Minerals

16 pages, 819 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Approximation of the Role of Mineralized Collagen Fibril Orientation in the Mechanical Properties of Bone: A Computational Study on Dehydrated Osteonal Lamellar Bone

by Onur Cem Namli and Feride Sermin Utku

Minerals 2024, 14(11), 1107; https://doi.org/10.3390/min14111107 - 30 Oct 2024

Viewed by 1091

Abstract

Bone is a natural composite of the hierarchical arrangement of mineralized collagen fibrils in various orientations. This study aims to understand how the orientation of the bone mineral, guiding the removal of water contained in the humidity-responsive layers during dehydration, affects its mechanical [...] Read more.

Bone is a natural composite of the hierarchical arrangement of mineralized collagen fibrils in various orientations. This study aims to understand how the orientation of the bone mineral, guiding the removal of water contained in the humidity-responsive layers during dehydration, affects its mechanical properties. A sublamellar pattern with mineralized collagen fibrils oriented between 0° to 150° at 5° angles was the model studied. Using basic transformational computational methods, dimensional change was calculated in the transverse and oblique planes of osteonal lamellar bone while considering bone components sensitive to dehydration in radial, tangential, and axial orientations. The anisotropy ratios of the change in the dimension of the variable mineralized collagen fibril orientations calculated using the computed model displayed values ranging between 0.847 to 2.092 for the transverse plane and 0.9856 to 1.0207 for the oblique plane. A comparison of the anisotropy results of the suggested model indicated that they approach the experimental results of both transversely and obliquely cut samples. As collagen fibril and mineral orientation take place both temporally and spatially in relationship with the static and dynamic loads placed on the different volumes of bone, the results may imply that the mechanical demands involved in bone resorption and deposition contribute to the formation of this multi-faceted and hierarchically structured natural composite. Full article

(This article belongs to the Special Issue Skeletal Tissues Mineralization)

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19 pages, 3360 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Enhancing Mineral Exploration Programs Through Quantitative XRD: A Case Study from the Gumsberg Polymetallic Sulphide Deposits, Sweden

by Sheida Makvandi, Evelien Rost, Thomas Witzke, Matteo Pernechele and Hein Raat

Minerals 2024, 14(11), 1100; https://doi.org/10.3390/min14111100 - 29 Oct 2024

Cited by 1 | Viewed by 1436

Abstract

As challenges in precious and base metal exploration intensify due to the diminishing availability of high-grade ore deposits, rising demand, energy costs, and stricter regulations towards net-zero carbon activities, advanced techniques to enhance exploration efficiency are becoming increasingly critical. This study demonstrates the [...] Read more.

As challenges in precious and base metal exploration intensify due to the diminishing availability of high-grade ore deposits, rising demand, energy costs, and stricter regulations towards net-zero carbon activities, advanced techniques to enhance exploration efficiency are becoming increasingly critical. This study demonstrates the effectiveness of quantitative X-ray diffraction (QXRD) with Rietveld refinement, coupled with multivariate statistical analysis (including agglomerative hierarchical clustering, principal component analysis, and fuzzy analysis), in characterizing the complex mineralogy of strata-bound volcanic-associated limestone-skarn Zn-Pb-Ag-(Cu-Au)-type sulphide deposits (SVALS). Focusing on 113 coarse rejects from the Gumsberg project located in the Bergslagen mining district in central Sweden, the research identified five distinct mineralogical clusters corresponding to polymetallic base metal sulphide mineralization, its proximal alteration zones, and variably metamorphosed host rocks. The results reveal significant sulphide mineralization, ranging from disseminated to massive occurrences of sphalerite, pyrrhotite, pyrite, and galena, with trace amounts of secondary minerals like anglesite in certain samples indicating weathering processes. The study also identifies rare minerals such as armenite, often overlooked in traditional geological logging. These findings underscore the potential of QXRD to enhance resource estimation, optimize exploration strategies, and contribute to more efficient and sustainable mineral exploration programs. The accuracy of QXRD was cross-validated with geological logs and geochemical data, confirming its reliability as a mineralogical discrimination tool. Full article

(This article belongs to the Special Issue Mineralogical and Geochemical Characterization of Geological Materials)

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19 pages, 5921 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Geochemical Dynamics and Evolutionary Implications of Sediments at the Xingu–Amazon Rivers’ Confluence: Proxies for Mixing, Mobility and Weathering

by Lucio Cardoso Medeiros Filho, Nils Edvin Asp, Jean Michel Lafon, Thiago Pereira Souza, José Francisco Berredo and Gabriel Negreiros Salomão

Minerals 2024, 14(11), 1101; https://doi.org/10.3390/min14111101 - 29 Oct 2024

Cited by 1 | Viewed by 1379

Abstract

This study investigates the geochemical characteristics and evolutionary implications of sediments at the confluence of the Xingu and Amazon Rivers. The main objective is to understand sediment mixing, mobility, and weathering processes through geochemical proxies. Samples were collected from various sections of the [...] Read more.

This study investigates the geochemical characteristics and evolutionary implications of sediments at the confluence of the Xingu and Amazon Rivers. The main objective is to understand sediment mixing, mobility, and weathering processes through geochemical proxies. Samples were collected from various sections of the lower Xingu River, focusing on its interaction with the Amazon River. Analytical techniques such as X-ray diffraction (XRD), X-ray fluorescence (XRF), and inductively coupled plasma mass spectrometry (ICP-MS) were employed to analyze major and trace elements. The results reveal significant spatial variations in mineralogical and textural patterns, with sediments forming distinct groupings based on their location. The data suggest that the lower Xingu River is strongly influenced by sediment inputs from the Amazon River, particularly affecting sediment composition and chemical weathering processes. This research highlights the critical interactions between river systems and their implications for the evolution of the Amazon basin, especially regarding sediment contributions from various geological sources. Even though the Xingu River drains cratonic regions at higher elevations, the geochemistry of the bottom sediments confirms that the bedload is derived from heterogeneous sources with primarily intermediate igneous compositions and has undergone substantial recycling during river transport. Full article

(This article belongs to the Special Issue Potentially Toxic Elements: Source, Distribution, Risk Assessment and Remediation)

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26 pages, 11780 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Peridotite Weathering and Ni Redistribution in New Caledonian Laterite Profiles: Influence of Climate, Hydrology, and Structure

by Michel Cathelineau, Yoram Teitler, Jean-Louis Grimaud, Sylvain Favier, Fabrice Golfier, Erick Ramanaidou, Sylvain Grangeon, Yohann Kerreveur, Julie Jeanpert, Samuel Étienne, Manuel Muñoz and Marc Ulrich

Minerals 2024, 14(11), 1082; https://doi.org/10.3390/min14111082 - 27 Oct 2024

Cited by 1 | Viewed by 1347

Abstract

The peridotite massifs of New Caledonia are characterised by complex hydrodynamics influenced by intense inherited fracturing, uplift, and erosion. Following the formation of the erosion surfaces and alteration processes, these processes drive chemical redistribution during weathering; particularly lateritisation and saprolitisation. Magnesium, silica, and [...] Read more.

The peridotite massifs of New Caledonia are characterised by complex hydrodynamics influenced by intense inherited fracturing, uplift, and erosion. Following the formation of the erosion surfaces and alteration processes, these processes drive chemical redistribution during weathering; particularly lateritisation and saprolitisation. Magnesium, silica, and trace elements such as nickel and cobalt—released as the dissolution front advances—are redistributed through the system. New observations and interpretations reveal how lateritic paleo-land surfaces evolved, and their temporal relationship with alteration processes since the Oligocene. Considering the geometry of discontinuity networks ranging from micro-fractures to faults, the transfers occur in dual-permeability environments. Olivine dissolution rates are heterogeneously due to differential solution renewal caused by erosion and valley deepening. Differential mass transfer occurs between mobile regions of highly transmissive faults, while immobile areas correspond to the rock matrix and the secondary fracture network. The progression of alteration fronts controls the formation of boulders and the distribution of nickel across multiple scales. In the saprolite, nickel reprecipitates mostly in talc-like phases, as well as minor nontronite and goethite with partial diffusion in inherited serpentine. The current nickel distribution results from a complex interplay of climatic, hydrological and structural factors integrated into a model across different scales and times. Full article

(This article belongs to the Special Issue Chemical Weathering Studies)

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8 pages, 1837 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Gypsum Crystals Formed by the Anhydrite–Gypsum Transformation at Low Temperatures: Implications for the Formation of the Geode of Pulpí

by Andrea Cotellucci, Juan-Manuel Garcia-Ruiz, Fermín Otálora, Àngels Canals, Marco Bruno, Quentin Wehrung, Luca Pellegrino, Dino Aquilano and Linda Pastero

Minerals 2024, 14(11), 1074; https://doi.org/10.3390/min14111074 - 25 Oct 2024

Viewed by 1496

Abstract

Determining the mechanisms of the formation of giant crystals is a challenging subject. Gypsum, calcium sulfate dihydrate (CaSO₄·2H₂O), is known to form crystals larger than one meter in several locations worldwide. These selenite crystals grow at different temperatures, either [...] Read more.

Determining the mechanisms of the formation of giant crystals is a challenging subject. Gypsum, calcium sulfate dihydrate (CaSO₄·2H₂O), is known to form crystals larger than one meter in several locations worldwide. These selenite crystals grow at different temperatures, either in sedimentary or hydrothermal systems. The famous selenite crystals of the geode of Pulpí (Almería, Spain) are known to have grown at a temperature T = 20 ± 5 °C and have been proposed to form in a subaqueous environment by a self-feeding mechanism triggered by anhydrite dissolution and the ripening of microcrystalline gypsum, enhanced by oscillations in temperature. This paper reports the monitored crystallization of gypsum crystals, from anhydrite powder dissolution, inside airtight evaporation-free reactors under oscillating low temperatures (15 °C < T < 25 °C). These crystals are clearly smaller than the ones in the Pulpí mine but exhibit similar habits (i.e., single blocky crystals and twins following the 100 twinning law). The growth rate of gypsum single crystals has been measured to be between 3.8 and 35.3 µm/day. Noteworthy, we document the occurrence of the 100 contact twinning law of gypsum, which is the most widespread twinning law in natural environments but never univocally reported in laboratory experiments. The selection of the 100 contact twinning law has been correlated to the low supersaturation values obtained in the experiment, where the concentration in these long-duration experiments can be safely assumed to be the equilibrium concentration, i.e., 0.3 (at 25 °C) ≤ SI ≤ 0.4 (at 15 °C). We discuss the relevance of our experiment for forming the gypsum crystals of Pulpí in the framework of the geological history of Pulpí mineralization. These laboratory model experiments contribute to a deeper understanding of mineral nucleation and growth processes in natural environments. Full article

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

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16 pages, 5730 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Modeling and Hybrid Inversion of Mineral Deposits Using the Dipping Dike Model with Finite Depth Extent

by Saulo Pomponet Oliveira, Juarez dos Santos Azevedo, Joelson da Conceição Batista and Diego Menezes Novais

Minerals 2024, 14(10), 1054; https://doi.org/10.3390/min14101054 - 21 Oct 2024

Cited by 1 | Viewed by 1116

Abstract

The dipping dike model has shown to be a useful approximation for mineral deposits. To make this model more realistic, we include the thickness, which yields the depth to the bottom, as an additional parameter. The magnetic anomaly is obtained by combining the [...] Read more.

The dipping dike model has shown to be a useful approximation for mineral deposits. To make this model more realistic, we include the thickness, which yields the depth to the bottom, as an additional parameter. The magnetic anomaly is obtained by combining the anomalies of two infinite dikes, so that the resulting expression is simpler than the classical prismatic models with polygonal cross section. We employ a Metropolis-Hasting (MH) algorithm coupled with the Levenberg-Marquardt (LM) method to invert magnetic profiles assuming a model of multiple dike-like sources. We use a few iterations of the LM method to improve the candidate solutions at the end of each random walk generated by MH. The following parameters are obtained: depth to the top, thickness, half-width, horizontal location of the top center, geological dip, in addition to two effective parameters that depend on the intensity of magnetization and the directions of the induced and remanent fields. For synthetic anomalies, both noise-free and noisy magnetic data are considered, with examples presented for each scenario. These examples highlight the discrepancy between models with finite and infinite sources. They also illustrate the higher accuracy of the hybrid MH-LM method over the pure MH approach. Moreover, two field examples related to mineral exploration have been considered: the Pima copper mine, United States, where the relative differences between the parameters obtained by our algorithm and those known from drilling are not higher than 10%, and a magnetic profile over iron ore deposits located in Laje, northeast Brazil, where the inverted parameters were useful for detailing previous studies. Full article

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

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14 pages, 4268 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

‘Rhythmite’, Ca₂₉(SiO₄)₈Cl₂₆, an Anthropogenic Phase from the Chelyabinsk Coal Basin (Ural, Russia) with a Complex Modular Structure Related to α-Ca₃SiO₄Cl₂ (‘Albovite’): Crystal Structure, Raman Spectra, and Thermal Expansion

by Margarita S. Avdontceva, Andrey A. Zolotarev, Anastasia S. Brazhnikova, Vladimir N. Bocharov, Natalia S. Vlasenko, Mikhail A. Rassomakhin and Sergey V. Krivovichev

Minerals 2024, 14(10), 1048; https://doi.org/10.3390/min14101048 - 18 Oct 2024

Viewed by 1085

Abstract

‘Rhythmite’, Ca₂₉(SiO₄)₈Cl₂₆, an anthropogenic calcium chloride silicate from the Chelyabinsk coal basin (South Ural, Russia), was investigated using chemical microprobe analysis, in situ single-crystal X-ray diffraction analysis (27–727 °C), and Raman spectroscopy. ‘Rhythmite’ is orthorhombic, [...] Read more.

