatic conditions. The petrographic features of apatite in some carbonatite samples, exhibiting preferred orientation in a particular direction and spongy or murky textures, indicate that the studied rocks underwent post-magmatic deformation or hydrothermal alteration. Calcite and dolomite, coexisting in some carbonatite samples, exhibit significant Mg-Fe variation, which is possibly related to magmatic differentiation. The pyroxene compositions vary from a low-calcium enstatite–ferrosilite series to high-calcium diopside, suggesting variable crystallization environments among the carbonatite bodies studied. The abundance of REE-bearing phases in the studied carbonatites emphasizes their high economic potential. These findings indicate that the PPAIP carbonatites originated from mantle-derived magmas and subsequently experienced metamorphic/metasomatic overprinting during their tectonic evolution. The abundance of REE-rich phases such as apatite, pyrochlore, monazite, and britholite underscores their high economic potential. Full article

(This article belongs to the Special Issue Geochemistry and Geochronology of High-Grade Metamorphic Rocks)

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23 pages, 57804 KiB

Open AccessArticle

Multiscale Characteristics and Controlling Factors of Shale Oil Reservoirs in the Permian Lucaogou Formation (Jimusaer Depression, Junggar Basin, NW China)

by Yang Lian, Liping Zhang, Xuan Chen, Xin Tao, Yuhao Deng and Peiyan Li

Minerals 2025, 15(5), 438; https://doi.org/10.3390/min15050438 - 23 Apr 2025

Abstract

The Permian Lucaogou Formation (PLF) shale oil reservoirs in the Junggar Basin exhibit significant lithological heterogeneity, which limits the understanding of the relationship between macroscopic and microscopic reservoir characteristics, as well as insights into reservoir quality. To address this gap, thirty core samples, [...] Read more.

The Permian Lucaogou Formation (PLF) shale oil reservoirs in the Junggar Basin exhibit significant lithological heterogeneity, which limits the understanding of the relationship between macroscopic and microscopic reservoir characteristics, as well as insights into reservoir quality. To address this gap, thirty core samples, exhibiting typical sedimentary features, were selected from a 46 m section of the PLF for sedimentological analysis, thin section examination, high-performance microarea scanning, and scanning electron microscopy. Seven main lithofacies were identified, including massive bedding slitstone/fine-grained sandstone (LS1), cross to parallel bedding siltstone (LS2), climbing ripple laminated argillaceous siltstone (LS3), paired graded bedding argillaceous siltstone (LS4), irregular laminated argillaceous siltstone (LS5), irregular laminated silty mudstone (LM2), and horizontal laminated mudstone (LM2). The paired graded bedding sequences with internal erosion surfaces, massive bedding, and terrestrial plant fragments suggest a lacustrine hyperpycnal flow origin. The channel subfacies of hyperpycnal flow deposits, primarily consisting of LS1 and LS2, reflect strong hydrodynamic conditions, with a single-layer thickness ranging from 1.3 to 3.8 m (averaging 2.2 m) and porosity between 7.8 and 14.2% (averaging 12.5%), representing the primary sweet spot. The lobe subfacies, composed mainly of LS3, LS4, and LS5, reflect relatively strong hydrodynamic conditions, with a single-layer thickness ranging from 0.5 to 1.4 m (averaging 0.8 m) and porosity between 4.2 and 13.8% (averaging 9.6%), representing the secondary sweet spot. In conclusion, strong hydrodynamic conditions and depositional microfacies are key factors in the formation and distribution of sweet spots. The findings of this study are valuable for identifying sweet spots in the PLF and provide useful guidance for the exploration of lacustrine shale oil reservoirs in the context of hyperpycnal flow deposition globally. Full article

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18 pages, 7564 KiB

Open AccessArticle

Elemental Composition, Rock-Magnetic Characterization, and Archaeomagnetic Dating of Ceramic Fragments from the Paquimé Archaeological Site (Northern Mexico)

by Juan Morales, Fátima Karina Gutiérrez, Nayeli Pérez-Rodríguez, Eduardo Gamboa, Avto Goguitchaichvili and Rodrigo Esparza

Minerals 2025, 15(5), 437; https://doi.org/10.3390/min15050437 - 23 Apr 2025

Abstract

Paquimé is a remarkable pre-Hispanic settlement that flourished between the 13th and 15th centuries in northwest Chihuahua, Mexico. This site is recognized for its distinctive fusion of Mesoamerican and Southwestern American cultural traits. Although much of the explanatory models about this settlement’s development [...] Read more.

