Minerals

19 pages, 10871 KiB

Open AccessArticle

The Development of Dolomite Within a Sequence Stratigraphic Framework: Cambrian Series 2 Changping Formation, Xiaweidian, China

by Shan Zhong, Zhaoqian Liu, Zhenkui Jin, Hongyu Tian, Madaki Agwom Istifanus and Simon C. George

Minerals 2024, 14(12), 1189; https://doi.org/10.3390/min14121189 - 22 Nov 2024

Abstract

The Lower Cambrian Changping Formation in the Western Hills of Beijing hosts tidal flat and lagoonal carbonates comprising dolomites, limestones, and dolomitic limestones, reflecting the processes of dolomite cementation and dolomitization within a sedimentary framework. Based on petrographic textures, two types of dolomites [...] Read more.

The Lower Cambrian Changping Formation in the Western Hills of Beijing hosts tidal flat and lagoonal carbonates comprising dolomites, limestones, and dolomitic limestones, reflecting the processes of dolomite cementation and dolomitization within a sedimentary framework. Based on petrographic textures, two types of dolomites were identified: microcrystalline dolomite and fine-mesocrystalline dolomite. Integrating petrological and geochemical data unveils two diagenetic stages. The initial dolomite formation, attributed to hypersaline fluids, occurred in a supratidal-sabkha setting during the early Cambrian. The dolomitization at the top of the Changping Formation, driven by evaporatively concentrated brines from the overlying Mantou Formation, altered peritidal carbonates. This study evaluates the original sedimentary environment and dolomitization within a sequence stratigraphic context, revealing a correlation between dolomitization episodes and the stratigraphic framework in the study area. Factors influencing this framework profoundly impact depositional environments and material composition, leading to micromorphological differences in dolomites. Sabkha dolomite formation, associated with evaporative pumping, predominates near the base of transgressive systems tracts. Seepage reflux dolomite, often linked with evaporative pumping dolomite, constitutes a vertical cycle in the sequence framework. The sequence from bottom to top is sabkha microcrystalline dolomite, limestone and dolomitic limestone, seepage reflux saccharoidal dolostone, and sabkha dolomite. Full article

(This article belongs to the Special Issue Life and Carbonate: Biotic and Abiotic Fingerprints in Past and Recent Carbonate Sediments)

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20 pages, 4829 KiB

Open AccessArticle

Structural and Kinematic Analysis of the Xipu Dome in the Tingri Area, Southern Tibet, and New Exploration Discoveries

by Songtao Yan, Ailing Ding, Jie Wang, Hao Huang, Hu Li, Song Chen, Tao Liu and Lidong Zhu

Minerals 2024, 14(12), 1188; https://doi.org/10.3390/min14121188 - 22 Nov 2024

Abstract

The newly delineated Xipu Dome, located in the central North Himalayan Gneiss Dome (NHGD), exhibits a significant spatiotemporal relationship with Himalayan polymetallic mineralization. Based on field geological surveys and geochronological analyses, this study provides a comprehensive assessment of the lithological assemblage, tectonic deformation, [...] Read more.

The newly delineated Xipu Dome, located in the central North Himalayan Gneiss Dome (NHGD), exhibits a significant spatiotemporal relationship with Himalayan polymetallic mineralization. Based on field geological surveys and geochronological analyses, this study provides a comprehensive assessment of the lithological assemblage, tectonic deformation, and metallogenic processes of the Xipu Dome. The findings reveal a three-tiered structure: the core consists of early Paleozoic granitic gneiss (523 Ma) and Miocene leucogranite (13.5 Ma), overlain by a cover of low-grade metamorphic or unmetamorphosed sedimentary rocks, and a detachment zone composed of heavily deformed schists and phyllites. The Xipu Dome underwent three phases of tectonic deformation: a southward thrust caused by continental collision, northward extensional activity driven by the South Tibet Detachment System (STDS), and gravitational collapse and downslope sliding following the emplacement of the dome. Two types of mineralization were identified: structural hydrothermal Au-Cu polymetallic deposits related to detachment and skarn-type Cu-Ag polymetallic deposits associated with leucogranite intrusion. This study enhances the understanding of the spatial distribution and metallogenic potential within the Himalayan Be-Sn rare metal-Pb-Zn-Sb-Au belt, offering a valuable direction for strategic mineral exploration in the Tethyan Himalaya (TH). Full article

