Minerals

17 pages, 16927 KiB

Open AccessArticle

Distribution and Enrichment Mechanisms of Selenium in Stibnite from the Xujiashan Sb Deposit, Hubei Province, China

by Yuhang Liu, Dazhao Wang, Ruolong Huang, Guanzhi Wang, Wei Wan and Yu Kong

Minerals 2024, 14(7), 684; https://doi.org/10.3390/min14070684 (registering DOI) - 29 Jun 2024

The Xujiashan Sb deposit located at the Mufushan fold thrust belt of the Yangtze block is one of the most important Sb deposits in this district. Stibnite in this deposit contains high and various contents of Se, but research on the distribution and [...] Read more.

The Xujiashan Sb deposit located at the Mufushan fold thrust belt of the Yangtze block is one of the most important Sb deposits in this district. Stibnite in this deposit contains high and various contents of Se, but research on the distribution and enrichment of Se in stibnite remains limited. This paper conducts geochemical composition, C-H-O isotopic composition, and scanning electron microscopy morphology of the Xujiashan deposit to discuss the sources of ore-forming materials and fluid, as well as the distribution and enrichment mechanisms of selenium in stibnite. The results showed that the ores have trace element compositions comparable with the wall rocks, and Sb and Se contents are significantly higher than the average carbonate rocks. The δ¹³C_PDB values of calcite and quartz range from −12.8‰ to 5.5‰, the δ¹⁸O_SMOW values range from 20.4‰ to 24‰, and the δD_V-SMOW values range from −57.8‰ to −86.9‰. Trace element and isotope compositions indicate that the ore-forming materials were mainly derived from the wall rocks (sedimentary–metamorphic rocks) that S, Se, and Sb dissolved during fluid–rock interactions. The ore-forming fluids were metamorphic water produced by metamorphism, which had experienced multistage mixing with meteoric water and organic-rich fluids. Selenium substitutes for sulfur in the stibnite crystal lattice, causing rhythmically distributed Se contents in stibnite, which resulted from multistage physicochemical changes in ore-forming fluids during crystallization. The varied patterns of Se contents are the result of different cross-sections of the stibnite. Full article

(This article belongs to the Special Issue Selenium, Tellurium and Precious Metal Mineralogy)

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15 pages, 3157 KiB

Open AccessArticle

Spectroscopic Identification of Mineral Pigments in White Decorated Prehistoric Pottery from Bulgaria

by Vani Tankova, Victoria Atanassova, Valentin Mihailov and Angelina Pirovska

Minerals 2024, 14(7), 683; https://doi.org/10.3390/min14070683 (registering DOI) - 29 Jun 2024

Abstract

In the prehistoric period on the Balkan Peninsula, the technology of white decoration underwent a drastic change. At the beginning of the Neolithic white pigment was applied as paint on a polished surface. At the end of the epoch, white paste was inlaid [...] Read more.

In the prehistoric period on the Balkan Peninsula, the technology of white decoration underwent a drastic change. At the beginning of the Neolithic white pigment was applied as paint on a polished surface. At the end of the epoch, white paste was inlaid in incised channels on the surfaces of vessels. This study is focused on the identification of mineral pigments used for white decoration of Neolithic and Chalcolithic pottery from the territory of Bulgaria. The aim of this work is to answer the question of whether the composition of the white pigment varies according to the technique of decoration (paint and inlay). A set of 41 pottery fragments from 11 archaeological sites on the territory of Bulgaria was analyzed utilizing two spectroscopic techniques: laser-induced breakdown spectroscopy (LIBS) and Fourier-transform infrared spectroscopy (FTIR). Additionally, the experimental data from the LIBS were statistically treated with the multivariate technique, principal component analysis (PCA). The results from the spectral analysis indicated that the main constituent in the white decorated sherds is calcite in various combinations with carrier materials like quartz, feldspars, and metal oxides. The statistical analysis revealed that the primal constituent in the inlaid sherds is calcite while in the painted part, the carrier material is dominant. In some particular sherds, gypsum, hydroxylapatite, kaolinite, and aragonite were also detected. Full article

(This article belongs to the Special Issue Mineralogical Approaches to Archaeological and Cultural Heritage Materials)

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14 pages, 8121 KiB

Open AccessArticle

Biogenic Calcium Carbonate: Phase Conversion in Aqueous Suspensions

by Brian Espinosa-Acosta, Jake J. Breen, Meghan Burchell and Kristin M. Poduska

Minerals 2024, 14(7), 682; https://doi.org/10.3390/min14070682 (registering DOI) - 29 Jun 2024

Abstract

Powdered biogenic calcium carbonate from butter clams shows variations in its tendency to convert from aragonite to calcite when suspended in water, depending on whether the suspension has additional calcite or not. Our investigations treat these biogenic samples as complex hierarchical materials, considering [...] Read more.

Powdered biogenic calcium carbonate from butter clams shows variations in its tendency to convert from aragonite to calcite when suspended in water, depending on whether the suspension has additional calcite or not. Our investigations treat these biogenic samples as complex hierarchical materials, considering both their mineral and organic components. We assess the mineral composition from Attenuated Total Reflection Fourier Transform Infrared spectroscopy peak shifts, as well as quantitative assessments of lattice constant refinements (powder X-ray diffraction). To isolate the mineral portions, we compare results from samples where the periostracum is removed mechanically and samples that are heated to temperatures that are sufficient to remove organic material but well below the temperature for thermal phase conversion from aragonite to calcite. The results show that the total organic content does not play a significant role in the aqueous mineral phase conversion. These results have potential implications for understanding carbonate mineral interactions in ocean sediments. Full article

(This article belongs to the Special Issue Texture and Microstructural Analysis of Crystalline Solids, Volume II)

21 pages, 1513 KiB

Open AccessArticle

Early Cretaceous A-Type Acidic Magmatic Belt in Northern Lhasa Block: Implications for the Evolution of the Bangong–Nujiang Ocean Lithosphere

by Deng Xiao, Xinjie Yang, Chao Teng, Tianshe Cheng, Ning Zhu and Jun Cao

Minerals 2024, 14(7), 681; https://doi.org/10.3390/min14070681 (registering DOI) - 29 Jun 2024

Abstract

A-type granites have been the subject of considerable interest due to their distinct anorogenic geological background. The A-type and arc-related granites are crucial in deciphering the evolution of the ocean closure and continental collision in the Tibet Plateau. The demise of the Bangong–Nujiang [...] Read more.

A-type granites have been the subject of considerable interest due to their distinct anorogenic geological background. The A-type and arc-related granites are crucial in deciphering the evolution of the ocean closure and continental collision in the Tibet Plateau. The demise of the Bangong–Nujiang suture zone (BNSZ) and the Yarlung–Tsangpo suture zone was accompanied by the emplacement of volumes of syn-collisional and post-collisional granites. Controversy has persisted regarding the contribution of the collisional granites within the Lhasa Block to the growth of the Tibetan Plateau. This study provides key evidence about the evolution of the Lhasa Block and Bangong–Nujiang Ocean (BNO) by the newly documented 1200 km long, Early Cretaceous A-type acidic magmatic belt. The resolution was achieved through the utilization of petrology, whole-rock geochemistry, zircon U-Pb geochronology, and in situ zircon Hf isotope analysis of the Burshulaling Granites in the eastern segment and previous existing data in the central and western segment of the Lhasa Block. The Burshulaling Granites are characterized as peraluminous, high-K calc-alkaline series, indicating a post-collision setting with high temperature and low pressure. The zircon grains from two granite samples yield ²⁰⁶Pb/²³⁸U ages of 115–113 Ma. In situ zircon Hf analyses with ²⁰⁶Pb/²³⁸U ages give ε_Hf(t) of −6.2–0.6, showing prominent characteristics of crust-mantle interaction. Granites from east to west exhibit whole-rock geochemical and geochronological similarities that fall within the well-constrained Early Cretaceous time frame (117–103 Ma) and track post-collisional A-type acidic magmatic belt along BNSZ. We argue that this magmatism resulted from slab break-off or orogenic root detachment, leading to melting and mixing of the lower crust. Meanwhile, this study indicates the existence of the Bangong–Nujiang Ocean southward subduction or a collapse following an Andean-type orogen. Full article

(This article belongs to the Special Issue Genesis of Calc-Alkaline Granitic Rocks: Evidence from Petrology and Geochemistry)

17 pages, 4388 KiB

Open AccessArticle

Geochemical Study of the Osumi Granodiorite, Southwestern Japan

by Haozhen Xue, Kazuya Shimooka and Motohiro Tsuboi

Minerals 2024, 14(7), 680; https://doi.org/10.3390/min14070680 (registering DOI) - 29 Jun 2024

Abstract

The Osumi Granodiorite, located on the Osumi Peninsula in southwest Japan, is an example of outer zone granites that were formed during a limited period (13–15 Ma) in response to the subduction of the Philippine Sea Plate. This event, which is linked to [...] Read more.