Paquimé is a remarkable pre-Hispanic settlement that flourished between the 13th and 15th centuries in northwest Chihuahua, Mexico. This site is recognized for its distinctive fusion of Mesoamerican and Southwestern American cultural traits. Although much of the explanatory models about this settlement’s development and regional role have focused on trade, pottery from the Salado tradition, particularly Polychrome Gila and Polychrome Tonto, has generally been presumed to have originated in the American Southwest. To confirm the interaction between both cultures and contribute to the clarification of the absolute chronology of Paquimé, the geochemical characterization and rock-magnetic characterization of sherds of local and presumably foreign manufacture were carried out, including sherds with manufacture that seems to be the result of the abovementioned relationship. SiO₂ and Al₂O₃ contribute more than 75% to the observed variation. The Casas Grandes pottery shares the geochemical signatures of both local and foreign types. High-coercivity magnetic grains dominate in the foreign-type pottery samples. In contrast, relatively low-coercivity ferrimagnetic grains are the main features of local-type sherds. Essentially similar absolute intensity values were obtained for both potsherd wares. The most probable age intervals obtained for all ceramic samples studied range from 990 AD to 1310 AD, in agreement with previous surveys and local archaeological frameworks. Full article

(This article belongs to the Special Issue Applications of Paleomagnetism and Rock Magnetism in Geochronology)

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23 pages, 16107 KiB

Open AccessArticle

Utilizing Lineaments Extracted from Radar Images and Drainage Network to Evaluate the Mineral Potential of Au and Cu in the Bom Jardim Group (Neoproterozoic), Southern Brazil

by Marco Antonio Fontoura Hansen, César Augusto Moreira, Henri Masquelin, José Pedro Rebés Lima, Lenon Melo Ilha, Luiza Lima Alves, Sissa Kumaira and Ana Flávia da S. Araújo

Minerals 2025, 15(5), 436; https://doi.org/10.3390/min15050436 - 23 Apr 2025

Abstract

The exploration of gold and copper is essential for the sustainable development of mining worldwide and in Brazil, given the dependency on copper imports. This study aims to reassess and identify promising areas for sulfide prospecting in southern Brazil, with technologies, including radar [...] Read more.

The exploration of gold and copper is essential for the sustainable development of mining worldwide and in Brazil, given the dependency on copper imports. This study aims to reassess and identify promising areas for sulfide prospecting in southern Brazil, with technologies, including radar images (ALOS PALSAR) and software (PCI Geomatics CATALYST Professional Complete, version 2023, QGIS 3.38.1 (Grenoble), Spring 5.5.6, and Orient 3.20.0), for the extraction and processing of tectonic lineaments. The comparative analysis between these linear structures and the drainage networks allows for the assessment of alluvial gold minerals and disseminated copper in andesites, as observed in the abandoned Seival mines. The methods employed include the extraction of tectonic lineaments and the evaluation of mineral occurrences in the Hilário (volcanogenic) and Arroio dos Nobres (sedimentary) formations of the Bom Jardim Group (Neoproterozoic) and their drainage networks. As a result, this article concludes that the main tectonic alignment directions for copper and gold occurrences disseminated in andesites are predominantly E–W, N–S, N 5° W, N 58° W, N 62° E, and N 23° E, and for alluvial gold N–S and N 45° W. These results are crucial for reassessing abandoned mining areas and identifying the primary mineral orientations in rocks and the predominant orientation of alluvial deposits, serving as structural controls for discovering new mineral occurrences. It is concluded that geotechnologies have expanded the possibilities for study, enabling a more detailed analysis of tectonic lineaments and drainage systems and providing a valuable prospective guide for gold and copper mineral exploration. Full article

(This article belongs to the Special Issue Geophysical Signatures of Mineral Deposits in Tropical and Subtropical Settings)

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17 pages, 4722 KiB

Open AccessArticle

Interactions of Mineral Surfaces with Water Vapor: A Method for Analyzing Surface Condensation on Halite Crystals

by Tymoteusz Piga, Paweł Jamróz and Dominik Buksa

Minerals 2025, 15(5), 435; https://doi.org/10.3390/min15050435 - 22 Apr 2025

Abstract

Condensation on mineral surfaces plays an important role in both natural and industrial environments, especially in the context of protecting sensitive geological formations. This paper presents the results of a new measurement method based on image analysis for non-invasive detection and classification of [...] Read more.

Condensation on mineral surfaces plays an important role in both natural and industrial environments, especially in the context of protecting sensitive geological formations. This paper presents the results of a new measurement method based on image analysis for non-invasive detection and classification of surface condensation on halite crystals. The presented method allows continuous monitoring of optical changes on the crystal surface in the visible light spectrum and also under natural (in situ) conditions. Based on the experiments carried out using halite samples from the Crystal Caves in the Wieliczka Salt Mine and literature data, four characteristic states of the crystal surface were distinguished. This classification was based on the values of relative humidity: (1) dry state (<65.0%), (2) quasi-static condensation (65.0%–75.5%), (3) transient unstable state (75.5%–77.0%), and (4) dynamic condensation (>77.0%), leading to intensive formation of brine solution on its surface. For the halite samples studied, the critical relative humidity (CRH) value was determined to be around 77.0%. The proposed measurement technique allows early detection of the presence of condensate and can be used as a qualitative classifier of the state of surface moisture, which allows automatic assessment of the risk of degradation. This method can find application in the protection of non-living nature reserves and cultural heritage sites, especially in the context of climate change and sustainable management of the underground environment. Full article