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

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11 pages, 6502 KiB

Open AccessArticle

Quantifying the Impurity Distribution in Spherical Graphite: The Limitation of Flotation for Graphite Purification Explained

by Huazhong Dong, Yangshuai Qiu, Yigan Mai, Jilin Liu, Dahai You and Kangkang Sun

Minerals 2024, 14(12), 1187; https://doi.org/10.3390/min14121187 - 22 Nov 2024

Abstract

Spherical graphite (SG) is a crucial raw material for the preparation of lithium-ion battery anodes. The rapid advancement of Li-ion battery materials has imposed rigorous demands on the production of ultrapure SG materials. However, SG derived from natural flake graphite (FG) via spheronization [...] Read more.

Spherical graphite (SG) is a crucial raw material for the preparation of lithium-ion battery anodes. The rapid advancement of Li-ion battery materials has imposed rigorous demands on the production of ultrapure SG materials. However, SG derived from natural flake graphite (FG) via spheronization often fails to meet these quality requirements. This study investigates the physical and chemical properties of SG and the natural FG used in its production, employing techniques such as X-ray diffraction (XRD), X-ray fluorescence (XRF) analysis, and various microscopy techniques. Results reveal that FG purified via flotation retains significant impurities, and the spheronization process yields only marginal improvements in SG quality. Most impurities are distributed in the intercalation of the graphite flakes, while a smaller fraction is contributed by flotation entrainment. These distributions were visualized using FIB-SEM-EDS analysis and quantified through additional flotation tests in highly dilute solutions. This study offers a promising strategy for determining the distribution of impurities in graphite minerals and explains the limitations of flotation in upgrading graphite materials from a more microscopic perspective. Furthermore, it provides practical guidance for further SG purification using hydrometallurgical leaching techniques. Full article

(This article belongs to the Special Issue Graphite Minerals and Graphene, 2nd Edition)

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41 pages, 18293 KiB

Open AccessArticle

Nephrite Jade and Related Rocks from Western Washington State, USA: A Geologic Overview

by George E. Mustoe

Minerals 2024, 14(12), 1186; https://doi.org/10.3390/min14121186 - 21 Nov 2024

Abstract

The geologic framework of western Washington, USA, is the result of collisional tectonics, where oceanic plate materials were subducted beneath the continental margin. As part of this process, fragments of mantle peridotites were transported into the upper crust along deep faults. The hydration [...] Read more.

The geologic framework of western Washington, USA, is the result of collisional tectonics, where oceanic plate materials were subducted beneath the continental margin. As part of this process, fragments of mantle peridotites were transported into the upper crust along deep faults. The hydration of these ultramafic materials produced bodies of serpentinite. Subsequent regional metamorphism caused metasomatism of the serpentinite to produce a variety of minerals, which include nephrite jade, grossular, chlorite, diopside, vesuvianite, and pumpellyite. Many of the nephrite-bearing rocks are located along the Darrington–Devils Mountain Fault Zone in Skagit and Snohomish Counties. Intense prospecting has led to the establishment of many mining claims, but recreational collecting remains a popular activity. Full article

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

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28 pages, 23221 KiB

Open AccessArticle

The Paleoproterozoic Raimunda Porphyry-Type Gold Deposit, Juruena Mineral Province, Amazonian Craton (Brazil): Constraints Based on Petrological, Fluid Inclusion and Stable Isotope Data

by Adriana Araujo Castro Lopes and Márcia Abrahão Moura

Minerals 2024, 14(12), 1185; https://doi.org/10.3390/min14121185 - 21 Nov 2024

Abstract

The Juruena Mineral Province is an emerging world-class mineral province in the southern Amazonian Craton, due to numerous Au-Cu and base metal deposits, such as the Raimunda deposit, related to Novo Mundo 2.03–1.98 Ga I-type calc-alkaline granites. Its hydrothermal alteration zones comprise Na-metasomatism, [...] Read more.