The Osumi Granodiorite, located on the Osumi Peninsula in southwest Japan, is an example of outer zone granites that were formed during a limited period (13–15 Ma) in response to the subduction of the Philippine Sea Plate. This event, which is linked to the separation of southwest Japan from continental Asia, resulted in unique igneous activity. The Osumi Granodiorite is the largest Miocene granite body in the region. It intrudes into the Mesozoic to Paleogene accretionary complex of the Shimanto Belt and affects contact metamorphism. Despite considerable research on the Osumi Granodiorite, limited geochemical studies, especially on trace and rare earth element (REE) analyses, have been conducted. Furthermore, there are insufficient data on the Rb–Sr isotopic system, leaving the formation process unclear. This study presents whole-rock geochemical and Rb-Sr isotopic data to investigate the petrogenesis of the Osumi Granodiorite. The results suggest a common magma origin for this pluton, as indicated by linear trends on the Harker diagrams and similar REE patterns. The presence of a relatively large Eu anomaly implies formation under a reducing environment. The AKF diagram indicates predominant contamination by pelitic rocks of the Shimanto Belt during magma formation. The Rb–Sr whole-rock isochron diagram and SrI–1000/Sr diagram suggest that the Osumi Granodiorite body was formed by heterogeneous assimilation of magma into the Shimanto Belt. Furthermore, the whole-rock isochron age is 64.3 Ma, which differs by approximately 50 My from the previously reported biotite K–Ar age (14–22 Ma). This age is considered to be a pseudo-isochron age, rather than the consolidation age. During the middle Miocene, the compressive stress field in the outer zone south of the Butsuzo Tectonic Line made it difficult for magma to rise. As a result, it reacted with the sedimentary rocks of the Shimanto Belt to various degrees. The Osumi Granodiorite underwent magma differentiation upon intrusion into the Shimanto Belt. It subsequently ascended, cooled, and interacted with pelitic rocks under stable geological conditions. Full article

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

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38 pages, 14520 KiB

Open AccessArticle

Mineralogy and Geochemistry of Titaniferous Iron Ores in El-Baroud Layered Gabbros: Fe-Ti Ore Genesis and Tectono-Metallogenetic Setting

by Mohamed Zaki Khedr, Ahmed Moftah, N. H. El-Shibiny, Akihiro Tamura, Wei Tan, Yuji Ichiyama, Eiichi Takazawa, Ali Y. Kahal and Kamal Abdelrahman

Minerals 2024, 14(7), 679; https://doi.org/10.3390/min14070679 (registering DOI) - 29 Jun 2024

Abstract

The Neoproterozoic pyroxene gabbros and gabbronorites in the El-Baroud mafic intrusion in the Northern Eastern Desert (NED) of Egypt host Fe-Ti oxide ore deposits. This study discusses the major and trace elements of both titaniferous iron ores and their host rocks, along with [...] Read more.

The Neoproterozoic pyroxene gabbros and gabbronorites in the El-Baroud mafic intrusion in the Northern Eastern Desert (NED) of Egypt host Fe-Ti oxide ore deposits. This study discusses the major and trace elements of both titaniferous iron ores and their host rocks, along with the mineral chemistry (major and in situ trace elements) of interstitial clinopyroxene (Cpx), to gain a deeper understanding of the Fe-Ti oxide genesis. These ores occur as disseminated (55–60 vol.% of Fe-Ti oxides) and massive types (85–95 vol.%) in the form of the dyke, layer, and lens. They are composed of titanomagnetite (80–87 vol.%) with subordinate ilmenite (10–15 vol.%) and magnetite (3–5 vol.%), in accordance with their high Fe₂O₃ (75.66 wt.% on average) and TiO₂ contents (16.30–17.60 wt.%). The Cpx in the investigated ores is diopside composition (Mg#; 0.72–0.83) and exhibits a nearly convex upward REE pattern, similar to Cpxs in the ferropicrite that originated from the primitive mantle. Melts in equilibrium with this Cpx resemble Greenstone ferropicrite melts; the parent melt of El-Baroud gabbros is possibly a ferropicritic melt that was derived from the lithospheric mantle during plume interaction. The El-Baroud gabbroic rocks were generated during the arc rifting and crystallized under a high oxygen fugacity at a temperature of 800–1000 °C and a pressure of 3 kbar with a depth of 12 km. The Fe-Ti oxide ores have been formed from ferropicritic parent melts by two processes, including in situ crystallization that leads to the formation of disseminated Fe-Ti oxides in the iron-rich gabbros at the bottom and liquid immiscibility that is responsible for the formation of thick Fe-Ti ore lenses and layers at the top of the gabbroic intrusion. Initially, titanomagnetite crystallized from the primary Ti-rich oxide melt. As cooling progressed, some of the excess titanium in this melt was exsolved in the form of the exsolution ilmenite lamellae within the titanomagnetite. The Fe-Ti oxide layers in the NED follow the trend of NW-SE (Najd trend), where their distribution is possibly controlled by the composition of parent melts (rich in Ti and Fe), high oxygen fugacity, and the structure related to the Najd fault system. The distribution of Fe-Ti oxide ores increases from the NED to the Southern Eastern Desert (SED), suggesting the dominant mantle plumes and/or shear zones in the SED relative to the NED. Full article

(This article belongs to the Special Issue Using Mineral Chemistry to Characterize Ore-Forming Processes)

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24 pages, 3941 KiB

Open AccessArticle

Unraveling Dry Jigging: Insights into Pulsation, Energy Consumption, and Stratification Dynamics

by Fortunato Lucas Quembo Raposo, Carlos Otávio Petter and Weslei Monteiro Ambrós

Minerals 2024, 14(7), 678; https://doi.org/10.3390/min14070678 (registering DOI) - 28 Jun 2024

Abstract

The increasing concerns regarding water usage in mineral processing have led to a growing interest in dry jigging in recent years. However, there is still a need for a more comprehensive examination of the operational aspects of the technique. In this sense, this [...] Read more.

The increasing concerns regarding water usage in mineral processing have led to a growing interest in dry jigging in recent years. However, there is still a need for a more comprehensive examination of the operational aspects of the technique. In this sense, this study focused on three main elements: (a) examining the air pulse pattern during dry jig operation; (b) assessing the evolution of the stratification profile over time using partition analysis; and (c) evaluating the specific energy consumption of batch dry jigging during operation. Also, an innovative operational strategy known as "transient pulsing" was proposed and analyzed, involving varying the intensity and frequency of the air pulse throughout the stratification process. All tests were conducted using density tracers spread across 11 density ranges (0.4–2.4 g/cm³) and a base bed (gravel) to analyze their separation in a batch, pilot-scale dry jig. Pressure drop and active power data were collected to measure the pulse characteristics and energy consumption. The airflow curves, obtained through pressure drop data, indicated that the pulsation process is more unstable as the airflow increases, possibly due to the pressure fluctuations experienced by air during valve closure. For the pulsation conditions used in the tests, the specific energy consumption was 10.66 Wh/kg of jigged material, with most of it related to the blower drive system. Analysis of the stratification evolution over time showed an oscillatory behavior, alternating between states of better (Ep < 0.1) and worse (Ep > 0.1) separation, especially for the near-gravity material (NGM). Results of the transient pulsation tests suggested that progressively increasing the vertical displacement of the bed during stratification resulted in slightly better segregation levels and more stable jigging evolution over time in comparison to stationary pulse conditions. Full article

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

16 pages, 7136 KiB

Open AccessArticle

Application of Integrated Geological and Geophysical Surveys on the Exploration of Chalcedony Deposits: A Case Study on Nanhong Agate in Liangshan, China

by Shengping Gong, Keqiang Zhao, Mingming Wang, Shengwu Yan, Yong Li and Jianzhou Yang

Minerals 2024, 14(7), 677; https://doi.org/10.3390/min14070677 (registering DOI) - 28 Jun 2024

Abstract

Nanhong agate, esteemed for its vivid color and natural shine, is experiencing a scarcity in supply despite its high demand. The primary deposits of agate, typically found near the surface, have not been extensively explored due to the predominance of traditional manual excavation [...] Read more.