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

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22 pages, 7582 KiB

Open AccessArticle

Computational and Experimental Research on Dense Medium Separation of Low-Grade Spodumene

by Shuli Wang, Jun Wang, Guanzhou Qiu, Li Shen, Rui Liao and Lianjun Wu

Minerals 2025, 15(5), 434; https://doi.org/10.3390/min15050434 - 22 Apr 2025

Abstract

Due to the increasing demand for lithium resources, the efficient exploitation and utilization of low-grade hard-rock deposits has become an inevitable trend. This study conducted comprehensive heavy liquid separation (HLS), numerical simulation, and dense medium separation (DMS) tests using a laboratory dense medium [...] Read more.

Due to the increasing demand for lithium resources, the efficient exploitation and utilization of low-grade hard-rock deposits has become an inevitable trend. This study conducted comprehensive heavy liquid separation (HLS), numerical simulation, and dense medium separation (DMS) tests using a laboratory dense medium cyclone (DMC) on a low-grade spodumene ore to demonstrate the potential role of DMS technology in this task. HLS tests verified the feasibility of directly producing qualified concentrate and rejecting waste under different separation densities. A two-stage DMS circuit was then proposed, with the influence of key parameters investigated by numerical simulations using the two-fluid model and dispersed model. The optimized set of structural and operational parameters was finally identified by DMS tests. A continuously operated test conducted on −8 + 0.5 mm ore produced a spodumene concentrate grading 5.68% Li₂O with over 80% lithium recovery while rejecting 0.13% Li₂O waste to tailings with ~70% disposal rate but only 7.44% lithium losses. The middling with a yield of 12.66% can be further subjected to a traditional grinding-flotation process. The findings underscore the importance of parameter matching in the DMS and demonstrate the application potential of DMS in the development of low-grade spodumene from other hard-rock occurrences. Full article

(This article belongs to the Special Issue Recent Advances in Ore Comminution)

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16 pages, 13448 KiB

Open AccessArticle

Formation Mechanism of Plagioclase–Amphibole and Amphibole–Spinel Symplectites in the Bijigou Layered Intrusion: Insights from Mineralogical and Crystallographic Constraints

by Baoqun Sun, Xinyu Wei and Huan Dong

Minerals 2025, 15(5), 433; https://doi.org/10.3390/min15050433 - 22 Apr 2025

Abstract

The Bijigou layered intrusion is located in the northern margin of the Yangtze block. Based on cumulus mineral assemblages, the intrusion is divided into three major units from the base upwards: the lower zone (LZ), dominated by olivine gabbro; the middle zone (MZ), [...] Read more.

The Bijigou layered intrusion is located in the northern margin of the Yangtze block. Based on cumulus mineral assemblages, the intrusion is divided into three major units from the base upwards: the lower zone (LZ), dominated by olivine gabbro; the middle zone (MZ), composed of gabbro and Fe-Ti oxide ore layers; and the upper zone (UZ), characterized by (quartz) diorite. Previous studies reported various vermicular symplectite textures in layered intrusions, which are thought to be related to the magmatic evolution of the layered intrusions and the mineralization of vanadium–titanium magnetite. However, detailed studies on the specific reaction mechanism of those symplectites are lacking. In this study, the characteristics, mineral compositions, and crystal orientation relationships of minerals in symplectites from Fe-Ti oxide Fe-Ti oxide-rich gabbro are in the Bijigou layered intrusion investigated by an Electron Probe Microanalyzer (EPMA) and Electron Backscattered Diffraction (EBSD) to reveal the formation process of symplectites in gabbros. In the Fe-Ti oxide-rich gabbro, abundant amphibole + spinel (Amp₁ + Spl) symplectite and amphibole + plagioclase (Pl₂ + Amp₂) symplectite are developed between the primocryst plagioclase (Pl₁) and Fe-Ti oxide; Pl₂ had significantly higher An contents (An_92–97) relative to Pl₁. The Mg # for Amp₁ and Amp₂ was 0.78–1 and 0.6–0.84, respectively. Amphibole geothermometer calculations show Amp₁ and Amp₂ at 934–953 °C and 834–914 °C, suggesting that these symplectites crystallized at a late stage of magmatic evolution. The crystallographic orientation relationship between Amp₁ and Spl varies in different areas, and Spl has a particular orientation relationship with the external Ilm. Pl₂ and Amp₂ inherit the crystallographic orientation of Amp₁ and Pl₁, respectively. We speculate that in the Bijigou layered intrusions, Amp₁ + Spl and Pl₂ + Amp₂ were formed in two stages: Amp₁ + Spl symplectite due to Ilm epitaxial growth as a result of supersaturation and rapid nucleation; and Pl₂ + Amp₂ symplectite due to dissolution–precipitation. Full article