‘Rhythmite’, Ca₂₉(SiO₄)₈Cl₂₆, an anthropogenic calcium chloride silicate from the Chelyabinsk coal basin (South Ural, Russia), was investigated using chemical microprobe analysis, in situ single-crystal X-ray diffraction analysis (27–727 °C), and Raman spectroscopy. ‘Rhythmite’ is orthorhombic, Pnma: a = 17.0749(6), b = 15.1029(5), c = 13.2907(4) Å, and V = 3427.42(18) Å³ (R₁ = 0.045). The crystal structure of ‘rhythmite’ consists of a porous framework formed by Ca-O bonds and SiO₄ tetrahedra with additional Ca²⁺ cations and Cl⁻ anions in the structure interstices. The framework is built up from multinuclear [Ca₁₅(SiO₄)₄]¹⁴⁺ fundamental building blocks (FBBs) cut from the crystal structure of α-Ca₃SiO₄Cl₂ (‘albovite’). The FBBs are linked by sharing common Ca atoms to form a network with an overall pcu topology. The empirical chemical formula was calculated as Ca_29.02(Si_7.89Al_0.05P_0.05)_Ʃ7.99O₃₂Cl₂₆ (on the basis of Cl + O = 58). ‘Rhythmite’ is stable up to 627 °C and expands slightly anisotropically (α_max/α_min = 1.40) in the ab and bc planes and almost isotropically in the ac plane (α₃₃/α₁₁ = 1.02) with the following thermal expansion coefficients (×10⁶ °C⁻¹): α₁₁ = 14.6(1), α₂₂ = 20.5(4), α₃₃ = 15.0(3), and α_V = 50.1(6) (room temperature). During expansion, the silicate tetrahedra remain relatively rigid with average bond length changes of less than 0.5%. A structural complexity analysis indicates that ‘rhythmite’ is complex, with I_G,total = 920.313 (bits/u.c.), which significantly exceeds the average value of structural complexity for silicates and is caused by the modular framework construction and the presence of a large number of independent positions in the crystal structure. Full article

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

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19 pages, 15038 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Enhancing Iron Ore Grindability through Hybrid Thermal-Mechanical Pretreatment

by Sefiu O. Adewuyi, Hussin A. M. Ahmed, Angelina Anani, Abdu Saeed, Haitham M. Ahmed, Reem Alwafi and Kray Luxbacher

Minerals 2024, 14(10), 1027; https://doi.org/10.3390/min14101027 - 14 Oct 2024

Viewed by 1361

Abstract

Grinding is an important process of ore beneficiation that consumes a significant amount of energy. Pretreating ore before grinding has been proposed to improve ore grindability, reduce comminution energy, and enhance downstream operations. This paper investigates hybrid thermal mechanical pretreatment to improve iron [...] Read more.

Grinding is an important process of ore beneficiation that consumes a significant amount of energy. Pretreating ore before grinding has been proposed to improve ore grindability, reduce comminution energy, and enhance downstream operations. This paper investigates hybrid thermal mechanical pretreatment to improve iron ore grinding behavior. Thermal pretreatment was performed using conventional and microwave approaches, while mechanical pretreatment was conducted with a pressure device using a piston die. Results indicate that conventional (heating rate: 10 °C; maximum temperature: 400 °C), microwave (2.45 GHz, 1.7 kW, 60 s), and mechanical (14.86 MPa, zero delay time) pretreatments improved the studied iron ore grindability by 4.6, 19.8, and 15.4%, respectively. Meanwhile, conventional-mechanical and microwave-mechanical pretreatments enhanced the studied iron ore grindability by 19.2% and 22.6%, respectively. These results suggest that stand-alone mechanical pretreatment or microwave pretreatment may be more beneficial in improving the grinding behavior of the studied fine-grain iron ore sample. The results of the mechanical pretreatment obtained in this study may be used in a simulation of the HPGR system for grinding operations of similar iron ore Full article

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

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18 pages, 11767 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Aeschynite Group Minerals Are a Potential Recovery Target for Niobium Resources at the Giant Bayan Obo Nb–REE–Fe Deposit in China

by Bo Yang, Li Yang, Yong-Gang Zhao, Guo-Ying Yan, Jian-Yong Liu, Wen-Xiang Meng, Jun-Fang Yu, Lei Chen, Xiao-Chun Li and Xian-Hua Li

Minerals 2024, 14(10), 1029; https://doi.org/10.3390/min14101029 - 14 Oct 2024

Cited by 1 | Viewed by 1642

Abstract

With the development of the steel industry, China’s demand for niobium is increasing. However, domestic niobium resources are not yet stably supplied and are heavily dependent on imports from abroad (nearly 100%). It is urgent to develop domestic niobium resources. The Bayan Obo [...] Read more.

With the development of the steel industry, China’s demand for niobium is increasing. However, domestic niobium resources are not yet stably supplied and are heavily dependent on imports from abroad (nearly 100%). It is urgent to develop domestic niobium resources. The Bayan Obo deposit is the largest rare earth element deposit in the world and contains a huge amount of niobium resources. However, the niobium resource has not been exploited due to the fine-grained size and heterogeneous and scattered occurrences of Nb minerals. To promote the utilization of niobium resources in the Bayan Obo deposit, we focused on the mineralogical and geochemical characterization of six types of ores and mineral processing samples from the Bayan Obo deposit, using optical microscopes, EPMA, TIMA, and LA–ICP–MS. Our results show that: (1) the niobium mineral compositions are complex, with the main Nb minerals including aeschynite group minerals, columbite–(Fe), fluorcalciopyrochlore, Nb–bearing rutile, baotite, fergusonite–(Y), fersmite, and a small amount of samarskite–(Y). Aeschynite group minerals, columbite–(Fe), and fluorcalciopyrochlore are the main niobium-carrying minerals and should be the primary focus of industrial recycling and utilization. Based on mineralogical and geochemical investigation, the size of the aeschynite group minerals is large enough for mineral processing. Aeschynite group minerals are thus a significant potential recovery target for niobium, as well as for medium–heavy REE resources. The Nb–rich aegirine-type ores with aeschynite group mineral megacrysts are suggested to be the most significant niobium resource for mineral processing and prospecting. Combined with geological features, mining, and mineral processing, niobium beneficiation efforts of aeschynite group minerals are crucial for making breakthroughs in the utilization of niobium resources at the Bayan Obo. Full article

(This article belongs to the Special Issue Mineral Resources in North China Craton)

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15 pages, 9591 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Influence of Steel and Poly Vinyl Alcohol Fibers on the Development of High-Strength Geopolymer Concrete

by Shaik Hussain, John Matthews, Sudhir Amritphale, Richard Edwards, Elizabeth Matthews, Niloy Paul and John Kraft

Minerals 2024, 14(10), 1007; https://doi.org/10.3390/min14101007 - 5 Oct 2024

Cited by 4 | Viewed by 1217

Abstract

The present study focuses on the mechanical performance of steel and polyvinyl alcohol fibers embedded in the geopolymer matrix. A high-strength geopolymer concrete with fly ash, slag and silica fume as precursors and sodium hydroxide and sodium silicate solutions as activators has been [...] Read more.

The present study focuses on the mechanical performance of steel and polyvinyl alcohol fibers embedded in the geopolymer matrix. A high-strength geopolymer concrete with fly ash, slag and silica fume as precursors and sodium hydroxide and sodium silicate solutions as activators has been tested for its strength in compression and flexure. The influence of fibers on flowability, long-term shrinkage and sulphuric acid attack on the geopolymer concrete has also been studied. The dosage of fibers was maintained at 1%, 2% and 3% by volume, and fibers of length 13 mm have been used in the study. Results indicate that slag with 3% steel fibers by volume had a predominant influence on the strength development of steel fiber-reinforced geopolymer concrete, yielding a compressive strength of 107 MPa after 28 days. Blast furnace slag resulted in increasing the shrinkage of concrete due to rapid gel formation owing to the presence of calcium ions, although the fibers helped reduce the shrinkage to some extent. The strength of steel fiber geopolymer concrete was superior to PVA fiber geopolymer concrete; however, after an acid attack, the strength of steel fiber geopolymer concrete was reduced more than PVA fiber geopolymer concrete due to the enhanced corrosion resistance of PVA fibers. Full article

(This article belongs to the Special Issue Geopolymers: Synthesis, Characterization and Application)

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31 pages, 15724 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Mineralogy and Geochemistry of Listvenite-Hosted Ni–Fe Sulfide Paragenesis—A Case Study from Janjevo and Melenica Listvenite Occurrences (Kosovo)

by Konrad Kluza, Jaroslav Pršek and Sławomir Mederski

Minerals 2024, 14(10), 1008; https://doi.org/10.3390/min14101008 - 5 Oct 2024

Cited by 1 | Viewed by 2122

Abstract

The main goal of this paper is to determine the order of the paragenetic sequence and phase transitions of the Ni–Fe sulfide association hosted in listvenites. Listvenites are hydrothermally altered mafic and ultramafic rocks that are often associated with active tectonic settings, such [...] Read more.

The main goal of this paper is to determine the order of the paragenetic sequence and phase transitions of the Ni–Fe sulfide association hosted in listvenites. Listvenites are hydrothermally altered mafic and ultramafic rocks that are often associated with active tectonic settings, such as transform faults, suture zones, and regional extensional faults, usually in contact with volcanic or carbonate rocks. Listvenitization is displayed by a carbonation process when the original olivine, pyroxene, and serpentine group minerals are altered to Mg–Fe–Ca carbonates (magnesite, calcite, dolomite, and siderite), talc, quartz, and accessory Cr spinel, fuchsite, and Ni–Fe sulfides. The formed rocks are highly reactive; therefore, very often, younger hydrothermal processes are observed, overprinting the mineralogy and geochemistry of the original listvenitization products, including accessory Ni–Fe sulfide paragenesis. The studied samples of listvenites were collected from two locations in Kosovo (Vardar Zone): Janjevo and Melenica. The Ni–Fe sulfide textures and relationships with the surrounding listvenite-hosted minerals were obtained using reflected and transmitted light microscopy, while their chemical composition was determined using an electron microprobe. They form accessory mono-or polymetallic aggregates that usually do not exceed 100 μm in size disseminated in the studied listvenites. Generally, the paragenetic sequence of Ni–Fe sulfides is divided into three stages. The first pre-listvenite magmatic phase is represented by pentlandite and millerite. The second listvenite stage consists of Ni–Co bearing pyrite I (Ni content up to 11.57 wt.% [0.24 apfu], and Co content up to 6.54 wt.% [0.14 apfu]) and differentiated thiospinels (violarite + siegenite ± polydymite). The last, late listvenite stage is represented by younger gersdorffite−ullmannite and base metal mineralization: pyrite + marcasite + sphalerite + galena ± chalcopyrite ± sulfosalts. The findings obtained should help in the interpretation of many disseminated accessory Ni–Fe–Co mineralizations associated with mafic and ultramafic rocks worldwide. Full article

(This article belongs to the Special Issue Sulfide Mineralogy and Geochemistry)

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24 pages, 6021 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Analytical Techniques for Detecting Rare Earth Elements in Geological Ores: Laser-Induced Breakdown Spectroscopy (LIBS), MFA-LIBS, Thermal LIBS, Laser Ablation Time-of-Flight Mass Spectrometry, Energy-Dispersive X-ray Spectroscopy, Energy-Dispersive X-ray Fluorescence Spectrometer, and Inductively Coupled Plasma Optical Emission Spectroscopy

by Amir Fayyaz, Muhammad Aslam Baig, Muhammad Waqas and Usman Liaqat

Minerals 2024, 14(10), 1004; https://doi.org/10.3390/min14101004 - 2 Oct 2024

Cited by 6 | Viewed by 3176

Abstract

Rare earth elements (REEs) hold significant industrial, scientific, and modern technological worth. This study focused on detecting and quantifying REEs in various geological ore samples. These samples were collected from different REE-bearing locations recommended by geological experts. The analysis was conducted using laser-induced [...] Read more.