Nanhong agate, esteemed for its vivid color and natural shine, is experiencing a scarcity in supply despite its high demand. The primary deposits of agate, typically found near the surface, have not been extensively explored due to the predominance of traditional manual excavation methods. This research examined the Nanhong agate deposits in the Zhaojue–Meigu region of Liangshan, China, employing the integration of geological and geophysical surveys. Field geological surveys allowed us to outline the general areas where agate is found. Following this, using magnetic surveys, vertical electrical sounding, and controlled-source audio magnetotellurics, agate deposits were located within the conglomerate layer of the second member of the Feixianguan Formation from the Lower Triassic period at depths of less than 100 m. Our results identify mineralized layers, Xuanwei Formation mudstone, and the underlying bedrock, thus supporting the creation of a mineral prediction map. This research provides essential insights and guidance for agate exploration and the development of associated mineral resources. Full article

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

13 pages, 2111 KiB

Open AccessArticle

Feasibility Analysis of Bacterial-Treated Coal Gangue for Soil Improvement: Growth-Promoting Effects of Alfalfa

by Yaya Wang, Mingwu Liu, Zhiting Di, Weilong Cao and Shihua He

Minerals 2024, 14(7), 676; https://doi.org/10.3390/min14070676 (registering DOI) - 28 Jun 2024

Abstract

The long-term storage of coal gangue (CG) mountains causes serious environmental problems such as water and air pollution. Thus, sustainable reclamation practices are urgently needed to minimize the environmental impacts brought by CG mountains. Pikovskaya medium was employed to screen microorganisms, which were [...] Read more.

The long-term storage of coal gangue (CG) mountains causes serious environmental problems such as water and air pollution. Thus, sustainable reclamation practices are urgently needed to minimize the environmental impacts brought by CG mountains. Pikovskaya medium was employed to screen microorganisms, which were subsequently utilized to promote the solubilization of CG. XRF, SEM, XRD, and HPLC techniques were employed to characterize the CG before and after bacterial treatment. In this study, we have successfully isolated and purified a bacterial strain, identified as Stenotrophomonas bentonitica BII-R7, which possesses the ability to facilitate the solubilization of nutrient elements from CG. Factors including initial inoculation ratio, incubation time, CG particle size, CG concentration, pH, and temperature were examined to investigate their effects on the biosolubilization of CG. Furthermore, the mechanism underlying the CG solubilization was also probed. Our data demonstrated that low-molecular-weight organic acids, such as acetic acid and formic acid, may harbor a crucial role in promoting the solubilization of CG. Lastly, we found that Stenotrophomonas bentonitica BII-R7, in conjugation with CG, can increase the alfalfa seed germination percentage and promote the growth of alfalfa. Together, these data provide evidence that bacterial-treated CG can be utilized for soil improvement and land reclamation. Full article

(This article belongs to the Section Biomineralization and Biominerals)

16 pages, 1640 KiB

Open AccessArticle

Mineralogy of Gold, Tellurides and Sulfides from Lianzigou Gold Deposits in the Xiaoqinling Region, Central China: Implications for Ore-Forming Conditions and Processes

by Guoming Weng, Jiajun Liu, Emmanuel John M. Carranza, Fangfang Zhang, Degao Zhai, Yinhong Wang, Shen Gao, Mingyang Si, Zaixin Su and Yingying Zhang

Minerals 2024, 14(7), 675; https://doi.org/10.3390/min14070675 (registering DOI) - 28 Jun 2024

Abstract

The Lianzigou deposit, which has an Au–Te paragenetic association, is hosted in plagioclase gneiss of the Qincanggou Formation in the Taihua Group in the Xiaoqinling region, central China. This quartz vein-type Au deposit comprises native Au and a variety of tellurides. The latter [...] Read more.

The Lianzigou deposit, which has an Au–Te paragenetic association, is hosted in plagioclase gneiss of the Qincanggou Formation in the Taihua Group in the Xiaoqinling region, central China. This quartz vein-type Au deposit comprises native Au and a variety of tellurides. The latter include calaverite (AuTe₂), krennerite (Au₃AgTe₈), petzite (Au₃AgTe₂), hessite (Ag₂Te), melonite (NiTe₂), and altaite (PbTe). Four stages have been recognized in this deposit: stage I consists of K-feldspar and quartz; stage II is of milky quartz veins accompanied by coarse-grained disseminated and lumps of pyrite with weak Au mineralization; stage III is composed mainly of Au, tellurides, and sulfides; and stage IV is characterized by abundant carbonate and quartz. Based on mineral assemblage and thermodynamic data, we estimated the physicochemical conditions of the main metallogenic stages. Based on thermodynamic modelling, the physicochemical conditions of Au–Ag–Te mineral associations were estimated. The Au–Ag–Te minerals from stage III formed mainly under conditions of logƒO₂ = −43.15 to −33.31, logƒH₂S = ~−9.29, pH < 7, logfTe₂ = −10.6 to −9.8 and logαAu⁺/αAg⁺ = −7.2 to −6.5. In contrast, the physicochemical conditions of stage II were higher, specifically pH (8.3–8.5) and logƒO₂ (−34.90−31.96). In the ore-forming fluids of the Lianzigou deposit, the dominant Au species was Au(HS)₂⁻ while the dominant Te species were HTe⁻(aq) and Te₂²⁻(aq). Moreover, the Au–Ag–Te metal associations in the Lianzigou Au deposit were derived from mantle materials related to lithospheric thinning of the eastern North China craton in the Early Cretaceous under an extensional tectonic system. Full article

(This article belongs to the Section Mineral Deposits)

12 pages, 1486 KiB

Open AccessArticle

Use of Submarine Tailings Disposal as Alternative Tailings Management System

by Erol Yilmaz

Minerals 2024, 14(7), 674; https://doi.org/10.3390/min14070674 (registering DOI) - 28 Jun 2024

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Abstract

The importance of the mining/milling industry in increasing the growth level and welfare of countries is quite high. However, at the end of mining/milling processes, huge amounts of waste (often known as tails) are inevitably produced that have no economic value and can [...] Read more.

The importance of the mining/milling industry in increasing the growth level and welfare of countries is quite high. However, at the end of mining/milling processes, huge amounts of waste (often known as tails) are inevitably produced that have no economic value and can even be considered dangerous due to some heavy metals they contain. These tails are highly problematic due to both their volume (difficult to manage environmentally) and toxicity (potential to cause acid/leach waters) and need to be handled outside of existing disposal methods. This article presents the effective and sustainable handling and application of tails resulting from the enrichment of copper–zinc ores, which are actively engaged in metallic mining activities in the northeast of Türkiye, with the submarine tails disposal (STD) method. In the mining operation under study, some (55–60 wt.%) of the tails are employed as underground fill, even though the residual part is disposed of by the STD method. The characterization of ore beneficiation tails, their transportation to the subsea via a pipeline system, and discharge monitoring results are detailed in the present investigation. According to the limitations which are indicated by the Turkish Control of Water Contamination regulation, the concentration of Pb-Cu found in the results was under the allowable limit of 0.05 mg/L. The allowed 2 mg/L limit for Zn was not surpassed mainly by the concentration found in the collected samples. pH values were almost above the allowable limit of pH > 5. The results reveal that the STD technique works quite well as an integrated mine tails method in the mine under study. Full article

(This article belongs to the Special Issue Cemented Mine Waste Backfill: Experiment and Modelling: 2nd Edition)

18 pages, 1863 KiB

Open AccessArticle

Stability Analysis of a Mine Wall Based on Different Roof-Contact Filling Rates

by Jiang Guo, Wenjun Yang, Yan Zhao and Wanzhong Zhang

Minerals 2024, 14(7), 673; https://doi.org/10.3390/min14070673 (registering DOI) - 28 Jun 2024

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Abstract

This study takes the mine wall of the isolated mine pillar in the Dongguashan Copper Mine as the research object. Based on the mechanical model of the mine wall under the trapezoidal loading of the backfill, the expressions for calculating the safety factor [...] Read more.