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

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20 pages, 2339 KiB

Open AccessArticle

Geometallurgical Modeling of Influence of Mineral Composition of Sulfide Copper Ore (Southwest Poland) on Enrichment Selectivity

by Magdalena Duchnowska and Alicja Bakalarz

Minerals 2025, 15(4), 432; https://doi.org/10.3390/min15040432 - 20 Apr 2025

Abstract

The aim of this research was to determine a relationship that would allow the results of the enrichment process to be predicted from the mineral and chemical composition of the of sedimentary copper ores present in the Fore-Sudetic monocline (SW Poland). A series [...] Read more.

The aim of this research was to determine a relationship that would allow the results of the enrichment process to be predicted from the mineral and chemical composition of the of sedimentary copper ores present in the Fore-Sudetic monocline (SW Poland). A series of laboratory flotation tests of feeds with different lithological compositions of copper ores (sandstone, dolomitic, and shale) as well as detailed chemical and mineral analyses of feeds and flotation products were carried out. Based on the obtained results, enrichment selectivity indicators were determined and used in modeling. Among the methods of statistical dimensional analysis, multivariate correlation was used for modeling. The result of modeling was the equation that allowed the prediction of the results of the copper ore enrichment process from the contents of the main rock-forming minerals (clays/micas and carbonates) and copper in the feed. The equation is highly precise and can be used to predict the results of copper ore enrichment on the basis of the mineral and chemical compositions of the feed (correlation coefficient of 0.78). The proposed equations may be employed in an industrial process to determine its metallurgical result in the case of variable ore lithology. Full article

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

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17 pages, 4541 KiB

Open AccessArticle

SAG Mill Grinding Media Stress Evaluation—A DEM Approach

by Murray Mulenga Bwalya, Oliver Shwarzkopf Samukute and Ngonidzashe Chimwani

Minerals 2025, 15(4), 431; https://doi.org/10.3390/min15040431 - 20 Apr 2025

Abstract

The volatility of commodity prices has obligated primary metal producers to continuously seek ways of cutting costs in mineral processing units. Improving the wear characteristics and reducing the probability of grinding media fracture can potentially reduce production costs. Characterisation of the impact-loading environment [...] Read more.

The volatility of commodity prices has obligated primary metal producers to continuously seek ways of cutting costs in mineral processing units. Improving the wear characteristics and reducing the probability of grinding media fracture can potentially reduce production costs. Characterisation of the impact-loading environment and stress induced into the grinding media in SAG mills aids manufacturers in developing grinding media with superior mechanical properties. Such grinding media development emanates from a firm understanding of the SAG process supported by computer modelling tools and well-established engineering designs. The discrete element method (DEM) is a numerical technique for evaluating collision behaviour in particulate systems. This paper discusses the application of the DEM to estimate survivability and stress, induced into grinding media in a SAG mill. Full article

(This article belongs to the Special Issue Comminution and Comminution Circuits Optimisation: 3rd Edition)

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26 pages, 7042 KiB

Open AccessArticle

Thermodynamic Stability of Clay Minerals in Boreal Forest Soil and Its Relationship to the Properties of Soil Organic Matter

by Igor V. Danilin, Yulia G. Izosimova, Ruslan A. Aimaletdinov and Inna I. Tolpeshta

Minerals 2025, 15(4), 430; https://doi.org/10.3390/min15040430 - 20 Apr 2025

Abstract

This paper assesses the thermodynamic stability of clay minerals in the upper organo-mineral horizon of podzolic soil, as well as in the rhizosphere of Norway spruce (Picea abies (L.) H. Karst.) and Norway maple (Acer platanoides L.). Moreover, it determines the [...] Read more.

This paper assesses the thermodynamic stability of clay minerals in the upper organo-mineral horizon of podzolic soil, as well as in the rhizosphere of Norway spruce (Picea abies (L.) H. Karst.) and Norway maple (Acer platanoides L.). Moreover, it determines the impact of soil organic matter on the thermodynamic stability of clay minerals. Calculations of ΔG_f and the saturation index (SI) for clay minerals in laboratory experiments simulating soil conditions without soil moisture outflow allowed us to find out that the thermodynamic stability of clay minerals decreased in the series kaolinite > illite > vermiculite > chlorite. In the rhizosphere of spruce, kaolinite, vermiculite and illite have the lowest, and in the soil under maple-the highest thermodynamic stability, which is associated with differences in the properties of soil organic matter of rhizospheres of different tree species. Laboratory experiments on the sorption of soil humic acid (HA) on clay minerals demonstrated that sorbed HA decreased the thermodynamic stability of biotite and increased the thermodynamic stability of kaolinite and muscovite. Thermodynamic stability of clay minerals decreased with increased proportion of sorbed thermolabile organic matter. Full article