Rare earth elements (REEs) hold significant industrial, scientific, and modern technological worth. This study focused on detecting and quantifying REEs in various geological ore samples. These samples were collected from different REE-bearing locations recommended by geological experts. The analysis was conducted using laser-induced breakdown spectroscopy (LIBS) and laser ablation time-of-flight mass spectrometry (LA-TOF-MS). In this work, LIBS methodology was employed using three different configurations: standard LIBS, LIBS with an applied magnetic field, and LIBS with both an applied magnetic field and target sample heating within an optimal temperature range. Elements from the REE group, specifically lanthanum (La), cerium (Ce), and neodymium (Nd), were identified and quantified. To detect, quantify, and validate the results from LIBS and LA-TOF-MS, we utilized an array of analytical techniques—Energy-Dispersive X-ray Spectroscopy (EDX), Energy-Dispersive X-ray Fluorescence Spectrometer (ED-XRF), and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Interestingly, the quantitative results for REEs (La, Ce, and Nd) in the ore samples obtained using the LIBS technique with various configurations were found to be in agreement with those from LA-TOF-MS, EDX, XRF, and ICP-OES. In addition, LIBS enables detailed microchemical imaging, allowing the map of the spatial distribution of elements within the mineral–ore matrix. The high-resolution microscale elemental mapping of REEs was accomplished using the emission lines Ce (II) at 446.0 nm, La (II) at 492.1 nm, and Nd (II) at 388.8 nm. By integrating multiple analytical techniques, our study enabled the construction of a complete elemental distribution map, providing new insights into the geochemical processes and mineral composition of rare earth ores, while advancing geochemistry and contributing valuable data for rare earth resource exploration. Full article

(This article belongs to the Special Issue Laser-Induced Breakdown Spectroscopy (LIBS) Applied to Determination of Rare Earth Elements and Critical Minerals)

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21 pages, 1691 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Ultrasonic Enhancement for Mineral Flotation: Technology, Device, and Engineering Applications

by Xiaoou Zhang, Huaigang Cheng, Kai Xu, Danjing Ding, Xin Wang, Bo Wang and Zhuohui Ma

Minerals 2024, 14(10), 986; https://doi.org/10.3390/min14100986 - 30 Sep 2024

Cited by 5 | Viewed by 2051

Abstract

In the past five years, the number of articles related to ultrasonic mineral flotation has increased by about 50 per year, and the overall trend is on the rise. The most recent developments in ultrasonics for flotation process intensification are reviewed herein, including [...] Read more.

In the past five years, the number of articles related to ultrasonic mineral flotation has increased by about 50 per year, and the overall trend is on the rise. The most recent developments in ultrasonics for flotation process intensification are reviewed herein, including effects of ultrasound treatment on an aqueous slurry, improvement in flotation methods and technological processes, device development tracking, and application effects in mineral process engineering. At this point in time, there are pilot-scale flotation tests to evaluate the feasibility of ultrasonic pretreatment technology for industrial use to enhance residue flotation separation, and the results showed that the recovery rate of concentrate is increased by about 10%. Four aspects of ultrasonic flotation process improvement are summarized, namely, changing the ultrasonic parameters, the synergistic effect of ultrasound and reagents, the ultrasonic effect of particles with different-sized fractions, and application to new systems. In addition, the effect of ultrasonic flotation mechanisms is explored through a quadratic model and numerical simulation. The combination of ultrasonic flotation with other fields, such as magnetic fields, to enhance the separation efficiency and recovery of minerals is also a future trend. It is also proposed that ultrasonic flotation technology will be used with big data, industrial Internet of Things, and automatic control technology to achieve deep bundling, optimizing the flotation process by implementing remote monitoring and control of the flotation process. Full article

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

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42 pages, 852 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Chiral Minerals

by David Avnir

Minerals 2024, 14(10), 995; https://doi.org/10.3390/min14100995 - 30 Sep 2024

Cited by 4 | Viewed by 2265

Abstract

Hundreds of minerals are chiral, that is, they appear in nature in two forms—left-handed and right-handed. Yet except for quartz, this key structural property has remained, by and large, in shadow in the world of minerals in research, in museum displays and for [...] Read more.

Hundreds of minerals are chiral, that is, they appear in nature in two forms—left-handed and right-handed. Yet except for quartz, this key structural property has remained, by and large, in shadow in the world of minerals in research, in museum displays and for collectors. This review is devoted to providing a full picture of chiral minerals in nature. It starts with a general outline of the crystallographic background needed for the characterization of chiral minerals, continues with a detailed description of the many chemical and physical processes leading to their formation and follows with their chemical reactivities and transformations, with their physical properties and with the ways to analyze and identify them. Many tables with listings of various types of chiral minerals are provided. The “missing-glove” situation, in which the recognition that a chiral mineral appears in nature in two distinctly forms is, by and large, missing, is described, and it is hoped that this review will spark interest in this aspect of nature’s crystals. Full article

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

22 pages, 9844 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Numerical Investigation of Heterogeneous Calcite Distributions in MICP Processes

by Lingxiang Wang, Yajie Chu, Xuerui Wang, Pengzhi Pan and Dianlei Feng

Minerals 2024, 14(10), 999; https://doi.org/10.3390/min14100999 - 30 Sep 2024

Cited by 2 | Viewed by 1096

Abstract

Microbially induced calcite precipitation (MICP) is a sustainable and environmentally friendly technology with applications in soil stabilization, concrete crack repair, and wastewater treatment. This study presents an improved Darcy-scale numerical model to simulate the MICP processes in heterogeneous porous media. It focuses on [...] Read more.

Microbially induced calcite precipitation (MICP) is a sustainable and environmentally friendly technology with applications in soil stabilization, concrete crack repair, and wastewater treatment. This study presents an improved Darcy-scale numerical model to simulate the MICP processes in heterogeneous porous media. It focuses on the effects of porosity heterogeneity, characterized by average porosity and correlation length, as well as injection strategies. Both average porosity and correlation length are critical factors influencing mass transport and calcite distribution during MICP treatment. An increase in average porosity leads to significant reductions in transport distance and total calcite mass. Notably, in the case of low averaged porosity, a larger correlation length results in more heterogeneous calcite distributions. However, there exists an upper threshold value of the initial averaged porosity (

ϕ_{0} = 0.45

) above which the heterogeneity of the calcite does not present clear dependence on the correlation length. Additionally, injection strategies significantly impact the consolidation effects. Compared to continuous injection, using the phased injection strategy can greatly improve the precipitated calcite area and mass due to its high utility and the efficiency of reactants. Full article

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

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20 pages, 6163 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Review on the Challenges of Magnesium Removal in Nickel Sulfide Ore Flotation and Advances in Serpentinite Depressor

by Fengxiang Yin, Chengxu Zhang, Yao Yu, Chenyang Lv, Zhengbo Gao, Bingang Lu, Xiaohui Su, Chunhua Luo, Xiangan Peng, Belinda McFadzean and Jian Cao

Minerals 2024, 14(10), 965; https://doi.org/10.3390/min14100965 - 25 Sep 2024

Cited by 2 | Viewed by 1421

Abstract

Nickel is an important raw metal material in industry, which has been identified as a strategic mineral resource by the Chinese Ministry of Land and Resources. Nickel sulfide ore accounts for 40% of all nickel ores worldwide. However, magnesium silicate gangue minerals in [...] Read more.

Nickel is an important raw metal material in industry, which has been identified as a strategic mineral resource by the Chinese Ministry of Land and Resources. Nickel sulfide ore accounts for 40% of all nickel ores worldwide. However, magnesium silicate gangue minerals in sulfide nickel ores, particularly serpentine, pose significant challenges to the flotation of nickel sulfide ores. The presence of magnesium silicate gangue leads to a series of issues, including increased energy consumption in subsequent smelting processes, accelerated equipment wastage, and increased SO₂ emissions, which severely impact the comprehensive utilization of nickel resources in sulfide nickel ores. In this regard, flotation depressants are the most direct and effective method to reduce adverse influences caused by magnesium silicate gangue in the flotation of nickel sulfide ore concentrate. Based on the characteristics of the typical magnesium-containing nickel sulfide ore, this review illustrates the difficulties of the depression of magnesium silicate gangue during the flotation of nickel sulfide ore and gives an overview of the common depressants from six aspects (chelation depressants, dispersion depressants, flocculation depressants, depressants for grinding, depressants for slurry adjustment and combination depressants). Each section summarizes the relevant depression mechanisms and analyzes the advantages and disadvantages of various reagents, providing a reference for designing depressants specifically targeting serpentine. Full article

(This article belongs to the Special Issue Selected Papers from the 7th International Conference of Young Scholars in Mineral Processing)

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18 pages, 3488 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Adsorption of Ciprofloxacin and Lidocaine by Non-Fibrous Raw Mg-Clays: The Role of Composition and Texture

by Maria Eugenia Roca-Jalil, Telma Musso, Vanina Rodriguez-Ameijide, Micaela Sanchez, Andrea Maggio, Miria Teresita Baschini, Gisela Pettinari, Luis Villa, Manuel Pozo and Alejandro Pérez-Abad

Minerals 2024, 14(10), 966; https://doi.org/10.3390/min14100966 - 25 Sep 2024

Viewed by 1030

Abstract

This study evaluated non-fibrous Mg-clays as potential adsorbents of emerging contaminants (ECs) from water. The materials were characterized, and their textural and structural properties were related to their ability to remove two model EC molecules: ciprofloxacin (CPX) and lidocaine (LID). The results showed [...] Read more.

This study evaluated non-fibrous Mg-clays as potential adsorbents of emerging contaminants (ECs) from water. The materials were characterized, and their textural and structural properties were related to their ability to remove two model EC molecules: ciprofloxacin (CPX) and lidocaine (LID). The results showed that Ad-6 and Ad-7 are mixed-layer kerolite/stevensite, while Ad-5 and Ad-8 are mainly composed of smectite minerals like stevensite and saponite, respectively. Ad-8 exhibited the highest CPX-adsorption capacity (0.91 mmol·g⁻¹ clay), likely due to its saponite content. Mixed-layer materials also performed well, with Ad-6 and Ad-7 achieving an adsorption capacity of 0.8 and 0.55 mmol·g⁻¹ clay, respectively. Adsorption studies suggested that CPX is adsorbed through ion exchange in materials with high smectite content (Ad-8 and Ad-5), while interstratified materials showed enhanced retention due to kerolite presence, which improves their porous structures. Similar findings were observed for LID, indicating a cationic-exchange mechanism for LID adsorption in all the materials and suggesting that the molecular size of the EC could regulate the removal capacity of these materials. This work showed that the studied Mg-clays could be effectively used for the removal of pharmaceutical pollutants, expanding their commercial possibilities. Full article

(This article belongs to the Special Issue Mineralogical and Geochemical Characterization of Geological Materials)

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15 pages, 4732 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

About the Origin of Carbonado

by Valentin Afanasiev, Vladimir Kovalevsky, Alexander Yelisseyev, Rudolf Mashkovtsev, Sergey Gromilov, Sargylana Ugapeva, Ekaterina Barabash, Oksana Ivanova and Anton Pavlushin

Minerals 2024, 14(9), 927; https://doi.org/10.3390/min14090927 - 11 Sep 2024

Viewed by 2375

Abstract

Carbonado is a specific variety of diamonds, typical representatives of which are distributed in the diamond placers of Central Africa, Brazil, and Venezuela. Carbonado consists of the microcrystalline aggregates of diamonds, with inclusions of mineral matter. These aggregates appear as fragments that are [...] Read more.