This study takes the mine wall of the isolated mine pillar in the Dongguashan Copper Mine as the research object. Based on the mechanical model of the mine wall under the trapezoidal loading of the backfill, the expressions for calculating the safety factor of the mine wall were derived by considering the load-bearing conditions of the backfill–mine-wall system under different roof-contacted filling rates. On this basis, the variation law of the safety factor of the mine wall with the roof-contacted filling rate was obtained, and the calculation result was verified by a numerical simulation and a field test. The research shows that for the same mine wall width, when the roof-contacted filling rate exceeds 9.53%, the safety factor of the mine wall exhibits a "trapezoidal" variation pattern with the increase in the roof-contacted filling rate. Moreover, the comprehensive benefits of isolated pillar recovery are made more credible by maintaining a wall width of 3 m and a filler jointing rate between 30% and 74.49%. This study analyzes the effect of the roof-contacted filling rate on the stability of the mine wall, which can provide a theoretical basis for mining isolated pillars by the filler method in deep mines. Full article

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

3 pages, 178 KiB

Open AccessEditorial

Editorial for Special Issue: “Geochemistry and Mineralogy of Basic–Ultrabasic and Alkaline Intrusions and Related Magmatic Deposits”

by Nadezhda Krivolutskaya

Minerals 2024, 14(7), 672; https://doi.org/10.3390/min14070672 (registering DOI) - 28 Jun 2024

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Abstract

Magmatic deposits are sources of strategic metals provided to the global market. Ultramafic–mafic intrusions contain PGE, Cu-Ni, Cr, Ti, and V deposits, while many rare metal deposits (e.g., Zr, Ta, Nb, Be, Y, Sc, Li, and Ge) are linked to alkaline intrusions. Full article

(This article belongs to the Special Issue Geochemistry and Mineralogy of Basic–Ultrabasic and Alkaline Intrusions and Related Magmatic Deposits)

37 pages, 46986 KiB

Open AccessArticle

Barite Replacement as a Key Factor in the Genesis of Sediment-Hosted Zn-Pb±Ba and Barite-Sulfide Deposits: Ore Fluids and Isotope (S and Sr) Signatures from Sediment-Hosted Zn-Pb±Ba Deposits of Iran

by Abdorrahman Rajabi, Pouria Mahmoodi, Pura Alfonso, Carles Canet, Colin Andrew, Saeideh Azhdari, Somaye Rezaei, Zahra Alaminia, Somaye Tamarzadeh, Ali Yarmohammadi, Ghazaleh Khan Mohammadi and Rasoul Saeidi

Minerals 2024, 14(7), 671; https://doi.org/10.3390/min14070671 (registering DOI) - 28 Jun 2024

Viewed by 63

Abstract

Iran hosts more than 350 Precambrian to Cenozoic sediment-hosted Zn-Pb±Ba and barite-sulfide deposits, including shale-hosted massive sulfide (SHMS, also called SEDEX) and Irish-type and Mississippi Valley-type (MVT) mineralization, and barite is a common mineral in these deposits. In the SHMS deposits, barite is [...] Read more.

Iran hosts more than 350 Precambrian to Cenozoic sediment-hosted Zn-Pb±Ba and barite-sulfide deposits, including shale-hosted massive sulfide (SHMS, also called SEDEX) and Irish-type and Mississippi Valley-type (MVT) mineralization, and barite is a common mineral in these deposits. In the SHMS deposits, barite is typically found as fine-grained disseminations in thin laminae. In these deposits, the sulfide laminae often occur as diagenetic replacements and as bands containing authigenic and diagenetic barite and pyrite framboids. In the Irish-type Zn-Pb-Ba and stratabound barite-sulfide deposits, barite exhibits various textures, including fine-grained disseminated barite, banded zebra textures, veins, and massive barite lenses. In some of the giant Irish-type deposits, as well as in the stratabound barite-sulfide mineralization, the main stratabound sulfide ore is developed within a barite envelope and is characterized by the replacement of barite and pyrite by chalcopyrite, galena, and sphalerite. In the MVT deposits, the formation of barite is often related to dolomitization, and sulfide mineralization involves the replacement of the dolomitized carbonate rocks, as well as associated barite. Fluid inclusion studies on the Irish-type deposits indicate that the temperatures and salinities of the sulfide-forming fluids are higher compared to those of the barite-forming fluids. Fluid inclusion analyses of coarse-grained barites from Irish and MVT deposits reveal their hydrothermal origin. The δ³⁴S values of sulfide minerals (pyrite, sphalerite, and galena) in Irish-type deposits exhibit a broad range of low values (mostly −28 to +5‰), primarily revealing a process of bacterial sulfate reduction (BSR). However, the textures (replacement, colloform, and banded) and more positive sulfur isotope values (+1 to +36‰) in the SHMS Zn-Pb deposits suggest that bacterial sulfate reduction (BSR) plays a less significant role. We suggest that thermochemical sulfate reduction (TSR) connected to the direct replacement of barite plays a more relevant role in providing sulfur for the sulfide mineralization in the SHMS, barite-sulfide, and MVT deposits. Based on the textual evidence, sulfur isotopic data, and fluid inclusion studies, barite has been identified as a key controller for the subsequent Zn-Pb mineralization by providing a suitable host and significant sulfur contribution in the sediment-hosted Zn-Pb and stratabound barite-sulfide deposits. This implies that diagenetic barite might be a precursor to all types of sediment-hosted Zn-Pb mineralization. Full article

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

25 pages, 6355 KiB

Open AccessArticle

Numerical Investigation of the Applicability of Preferential Grade Deportment by Size

by Nazym Baizhiyen, Peter Dowd, Chaoshui Xu and David Lewis

Minerals 2024, 14(7), 670; https://doi.org/10.3390/min14070670 - 28 Jun 2024

Viewed by 142

Abstract

The effective separation of ore is based on two fundamental processes: liberation and separability. Liberation involves the reduction of size, yielding smaller particles with enhanced compositional homogeneity. Understanding liberation requires an understanding of rock breakage, as it impacts mineral liberation and helps identify [...] Read more.

The effective separation of ore is based on two fundamental processes: liberation and separability. Liberation involves the reduction of size, yielding smaller particles with enhanced compositional homogeneity. Understanding liberation requires an understanding of rock breakage, as it impacts mineral liberation and helps identify ores suitable for pre-concentration. Non-random breakage, influenced by textural and mineral properties, introduces heterogeneity in mineral distribution across size fractions. Physical attributes, including ore and gangue mineralogy and texture, influence fractionation tendencies during breakage. Notably, the presence of mineralization in veins substantially assists early-stage liberation in mineral processing. The aim of this study is to develop a methodology that allows the prediction of natural fractionation tendencies based on geological, mineralogical, and textural data using Discrete Element Method (DEM) modeling. DEM simulations provide insights into granular material behavior, capturing phenomena such as crack initiation and propagation. The use of DEM, particularly with models such as the Flat Joint Model (FJM), enhances our understanding of rock damage mechanisms. In this paper, DEM is used to predict preferential grade by size deportment, and a numerical model is developed to reflect grade distributions across size fractions. A fragmentation analysis is conducted after rock breakage simulations using DEM to analyze the fragment sizes and grades and calculate the Response Rankings of synthetic specimens. Full article

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

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14 pages, 6673 KiB

Open AccessArticle

In Situ Carbonate U-Pb Dating of Gold and Mercury Deposits in the Youjiang Metallogenic Province, SW China, and Implications for Multistage Mineralization

by Jinwei Li, Yuzhou Zhuo, Yitong Guo, Xinyue Lu and Xinlu Hu

Minerals 2024, 14(7), 669; https://doi.org/10.3390/min14070669 - 28 Jun 2024

Viewed by 118

Abstract

The Youjiang metallogenic province (YMP) is a famous ore-concentrating area in South China, known for its substantial Carlin-type gold deposits, antimony deposits, and mercury deposits. Previous studies have yielded conflicting views regarding the ages of mineralization in this area, particularly regarding the occurrence [...] Read more.