The Juruena Mineral Province is an emerging world-class mineral province in the southern Amazonian Craton, due to numerous Au-Cu and base metal deposits, such as the Raimunda deposit, related to Novo Mundo 2.03–1.98 Ga I-type calc-alkaline granites. Its hydrothermal alteration zones comprise Na-metasomatism, microclinization, propylitic and sericitic alteration, silicification, a sulfide stage, and late carbonate alteration. The disseminated mineralization, associated with the sulfide stage, the main mineralization stage, is represented by gold inclusions and fracture-filling grains in pyrite, chalcopyrite, and Cu-Bi sulfides. Chlorite geothermometer and fluid inclusion data indicate temperature conditions of 325–380 °C for the mineralization. The coexistence of high-temperature aqueous and aqueous-carbonic fluid inclusions, based on a microthermometric study of fluid inclusions, reveals a mixing of medium-saline hot fluids with cooler and low-saline fluid. The δ¹⁸O_fluid (3.11–7.86‰) and δ³⁴S_py data (−1.4–0.1‰) are coherent to the magmatic origin of the mineralizing fluid. Gold was initially transported as chlorine complexes in a hot, high-salinity, acidic, and oxidized fluid from the magma chamber, and later as H₂S⁻ complexes. The chemical-physical instability during fluid ascent is interpreted as a triggering factor for ore precipitation. The results offer valuable insights into the genesis of porphyry–Au deposits and their implications for prospecting in the Amazonian Craton. Full article

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

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15 pages, 12303 KiB

Open AccessEssay

Characteristics and Genesis of Collophane in Organic-Rich Shale of Chang 7 Member in Ordos Basin, North China

by Yu Zhang, Chaocheng Dai, Congsheng Bian, Bin Bai and Xingfu Jiang

Minerals 2024, 14(12), 1184; https://doi.org/10.3390/min14121184 - 21 Nov 2024

Abstract

(1) Background: The Ordos Basin is one of the sedimentary basins in China that is richest in oil and gas resources. The Chang 7 member of the Yanchang Formation is a set of organic-rich shale, abundant in collophane. (2) Methods: The observation and [...] Read more.

(1) Background: The Ordos Basin is one of the sedimentary basins in China that is richest in oil and gas resources. The Chang 7 member of the Yanchang Formation is a set of organic-rich shale, abundant in collophane. (2) Methods: The observation and analysis of rock thin sections, combined with major elements, trace elements, electron probes, and other technical means, the characteristics and genesis mechanism of collophane in the organic-rich shale of the Chang 7 member of the Yanchang Formation in the Ordos Basin were studied. (3) Results: Collophane are divided into oolitic collophane, red-yellow aggregate collophane, and apatite-containing crystalline collophane; the main chemical compositions of the collophane were CaO, P₂O₅, FeO, Al₂O₃, and MgO. (4) Conclusions: Phosphorus elements of collophane in the organic-rich shale of the Chang 7 member of the Ordos continental lake basin are mainly derived from the nutrients carried by the volcanic ash sediments around the basin and the hydrothermal fluid at the bottom of the lake. The formation of collophane is divided into two periods: during the sedimentary period, the phosphorus released by the aerobic decomposition of phytoplankton to the mineralization and degradation of organic matter, and the death of phosphorus-rich organisms is preserved in the sediment by adsorption and complexation with iron oxides and then combined with calcium and fluoride plasma to form collophane; during the early diagenesis process, collophane underwent recrystallization, forming a colloidal, cryptocrystalline, and microcrystalline apatite assemblage. Full article

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

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21 pages, 2146 KiB

Open AccessArticle

Optimization Model for Mine Backfill Scheduling Under Multi-Resource Constraints

by Yuhang Liu, Guoqing Li, Jie Hou, Chunchao Fan, Chuan Tong and Panzhi Wang

Minerals 2024, 14(12), 1183; https://doi.org/10.3390/min14121183 - 21 Nov 2024

Abstract

Addressing the resource constraints, such as manpower and equipment, faced by mine backfilling operations, this study proposed an optimization model for backfill scheduling based on the Resource-Constrained Project Scheduling Problem (RCPSP). The model considered backfilling’s multi-process, multi-task, and multi-resource characteristics, aiming to minimize [...] Read more.