Carbonado is a specific variety of diamonds, typical representatives of which are distributed in the diamond placers of Central Africa, Brazil, and Venezuela. Carbonado consists of the microcrystalline aggregates of diamonds, with inclusions of mineral matter. These aggregates appear as fragments that are rounded to varying degrees. Carbonado has been known for a long time, but its primary sources have not been found and its genesis remains unclear. We have substantiated the hypothesis that the most probable precursor of carbonado is shungite. Shungite is a specific form of non-crystalline, non-graphitic, fullerene-like carbon. Shungite rocks, currently known in Karelia (Russia), are natural microdispersed composite materials containing shungite—carbonaceous matter and mineral components of different compositions. The content of carbonaceous matter in shungite rocks is from less than 10% to 98%. The carbon isotopic composition of shungite is light ẟ¹³C from −25‰ to −40‰. The age of shungite rock is more than 2 billion years old, but earlier shungite was probably much more widespread. Known shungite rocks are more than 2 billion years old, but earlier shungite was probably much more widespread. Shungite rocks could recrystallize into diamond rock upon subduction to high pressure and temperature. The diamond rocks could then be exhumed to the Earth’s surface, where they could undergo disruption and reworking with formation of those very fragments that are known as “carbonado”. Full article

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

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20 pages, 12039 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Innovative Seismic Imaging of the Platinum Deposits, Maseve Mine: Surface and In-Mine

by Moyagabo Rapetsoa, Musa Manzi, Ian James, Mpofana Sihoyiya, Raymond Durrheim and Michelle Pienaar

Minerals 2024, 14(9), 913; https://doi.org/10.3390/min14090913 - 6 Sep 2024

Cited by 2 | Viewed by 4160

Abstract

Maseve Mine is located in the western limb of the Bushveld Complex, recognized as the largest layered igneous intrusion in the world. The study shows results from surface (SP1, SP2, and SP3) and tunnel (T3a, T3b, and TP4b) reflection seismic profiles, totaling 4150 [...] Read more.

Maseve Mine is located in the western limb of the Bushveld Complex, recognized as the largest layered igneous intrusion in the world. The study shows results from surface (SP1, SP2, and SP3) and tunnel (T3a, T3b, and TP4b) reflection seismic profiles, totaling 4150 m. Tunnel seismic data were acquired using a seismic landstreamer and spiked geophones with 5 m receiver and shot spacing, as well as a sledgehammer for shots due to space constraints and safety. The profiles, 10–50 m above mineral deposits, crossed major geological structures. Surface seismic profiles used cabled systems and wireless sensors with 5 m and 10 m receiver spacing, respectively, and a 500 kg drop hammer as a source with 10 m shot spacing. Despite high noise levels from mine infrastructure and power cables, a careful processing workflow enhanced target reflections. Interpretation was constrained using borehole data, geological models, and 2D/3D seismic modeling. The processed data exhibit gently dipping reflections associated with faults and dykes, imaging the target mineralization (Merensky Reef and Upper Group 2) and a possible extension. Tunnel seismic experiments demonstrated the application of seismic methods using in-mine infrastructure, while surface experiments proved efficient, illustrating small-scale seismic surveys’ capability to image the subsurface, adding value in active mining environments for exploration with cost-effective seismic equipment. Full article

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

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22 pages, 7448 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Dissolution Mechanisms and Surface Charge of Clay Mineral Nanoparticles: Insights from Kinetic Monte Carlo Simulations

by Inna Kurganskaya

Minerals 2024, 14(9), 900; https://doi.org/10.3390/min14090900 - 2 Sep 2024

Viewed by 1363

Abstract

The widespread use of clay minerals and clays in environmental engineering, industry, medicine, and cosmetics largely stems from their adsorption properties and surface charge, as well as their ability to react with water. The dissolution and growth of minerals as a function of [...] Read more.

The widespread use of clay minerals and clays in environmental engineering, industry, medicine, and cosmetics largely stems from their adsorption properties and surface charge, as well as their ability to react with water. The dissolution and growth of minerals as a function of pH are closely related to acid–base reactions at their surface sites and their surface charge. The vivid tapestry of different types of surface sites across different types of clay minerals generates difficulties in experimental studies of structure–property relationships. The aim of this paper is to demonstrate how a mesoscale stochastic kinetic Monte Carlo (kMC) approach altogether with atomistic acid-base models and empirical data can be used for understanding the mechanisms of dissolution and surface charge behavior of clay minerals. The surface charge is modeled based on equilibrium equations for de/protonated site populations, which are defined by the pH and site-specific acidity constants (pK_as). Lowered activation energy barriers for these sites in de/protonated states introduce pH-dependent effects into the dissolution kinetics. The V-shaped curve observed in laboratory experiments is reproduced with the new kMC model. A generic rate law for clay mineral dissolution as a function of pH is derived from this study. Thus, the kMC approach can be used as a hypothesis-testing tool for the verification of acid–base models for clay and other minerals and their influence on the kinetics of mineral dissolution and growth. Full article

(This article belongs to the Special Issue Feature Papers in Clays and Engineered Mineral Materials)

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21 pages, 5593 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Moment Estimation from Time Domain Electromagnetic Data

by Marc A. Vallée and Mouhamed Moussaoui

Minerals 2024, 14(9), 888; https://doi.org/10.3390/min14090888 - 30 Aug 2024

Viewed by 1187

Abstract

Moment representations have been proposed to facilitate the interpretation of geophysical time domain electromagnetic responses. We present a new methodology for estimating these moments from field data for different system waveforms when on-time and off-time measurements are available. Quadrature impulse response moments are [...] Read more.

Moment representations have been proposed to facilitate the interpretation of geophysical time domain electromagnetic responses. We present a new methodology for estimating these moments from field data for different system waveforms when on-time and off-time measurements are available. Quadrature impulse response moments are estimated by a recursive relation involving moments of the input waveform and moments of the observed response. After adapting this method to time domain electromagnetic applications—in particular, MEGATEM and AeroTEM (AirTEM) airborne electromagnetic systems—we present the results from applying this method on synthetic and real data collected over the Reid–Mahaffy test site in northern Ontario, Canada. 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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32 pages, 7574 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Source Rock Assessment of the Permian to Jurassic Strata in the Northern Highlands, Northwestern Jordan: Insights from Organic Geochemistry and 1D Basin Modeling

by Dina Hamdy, Sherif Farouk, Abdelrahman Qteishat, Fayez Ahmad, Khaled Al-Kahtany, Thomas Gentzis, Luigi Jovane and Amr S. Zaky

Minerals 2024, 14(9), 863; https://doi.org/10.3390/min14090863 - 25 Aug 2024

Cited by 4 | Viewed by 1798

Abstract

The present study focused on the Permian to Jurassic sequence in the Northern Highlands area, NW Jordan. The Permian to Jurassic sequence in this area is thick and deeply buried, consisting mainly of carbonate intercalated with clastic shale. This study integrated various datasets, [...] Read more.

The present study focused on the Permian to Jurassic sequence in the Northern Highlands area, NW Jordan. The Permian to Jurassic sequence in this area is thick and deeply buried, consisting mainly of carbonate intercalated with clastic shale. This study integrated various datasets, including total organic carbon (TOC, wt%), Rock-Eval pyrolysis, visual kerogen examination, gross composition, lipid biomarkers, vitrinite reflectance (VRo%), and bottom-hole temperature measurements. The main aim was to investigate the source rock characteristics of these strata regarding organic richness, kerogen type, depositional setting, thermal maturity, and hydrocarbon generation timing. The Permian strata are poor to fair source rocks, primarily containing kerogen type (KT) III. They are immature in the AJ-1 well and over-mature in the NH-2 well. The Upper Triassic strata are poor source rocks in the NH-1 well and fair to marginally good source rocks in the NH-2 well, containing highly mature terrestrial KT III. These strata are immature to early mature in the AJ-1 well and at the peak oil window stage in the NH-2 well. The Jurassic strata are poor source rocks, dominated by KT III and KT II-III. They are immature to early mature in the AJ-1 well and have reached the oil window in the NH-2 well. Biomarker-related ratios indicate that the Upper Triassic oils and Jurassic samples are source rocks that received mainly terrestrial organic input accumulated in shallow marine environments under highly reducing conditions. These strata are composed mostly of clay-rich lithologies with evidence of deposition in hypersaline and/or stratified water columns. 1D basin models revealed that the Upper Triassic strata reached the peak oil window from the Early Cretaceous (~80 Ma) to the present day in the NH-1 well and from ~130 Ma (Early Cretaceous) to ~90 Ma (Late Cretaceous) in the NH-2 well, with the late stage of hydrocarbon generation continuing from ~90 Ma to the present time. The present-day transformation ratio equals 77% in the Upper Triassic source rocks, suggesting that these rocks have expelled substantial volumes of hydrocarbons in the NH-2 well. To achieve future successful hydrocarbon discoveries in NW Jordan, accurate seismic studies and further geochemical analyses are recommended to precisely define the migration pathways. Full article

(This article belongs to the Special Issue Environmental Geochemistry and Mineralogy: Application for Hydrocarbon Exploration and Ore Deposits)

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45 pages, 22848 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Syn-Sedimentary Exhalative or Diagenetic Replacement? Multi-Proxy Evidence for Origin of Metamorphosed Stratiform Barite–Sulfide Deposits near Aberfeldy, Scottish Highlands

by Norman R. Moles, Adrian J. Boyce, Matthew R. Warke and Mark W. Claire

Minerals 2024, 14(9), 865; https://doi.org/10.3390/min14090865 - 25 Aug 2024

Cited by 2 | Viewed by 1796

Abstract

Bedded barite, Fe-Zn-Pb sulfides, carbonates, and cherts within Ediacaran (Dalradian Supergroup) graphitic metasediments near Aberfeldy in Scotland have previously been interpreted as chemical sediments precipitated from hydrothermal fluids episodically exhaled into marine basins filled with organic-rich mud, silt, and sand. Lithological variation and [...] Read more.

Bedded barite, Fe-Zn-Pb sulfides, carbonates, and cherts within Ediacaran (Dalradian Supergroup) graphitic metasediments near Aberfeldy in Scotland have previously been interpreted as chemical sediments precipitated from hydrothermal fluids episodically exhaled into marine basins filled with organic-rich mud, silt, and sand. Lithological variation and compositional diversity in pyrite and sphalerite reflect varied redox environments and proximity to hydrothermal discharges. Thick beds (>2 m) of barite have relatively uniform δ³⁴S of +36 ± 1.5‰, considered to represent contemporaneous seawater sulfate, as negative Δ¹⁷O indicates incorporation of atmospheric oxygen during precipitation in the water column. However, certain features suggest that diagenetic processes involving microbial sulfate reduction modified the mineralogy and isotopic composition of the mineralization. Barite bed margins show decimeter-scale variation in δ³⁴S (+32 to +41‰) and δ¹⁸O (+8 to +21‰), attributed to fluid-mediated transfer of dissolved barium and sulfate between originally porous barite and adjacent sediments, in which millimetric sulfate crystals grew across sedimentary lamination. Encapsulated micron-sized barium carbonates indicate early diagenetic barite dissolution with incorporation of sulfur into pyrite, elevating pyrite δ³⁴S. Subsequently, sulfidation reactions produced volumetrically minor secondary barite with δ³⁴S of +16 to +22‰. Overall, these processes affected small volumes of the mineralization, which originally formed on the seafloor as a classic SEDEX deposit. Full article

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

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31 pages, 7774 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Monchegorsk Mafic–Ultramafic Layered PGE-Bearing Complex (2.5 Ga, Kola Region, Russia): On the Problem of Relationships between Magmatic Phases Based on the Study of Cr-Spinels

by Pavel Pripachkin, Tatiana Rundkvist, Artem Mokrushin and Aiya Bazai

Minerals 2024, 14(9), 856; https://doi.org/10.3390/min14090856 - 24 Aug 2024

Viewed by 913

Abstract

The composition of Cr-spinels from rocks of the Monchegorsk layered complex (2.5 Ga) basically corresponds to the evolutionary trend that is typical for layered mafic–ultramafic intrusions (late magmatic phases contain Cr-spinels enriched in Fe and depleted in Mg, Cr, and Al). Cr-spinels within [...] Read more.

The composition of Cr-spinels from rocks of the Monchegorsk layered complex (2.5 Ga) basically corresponds to the evolutionary trend that is typical for layered mafic–ultramafic intrusions (late magmatic phases contain Cr-spinels enriched in Fe and depleted in Mg, Cr, and Al). Cr-spinels within the Dunite Body of the Sopcha massif are almost identical to those within the Dunite Block rocks and are close to those from harzburgite of the NKT massif. Cr-spinels within the satellite bodies of the Ore Layer 330 are shown to have zonal structure, which confirms their origin from a new portion of melt, which may have been injected with several pulses. The composition of accessory Cr-spinels may indicate that the layered complex of rocks of the South Sopcha massif was formed from the most evolved portion of magmatic melt (linked with the Monchetundra intrusion), and its vein complex may be considered the one formed at the final stages of the magmatic system evolution. The composition of Cr-spinels from the Pentlandite Gorge mafic–ultramafic rocks may indicate that they are fragments of the NKT massif and not of the Monchetundra massif, as it was believed earlier. Full article

(This article belongs to the Section Mineral Deposits)

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39 pages, 3652 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Coal and Coal By-Products as Unconventional Lithium Sources: A Review of Occurrence Modes and Hydrometallurgical Strategies for Metal Recovery

by Ewa Rudnik

Minerals 2024, 14(8), 849; https://doi.org/10.3390/min14080849 - 22 Aug 2024

Cited by 5 | Viewed by 2700

Abstract

Lithium, a critical material for the global development of green energy sources, is anomalously enriched in some coal deposits and coal by-products to levels that may be considered economically viable. Recovering lithium from coal, particularly from coal gangue or coal ashes, offers a [...] Read more.