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

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19 pages, 16833 KiB

Open AccessArticle

Evaluation of the Capabilities of Grounded-Wire Source Surface-Borehole Transient Electromagnetic Detection in Complex Geological Settings

by Xianxiang Wang and Wanting Ma

Minerals 2025, 15(4), 429; https://doi.org/10.3390/min15040429 - 20 Apr 2025

Abstract

The surface-borehole transient electromagnetic method exhibits significant advantages in identifying deep targets, as its closer distance to subsurface targets results in more pronounced effective anomalies when compared to surface-based techniques. The grounded-wire source TEM demonstrates enhanced capabilities for deep exploration, featuring increased penetration [...] Read more.

The surface-borehole transient electromagnetic method exhibits significant advantages in identifying deep targets, as its closer distance to subsurface targets results in more pronounced effective anomalies when compared to surface-based techniques. The grounded-wire source TEM demonstrates enhanced capabilities for deep exploration, featuring increased penetration depth, enhanced signal response, superior resolution, and minimized volume effects, which render it especially effective for examining intricate deep reservoirs. This study utilizes a time-domain finite-element method with unstructured tetrahedral grids to conduct three-dimensional numerical simulations of grounded-wire source SBTEM in complex terrains, capitalizing on the flexibility and precision of this method for modeling detailed geological structures. A comparative analysis of electromagnetic field responses between conductive and high-resistivity targets indicates that the detection capability of magnetic field components decreases more markedly than that of the vertical electric field Ez as the burial depth of the target increases. The grounded-wire source SBTEM exhibits enhanced sensitivity and better identification capabilities for conductive targets when compared to high-resistivity alternatives. The present research represents a detailed analysis of the impact of complex terrain on the detection capabilities of grounded-wire source SBTEM, utilizing electromagnetic response simulations of typical three-dimensional complex geological models. The results provide robust theoretical backing and empirical evidence for an enhanced understanding of subsurface resource exploration. Full article

(This article belongs to the Special Issue Gravity, Magnetic, and Electromagnetic (GME) Geophysical Data Interpretation for Mineral Exploration and Crustal Structure Investigation)

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14 pages, 7580 KiB

Open AccessArticle

Siderite Decomposition Kinetics—Influence of Time, Temperature, and Isomorphous Impurities

by Mariola Kądziołka-Gaweł, Zdzisław Adamczyk, Dariusz Łukowiec, Joanna Klimontko, Marcin Wojtyniak and Jacek Nowak

Minerals 2025, 15(4), 428; https://doi.org/10.3390/min15040428 - 19 Apr 2025

Abstract

Siderite (FeCO₃) is an iron-bearing carbonate mineral that is the most abundant sedimentary iron formation on Earth. The influence of time, temperature, and isomorphous impurities on the kinetics of siderite decomposition in air was studied using Mössbauer spectroscopy, X-ray diffraction, X-ray [...] Read more.

Siderite (FeCO₃) is an iron-bearing carbonate mineral that is the most abundant sedimentary iron formation on Earth. The influence of time, temperature, and isomorphous impurities on the kinetics of siderite decomposition in air was studied using Mössbauer spectroscopy, X-ray diffraction, X-ray fluorescence spectroscopy, and the Transmission Electron Microscopy method. Two rock siderite samples were used for investigations, one containing a significant amount of magnesium. The siderite decomposition process begins at a temperature of 300 °C. In a sample containing practically no magnesium, complete decomposition occurs at a temperature of 450 °C, and in a sample with magnesium at a temperature of 500 °C. The annealing time does not affect the width of the temperature range where siderite decomposition occurs. Still, it affects the degree of siderite decomposition: the longer the annealing time, the greater the amount of siderite decomposition. The decomposition products of siderite annealed in air are iron oxides. In the sample containing practically no Mg, this oxide was mainly hematite, and in the sample containing magnesium, it was magnesioferrite. Iron oxides formed directly in siderite decomposition are poorly crystalline, and we can treat them as iron oxide nanoparticles. They maintain this form in a wide temperature range, especially in a magnesium-containing sample. The presence of this element significantly slows down the process of magnesioferrite crystallization. Full article

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

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19 pages, 752 KiB

Open AccessArticle

Optimization in Mineral Processing: A Novel Matheuristic for a Variant of the Knapsack Problem

by Carlos Leiva, Hernán Lespay, Aldo Quelopana and Alessandro Navarra

Minerals 2025, 15(4), 427; https://doi.org/10.3390/min15040427 - 19 Apr 2025

Abstract

This study introduces a novel heuristic approach to optimize mineral processing in metallurgical plants, framed as a variant of the fractional knapsack problem. The optimization framework integrates plant operational modes, blending requirements, and processing constraints to maximize the recoverable value of mineral blocks [...] Read more.