The Youjiang metallogenic province (YMP) is a famous ore-concentrating area in South China, known for its substantial Carlin-type gold deposits, antimony deposits, and mercury deposits. Previous studies have yielded conflicting views regarding the ages of mineralization in this area, particularly regarding the occurrence of Yanshanian versus Indosinian ore-forming events during the Mesozoic era. To resolve these discrepancies, this study utilized in situ LA-ICP-MS U-Pb dating on carbonate minerals from the Lannigou Carlin-type Au deposit, the Lanmuchang Hg-(Tl) deposit, and the Sixiangchang Hg deposit to accurately determine their mineralization ages. Our results indicate that the three deposits formed at 137 ± 9 Ma, ~97 Ma, and 454 ± 21 Ma, respectively. By integrating previously reported geochronological data, we propose that the low-temperature Au-As-Sb-Hg-Tl deposits in the YMP were formed during two major periods, Late Triassic and Late Jurassic to Cretaceous, with the latter being more prevalent. Additionally, there was a Paleozoic hydrothermal mercury mineralization event at the northeastern edge of this region. These newly acquired data significantly enhance our understanding of multistage, low-temperature mineralization events in the YMP. Our study also demonstrates that in situ carbonate U-Pb dating is an excellent method for investigating the timing of low-temperature mineralization events. Full article

(This article belongs to the Special Issue Using Mineral Chemistry to Characterize Ore-Forming Processes)

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26 pages, 6806 KiB

Open AccessArticle

Pyrite-Goethite Alteration in Supergene Oxidation Processes in Till: Elemental Distribution and Evaluation of Goethite Usability as a Fingerprinting Tool for Vectoring Mineral Deposits

by Atte Taivalkoski, Jukka-Pekka Ranta, Pertti Sarala, Marko Moilanen, Paavo Nikkola and Tapio Soukka

Minerals 2024, 14(7), 668; https://doi.org/10.3390/min14070668 - 27 Jun 2024

Viewed by 232

Abstract

In the formerly glaciated terrains in the northern hemisphere and countries such as Finland, till is the most common sediment covering the bedrock. Specifically, indicator or heavy mineral studies utilising till as a vector for mineral deposits undercover have been successful. The pyrite [...] Read more.

In the formerly glaciated terrains in the northern hemisphere and countries such as Finland, till is the most common sediment covering the bedrock. Specifically, indicator or heavy mineral studies utilising till as a vector for mineral deposits undercover have been successful. The pyrite trace-element composition from in situ mineral analyses has been shown to be an effective discriminator between different mineral deposit types, and this has led to research using heavy mineral pyrite in till to identify potential mineral deposits in a given area. However, pyrite is easily oxidised in till beds, and thus, alternative methods should be considered. Goethite pseudomorphs are more commonly found in the till sediments as remnants after pyrite oxidation. This study evaluates trace element compositions of goethitised pyrite recovered in the till beds from central Lapland in northern Finland. Intra-grain trace-elemental variations gathered using laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) between the intact pyrite core and oxidised rim demonstrated complex dynamics and variations between different trace-element values. For example, Cu, V and Mn exhibited elevated trace-element values in the goethite rim compared to the pyrite core. However, elemental ratios such as Ni/As and Co/Ni remain stable between the pyrite core and oxidised rim. Therefore, these ratios have the potential to be used as a discriminating tool between the pyrite core and oxidised rim. In addition, nanoscale variabilities using focused ion beam (FIB) and transmission electron microscopy (TEM) were utilised to inspect possible nano inclusions within the studied heavy mineral grain. The FIB and TEM studies revealed a nanocrystalline pyrite nodule observation within the goethite rim. Full article

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

17 pages, 8826 KiB

Open AccessArticle

The Middle Triassic Intermediate to Basic Rocks in the Eastern Kunlun Orogenic Belt, Northeast Tibet: Implication for the Paleo-Tethyan Ocean Closure

by Wei Du, Lei Pei, Zuochen Li, Ruibao Li, Youxin Chen, Chengjun Liu, Guochao Chen and Xianzhi Pei

Minerals 2024, 14(7), 667; https://doi.org/10.3390/min14070667 - 27 Jun 2024

Viewed by 181

Abstract

Large volumes of Early Mesozoic intermediate to basic igneous rocks related to the evolution of the Paleo-Tethys Ocean are exposed in the East Kunlun Orogenic Belt (EKOB). The petrography, geochemistry, and results of zircon U-Pb dating of Defusheng intermediate to basic rocks from [...] Read more.

Large volumes of Early Mesozoic intermediate to basic igneous rocks related to the evolution of the Paleo-Tethys Ocean are exposed in the East Kunlun Orogenic Belt (EKOB). The petrography, geochemistry, and results of zircon U-Pb dating of Defusheng intermediate to basic rocks from the eastern segment of the EKOB are presented in this report. Zircon U–Pb dating of the intermediate to basic rocks yields ages of 239–245 Ma (Middle Triassic). Defusheng intermediate to basic rocks have low TiO₂ contents (0.80–1.47 wt.%) and widely varying MgO (3.14–6.08 wt.%), and are enriched in large ion lithophile elements and light rare earth elements, having a geochemical composition similar to that of island arc basalts. The variation diagrams of major elements indicate that the Defusheng intermediate to basic rocks underwent fractional clinopyroxene and olivine crystallization. Depletion of the high-field-strength elements Nb, Ta, and Ti may have been caused by the mantle wedge having been infiltrated by fluids derived from the subducted slab. The Defusheng intermediate to basic rocks represent magmatic records of the Early Mesozoic oceanic crust subduction in Eastern Kunlun. This indicates that the final closure of the Paleo-Tethyan Ocean and the beginning of collisional orogeny occurred after the Middle Triassic. Full article

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

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20 pages, 23085 KiB

Open AccessArticle

Origin of the Kunduleng Granite and Its Associated Uranium Anomaly in the Southern Great Xing’an Range, NE China

by Jiaxing Sun, Deyou Sun, Jun Gou, Dongguang Yang, Changdong Wang, Li Tian and Duo Zhang

Minerals 2024, 14(7), 666; https://doi.org/10.3390/min14070666 - 27 Jun 2024

Viewed by 135

Abstract

The Kunduleng granite hosts one of several significant uranium anomalies within the southern Great Xing’an Range, NE China. Whole-rock geochemistry and mineral chemistry data, along with the zircon U-Pb-Hf isotope have been used to constrain the petrogenesis of this granitic intrusion and the [...] Read more.

The Kunduleng granite hosts one of several significant uranium anomalies within the southern Great Xing’an Range, NE China. Whole-rock geochemistry and mineral chemistry data, along with the zircon U-Pb-Hf isotope have been used to constrain the petrogenesis of this granitic intrusion and the origin of the uranium anomaly. Microscopically, quartz, alkali-feldspar, and plagioclase are the essential mineral constituents of the granite, with minor biotite, while monazite, apatite, xenotime, and zircon are accessory minerals. Geochemically, the silica- and alkali-rich granites show a highly fractionated character with “seagull-shaped” REE patterns and significant negative anomalies of Ba and Sr, along with low Zr/Hf and Nb/Ta ratios. The granite has positive zircon ε_Hf(t) values ranging from +12.7 to +14.5 and crustal model ages (T_DM2) of 259–376 Ma, indicating a Paleozoic juvenile crustal source. Uraninite and brannerite are the main radioactive minerals responsible for the uranium anomaly within the Kunduleng granite. Uraninite presents well-developed cubic crystals and occurs as tiny inclusions in quartz and K-feldspar with magmatic characteristics (e.g., elevated ThO₂, Y₂O₃, and REE₂O₃ contents and low CaO, FeO, and SiO₂ concentrations). The calculated U-Th-Pb chemical ages (135.4 Ma) are contemporaneous with the U-Pb zircon age (135.4–135.6 Ma) of the granite, indicating a magmatic genesis for uraninite. The granites are highly differentiated, and extreme magmatic fractionation might be the main mechanism for the initial uranium enrichment. Brannerite is relatively less abundant and typically forms crusts on ilmenite and rutile or it cements them, representing the local redistribution and accumulation of uranium. Full article