Lithium, a critical material for the global development of green energy sources, is anomalously enriched in some coal deposits and coal by-products to levels that may be considered economically viable. Recovering lithium from coal, particularly from coal gangue or coal ashes, offers a promising alternative for extracting this element. This process could potentially lead to economic gains and positive environmental impacts by more efficiently utilizing coal-based waste materials. This review focuses on lithium concentrations in coal and coal by-products, modes of lithium occurrence, methods used to identify lithium-enriched phases, and currently available hydrometallurgical recovery methods, correlated with pretreatment procedures that enable lithium release from inert aluminosilicate minerals. Leaching of raw coal appears inefficient, whereas coal gangue and fly ash are more feasible due to their simpler composition and higher lithium contents. Lithium extraction can achieve recovery rates of over 90%, but low lithium concentrations and high impurity levels in the leachates require advanced selective separation techniques. Bottom ash has not yet been evaluated for lithium recovery, despite its higher lithium content compared to feed coal. Full article

(This article belongs to the Special Issue Beneficiation and Extraction of Critical Metals from Ores and Secondary Resources)

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22 pages, 5061 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

A Protocol for Electron Probe Microanalysis (EPMA) of Monazite for Chemical Th-U-Pb Age Dating

by Bernhard Schulz, Joachim Krause and Wolfgang Dörr

Minerals 2024, 14(8), 817; https://doi.org/10.3390/min14080817 - 12 Aug 2024

Cited by 3 | Viewed by 2035

Abstract

A protocol for the monazite (LREE,Y,Th,U,Si,Ca)PO₄ in situ Th-U-Pb dating by electron probe microanalyser (EPMA) involves a suitable reference monazite. Ages of several potential reference monazites were determined by TIMS-U-Pb isotope analysis. The EPMA protocol is based on calibration with REE-orthophosphates and [...] Read more.

A protocol for the monazite (LREE,Y,Th,U,Si,Ca)PO₄ in situ Th-U-Pb dating by electron probe microanalyser (EPMA) involves a suitable reference monazite. Ages of several potential reference monazites were determined by TIMS-U-Pb isotope analysis. The EPMA protocol is based on calibration with REE-orthophosphates and a homogeneous Th-rich reference monazite at beam conditions of 20 kV, 50 nA, and 5 µm for best possible matrix matches and avoidance of dead time bias. EPMA measurement of samples and repeated analysis of the reference monazite are performed at beam conditions of 20 kV, 100 nA, and 5 µm. Analysis of Pb and U on a PETL crystal requires YLg-on-PbMa and ThMz-on-UMb interference corrections. Offline re-calibration of the Th calibration on the Th-rich reference monazite, to match its nominal age, is an essential part of the protocol. EPMA-Th-U-Pb data are checked in ThO₂*-PbO coordinates for matching isochrones along regressions forced through zero. Error calculations of monazite age populations are performed by weighted average routines. Depending on the number of analyses and spread in ThO₂*-PbO coordinates, minimum errors <10 Ma are possible and realistic for Paleozoic monazite ages. A test of the protocol was performed on two garnet metapelite samples from the Paleozoic metamorphic Zone of Erbendorf-Vohenstrauß (NE-Bavaria, western Bohemian Massif). Full article

(This article belongs to the Special Issue In-Situ Microanalytical Techniques in Geological and Geochronological Research)

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23 pages, 3689 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Gypsum on Mars: A Detailed View at Gale Crater

by David Vaniman, Steve Chipera, Elizabeth Rampe, Thomas Bristow, David Blake, Johannes Meusburger, Tanya Peretyazhko, William Rapin, Jeff Berger, Douglas Ming, Patricia Craig, Nicholas Castle, Robert T. Downs, Shaunna Morrison, Robert Hazen, Richard Morris, Aditi Pandey, Allan H. Treiman, Albert Yen, Cherie Achilles, Benjamin Tutolo, Elisabeth Hausrath, Sarah Simpson, Michael Thorpe, Valerie Tu, David J. Des Marais, John Grotzinger and Abigail Fraeman Show full author list Hide full author list

Minerals 2024, 14(8), 815; https://doi.org/10.3390/min14080815 - 12 Aug 2024

Cited by 7 | Viewed by 2767

Abstract

Gypsum is a common mineral at Gale crater on Mars, currently being explored by the Mars Science Laboratory (MSL) rover, Curiosity. In this paper, we summarize the associations of gypsum with other sulfate minerals (bassanite, anhydrite, jarosite, starkeyite, and kieserite) from the [...] Read more.

Gypsum is a common mineral at Gale crater on Mars, currently being explored by the Mars Science Laboratory (MSL) rover, Curiosity. In this paper, we summarize the associations of gypsum with other sulfate minerals (bassanite, anhydrite, jarosite, starkeyite, and kieserite) from the lowest levels of the crater’s northern moat zone (Aeolis Palus) up through ~0.8 km of the stratigraphic section in the lower slopes of the sedimentary mound developed around the central peak, Aeolis Mons (informally, Mount Sharp). The analysis is based on results from the CheMin X-ray diffraction instrument on Curiosity, supplemented with information from the rover’s versatile instrument suite. Gypsum does not occur with the same frequency as less hydrous Ca-sulfates, likely, in most cases, because of its dehydration to bassanite and possibly to anhydrite. All three of these Ca-sulfate phases often occur together and, along with other sulfates, in mixed assemblages that are evidence of limited equilibration on a cold, dry planet. In almost all samples, at least one of the Ca-sulfate minerals is present, except for a very limited interval where jarosite is the major sulfate mineral, with the implication of more acidic groundwater at a much later time in Gale crater’s history. Although observations from orbit reveal a sulfate-rich surface, currently active dark basaltic dunes at Gale crater have only small amounts of a single sulfate mineral, anhydrite. Gale crater has provided the most complete mineralogical analysis of a site on Mars so far, but the data in hand show that Gale crater mineralogy is not a blueprint with planet-wide application. The concurrent study of Jezero crater by the Mars 2020 mission and comparisons to what is believed to be the most extensive deposit of gypsum on Mars, in the dune fields at the north polar ice cap, show significant diversity. Unraveling the stories of gypsum and other sulfates on Mars is just beginning. Full article

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

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25 pages, 3020 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Exploring Low-Grade Iron Ore Beneficiation Techniques: A Comprehensive Review

by Mompati Mpho Bulayani, Prasad Raghupatruni, Tirivaviri Mamvura and Gwiranai Danha

Minerals 2024, 14(8), 796; https://doi.org/10.3390/min14080796 - 2 Aug 2024

Cited by 11 | Viewed by 6254

Abstract

The beneficiation of low-grade iron ores is a key research and development topic in the mineral processing industry. The gradual exhaustion of high-grade iron ore reserves, and rising consumer iron and steel demand globally necessitate efficient low-quality iron ore beneficiation to meet steelmaking [...] Read more.

The beneficiation of low-grade iron ores is a key research and development topic in the mineral processing industry. The gradual exhaustion of high-grade iron ore reserves, and rising consumer iron and steel demand globally necessitate efficient low-quality iron ore beneficiation to meet steelmaking quality requirements. This comprehensive review explores various beneficiation techniques for low-quality iron ore, focusing on conventional methods including comminution, froth flotation and gravity separation. This article discusses the principles, processes, and equipment used in these techniques and highlights recent advancements and research efforts in the field. This review also emphasizes the importance of effective beneficiation processes in enhancing economic viability, sustainable resource management, and environmental conservation. Furthermore, it presents a case study of iron ore deposits in Botswana, highlighting the potential economic growth and sustainable development that can be achieved by maximizing resource utilization through reductive roasting, followed by magnetic separation of iron ore using semi-bituminous coal as a reductant. Overall, this review provides valuable insights into low-grade iron ore beneficiation techniques and their significance in meeting the growing demand for high-quality iron and steel products. Full article

(This article belongs to the Special Issue Recent Advances in Extractive Metallurgy)

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14 pages, 3452 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Influence of Pore Water Chemistry on Particle Association and Physical Properties of Lime-Treated Bentonite

by Enza Vitale, Dimitri Deneele and Giacomo Russo

Minerals 2024, 14(8), 795; https://doi.org/10.3390/min14080795 - 2 Aug 2024

Cited by 1 | Viewed by 912

Abstract

In the present work, an investigation on the influence of the chemical environment on the sedimentation behaviour of bentonite suspensions is performed with particular reference to the effect of lime addition on the clay particle arrangement. The role of lime content, cation valence [...] Read more.

In the present work, an investigation on the influence of the chemical environment on the sedimentation behaviour of bentonite suspensions is performed with particular reference to the effect of lime addition on the clay particle arrangement. The role of lime content, cation valence and source of calcium ions is considered in the experimental work. At the microscale, particle interaction is analysed by means of zeta potential measurements. Soil fabric formation during sedimentation and its physical properties are inferred from dynamic light scattering measurements, sedimentation tests and Atterberg limits. The addition of cations to pore water promotes the flocculation of montmorillonite particles favouring the formation of particle aggregates, whose dimension depends on ion valence and concentration. The final height of sediments reflects the combined effect of the mutual interactions among particles and the development of secondary phases due to pozzolanic reactions. The influence of clay mineralogy and its effects on the physical properties of lime-treated bentonite is highlighted by comparison with experimental evidence on lime-treated kaolin. Full article

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

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19 pages, 8127 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Key Technologies for Surface-Borehole Transient Electromagnetic Systems and Applications

by Qingming Guo, Yurong Mao, Liangjun Yan, Wenhui Chen, Jupeng Yang, Xingbing Xie, Lei Zhou and Haojin Li

Minerals 2024, 14(8), 793; https://doi.org/10.3390/min14080793 - 31 Jul 2024

Cited by 2 | Viewed by 1430

Abstract

The nonferrous metal mines in China are rapidly depleting due to years of mining, and it has become difficult to identify new mineral resources in the periphery of the old mining area. In order to deal with this situation, advanced technologies and equipment [...] Read more.

The nonferrous metal mines in China are rapidly depleting due to years of mining, and it has become difficult to identify new mineral resources in the periphery of the old mining area. In order to deal with this situation, advanced technologies and equipment must be deployed. The borehole transient electromagnetic method (TEM) has become a key technology due to its deep investigative capabilities within conductive geological structures. In the present study, in order to meet the exploration needs at depths of less than 3000 m, surface-borehole TEM exploration was used to analyze the characteristics of electromagnetic signals generated by a long wire source and a large loop source, providing essential data for the development of key technologies, such as sensor parameter design and signal gain optimization of the TEM system in the borehole. This study discussed in detail two key technical problems as follows: firstly, the efficient synchronization mechanism between the ground transmitter system and the borehole electromagnetic signal acquisition system ensured the accuracy and timeliness of data acquisition; and secondly, the realization of mass storage technology, which effectively solved the problem of mass storage and real-time transmission of data in a deep borehole environment. The effectiveness of the surface-borehole TEM systems with a long wire source and a large loop source was verified by tests in real mines. The surface-borehole electromagnetic signal acquisition system developed in this study effectively collected electromagnetic signals in the borehole, and the results accurately reflected the stratigraphic information of mineral resources in the study area. This study can pave a new technical path for the exploration of deep and peripheral areas of non-ferrous metal mines and provide valuable experience and insights for mineral resource exploration in similarly complex geological environments. Full article

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

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39 pages, 3950 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Expanded Insights into Martian Mineralogy: Updated Analysis of Gale Crater’s Mineral Composition via CheMin Crystal Chemical Investigations

by Shaunna M. Morrison, David F. Blake, Thomas F. Bristow, Nicholas Castle, Steve J. Chipera, Patricia I. Craig, Robert T. Downs, Ahmed Eleish, Robert M. Hazen, Johannes M. Meusburger, Douglas W. Ming, Richard V. Morris, Aditi Pandey, Anirudh Prabhu, Elizabeth B. Rampe, Philippe C. Sarrazin, Sarah L. Simpson, Michael T. Thorpe, Allan H. Treiman, Valerie Tu, Benjamin M. Tutolo, David T. Vaniman, Ashwin R. Vasavada and Albert S. Yen Show full author list Hide full author list

Minerals 2024, 14(8), 773; https://doi.org/10.3390/min14080773 - 29 Jul 2024

Cited by 8 | Viewed by 2662

Abstract

This study presents mineral composition estimates of rock and sediment samples analyzed with the CheMin X-ray diffraction instrument on board the NASA Mars Science Laboratory rover, Curiosity, in Gale crater, Mars. Mineral composition is estimated using crystal-chemically derived algorithms applied to X-ray [...] Read more.