This study introduces a novel heuristic approach to optimize mineral processing in metallurgical plants, framed as a variant of the fractional knapsack problem. The optimization framework integrates plant operational modes, blending requirements, and processing constraints to maximize the recoverable value of mineral blocks while adhering to plant capacity and feed limitations. Building on a previously established mixed-integer linear programming formulation, this study develops a heuristic algorithm employing a greedy strategy. This alternative approach significantly reduces computational time while achieving near-optimal solutions, making it suitable for practical implementation. Validation through a case study demonstrates the algorithm’s effectiveness in managing complex constraints and delivering actionable insights for real-world operations. These findings highlight the potential of this methodology to streamline the mineral processing stage of broader mine planning frameworks, complementing the initial optimization of block extraction with faster and more reliable processing calculations. Full article

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

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24 pages, 12852 KiB

Open AccessArticle

Zircon U-Pb Geochronology and Geochemical Constraints of Tiancang Granites, Southern Beishan Orogenic Belt: Implications for Early Permian Magmatism and Tectonic Evolution

by Chao Teng, Meiling Dong, Xinjie Yang, Deng Xiao, Jie Shao, Jun Cao, Yalatu Su and Wendong Lu

Minerals 2025, 15(4), 426; https://doi.org/10.3390/min15040426 - 19 Apr 2025

Abstract

The Beishan Orogenic Belt, situated along the southern margin of the Central Asian Orogenic Belt, represents a critical tectonic domain that archives the prolonged subduction–accretion processes and Paleo-Asian Ocean closure from the Early Paleozoic to the Mesozoic. Early Permian magmatism, exhibiting the most [...] Read more.

The Beishan Orogenic Belt, situated along the southern margin of the Central Asian Orogenic Belt, represents a critical tectonic domain that archives the prolonged subduction–accretion processes and Paleo-Asian Ocean closure from the Early Paleozoic to the Mesozoic. Early Permian magmatism, exhibiting the most extensive spatial-temporal distribution in this belt, remains controversial in its geodynamic context: whether it formed in a persistent subduction regime or was associated with mantle plume activity or post-collisional extension within a rift setting. This study presents an integrated analysis of petrology, zircon U-Pb geochronology, in situ Hf isotopes, and whole-rock geochemistry of Early Permian granites from the Tiancang area in the southern Beishan Orogenic Belt, complemented by regional comparative studies. Tiancang granites comprise biotite monzogranite, monzogranite, and syenogranite. Zircon U-Pb dating of four samples yields crystallization ages of 279.3–274.1 Ma. These granites are classified as high-K calc-alkaline to calc-alkaline, metaluminous to weakly peraluminous I-type granites. Geochemical signatures reveal the following: (1) low total rare earth element (REE) concentrations with light REE enrichment ((La/Yb)_N = 3.26–11.39); (2) pronounced negative Eu anomalies (Eu/Eu* = 0.47–0.71) and subordinate Ce anomalies; (3) enrichment in large-ion lithophile elements (LILEs: Rb, Th, U, K) coupled with depletion in high-field-strength elements (HFSEs: Nb, Ta, P, Zr, Ti); (4) zircon ε_Hf(t) values ranging from −10.5 to −0.1, corresponding to Hf crustal model ages (T_DMC) of 1.96–1.30 Ga. These features collectively indicate that the Tiancang granites originated predominantly from partial melting of Paleoproterozoic–Mesoproterozoic crustal sources with variable mantle contributions, followed by extensive fractional crystallization. Regional correlations demonstrate near-synchronous magmatic activity across the southern/northern Beishan and eastern Tianshan Orogenic belts. The widespread Permian granitoids, combined with post-collisional magmatic suites and rift-related stratigraphic sequences, provide compelling evidence for a continental rift setting in the southern Beishan during the Early Permian. This tectonic regime transition likely began with lithospheric delamination after the Late Carboniferous–Early Permian collisional orogeny, which triggered asthenospheric upwelling and crustal thinning. These processes ultimately led to the terminal closure of the Paleo-Asian Ocean’s southern branch, followed by intracontinental evolution. Full article

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

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12 pages, 3059 KiB

Open AccessArticle

Application of Surface-Modified Natural Magnetite as a Magnetic Carrier for Microplastic Removal from Water

by Palot Srichonphaisarn, Natatsawas Soonthornwiphat, Pongsiri Julapong, Thanakornkan Limlertchareonwanit, Thidarat Meekoch, Ilhwan Park, Mylah Villacorte-Tabelin, Onchanok Juntarasakul, Somsak Saisinchai, Carlito Baltazar Tabelin and Theerayut Phengsaart

Minerals 2025, 15(4), 425; https://doi.org/10.3390/min15040425 - 18 Apr 2025

Abstract

This study investigates the modification and application of natural, micro-scale magnetite (Fe₃O₄)—an iron oxide mineral and one of the most abundant iron ores in the world—as a magnetic carrier for removing six common types of microplastics (MPs) from water: [...] Read more.