(This article belongs to the Special Issue Mineralization in Subduction Zone)

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23 pages, 16032 KiB

Open AccessArticle

Energy Mechanism and Acoustic Emission Characteristics in Rock-Backfill Composite Structure Specimens under Multi-Level Cyclic Loads: Cement-Tailings Ratio Effect

by Dayu Long, Yu Wang, Changhong Li, Yunfeng Wu and Yongyue Hu

Minerals 2024, 14(7), 665; https://doi.org/10.3390/min14070665 - 27 Jun 2024

Viewed by 174

Abstract

This study aimed to investigate the effects of the cement-tailings ratio (CTR) on the fatigue properties, acoustic emission (AE) activities, energy dissipation, and fracture patterns of rock-backfill composite structure (RBCS) samples. The investigation employed multi-level cyclic loading tests combined with acoustic emission monitoring [...] Read more.

This study aimed to investigate the effects of the cement-tailings ratio (CTR) on the fatigue properties, acoustic emission (AE) activities, energy dissipation, and fracture patterns of rock-backfill composite structure (RBCS) samples. The investigation employed multi-level cyclic loading tests combined with acoustic emission monitoring and post-test CT scanning. The results indicated that the fatigue strength and fatigue lifetime of the RBCS samples initially increased and then decreased as the CTR was reduced from 1:4 to 1:12. The energy dissipation characteristics reflected the optimal energy absorption effect of the backfill at a CTR of 1:8. The AE ring counts/energy apparent skip phenomenon corresponded to the stress-strain curve from a dense to sparse pattern. The samples with CTRs of 1:4 and 1:8 showed a more significant increase in the peak frequency band at failure and released more energy. The fracture of the RBCS specimen was dominated by tensile cracking signals accompanied by some shear cracking signals. However, the proportion of shear signals was higher for samples with CTRs of 1:4 and 1:8. Similarly, the b value was smaller at failure. The 3D visualization images revealed that the fracture pattern of the RBCS was a mixed tensile-shear fracture, including shear fracture within the backfill, tensile cracking in the interface, and tensile-shear fracture within the rock. The volume and complexity of cracks increased and then decreased with decreasing CTR, i.e., from 1:4 to 1:12. The evolution of cracks probably involves internal backfill fracturing first, and then the fracture extends into the surrounding rock. A recommendation for the design of CTB was presented in this study to ensure the safety and stability of mine excavations. Full article

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

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23 pages, 12616 KiB

Open AccessArticle

Full-Waveform Modeling of Complex Media Seismic Waves for Irregular Topography and Its Application in Metal Ore Exploration

by Wenchao Su, Shoudong Huo and Xuhui Zhou

Minerals 2024, 14(7), 664; https://doi.org/10.3390/min14070664 - 27 Jun 2024

Viewed by 154

Abstract

Seismic exploration has caught widespread attention in metal ore exploration due to its higher resolution. However, the presence of topography and complex underground structures in metal ore exploration complicates seismic records. Therefore, it is essential to apply a numerical simulation method suitable for [...] Read more.

Seismic exploration has caught widespread attention in metal ore exploration due to its higher resolution. However, the presence of topography and complex underground structures in metal ore exploration complicates seismic records. Therefore, it is essential to apply a numerical simulation method suitable for metal ore exploration to study the propagation law of seismic waves in shallow and ore-forming zones, providing reliable theoretical support for multi-component seismic techniques. In particular, the presence of topography generates strong-amplitude surface waves, scattered waves, and converted waves, which consistently distort seismic records and affect the imaging accuracy of the metallogenic belts. Additionally, the propagation of seismic waves is also affected by the anisotropy and viscoelasticity of the underground medium. This paper proposes an elastic wave finite-difference numerical simulation method suitable for irregularly topographical and complex medium conditions, named the comprehensive parameter correction method, which implements a free-surface boundary condition based on the concept of medium averaging. It is algorithmically simple and implies no additional computational costs. Meanwhile, the results obtained by this method are highly consistent with those of the spectral element method, demonstrating its accuracy. By presenting several numerical simulation cases and illustrating the impact of topography and medium conditions on seismic records, this paper demonstrates the necessity of considering irregularly topographical and complex medium conditions in metal ore exploration. In conclusion, the numerical simulation method we propose provides a solid theoretical foundation for the application of seismic exploration methods in metal ore exploration. Full article

(This article belongs to the Special Issue Seismics in Mineral Exploration)

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12 pages, 2603 KiB

Open AccessArticle

Inhibiting Mechanism of High pH on Molybdenite Flotation. An Experimental and DFT Study

by Enxiang Wang, He Wan, Juanping Qu, Peng Yi and Xianzhong Bu

Minerals 2024, 14(7), 663; https://doi.org/10.3390/min14070663 - 27 Jun 2024

Viewed by 130

Abstract

The inhibiting mechanism of high pH on the molybdenite flotation was studied using an experimental and DFT method. The experimental results found that adverse effects of pH on molybdenite flotation should be attributed to the adsorption of OH⁻ on molybdenite [100] surface [...] Read more.

The inhibiting mechanism of high pH on the molybdenite flotation was studied using an experimental and DFT method. The experimental results found that adverse effects of pH on molybdenite flotation should be attributed to the adsorption of OH⁻ on molybdenite [100] surface (MS100). The DFT results show the adsorption energy of H₂O/OH⁻ to molybdenite [001] surface (MS001) and MS100 is −8.61/288.30 kJ·mol⁻¹ and −226.81/−302.44 kJ·mol⁻¹. These indicate that H₂O is weakly adsorbed on MS001, while OH⁻ is not. Both H₂O and OH⁻ can be adsorbed onto MS100. The adsorption energy of OH⁻ to MS100 is much stronger than that of H₂O. The results of state density and charge transfer of the adsorption of OH⁻ on MS100 further show that OH⁻ can be chemically adsorbed on MS100 through the bonding of the O atom of OH⁻ and the Mo atom of MS100. This causes a significant reduction in the MS100 hydrophobicity and deteriorates the fine molybdenite flotation. Full article

(This article belongs to the Special Issue Advances in Flotation of Copper, Lead and Zinc Minerals)

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27 pages, 12287 KiB

Open AccessArticle

Molybdenum Mineralization in Eastern Hebei, China: Evidence from Geochronology and Isotopic Composition

by Jinlong Sun, Yang Cheng, Xinxing Liu, Guang’an Meng and Xintong Dong

Minerals 2024, 14(7), 662; https://doi.org/10.3390/min14070662 - 27 Jun 2024

Viewed by 163

Abstract

The northern margin of the North China Craton is one of the most important porphyry-skarn molybdenum ore belts in the world. The eastern Hebei Province, which contains a high number of molybdenum and gold (molybdenum) resources, is an important portion of the northern [...] Read more.