This study presents mineral composition estimates of rock and sediment samples analyzed with the CheMin X-ray diffraction instrument on board the NASA Mars Science Laboratory rover, Curiosity, in Gale crater, Mars. Mineral composition is estimated using crystal-chemically derived algorithms applied to X-ray diffraction data, specifically unit-cell parameters. The mineral groups characterized include those found in major abundance by the CheMin instrument (i.e., feldspar, olivine, pyroxene, and spinel oxide). In addition to estimating the composition of the major mineral phases observed in Gale crater, we place their compositions in a stratigraphic context and provide a comparison to that of martian meteorites. This work provides expanded insights into the mineralogy and chemistry of the martian surface. Full article

(This article belongs to the Special Issue Mineralogy and Geochemistry of Mars: Everything You Need to Know about the Red Planet)

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15 pages, 2881 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

In Search of Phytoremediation Candidates: Eu(III) Bioassociation and Root Exudation in Hydroponically Grown Plants

by Max Klotzsche, Viktor Dück, Björn Drobot, Manja Vogel, Johannes Raff, Thorsten Stumpf and Robin Steudtner

Minerals 2024, 14(8), 754; https://doi.org/10.3390/min14080754 - 26 Jul 2024

Cited by 1 | Viewed by 1066

Abstract

Lanthanides and actinides are emerging contaminants, but little is known about their uptake and distribution by plants and their interactions in the rhizosphere. To better understand the fate of these metals in plants, the bioassociation of 2, 20 and 200 µM Eu(III) by [...] Read more.

Lanthanides and actinides are emerging contaminants, but little is known about their uptake and distribution by plants and their interactions in the rhizosphere. To better understand the fate of these metals in plants, the bioassociation of 2, 20 and 200 µM Eu(III) by five hydroponically grown crops endemic to Europe was assessed. The metal’s concentration and its speciation were monitored by inductively coupled plasma mass spectrometry and laser spectroscopy, whereas root exudation was investigated by chromatographic methods. It has been shown, that Eu(III) bioassociation is a two-stage process, involving rapid biosorption followed by accumulation in root tissue and distribution to the stem and leaves. Within 96 h of exposure time, the plant induces a change of Eu(III) speciation in the liquid medium, from a predominant Eu(III)aquo species, as calculated by thermodynamic modelling, to a species with longer luminescence lifetime. Root exudates such as citric, malic, and fumaric acid were identified in the cultivation medium and affect Eu(III) speciation in solution, as was shown by a change in the thermodynamic model. These results contribute to a comprehensive understanding of the fate of lanthanides in the biosphere and provide a basis for further investigations with the chemical analogues Cm(III) and Am(III). Full article

(This article belongs to the Special Issue Radionuclide Interactions with Natural and Synthetic Solids)

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14 pages, 4332 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Impacts of Impurity Removal Chemical Pretreatment Procedures on the Composition and Adsorption Properties of Bentonites

by Tatiana Koroleva, Victoria Krupskaya, Ekaterina Tyupina, Ivan Morozov, Pavel Kozlov, Boris Pokidko, Sergey Zakusin and Tatiana Zaitseva

Minerals 2024, 14(8), 736; https://doi.org/10.3390/min14080736 - 23 Jul 2024

Cited by 1 | Viewed by 1404

Abstract

This work is based on a detailed study of samples from three industrial bentonite deposits in Russia (10th Khutor, Zyryanskoe) and Kazakhstan (Taganskoe). The samples of the listed bentonites were undergoing stage-by-stage purification from carbonates, organic matter, and non-clay iron-bearing phase procedures. The [...] Read more.

This work is based on a detailed study of samples from three industrial bentonite deposits in Russia (10th Khutor, Zyryanskoe) and Kazakhstan (Taganskoe). The samples of the listed bentonites were undergoing stage-by-stage purification from carbonates, organic matter, and non-clay iron-bearing phase procedures. The conducted research revealed changes in the composition of bentonites already at the first stage of purification, which, however, were not noted for all bentonites, as well as a change in the forms of Fe in smectite structure. The latter is probably associated with changes in cis- and trans-vacant positions. Sorption characteristics with respect to ¹³⁷Cs are determined using the localization and charges in the smectite layer and the slight changes during purification, along with the specific surface area indicators. Full article

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

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13 pages, 4021 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Accuracy and Precision of the Geopyörä Breakage Test

by Marcos Bueno, Thiago Almeida, Leonardo Lara, Malcolm Powell and Homero Delboni

Minerals 2024, 14(8), 738; https://doi.org/10.3390/min14080738 - 23 Jul 2024

Viewed by 1023

Abstract

The Geopyörä breakage test uses two counter-rotating wheels to nip and crush rock specimens with a tightly controlled gap between rollers. This paper presents the detailed measures conducted to evaluate the accuracy and precision of energy measurements across various ore types using the [...] Read more.

The Geopyörä breakage test uses two counter-rotating wheels to nip and crush rock specimens with a tightly controlled gap between rollers. This paper presents the detailed measures conducted to evaluate the accuracy and precision of energy measurements across various ore types using the Geopyörä. Force measurement was assessed just for its precision. The outputs were compared directly to the drop weight test (DWT) measures of fragmentation at the same energy and fitted A and b parameters. Test reproducibility was evaluated using a Round-Robin methodology, testing several samples in multiple laboratories. The results confirmed that the new test has sufficient accuracy to match DWT results and excellent precision to assure reproducibility. Full article

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

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27 pages, 380 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Recent Uses of Ionic Liquids in the Recovery and Utilization of Rare Earth Elements

by Francisco Jose Alguacil, Jose Ignacio Robla and Olga Rodriguez Largo

Minerals 2024, 14(7), 734; https://doi.org/10.3390/min14070734 - 22 Jul 2024

Cited by 5 | Viewed by 2705

Abstract

The importance of rare earth elements as a basis for the development of new technologies or the improvement of existing ones makes their recovery from raw and waste materials necessary. In this recovery, hydrometallurgy and its derivative solvometallurgy play key roles due to [...] Read more.

The importance of rare earth elements as a basis for the development of new technologies or the improvement of existing ones makes their recovery from raw and waste materials necessary. In this recovery, hydrometallurgy and its derivative solvometallurgy play key roles due to their operational characteristics, which are emphasized with the use of ionic liquids. This manuscript reviews the most recent advances (2023 and 2024) in the use of ionic liquids in unit operations (leaching and separation technologies) aimed at the recovery of these valuable and strategic metals. Moreover, a comprehensive review is presented of the use of these chemicals in the development of advanced materials containing some of these rare earth elements. Full article

(This article belongs to the Special Issue Solvent Extraction of Rare-Earth Elements with Ionic Liquids and Deep Eutectic Solvents)

12 pages, 5585 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

FIB-SEM Study of Archaeological Human Petrous Bones: 3D Structures and Diagenesis

by Jamal Ibrahim, Eugenia Mintz, Lior Regev, Dalit Regev, Ilan Gronau, Steve Weiner and Elisabetta Boaretto

Minerals 2024, 14(7), 729; https://doi.org/10.3390/min14070729 - 21 Jul 2024

Viewed by 1478

Abstract

The petrous bone generally preserves ancient DNA better than other fossil bones. One reason for this is that the inner layer of the petrous bone of pigs and humans contains about three times as many osteocytes as other bones, and hence more DNA. [...] Read more.

The petrous bone generally preserves ancient DNA better than other fossil bones. One reason for this is that the inner layer of the petrous bone of pigs and humans contains about three times as many osteocytes as other bones, and hence more DNA. A FIB-SEM study of modern pig petrous bones showed that the 3D structure of the thin inner layer is typical of woven bone that forms in the fetus, whereas the thicker outer layer has a lamellar structure. The lamellar structure is common in mammalian bones. Here we study human petrous bones that are about 2500 years old, obtained from three Phoenician sites in Sicily, Italy. A detailed FIB-SEM study of two of these bones, one well preserved and the other poorly preserved, shows that the 3D bone type structure of the human petrous inner layer is woven bone, and the outer layer is lamellar bone. These are the same bone type structures found in pig petrous bones. Furthermore, by comparing nine differently preserved petrous bones from the same archaeological region and age, we show that their collagen contents vary widely, implying that organic material can be significantly altered during diagenesis. The mineral crystals are better preserved and hence less crystalline in the inner layers compared to the outer layers. We therefore infer that the best-preserved DNA in fossil petrous bones should be found in the thin inner layers immediately adjacent to the otic cavity where much more DNA is initially present and the mineral phase tends to be better preserved. Full article

(This article belongs to the Section Biomineralization and Biominerals)

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20 pages, 4968 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Characterization of Incremental Markings in the Sagittal Otolith of the Pacific Sardine (Sardinops sagax) Using Different Imaging Modalities

by Kelsey C. James, Uwe Kierdorf, Victoria Cooley, Viktor Nikitin, Stuart R. Stock and Horst Kierdorf

Minerals 2024, 14(7), 705; https://doi.org/10.3390/min14070705 - 12 Jul 2024

Viewed by 4302

Abstract

Teleost fish possess calcium carbonate otoliths located in separate chambers (utriculus, sacculus, and lagena) of their membranous labyrinth. This study analyzed the surface topography of the sagittal otolith of the Pacific sardine (Sardinops sagax) and the daily and annual increments in [...] Read more.

Teleost fish possess calcium carbonate otoliths located in separate chambers (utriculus, sacculus, and lagena) of their membranous labyrinth. This study analyzed the surface topography of the sagittal otolith of the Pacific sardine (Sardinops sagax) and the daily and annual increments in these otoliths. The otolith surface, characterized by laser scanning confocal microscopy for the first time, consisted of a system of prominent ridges and valleys (grooves), but it is unclear whether these structures are functional or represent time-resolving markings reflecting growth periodicity. Within the first-year volume, daily increments, each consisting of an incremental (more mineralized) and a discontinuous (less mineralized) zone, were resolved by optical microscopy and backscattered electron (BSE) imaging in the scanning electron microscope (SEM). Daily growth increments could, however, not be resolved in volumes formed after the first year, presumably because otolith growth markedly slows down and spacing of incremental markings narrows in older fish. Throughout otolith growth, the crystalline network continues across the discontinuous zones. Fluorochrome labeling provides additional information on growth after the first year. Compared with optical and BSE imaging, synchrotron microComputed Tomography of intact otoliths (with 0.69 µm volume elements) was less able to resolve daily increments; X-ray phase contrast reconstructions provided more detail than reconstructions with absorption contrast. Future research directions are proposed. Full article

(This article belongs to the Special Issue Skeletal Tissues Mineralization)

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21 pages, 3649 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Comparing the Performance of Hydrocyclones and High-Frequency Screens in an Industrial Grinding Circuit: Part I—Size Separation Assessments

by Bruna Silveira Costa, Maurício Guimarães Bergerman and Homero Delboni Júnior

Minerals 2024, 14(7), 707; https://doi.org/10.3390/min14070707 - 12 Jul 2024

Cited by 1 | Viewed by 1477

Abstract

Industrial ball milling circuits usually include hydrocyclones in a closed configuration to achieve a specified grinding size. Although hydrocyclones are relatively simple to operate, their classification performance is generally low, leading to significant fines recirculation within the circuit, consequently overgrinding the product. Conversely, [...] Read more.

Industrial ball milling circuits usually include hydrocyclones in a closed configuration to achieve a specified grinding size. Although hydrocyclones are relatively simple to operate, their classification performance is generally low, leading to significant fines recirculation within the circuit, consequently overgrinding the product. Conversely, high-frequency screening potentially shows a relatively higher separation efficiency, as the entrainment of fines to the coarse product is significantly reduced. The present work compares the performance of hydrocyclones—HC and high-frequency screens—HFS based on four surveys conducted in Nexa’s Vazante Zinc ore industrial grinding circuit in Vazante, Brazil, which processes zinc silicate ore. The comparisons included the partition of solids, water split, and particle size distributions. Whiten’s partition curve model was adopted to obtain the selected performance parameters through mass balancing the experimental data. The industrial surveys comprised three different size separation configurations, i.e., HC-Only, HFS-Only, and a combined HC-HFS setup. In all cases, the assessments consistently indicated higher separation performances with HFS compared to the HC operation. The final product associated with the HC+HFS configuration showed a narrower size distribution around the grinding size. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Extractive Metallurgy of Base and Precious Metals)

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22 pages, 23827 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

The Role of Hydrocarbons in the Formation of Uranium Mineralization, Louzhuangzi District, Southern Junggar Basin (China)

by Zhong-Bo He, Bao-Qun Hu, Lin-Fei Qiu, Yun Wang, Hong Chen, Wei-Wei Jia, Yi-Fei Li, Hua-Li Ji and Man-Huai Zhu

Minerals 2024, 14(7), 709; https://doi.org/10.3390/min14070709 - 12 Jul 2024

Viewed by 1289

Abstract

In recent years, there have been important breakthroughs in the exploration for sandstone-hosted uranium (U) deposits in the Louzhuangzi district of the southern Junggar Basin. Between 2020 and 2023, a medium-sized sandstone-hosted uranium deposit production area was identified in the region. Only a [...] Read more.