This study investigates the modification and application of natural, micro-scale magnetite (Fe₃O₄)—an iron oxide mineral and one of the most abundant iron ores in the world—as a magnetic carrier for removing six common types of microplastics (MPs) from water: polypropylene (PP), polyethylene (PE), acrylonitrile butadiene styrene (ABS), polystyrene (PS), polyethylene terephthalate (PET), and polyvinyl chloride (PVC). Hexadecyltrimethoxysilane (HDTMS) was employed as a surfactant to modify the naturally hydrophilic magnetite, transforming it into a hydrophobic material. The characterization of magnetite treated with HDTMS for 0, 6, 12, 24, and 48 h was performed using a scanning electron microscope with energy-dispersive X-ray spectroscopy (SEM-EDS) and Fourier transform infrared spectroscopy (FT-IR). The results showed HDTMS sorption on the surface of natural magnetite, confirming successful surface modification. Carrier magnetic separation was then performed to remove PP, PE, ABS, PS, PET, and PVC using surface-modified, natural magnetite in two size fractions: +38–75 µm (fine-sized) and +75–150 µm (coarse-sized). Improved performance was observed with longer HDTMS treatment of magnetite, while greater than 90% MP removal was achieved using fine-sized, surface-modified, natural magnetite. These results suggest that surface modification enhanced the heterogenous interactions between magnetite and MPs via hydrophobic-hydrophobic interactions, leading to efficient MP removal via carrier magnetic separation. Full article

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

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22 pages, 10844 KiB

Open AccessArticle

Rapid Updating of Multivariate Resource Models Based on New Information Using EnKF-MDA and Multi-Gaussian Transformation

by Sultan Abulkhair, Peter Dowd, Chaoshui Xu and Penny Stewart

Minerals 2025, 15(4), 424; https://doi.org/10.3390/min15040424 - 18 Apr 2025

Abstract

Rapid resource model updating with real-time data is important for making timely decisions in resource management and mining operations. This requires optimal merging of models and observations, which can be achieved through data assimilation, and the ensemble Kalman filter (EnKF) has become a [...] Read more.

Rapid resource model updating with real-time data is important for making timely decisions in resource management and mining operations. This requires optimal merging of models and observations, which can be achieved through data assimilation, and the ensemble Kalman filter (EnKF) has become a popular method for this task. However, the modeled resources in mining usually consist of multiple variables of interest with multivariate relationships of varying complexity. EnKF is not a multivariate approach, and even for univariate cases, there may be slight deviations between its outcomes and observations. This study presents a methodology for rapidly updating multivariate resource models using the EnKF with multiple data assimilations (EnKF-MDA) combined with rotation-based iterative Gaussianization (RBIG). EnKF-MDA improves the updating by assimilating the same data multiple times with an inflated measurement error, while RBIG quickly transforms the data into multi-Gaussian factors. The application of the proposed algorithm is validated by a real case study with nine cross-correlated variables. The combination of EnKF-MDA and RBIG successfully improves the accuracy of resource model updates, minimizes uncertainty, and preserves the multivariate relationships. 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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36 pages, 5338 KiB

Open AccessArticle

Fluid and Solid Inclusions from Accessory Host Minerals of Permian Pegmatites of the Eastern Alps (Austria)—Tracing Permian Fluid, Its Entrapment Process and Its Role During Crustal Anatexis

by Kurt Krenn and Martina Husar

Minerals 2025, 15(4), 423; https://doi.org/10.3390/min15040423 - 18 Apr 2025

Abstract

To understand the fluid evolution of Permian pegmatites, three pegmatite fields of the Austroalpine basement units located in the Rappold Complex at St. Radegund, the Millstatt Complex, and the Polinik Complex were investigated. To achieve this goal, fluid inclusions trapped in the magmatic [...] Read more.