The northern margin of the North China Craton is one of the most important porphyry-skarn molybdenum ore belts in the world. The eastern Hebei Province, which contains a high number of molybdenum and gold (molybdenum) resources, is an important portion of the northern margin of the North China Craton. Xichanggou and Huashi, located in eastern Hebei, are quartz-molybdenum vein deposits that are intimately associated with intrusions that are deeply concealed in the mining area. This work presents two zircon U-Pb dates and ten molybdenite Re-Os ages from samples of the aforementioned two deposits in order to determine the timing of the intrusion and mineralization. The zircon U-Pb ages of the quartz monzonite porphyry from Xichanggou are determined to be 163.3 ± 0.3 Ma and 162.8 ± 0.4 Ma. The molybdenite Re-Os dating yielded ages of 160.3 ± 4.6 Ma for Xichanggou and 171.4 ± 19 Ma for Huashi, respectively. The isotopic composition of oxygen and hydrogen of the ore-forming fluid from Huashi, as indicated by the δD_V-SMOW values (−80.0‰ to −67.6‰) and δ¹⁸O_H₂O values (−1.86‰ to 2.33‰), suggests that the fluid is primarily composed of water derived from magma, with some contribution from atmospheric precipitation. The sulfur isotope values (δ³⁴S) of sulfides from Xichanggou range from 6.5‰ to 7.1‰, while the δ³⁴S values from Huashi range from 3.3‰ to 4.9‰. The lead isotope ratios (²⁰⁶Pb/²⁰⁴Pb and ²⁰⁷Pb/²⁰⁴Pb) of sulfides from Xichanggou and Huashi average at 17.414, 15.428, and 17.591, 15.379, respectively. The Re-Os isotopic compositions of ore sulfides mostly fall within the range of 318 ppm to 50,114 ppm. These isotopic compositions indicate that the materials responsible for the formation of the ores in Xichanggou and Huashi primarily originate from the melting of lower crust materials that have been contaminated by the mantle. Based on the regional data, the molybdenum deposits in eastern Hebei were formed in multiple periods, specifically approximately 170 Ma and 160 Ma in Huahsi and Xichanggou, respectively. The subduction of the Paleo-Pacific plate during the middle–late Jurassic period led to the partial remelting of lower crust material, resulting in the acquisition of a significant quantity of metal elements (Mo), which were subsequently deposited. Full article

(This article belongs to the Section Mineral Deposits)

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18 pages, 3624 KiB

Open AccessArticle

Enhancing Geopolymeric Material Properties: A Comparative Study of Compaction Effects via Alkaline and Acidic Routes

by Marwa Zribi, Maher Issa and Samir Baklouti

Minerals 2024, 14(7), 661; https://doi.org/10.3390/min14070661 - 27 Jun 2024

Viewed by 135

Abstract

This research undertakes a comparative study between compacted phosphate-based (CPG) and alkaline-based (CAG) geopolymeric materials. The obtained materials underwent comprehensive evaluation through mechanical, physical, and chemical analyses. CPG exhibited superior mechanical strength, demonstrating an exponential growth with curing age in contrast to CAG. [...] Read more.

This research undertakes a comparative study between compacted phosphate-based (CPG) and alkaline-based (CAG) geopolymeric materials. The obtained materials underwent comprehensive evaluation through mechanical, physical, and chemical analyses. CPG exhibited superior mechanical strength, demonstrating an exponential growth with curing age in contrast to CAG. Both materials exhibited stable density over time, with CPG displaying a notably higher density attributed to its enhanced reactivity in an acidic medium. Dimensional variations revealed stable dimensions for CPG and subtle shrinkage for CAG, potentially associated with an observed efflorescence phenomenon. Visual assessments during water immersion highlighted the enhanced stability of CPG. Chemical analyses confirmed the persistence of mineralogical phases, such as quartz and illite, and the emergence of an amorphous geopolymeric network in both CPG and CAG samples. CPG materials featured aluminum phosphate phases, reinforcing structural integrity, while CAG materials exhibited sodium carbonate phases, introducing impurities, elucidating the superior performance of CPG over CAG. For the formation kinetics, CPG exhibited a faster reaction time than CAG, as evidenced by the evolution of pH, densification rate, and FTIR band over curing time. Full article

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

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27 pages, 4867 KiB

Open AccessArticle

Deciphering Igneous Rock Crystals: Unveiling Multifractal Patterns in Crystal Size Dynamics

by Amir Eskandari and Behnam Sadeghi

Minerals 2024, 14(7), 660; https://doi.org/10.3390/min14070660 - 27 Jun 2024

Viewed by 178

Abstract

Understanding magma plumbing systems hinges upon an intricate comprehension of crystal populations concerning size, chemistry, and origin. We introduce an innovative, yet elegantly simple approach—the ‘number–length of crystals (N-LoC) multifractal model’—to classify crystal sizes, unveiling compelling insights into their distribution dynamics. This model, [...] Read more.

Understanding magma plumbing systems hinges upon an intricate comprehension of crystal populations concerning size, chemistry, and origin. We introduce an innovative, yet elegantly simple approach—the ‘number–length of crystals (N-LoC) multifractal model’—to classify crystal sizes, unveiling compelling insights into their distribution dynamics. This model, a departure from conventional crystal size distribution (CSD) diagrams, reveals multifractal patterns indicative of distinct class sizes within igneous rock crystals. By synthesizing multiple samples from experimental studies, natural occurrences, and numerical models, we validate this method’s efficacy. Our bi-logarithmic N-LoC diagrams for cooling-driven crystallized samples transcend the confines of traditional CSD plots, identifying variable thresholds linked to cooling rates and quenching temperatures. These thresholds hint at pulsative nucleation and size-dependent growth events, offering glimpses into crystallization regimes and post-growth modifications like coalescence and coarsening. Examining multifractal log–log plots across time-series samples unravels crystallization histories during cooling or decompression. Notably, microlites within volcano conduits delineate thresholds influenced by decompression rate and style, mirroring nucleation and growth dynamics observed in experimental studies. Our fractal methodology, presenting a more direct approach with fewer assumptions than the classic CSD method, stands poised as a potent alternative or complementary tool. We delve into its potential, facilitating comparisons between eruptive styles in volcanoes while deliberating on inherent limitations. This work not only advances crystal size analysis methodologies but also holds promise for inferring nuanced volcanic processes and offers a streamlined avenue for crystal size evaluation in igneous rocks. Full article

(This article belongs to the Special Issue Texture and Microstructural Analysis of Crystalline Solids, Volume II)

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18 pages, 4198 KiB

Open AccessArticle

Effect of Paleoenvironmental Conditions on the Distribution of Lower Carboniferous Shale in Yaziluo Rift Trough, South China: Insights from Major/Trace Elements and Shale Composition

by Xianglin Chen, Qiuchen Xu, Yinglun Qin, Rong Chen, Yufang Wang, Dishi Shi, Jing Bai, Kun Yuan, Wenpan Cen, Fei Li and Tuo Lin

Minerals 2024, 14(7), 659; https://doi.org/10.3390/min14070659 - 26 Jun 2024

Viewed by 235

Abstract

Paleoenvironmental conditions significantly influence the distribution patterns and organic matter enrichment of shale. This study investigated the vertical variations of major elements, trace elements, and total organic carbon (TOC) in the Lower Carboniferous marine shale from the Yaziluo Rift Trough, South China, to [...] Read more.

Paleoenvironmental conditions significantly influence the distribution patterns and organic matter enrichment of shale. This study investigated the vertical variations of major elements, trace elements, and total organic carbon (TOC) in the Lower Carboniferous marine shale from the Yaziluo Rift Trough, South China, to understand the paleoenvironmental conditions, including redox conditions, terrigenous detrital input, paleoproductivity, and paleo-seawater depth. The Lower Carboniferous formation consists of three sedimentary facies: basin facies, lower slope facies, and upper slope facies. From the basin to the lower slope and then to the upper slope facies, TOC, quartz, and pyrite contents gradually decrease, whereas the carbonate mineral content shows an increasing trend. A continuous decline in paleo-seawater depth transformed a deep-water anoxic environment with high paleoproductivity and low detrital input in the basin facies into a semi-deep-water environment with dysoxic-oxic conditions and moderate detrital influx in the lower slope facies, evolving further into a suboxic environment with high detrital flux in the upper slope facies. The geochemistry results suggest that anoxic conditions and high paleoproductivity were the primary controls on organic matter enrichment in the siliceous shale of the basin facies. In contrast, redox conditions significantly influenced organic matter accumulation in the mixed shale of the lower slope facies, attributed to relatively low paleoproductivity in a more restricted marine setting. Additionally, the adsorption of carbon components by clay minerals facilitated the preservation of organic matter in the calcareous shale of the upper slope facies. Full article

(This article belongs to the Topic Reservoir Characteristics and Evolution Mechanisms of the Shale)

16 pages, 6058 KiB

Open AccessArticle

The Memorial Chapel (Formerly Holy Trinity Church) in the Tempio Evangelico Valdese (Florence): Surveys and Characterization of Decorative Plasters for a Conservative Recovery

by Sara Calandra, Elena Pecchioni, Francesca Briani, Maria Di Benedetto, Carlo Alberto Garzonio, Eleonora Pica, Teresa Salvatici, Irene Centauro and Alba Patrizia Santo

Minerals 2024, 14(7), 658; https://doi.org/10.3390/min14070658 - 26 Jun 2024

Viewed by 217

Abstract

This study focuses on the Memorial Chapel, a historical site located inside the Tempio Evangelico Valdese in Florence. In 1843, the first Anglican church in Florence, known as Holy Trinity Church, was built by D. Giraldi. Around 1892, G. F. Bodley began the [...] Read more.