Addressing the resource constraints, such as manpower and equipment, faced by mine backfilling operations, this study proposed an optimization model for backfill scheduling based on the Resource-Constrained Project Scheduling Problem (RCPSP). The model considered backfilling’s multi-process, multi-task, and multi-resource characteristics, aiming to minimize total delay time. Constraints included operational limits, resource requirements, and availability. The goal was to determine optimal resource configurations for each stope’s backfilling steps. A heuristic genetic algorithm (GA) was employed for solution. To handle equipment unavailability, a new encoding/decoding algorithm ensured resource availability and continuous operations. Case verification using real mine data highlights the advantages of the model, showing a 20.6% decrease in completion time, an 8 percentage point improvement in resource utilization, and a 47.4% reduction in overall backfilling delay time compared to traditional methods. This work provides a reference for backfilling scheduling in similar mines and promotes intelligent mining practices. Full article

(This article belongs to the Special Issue Advances in Mine Backfilling Technology and Materials)

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24 pages, 5939 KiB

Open AccessArticle

Bismuth Sulfosalts from the Nistru Metallogenetic Field, Baia Mare Zone, NW Romania

by Floarea Damian, Gheorghe Damian, Nigel J. Cook, Vsevolod Yu. Prokofiev and Peter András

Minerals 2024, 14(11), 1182; https://doi.org/10.3390/min14111182 - 20 Nov 2024

Abstract

An association of bismuth sulfosalts coexisting with native gold is described from a sulfide-rich copper vein in the Nistru area, Baia Mare metallogenetic district, NW Romania. This mineralization is hosted within a Neogene calc-alkaline subvolcanic porphyry quartz-micromonzodiorite stock on the southern border of [...] Read more.

An association of bismuth sulfosalts coexisting with native gold is described from a sulfide-rich copper vein in the Nistru area, Baia Mare metallogenetic district, NW Romania. This mineralization is hosted within a Neogene calc-alkaline subvolcanic porphyry quartz-micromonzodiorite stock on the southern border of the Gutâi Mountains. Cu+Au+Bi mineralization represents the inner part of a zoned vein of a type specific to the SE part of the Nistru orefield. The Pb-Zn and Au-Ag veins are located towards the external zone at the boundary of the stock with the surrounding rocks. Bismuth sulfosalts are mainly represented by bismuthinite derivatives and members of the lillianite homologous series. Cosalite, matildite and wittichenite are also present in subordinate amounts. Bi-rich members of the bismuthinite-aikinite series (from krupkaite to bismuthinite) are predominant. A phase with the empirical formula CuPbBi₇S₁₂ was also identified and could potentially be a new bismuthinite derivative. The lillianite homologous series is represented by phases with composition between Gus₇₃ and Gus₅₉, with a dominance of members closer to gustavite (Gus_97–79) and less abundant members closer to lillianite (Gus₄₉). Native gold and Bi-sulfosalts are closely associated with the main sulfides (pyrrhotite, pyrite, chalcopyrite) and quartz, indicating simultaneous crystallization. Fluid inclusion data for quartz indicate a temperature interval between 205 and 247 °C. The assemblage within this vein was deposited from a low-salinity fluid (0.4–2.6 wt.% NaCl equiv.) and density from 0.80 to 0.87 g/cm³. Full article

(This article belongs to the Section Mineral Deposits)

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12 pages, 2138 KiB

Open AccessCommunication

First Optically Stimulated Luminescence and Radiocarbon Dating of the Late Quaternary Eruptions in the Xilinhot Volcanic Field, China

by Zhiwei Shi, Furong Cui, Zhidan Zhao, Zhida Bai, Zeguang Chang and Junxiang Zhao

Minerals 2024, 14(11), 1181; https://doi.org/10.3390/min14111181 - 20 Nov 2024

Abstract

Precise dating of prehistoric volcanic eruptions is essential for reconstructing eruption sequences and assessing volcanic hazards. The timing of the onset and termination of volcanic activity in the Xilinhot volcanic field (XVF) has been a topic of debate for years. Volcanic eruptions in [...] Read more.