To understand the fluid evolution of Permian pegmatites, three pegmatite fields of the Austroalpine basement units located in the Rappold Complex at St. Radegund, the Millstatt Complex, and the Polinik Complex were investigated. To achieve this goal, fluid inclusions trapped in the magmatic accessories of garnet, tourmaline, spodumene, and beryl were studied using host mineral chemistry combined with fluid inclusion microthermometry and Raman spectrometry. Taking into account the previous work by the authors on pegmatite fields in the Koralpe and Texel Mountains, Permian fluid was determined to have evolved from two stages: Stage 1 is characterized by the homogeneous entrapment of two cogenetic immiscible fluid assemblages, a CO₂-N₂ ± CH₄-rich and a low-saline H₂O-rich fluid. Both fluids are restricted to inclusions in the early-magmatic-garnet-core domains of the Koralpe Mountains. Stage 2 is linked with the CO₂-N₂-CH₄-H₂O-NaCl-CaCl₂ ± MgCl₂ fluid preserved as an inclusion in all the pegmatite accessories of the KWNS. It represents the mechanical mixture of the stage 1 fluid caused by compositional changes along the solvus, which is typical for a hydrothermal vein environment process. Increasing X_CH₄±N₂ proportions from the eastern toward the western pegmatite fields of the KWNS results in a tectonic model that includes magmatic redox-controlled fluid flow along deep crustal normal faults during the anatexis of metasediments in Permian asymmetric graben structures. Because of a high number of solids within the inclusions as well as their irregular shapes, post-entrapment modifications have caused density changes that have to be considered with caution. However, the conditions in the range of 6–8 kbar at >670 °C for stage 1 and ca. 4 kbar at <670 °C for stage 2 represent the best approximations to explain the uprise of a two-stage Permian fluid associated with accessory mineral crystallization in close relation to fractionating melt. Full article

(This article belongs to the Special Issue Pegmatites as Hosts of Critical Metals: From Petrogenesis to Mineral Exploration)

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18 pages, 3813 KiB

Open AccessArticle

Optimizing Dense Medium Separation Pre-Concentration by Comparative Evaluation of High-Pressure Grinding Rolls vs. Conventional Crushing

by Tebogo Mokgomola, Getrude Marape and Rabelani Mariba

Minerals 2025, 15(4), 422; https://doi.org/10.3390/min15040422 - 18 Apr 2025

Abstract

This paper investigated pre-concentration of a low-grade Upper Group 2 (UG2) ore to assess the possibility of rejecting waste at a typical discard Platinum Group Metals (PGMs) grade of <0.4 g/t at mass rejection to floats greater than 16% by comparing feed prepared [...] Read more.

This paper investigated pre-concentration of a low-grade Upper Group 2 (UG2) ore to assess the possibility of rejecting waste at a typical discard Platinum Group Metals (PGMs) grade of <0.4 g/t at mass rejection to floats greater than 16% by comparing feed prepared by High pressure grinding rolls (HPGR) to Conventional crushers (Cone crushers). Heavy Liquid Separation (HLS) was conducted as a benchmark test to Dense Medium Separation (DMS) to determine the expected grade, recovery, and mass yield for various size classes and crusher. The comparison between fine size classes −9.5 + 1.18 mm and −6.7 + 1.18 mm crushed by HPGR and conventional crushing showed that, under the conditions tested, the conventional crusher outperformed HPGR in terms of high sinks grade and a higher percentage of material exposed to pre-concentration. Looking at coarser size fractions (+12 mm), HLS results showed that under the conditions tested, size fraction −20 + 1.18 mm crushed by a conventional crusher at an optimum density of 3.4 g/cm³ is an optimized size fraction to run the DMS plant. The pilot DMS cyclone testwork showed that 61.1% by mass could be rejected to the floats stream based on Run of Mine (ROM) feed at 1.12% Cr₂O₃ and 0.42 g/t Total PGMs + Au grade, a typical discardable PGMs grade. Full article

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

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13 pages, 15917 KiB

Open AccessArticle

Alternative SEM-BEX Imaging of Rock Mini-Cores (Carbonate and Siliciclastic): Manual and Semi-Automated Acquisition

by Jim Buckman, Zaid Jangda, Helen Lewis and Kamaljit Singh

Minerals 2025, 15(4), 421; https://doi.org/10.3390/min15040421 - 17 Apr 2025

Abstract

An understanding of the textures (grain size, grain shape, porosity, etc.), composition (mineralogy), and distribution of constituent components of geological materials such as carbonate and siliciclastic sedimentary rocks is essential in their classification, interpretation, and significance in terms of their geomechanical strength and [...] Read more.

An understanding of the textures (grain size, grain shape, porosity, etc.), composition (mineralogy), and distribution of constituent components of geological materials such as carbonate and siliciclastic sedimentary rocks is essential in their classification, interpretation, and significance in terms of their geomechanical strength and liquid/gas storage potential. In terms of scanning electron microscopy (SEM), this is limited to relatively flat areas of selected rough surfaces, or the analysis of polished thin sections. Here, we illustrate a new technique that can image large areas of the external surface of mini-cores (approximately 10 mm or smaller in diameter) drilled from carbonate and siliciclastic rock samples. The technique utilises a specially developed horizontal rotation stage within an SEM and allows the collection of high-resolution images that can be reconstructed into realistic surface representations of the mini-core surfaces. Elemental data (representative of mineralogy) can also be added using a combined backscattered electron and X-ray (BEX) detector. Currently, these reconstructions can be used as a useful tool for the analysis of both carbonate and siliciclastic geological materials. Further work may allow such reconstructions to aid in the improvement of resolution in micro-CT scans and the direct identification of mineral phases within such scans. Full article

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

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