In recent years, there have been important breakthroughs in the exploration for sandstone-hosted uranium (U) deposits in the Louzhuangzi district of the southern Junggar Basin. Between 2020 and 2023, a medium-sized sandstone-hosted uranium deposit production area was identified in the region. Only a few investigations have been conducted at the Louzhuangzi U deposit, including those analyzing its geological–tectonic evolution, basic geological features, hydrogeology, and ore-controlling factors. It is generally believed that uranium mineralization at the Louzhuangzi U deposit is controlled by a redox zone. Organic matter (referred to as OM hereafter) consisting of bitumen and carbonaceous debris is very common in the uranium ores (especially in high-grade ores) at the Louzhuangzi U deposit. However, the characteristics of the OM and its contribution to uranium’s mineralization have not been studied in detail. In this study, OM-rich U-ores, altered sandstone, and barren sandstone samples were collected for petrography, mineralogical, micro-spectroscopy, carbon, and sulfur isotope studies. The results of this study show that the distribution of U minerals and metal sulfides (pyrite, sphalerite, etc.) was strictly controlled by bitumen at the Louzhuangzi U deposit. The bitumen may have been formed by hydrocarbon-rich and U-rich ore-forming fluids, which were formed after hydrocarbon generation and expulsion in the underlying Jurassic coal-bearing source rocks. The fluids contained U, Zn, Fe, and other metal elements, which migrated together and then precipitated into the oxidized Toutunhe Formation sandstone through cracking and differentiation processes. Therefore, the results indicate that migrated hydrocarbons were involved in U mineralization, in addition to oxidation–reduction processes, in the Louzhuangzi district, south of the Junggar Basin (China). Full article

(This article belongs to the Special Issue Uranium: Geochemistry and Mineralogy)

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21 pages, 4452 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Crystallization Sequence of the Spodumene-Rich Alijó Pegmatite (Northern Portugal) and Related Metasomatism on Its Host Rock

by Idoia Garate-Olave, Encarnación Roda-Robles, Nora Santos-Loyola, Tania Martins, Alexandre Lima and Jon Errandonea-Martin

Minerals 2024, 14(7), 701; https://doi.org/10.3390/min14070701 - 9 Jul 2024

Cited by 2 | Viewed by 2136

Abstract

The Barroso–Alvão region is an excellent setting for studying Li mineralization associated with granitic pegmatites and developing Li exploration techniques. Among the distinguished pegmatite types in this pegmatite field, the spodumene-bearing dyke from Alijó is a representative example of an Iberian Li–Cs–Ta (LCT) [...] Read more.

The Barroso–Alvão region is an excellent setting for studying Li mineralization associated with granitic pegmatites and developing Li exploration techniques. Among the distinguished pegmatite types in this pegmatite field, the spodumene-bearing dyke from Alijó is a representative example of an Iberian Li–Cs–Ta (LCT) pegmatite currently under exploitation. In this work, we examine the internal evolution of the Alijó dyke and its external metasomatic effect on the surrounding metasediments, contributing to lithium exploration techniques. Electron microprobe analyses provided clues about the crystallization conditions and the degree of differentiation of the pegmatitic melt, whereas the external metasomatism induced by the spodumene-bearing pegmatite was studied through whole-rock geochemistry. The obtained results indicate that the primary crystallization of the studied dyke likely occurred at temperatures between 450–500 °C, with emplacement at shallow crustal levels of about 2–3 kbar. The high concentrations of trace elements such as Li, Cs, Rb, Be, Sn, Nb, Ta, Ge, U, and Tl in the pegmatitic melt suggests high availability of these elements, allowing their partitioning into an early exsolved fluid phase. The exsolution of this fluid phase, subtracting components such as F and B, from the pegmatitic melt would cause a significant undercooling of the melt. Moreover, the interaction of this expelled fluid with the country rock generated a metasomatic overprint in the surrounding metasedimentary host rocks. The metasomatic effect in Alijó is strongly influenced by the nature of the host metasediments, with a significantly higher grade of metasomatism observed in pelitic (mica-rich) samples compared to psammitic (mica-poor) samples collected at same distances from the dyke. The greisen developed close to the pegmatite contact reflects this metasomatic signature, characterized by the mobilization of at least B, F, Li, Rb, Cs, Sn, Be, Nb, Ta, and Tl. We cautiously suggest that whole rock Li concentrations greater than 300 ppm, combined with a minimum value of 1000 ppm for the sum of B, F, Li, Rb, Cs, and Sn in pelitic metasediments of Barroso–Alvão, may be indicative of a mineralized pegmatite in this region. Full article

(This article belongs to the Special Issue Rare Metal and Related Deposits: Geology, Geochemistry and Mineralization)

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16 pages, 7601 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Surface-Functionalized Nano-Montmorillonite and Its Application as Crude Oil Flow Improver

by Kechen Liu, Michal Slaný, Alena Golian-Struhárová, Hailong Wang, Liyuan Zhang, Jiyou Fu, Gang Chen and Yingna Du

Minerals 2024, 14(7), 696; https://doi.org/10.3390/min14070696 - 8 Jul 2024

Cited by 1 | Viewed by 1540

Abstract

In view of the problem of poor flowability in the production and transportation of high-wax crude oil and high-viscosity crude oil, crude oil flow improvers are commonly used to reduce their viscosity and pour point. Although polymer-based crude oil flow improvers are highly [...] Read more.

In view of the problem of poor flowability in the production and transportation of high-wax crude oil and high-viscosity crude oil, crude oil flow improvers are commonly used to reduce their viscosity and pour point. Although polymer-based crude oil flow improvers are highly effective in improving crude oil flowability, there are still problems such as high cost and the need for a large amount of solvent dilution when used. In this work, highly dispersed organic modified nano-montmorillonite was prepared by using Na-based montmorillonite and quaternary ammonium salts, and the influencing factors on the viscosity of the crude oil were investigated. The most effective modified nano-montmorillonite (B@MMT) can reduce the viscosity by 96.7% (21 °C) and depress the pour point by 15 °C. Furthermore, it has shown a high improvement in flowability in the other four different sources of crude oil, with viscosity reduction rates of 52.2, 93.4, 79.1 and 67.4%, respectively. B@MMT was characterized by FTIR, SEM, zeta potential and contact angle. Based on DSC and wax crystal structure analysis, the mechanism of the influence of B@MMT on crude oil viscosity and pour point was explored. Finally, the cost of B@MMT was estimated, and the result shows that, compared with the crude oil flow improver in use, B@MMT has considerable commercial competitive advantages. Full article

(This article belongs to the Special Issue Applications of Clay-Based Materials)

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18 pages, 11734 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Enhancing Rare Earth Element Recovery from Coal Ash Using High-Voltage Electrical Pulses and Citric Acid Leaching

by Tlek Ketegenov, Kaster Kamunur, Lyazzat Mussapyrova, Aisulu Batkal and Rashid Nadirov

Minerals 2024, 14(7), 693; https://doi.org/10.3390/min14070693 - 3 Jul 2024

Cited by 2 | Viewed by 2039

Abstract

The study investigates the application of high-voltage electrical pulses (HVEP) as a pretreatment to enhance the leaching efficiency of rare earth elements (REE) from coal ash (CA) produced from the combustion of Ekibastuz Basin coal in Almaty, Kazakhstan. HVEP treatment was applied to [...] Read more.

The study investigates the application of high-voltage electrical pulses (HVEP) as a pretreatment to enhance the leaching efficiency of rare earth elements (REE) from coal ash (CA) produced from the combustion of Ekibastuz Basin coal in Almaty, Kazakhstan. HVEP treatment was applied to the finest (<40 µm) non-magnetic fraction of CA under controlled conditions, optimizing discharge current, voltage, and treatment duration. Leaching experiments with 1 M citric acid at various solid-to-liquid ratios, temperatures, and durations were conducted on both treated and untreated samples. Results indicated that HVEP-treated CA significantly improved REE recovery rates compared to untreated samples, with optimal conditions achieving 74% cerium, 79% yttrium, and 77% lanthanum recovery. The leaching of untreated CA under the specified conditions allowed no more than 28% REE to be extracted into the solution. The leaching process was found to follow first-order kinetics, with the chemical reaction of metal dissolution being the rate-limiting step. Full article

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

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28 pages, 16832 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

The Tepsi Ultrabasic Intrusion, the Northern Part of the Lapland–Belomorian Belt, Kola Peninsula, Russia

by Andrei Y. Barkov, Andrey A. Nikiforov, Robert F. Martin, Sergey A. Silyanov and Boris M. Lobastov

Minerals 2024, 14(7), 685; https://doi.org/10.3390/min14070685 - 29 Jun 2024

Cited by 3 | Viewed by 1150

Abstract

The Tepsi ultrabasic body is located in the northeastern Fennoscandian Shield close to the junction of the Serpentinite Belt–Tulppio Belt (SB–TB) with suites of the Lapland–Belomorian Belt (LBB) of Paleoproterozoic age. The body is a deformed laccolith that has tectonic contacts with Archean [...] Read more.

The Tepsi ultrabasic body is located in the northeastern Fennoscandian Shield close to the junction of the Serpentinite Belt–Tulppio Belt (SB–TB) with suites of the Lapland–Belomorian Belt (LBB) of Paleoproterozoic age. The body is a deformed laccolith that has tectonic contacts with Archean rocks. Its primary textures and magmatic parageneses are widely preserved. Fine-grained olivine varies continuously from Fo_90.5 to Fo_65.4. The whole-rock variations in MgO, Fe₂O₃, SiO₂, and other geochemical data are also indicative of a significant extent of differentiation. Compositional variations were examined in the grains of calcic and Mg-Fe amphiboles, clinochlore, micas, plagioclase, members of the chromite–magnetite series, ilmenite, apatite, pentlandite, and a number of other minor mineral species. Low-sulfide disseminated Ni-Cu-Co mineralization occurred sporadically, with the presence of species enriched in As or Bi, submicrometric grains rich in Pt and Ir, or diffuse zones in pentlandite enriched in (Pd + Bi). We recognize two series: the pentlandite series (up to 2.5–3 wt.% Co) and the cobaltpentlandite series (~1 to ~8 apfu Co). The latter accompanied serpentinization. The two series display differences in their substitutions: Ni ↔ Fe and Co → (Ni + Fe), respectively. Relative enrichments in H₂O, Cl, and F, observed in grains of apatite (plus high contents of Cl in hibbingite or parahibbingite), point to the abundance of volatiles accumulated during differentiation. We provide the first documentation of scheelite grains in ultrabasic rocks, found in evolved olivine-rich rocks (Fo_77–72). We also describe unusual occurrences of hypermagnesian clinopyroxene associated with tremolite and serpentine. Abundant clusters of crystallites of diopside display a microspinifex texture. They likely predated serpentinization and formed owning to rapid crystallization in a differentiated portion of a supercooled oxidized melt or, less likely, fluid, after bulk crystallization of the olivine. We infer that the laccolithic Tepsi body crystallized rapidly, in a shallow setting, and could thus not form megacycles in a layered series or produce a well-organized structure. Our findings point to the existence of elevated PGE-Au-Ag potential in numerous ultrabasic–basic complexes of the SB–TB–LBB megastructure. Full article

(This article belongs to the Special Issue From Mantle to Market: Platinum Group Elements and Minerals and Their Geological Significance)

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15 pages, 3423 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Preparation of Humic Acid from Weathered Coal by Mechanical Energy Activation and Its Properties

by Xiujuan Feng, Rilong Xiao, Sékou Mohamed Condé, Chengliang Dong, Yanping Xun, Dalong Guo, Hui Liu, Kunpeng Liu and Mingzhi Liang

Minerals 2024, 14(7), 648; https://doi.org/10.3390/min14070648 - 25 Jun 2024

Cited by 1 | Viewed by 2339

Abstract

Humic acid (HA) is rich in functional groups with high activity, which can effectively improve the soil environment. The large reserves of weathered coal in China provide sufficient raw material guarantee for HA extraction and utilization. At present, the activation side of weathered [...] Read more.