Precise dating of prehistoric volcanic eruptions is essential for reconstructing eruption sequences and assessing volcanic hazards. The timing of the onset and termination of volcanic activity in the Xilinhot volcanic field (XVF) has been a topic of debate for years. Volcanic eruptions in this area began during the Pliocene, with the K-Ar (Ar-Ar) method providing reliable ages for early formed volcanic rocks; however, this method is less effective for dating younger volcanic events that occurred since the Late Pleistocene. For younger volcanoes, sediments baked by volcanic materials, organic sediments, and silty mudstones entrapped in lava serve as excellent geological carriers for dating. In this study, suitable samples collected from the XVF were dated using ¹⁴C and optically stimulated luminescence (OSL) methods. The ¹⁴C ages obtained for the Gezishan volcano are ~6.8 cal. ka BP, while its OSL age is ~7.8 ka. The ages dated by these two methods, combined with volcano–sedimentary stratigraphic relationships and volcanic topography, confirm the Holocene eruptions of the Gezishan volcano, categorizing it as a broadly active volcano. The upper boundary age of the sandy loam layer beneath the Gezishan lava flow is ~15.5 ka, indicating that the south lava of the Gezishan effusion occurred later than the late stage of the Late Pleistocene. Additionally, the OSL ages of baked sediments at the bottom of the base surge deposits from a Maar-type volcano and aeolian sand interlayers within a Strombolian-type scoria cone in the study area are ~50 ka and ~60 ka, respectively, representing eruptions in the middle Late Pleistocene. These findings demonstrate that volcanic activity in the XVF remained vigorous during the Late Pleistocene to Holocene. This study provides significant insights for reconstructing the evolutionary history of Xilinhot volcanic activity and assessing regional volcanic hazards. Full article

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

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20 pages, 4203 KiB

Open AccessArticle

Impact of Inline Polyacrylamide Polymer Flocculation on the Mechanical and Hydrological Properties of Saline Tailings

by Bob Boshrouyeh, Mansour Edraki, Thomas Baumgartl, Allan Costine, Sebastian Quintero Olaya, Kateřina Lepková and Deepak Dwivedi

Minerals 2024, 14(11), 1180; https://doi.org/10.3390/min14111180 - 20 Nov 2024

Abstract

This study examines the geotechnical and hydro-mechanical behaviour of a model slurry used in high-solids, high-salinity applications, both before and after inline flocculation with an anionic polyacrylamide. Initial evaluations showed untreated tailings (UT) with a water content of 107%, void ratio of 2.6, [...] Read more.

This study examines the geotechnical and hydro-mechanical behaviour of a model slurry used in high-solids, high-salinity applications, both before and after inline flocculation with an anionic polyacrylamide. Initial evaluations showed untreated tailings (UT) with a water content of 107%, void ratio of 2.6, and dry density of 0.711 t/m³, compared to polymer-amended tailings (PAT) with 53% water content, a void ratio of 1.6, and a dry density of 1.069 t/m³. Post-flocculation consolidometer tests revealed a distinct consolidation mode, with PAT showing 60% less settlement within the first 48 h and achieving 50% more free water drainage. Polymer treatment improved consolidation parameters, yielding a lower compressibility index (Cc of 0.74 vs. 1.05 for raw slurry), a higher coefficient of consolidation (Cv of 0.005 cm²/s for PAT vs. 0.0009 cm²/s for raw slurry), and an increased water retention capacity. Additionally, PAT demonstrated a final void ratio of 0.62 compared to 0.51 for the UT sample and an internal porosity characterised by discrete voids, supporting enhanced stability for long-term rehabilitation. These findings underscore the potential of inline flocculation to improve tailings management in saline conditions. Full article