This study focuses on the Memorial Chapel, a historical site located inside the Tempio Evangelico Valdese in Florence. In 1843, the first Anglican church in Florence, known as Holy Trinity Church, was built by D. Giraldi. Around 1892, G. F. Bodley began the reconstruction of a new building of neo-Gothic style at the same site, which was completed in 1904. This new church had a space dedicated to memory called Memorial Chapel. In 1967, the monumental complex was acquired by the Waldensians, now known as the Tempio Evangelico Valdese. This interdisciplinary investigation aimed to study the most damaged painted walls of the chapel. For this purpose, samples of decorative plaster mortars were collected from various points, after carrying out a digital mapping of the degraded areas. Mineralogical, petrographic, optical, chemical, and microchemical analyses were performed. This study made it possible to highlight the composition and the characteristics of the different layers of the plaster mortars, permitting us also to identify the types of pigments used over time in the paintings; furthermore, it was possible to reconstruct the degradation phenomena on the walls and the events that caused them, providing valuable insight for targeted restoration efforts. Full article

(This article belongs to the Special Issue Geomaterials and Cultural Heritage)

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16 pages, 17205 KiB

Open AccessArticle

A Novel Method of Magnetic Sources Edge Detection Based on Gradient Tensor

by Wenjie Lv, Pei Huang, Yaxin Yang, Qibin Luo, Shangping Xie and Chen Fu

Minerals 2024, 14(7), 657; https://doi.org/10.3390/min14070657 - 26 Jun 2024

Viewed by 202

Abstract

The edge detection method based on the magnetic gradient tensor data plays an important role in magnetic exploration because it is free from geomagnetic interference and contains more abundant information. This paper proposes a new anomaly edge detection method using the magnetic gradient [...] Read more.

The edge detection method based on the magnetic gradient tensor data plays an important role in magnetic exploration because it is free from geomagnetic interference and contains more abundant information. This paper proposes a new anomaly edge detection method using the magnetic gradient tensor components. The model is established to compare with other methods, such as directional total horizontal derivative (THD_z), analytical signal (AS), tilt angle, theta map, and so on, under conditions of vertical magnetization, oblique magnetization, and noise interference. Through the study of the anomaly distribution of the rectangular model, it is observed that the edge detection method proposed in this paper is nearly impervious to noise interference, exhibits strong anti-interference capabilities, delivers a high-quality boundary identification effect, and provides greater accuracy in anomaly edges with minimal error. When multiple anomalous bodies are present, the edge detection results are less susceptible to interference from each other, resulting in higher resolution. The efficiency of the algorithm is demonstrated by real magnetic data from some study areas in Jiangxi Province, China. The experimental results show that the proposed method is more precise and accurate than the total horizontal derivative, analytical signal, tilt angle, and theta map methods. Full article

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

17 pages, 5657 KiB

Open AccessArticle

Developed Recyclable CaFe-Layered Double Hydroxide for Efficient Cadmium Immobilization in Soil: Performance and Bioavailability

by Yuqi Jing, Ran Chen, Jiayao Zhang, Liyun Hu and Xinhong Qiu

Minerals 2024, 14(7), 656; https://doi.org/10.3390/min14070656 - 26 Jun 2024

Viewed by 244

Abstract

Powdered layered double hydroxide (CaFe-LDH) was synthesized via hydrothermal co-precipitation, demonstrating successful preparation upon characterization. Subsequently, experiments were conducted to assess its efficacy in immobilizing divalent cadmium (Cd(II)). The findings substantiated the effectiveness of CaFe-LDH in immobilizing Cd(II) within soil. Various influencing factors, [...] Read more.

Powdered layered double hydroxide (CaFe-LDH) was synthesized via hydrothermal co-precipitation, demonstrating successful preparation upon characterization. Subsequently, experiments were conducted to assess its efficacy in immobilizing divalent cadmium (Cd(II)). The findings substantiated the effectiveness of CaFe-LDH in immobilizing Cd(II) within soil. Various influencing factors, including LDH dosage, pH, and soil heavy metal concentration, were systematically investigated, revealing CaFe-LDH’s superiority in Cd(II) immobilization. Notably, the leaching concentration of Cd(II) was notably reduced from 142.30 mg/L to 32.99 mg/L, with a maximum adsorption capacity of 31.10 mg/L, underscoring the significant role of CaFe-LDH in Cd(II) removal. Furthermore, the stability of CaFe-LDH was confirmed via toxicity characteristic leaching procedure (TCLP) experiments and plant potting tests. In-depth analysis of the immobilization mechanism through X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM) elucidated isomorphous substitution and surface adsorption as the primary mechanisms responsible for Cd(II) immobilization in contaminated soils. Additionally, isomorphic substitution and adsorption onto oxygen-containing functional groups were observed. This comprehensive study underscores the promising potential of CaFe-LDH in immobilizing Cd(II) in contaminated soil. With its commendable immobilization properties and recyclability, CaFe-LDH emerges as a promising solution for remediating heavy-metal-contaminated soils. Full article

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

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20 pages, 52685 KiB

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Characteristics and Metallogenic Significance of Fe-Mn Carbonate Minerals in the Erdaokan Ag Deposit, Heilongjiang Province, Northeast China: Constraints from Sm-Nd Geochronology and Trace Elements

by Yuanjiang Yang, Chenglu Li, Zeyu Wang, Huajuan Gu, Wenpeng Yang, Maowen Yuan, Anzong Fu, Bo Zheng, Zhaoxun Cheng and Baoshan Liu

Minerals 2024, 14(7), 655; https://doi.org/10.3390/min14070655 - 26 Jun 2024

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Abstract

Fe-Mn carbonate is the dominant mineral in the Erdaokan Ag deposit, which represents the first large independent silver deposit during the Late Triassic Period in the Duobaoshan Cu-Mo-Au mineralization concentrated area of Heilongjiang Province, NE China. The Fe-Mn carbonates in the deposit frequently [...] Read more.

Fe-Mn carbonate is the dominant mineral in the Erdaokan Ag deposit, which represents the first large independent silver deposit during the Late Triassic Period in the Duobaoshan Cu-Mo-Au mineralization concentrated area of Heilongjiang Province, NE China. The Fe-Mn carbonates in the deposit frequently co-exist with Ag minerals. Thus, the presence of Fe-Mn carbonates plays a crucial role in the ore-formation process, making their analysis essential for obtaining valuable metallogenic information about the Erdaokan deposit. Through microexamination, SEM and EDS analysis, a clear relationship between Fe-Mn carbonate minerals and Ag minerals was established. Furthermore, electron probe microanalysis, LA-ICP-MS, and Sr-Nd isotope tests were conducted to analyze Fe-Mn carbonates for significant metallogenic insights. The distribution pattern of trace elements and rare-earth elements in Fe-Mn carbonates is similar, characterized by Zr depletion (below 0.131 ppm), enrichment of light rare-earth elements, a noticeable deficit of Eu (δEu = 0.06–0.63), and an average Y/Ho value of 34.29, indicating the involvement of upper mantle-derived deep magma in the formation of ore-forming materials. The samples had a Sm-Nd isochron age of 233.7 ± 1.2 Ma, suggesting that the Erdaokan Ag deposit was formed during the Late Triassic Period. This study highlights the significance of Fe-Mn carbonate as a valuable mineral indicator for regional silver prospecting purposes, and confirms the Late Triassic Period as another important metallogenic stage in the Duobaoshan Cu-Mo-Au mineralization concentrated area. Full article

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

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Minerals, Volume 14, Issue 7 (July 2024) – 52 articles

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