Humic acid (HA) is rich in functional groups with high activity, which can effectively improve the soil environment. The large reserves of weathered coal in China provide sufficient raw material guarantee for HA extraction and utilization. At present, the activation side of weathered coal is still the main technical difficulty that restricts HA extraction. In this study, the weathered coal from Inner Mongolia was used as the raw material, and the mechanical energy was used to activate the weathered coal through a planetary ball mill, which improved the extraction rate of HA and optimized the molecular structure and composition of HA. The effects of four parameters, namely, ball material ratio, ball milling time, ball milling speed, and ball size, on the free HA content of weathered coal were investigated, the HA was extracted by alkaline extraction method, and the activated weathered coal and the extracted HA were characterized. The results showed that a ball material ratio of 9:1, a ball milling speed of 200 r/min, a ball milling time of 200 min, a milling ball size of Ф5:Ф10:Ф15 = 48:42:45 and 56:42:37 are the optimal parameters for the mechanical energy activation, and the HA extraction rate of activated weathered coal under these conditions reached 82.3%, which was 15% higher than that of the unactivated one. Moreover, the aroma of the ball-milled weathered coal increased, the content of oxygenated functional groups increased, and the molecular weight and aroma of HA increased. This provides scientific theoretical guidance for the preparation of HA with high aromaticity and large molecular weight from weathered coal. Full article

(This article belongs to the Special Issue Waste Minerals, Sediments and Their Environmental Mineralogy)

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20 pages, 9384 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Petrogenetic Implications of the Lithium-Rich Tongtianmiao Granite Pluton, South China: Evidence from Geochemistry and Geochronology

by Xinhui Yu, Yongzhang Zhou, Wei Cao, Hanyu Wang, Can Zhang, Lifeng Zhong, Wu Wei, Zhiqiang Wang, Jianying Yao, Zhiqiang Chen and Qinghe Xu

Minerals 2024, 14(7), 637; https://doi.org/10.3390/min14070637 - 21 Jun 2024

Viewed by 1490

Abstract

The South China Block, a region renowned for its extensive granite distribution and rich metal deposits, serves as a natural laboratory for the study of granite-related mineralization. This research focuses on the Tongtianmiao granite pluton, which is located at the intersection of the [...] Read more.

The South China Block, a region renowned for its extensive granite distribution and rich metal deposits, serves as a natural laboratory for the study of granite-related mineralization. This research focuses on the Tongtianmiao granite pluton, which is located at the intersection of the Qin-Hang and Nanling metallogenic belts and has been confirmed as a significant lithium mineral resource. Despite its discovery and ongoing development, the lithium-rich Tongtianmiao pluton has been understudied, particularly concerning its petrogenesis, which has only recently come to the forefront of scientific inquiry. By integrating an array of petrogeochemical data with geochronological studies derived from zircon and monazite dating, this study provides insights into the magmatic processes related to lithium enrichment in the Tongtianmiao granites. The Tongtianmiao granites are classified as A-type granites characterized by high SiO₂ contents (69.18–78.20 wt.%, average = 74.08 wt.%), K₂O + Na₂O contents (4.59–8.34 wt.%, average = 6.86 wt.%), A/CNK > 1.2, and low concentrations of Ca, Mg, and Fe. These granites are enriched in alkali metals such as Li, Rb, and Cs but are significantly depleted in Ba, Sr, and Eu. They show no significant fractionation of light or heavy rare-earth elements but present characteristic tetrad effects. A finding of this study is the identification of multiple ages from in situ zircon U–Pb dating, which implies a prolonged history of magmatic activity. However, given the high uranium content in zircons, which could render U–Pb ages unreliable, emphasis is placed on the monazite U–Pb ages. These ages cluster at approximately 172.1 ± 1.1 Ma and 167.9 ± 1.6 Ma, indicating a Middle Jurassic period of granite formation. This timing correlates with the retreat of the Pacific subduction plate and the associated NE-trending extensional fault activity, which likely provided favorable conditions for lithium enrichment. The study concluded that the Tongtianmiao granites were formed through partial melting of crustal materials and subsequent underplating by mantle-derived materials, and were contaminated by strata materials. This process resulted in the formation of highly differentiated granite through magmatic differentiation and external forces. These findings have significant implications for understanding the petrogenesis of lithium-rich granites and are expected to inform future exploration endeavors in the Tongtianmiao pluton. Full article

(This article belongs to the Special Issue In-Situ Microanalytical Techniques in Geological and Geochronological Research)

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25 pages, 3064 KiB

Open AccessFeature PaperEditor’s ChoiceReview

The Catalytic Potential of Modified Clays: A Review

by Altantuya Ochirkhuyag and Jadambaa Temuujin

Minerals 2024, 14(6), 629; https://doi.org/10.3390/min14060629 - 20 Jun 2024

Cited by 8 | Viewed by 3918

Abstract

The need for innovative catalysts and catalytic support materials is continually growing due to demanding requirements, stricter environmental demands, and the ongoing development of new chemical processes. Since about 80% of all industrial processes involve catalysts, there is a continuing need to develop [...] Read more.

The need for innovative catalysts and catalytic support materials is continually growing due to demanding requirements, stricter environmental demands, and the ongoing development of new chemical processes. Since about 80% of all industrial processes involve catalysts, there is a continuing need to develop new catalyst materials and supports with suitable qualities to meet ongoing industrial demands. Not only must new catalysts have tailored properties, but they must also be suitable for large-scale production through environmentally friendly and cost-effective processes. Clay minerals, with their rich history in medicine and ceramics, are now emerging as potential catalysts. Their transformative potential is exemplified in applications such as hydrogenating the greenhouse gas CO₂ into carbohydrate fuel, a crucial step in meeting the rising electrical demand. Moreover, advanced materials derived from clay minerals are proving their mettle in diverse photocatalytic reactions, from organic dye removal to pharmaceutical pollutant elimination and photocatalytic energy conversion through water splitting. Clay minerals in their natural state show a low catalytic activity, so to increase their reactivity, they must be activated. Depending on the requirements of a particular application, selecting an appropriate activation method for modifying a natural clay mineral is a critical consideration. Traditional clay mineral processing methods such as acid or alkaline treatment are used. Still, these have drawbacks such as high costs, long processing times, and the formation of hazardous by-products. Other activation processes, such as ultrasonication and mechanical activation routes, have been proposed to reduce the production of hazardous by-products. The main advantage of ultrasonication and microwave-assisted procedures is that they save time, whereas mechanochemical processing is simple and efficient. This short review focuses on modifying clay minerals using various new methods to create sophisticated and innovative new materials. Recent advances in catalytic reactions are specifically covered, including organic biogeochemical processes, photocatalytic processes, carbon nanotube synthesis, and energy conversion processes such as CO₂ hydrogenation and dry reforming of methane. Full article

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

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12 pages, 4631 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Surface Wettability Analysis from Adsorption Energy and Surface Electrical Charge

by Chen Zhang, Xuming Wang, Lixia Li, Jan D. Miller and Jiaqi Jin

Minerals 2024, 14(6), 628; https://doi.org/10.3390/min14060628 - 20 Jun 2024

Cited by 3 | Viewed by 2072

Abstract

Surface wettability is determined by the attraction of a liquid phase to a solid surface. It is typically quantified by using contact angle measurements at mineral surfaces in the case of the flotation of mineral particles. Contact angle research to describe wettability has [...] Read more.

Surface wettability is determined by the attraction of a liquid phase to a solid surface. It is typically quantified by using contact angle measurements at mineral surfaces in the case of the flotation of mineral particles. Contact angle research to describe wettability has been investigated at different scales by sessile drop measurements, molecular dynamic simulation, and atomic force microscopy. In this study, the density functional theory (DFT) was employed for predicting the surface free energy and contact angles of a well-known hydrophobic phyllosilicate mineral talc and a well-known hydrophilic phyllosilicate mineral muscovite based on the calculated interfacial energy and surface charge. The results revealed that the predicted contact angle at the atomic scale was larger than the experimental value, and identified two interactions: electrostatic interaction and hydrogen bonding, between the hydrophilic muscovite surface and the water layer, while a water-exclusion zone of 3.346 Å was found between the hydrophobic talc surface and the first water layer. This investigation gives a new perspective for wettability determination at the atomic scale. Full article

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

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20 pages, 2190 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Quantification of Feldspar and Quartz Nucleation Delay in a Hydrous Peraluminous Granitic Melt

by Maude Bilodeau and Don R. Baker

Minerals 2024, 14(6), 611; https://doi.org/10.3390/min14060611 - 15 Jun 2024

Viewed by 1442

Abstract

A modified model based on classical nucleation theory was applied to a natural hydrous peraluminous pegmatite composition and tested against crystallization experiments in order to further investigate the quantification of nucleation delay in felsic melts. Crystallization experiments were performed in a piston-cylinder apparatus [...] Read more.

A modified model based on classical nucleation theory was applied to a natural hydrous peraluminous pegmatite composition and tested against crystallization experiments in order to further investigate the quantification of nucleation delay in felsic melts. Crystallization experiments were performed in a piston-cylinder apparatus at 630 MPa and temperatures between 650 and 1000 °C for durations ranging from 0.3 to 211 h. Experimental run products were investigated by scanning electron microscopy paired with energy dispersive spectroscopy analyses of both crystalline and quenched liquid phases, the results of which were compared to an established theoretical nucleation delay model from the literature. The experiments showed good agreement (within a factor of 5) with the model for quartz, while it showed moderate agreement (within a factor of 10) with the model for sodic feldspar. Other crystals also nucleated, demonstrating abundant features of disequilibrium. Our research further demonstrates the potential of the model to predict nucleation delay, showing promising results for the quantification of the nucleation delay of quartz and feldspar in natural felsic melts, thus adding to previously published studies on hydrous, metaluminous, felsic melts and dry basaltic melts. Full article

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

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27 pages, 2235 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Clay Minerals and Biopolymers in Film Design: Overview of Properties and Applications

by Pollyana Trigueiro, Juliane P. de L. Pereira, Mirelly G. Ferreira, Lucas B. Silva, Luan Neves and Ramón R. Peña-Garcia

Minerals 2024, 14(6), 613; https://doi.org/10.3390/min14060613 - 15 Jun 2024

Cited by 4 | Viewed by 2422

Abstract

Research to replace petroleum-based plastics has been quite challenging. Currently, there is a lot of interest in biopolymers as an alternative. However, biopolymers do not have suitable mechanical properties when in film form, which limits their applications. To resolve this issue, clay minerals [...] Read more.

Research to replace petroleum-based plastics has been quite challenging. Currently, there is a lot of interest in biopolymers as an alternative. However, biopolymers do not have suitable mechanical properties when in film form, which limits their applications. To resolve this issue, clay minerals are being incorporated as a strategy. Clay minerals offer the films good barrier, thermal, rheological, optical, and mechanical properties. They can also work with other additives to promote antioxidant and antimicrobial activity. This brief review focuses on incorporating clay minerals with other nanofillers and bioactives to improve their physical, chemical, and functional characteristics. The synergy of these materials gives the films exceptional properties and makes them suitable for applications such as food coatings, packaging materials, dressings, and bandages for treating skin wounds. Full article

(This article belongs to the Special Issue Applications of Clay-Based Materials)

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20 pages, 4455 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Bulk and Surface Characterization of Distinct Hematite Morphology: Implications for Wettability and Flotation Response

by Lívia Marques Faustino, Belinda McFadzean, José Tadeu Gouvêa Junior and Laurindo de Salles Leal Filho

Minerals 2024, 14(6), 609; https://doi.org/10.3390/min14060609 - 14 Jun 2024

Cited by 1 | Viewed by 2160

Abstract

To understand why hematite of different genesis behave diversely in flotation systems, this study assesses the flotation response at pH 5 of bulk (morphology, texture, Crystal Preferential Orientation (CPO)) plus interfacial (surface area, zeta potential, immersion enthalpy, contact angle, induction time) characteristics of [...] Read more.

To understand why hematite of different genesis behave diversely in flotation systems, this study assesses the flotation response at pH 5 of bulk (morphology, texture, Crystal Preferential Orientation (CPO)) plus interfacial (surface area, zeta potential, immersion enthalpy, contact angle, induction time) characteristics of species formed under distinct metamorphic conditions: low-strain deformation (Hematite-1) versus high-strain deformation (Hematite-2). Hematite-2 (predominantly composed of specular and lamellar morphologies) shows (001) CPO and exhibits fewer Fe sites on its surface that undergo doubly coordinated Fe-OH when exposed to moisture. This results in a less reactive surface associated with a less ordered adsorbed water layer than Hematite-1, which is predominantly composed of granular and sinuous hematite. Those characteristics lead to a naturally hydrophobic behavior characterized by the exothermic energy below the Critical Immersion Enthalpy (

- {∆ H}_{i m m}

< 200 mJ/m²), lower values of zeta potential due to attenuated dissociation of Fe-OH_(surf), lower induction time (47 ms vs. 128 ms), higher contact angle (39° vs. 13°), and higher flotation recovery (21% vs. 12%) than Hematite-1. Full article

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

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