(This article belongs to the Special Issue Tailings Dams: Design, Characterization, Monitoring, and Risk Assessment, 2nd Edition)

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18 pages, 3743 KiB

Open AccessArticle

Efficient Reuse of Rare Earth Carbonate Precipitation Mother Liquor for Rare Earth Leaching in Strong Acid-Restricted Area

by Jian Feng, Xiaoyan Wu, Fang Zhou and Ruan Chi

Minerals 2024, 14(11), 1179; https://doi.org/10.3390/min14111179 - 20 Nov 2024

Abstract

Due to the restrictions of strong acids in some regions, the reuse process of rare earth (RE) precipitation mother liquor is difficult to carry out. To achieve the straightforward and efficient reuse of precipitation mother liquor in such areas, the potential for directly [...] Read more.

Due to the restrictions of strong acids in some regions, the reuse process of rare earth (RE) precipitation mother liquor is difficult to carry out. To achieve the straightforward and efficient reuse of precipitation mother liquor in such areas, the potential for directly reusing this liquor for rare earth (RE) leaching was explored. The results showed that when the RE concentration in the leachate ranged from 0.1 to 1.5 g/dm³ and the RE precipitation rate exceeded 96%, the residual total carbonate content in precipitation mother liquor was less than 0.01 mol/L, and the solution pH was 7–8. Furthermore, when the total carbonate content in leaching liquor was lower than 0.01 mol/L, the presence of carbonate had a minimal impact on the RE leaching efficiency, which was observed to exceed 93%. Additionally, the process of mother liquor leaching was analyzed using dynamic models and chromatography tray theory. It was found that the leaching results were well fitted with the shrinking core model, and the apparent activation energy of RE was 5.77 kJ/mol, indicating that the reaction was controlled by diffusion, and the reaction order was 0.672 for RE. This confirms that a total carbonate content below 0.01 mol/L in the precipitation mother liquor can be directly used for the RE leaching process. Full article

(This article belongs to the Special Issue Green and Efficient Recovery/Extraction of Rare Earth Resources)

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18 pages, 8943 KiB

Open AccessArticle

Micro-Topographic Controls on Rare Earth Element Accumulation and Fractionation in Weathering Profiles: Case Study of Ion-Adsorption Rare Earth Element Deposit in Hedi, Zhejiang Province, China

by Wenlin Guo, Zhi Zhao, Chengshan Wang, Denghong Wang, Xiaorong Chen, Xiaoliang Dang, Wei Zhang and Chenhui Zhao

Minerals 2024, 14(11), 1178; https://doi.org/10.3390/min14111178 - 20 Nov 2024

Abstract

Ion-adsorption rare earth element (REE) deposits are a major source of REEs and are found mainly in China. The formation of such deposits is affected by a combination of endogenic and exogenic factors. This study investigated the effect of micro-topography on the REE [...] Read more.

Ion-adsorption rare earth element (REE) deposits are a major source of REEs and are found mainly in China. The formation of such deposits is affected by a combination of endogenic and exogenic factors. This study investigated the effect of micro-topography on the REE distribution in four weathering profiles at different topographic sites on a knoll in Hedi, Zhejiang Province, China. The weathering profile and REE accumulation are both most developed at mid-slope positions of the knoll. The intensity of chemical weathering decreases in the order of mid-slope > base > summit. As weathering progressed, REE enrichment initially increased but later decreased, with a progressive increase in light/heavy REE fractionation. REE fractionation is more pronounced on the north-facing slope than on the south-facing slope. Weathering degrees and clay mineral characteristics are key factors influencing the varying REE distributions on the knoll. Water leaching and the evolution of clay minerals towards higher maturity reduce REE adsorption capacity. Clay minerals also play a significant role in REE fractionation; the abundance of these minerals and the presence of illite enable the retention of more HREEs with minimal desorption. Taking into account water content, it is inferred that hydrological conditions, modulated by the micro-topography, strongly affect the depth and extent of REE accumulation, as well as fractionation. Full article

(This article belongs to the Special Issue Metallogenic Regularity and Metallographic Prediction of Strategic Deposits)

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19 pages, 4109 KiB

Open AccessArticle

Preliminary Beneficiation Studies of Quartz Samples from the Northwest Territories, Canada

by Hanyu Zhang, Gideon Lambiv Dzemua and Qi Liu

Minerals 2024, 14(11), 1177; https://doi.org/10.3390/min14111177 - 20 Nov 2024

Abstract

Three quartz-rich geologic materials—vein quartz from the Great Bear Magmatic Zone, massive quartz from the Nechalacho rare earth deposit, and quartz sands from the Chedabucto silica sand deposit along the shores of the Northern Arm of the Great Slave Lake, Northwest Territories of [...] Read more.

Three quartz-rich geologic materials—vein quartz from the Great Bear Magmatic Zone, massive quartz from the Nechalacho rare earth deposit, and quartz sands from the Chedabucto silica sand deposit along the shores of the Northern Arm of the Great Slave Lake, Northwest Territories of Canada—were evaluated for their amenability to physical beneficiation into high-purity quartz (HPQ). The samples were subjected to various treatment processes, including crushing, grinding, calcining and quenching, acid leaching, wet high-intensity magnetic separation (WHIMS), and reverse flotation. After treatment, both the core and sand quartz samples met the requirements for HPQ, making them suitable for use in the production of semiconductor filters, liquid crystal displays (LCDs), and optical glass. However, the Al-bearing impurity content in the vein quartz products remained relatively high, and most of these impurities were dispersed in the quartz lattice, requiring further processing to meet the purity standards for HPQ required by these industries. Full article

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

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23 pages, 5951 KiB

Open AccessArticle

The Core Story: Intertwined Maternal and Progeny Signatures Enclosed in the Otolith

by Clara Anne Lord, Sophie Berland, Vincent Haÿ and Philippe Keith

Minerals 2024, 14(11), 1176; https://doi.org/10.3390/min14111176 - 20 Nov 2024

Abstract

Analytical imaging via synchrotron analysis was used to study sagittal otoliths of four freshwater pipefish species exhibiting amphidromous or freshwater resident lifestyles. We undertook a hyperfine elemental scanning of a 25 μm diameter length area centred on the core, namely the pre-hatch zone, [...] Read more.

Analytical imaging via synchrotron analysis was used to study sagittal otoliths of four freshwater pipefish species exhibiting amphidromous or freshwater resident lifestyles. We undertook a hyperfine elemental scanning of a 25 μm diameter length area centred on the core, namely the pre-hatch zone, corresponding to the sagitta formed during embryogenesis. We analysed calcium (Ca), strontium (Sr), manganese (Mn), chromium (Cr), cobalt (Co), nickel (Ni) and sulphur (S), with the latter serving to count growth increments. Whatever the species, a Ca pit consistently marked the core; the amphidromous species exhibited Mn enrichment at the core and the sagitta formed a week before hatching. These results illustrate common otolith formation mechanistic processes. Sr and heavy metals’ signals in the pre-hatch zone were compared to their signal in the edge of the otolith, an area encompassing the adult freshwater (adFW) environmental signature. We found that Co and Ni otolith signals had no relation to environmental conditions, but it is worth looking into Cr as a marker of early-life environment. While we caution against the use of a Sr:Ca ratio for life history interpretations at the core because of the Ca pit, the Sr signal analysis uncovered possible variations in the parental behaviour that potentially trigger newly-hatched juvenile migration to sea or residency. Finally, our results demonstrate that the microchemistry of otolith formation during early development is a melting of maternal signal during egg yolk elaboration, of the environmental signal during egg incubation, and of individual physiology during early growth. Full article

(This article belongs to the Section Biomineralization and Biominerals)

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21 pages, 2991 KiB

Open AccessArticle

Gypsum: From the Equilibrium to the Growth Shapes—Theory and Experiments

by Dino Aquilano, Marco Bruno and Stefano Ghignone

Minerals 2024, 14(11), 1175; https://doi.org/10.3390/min14111175 - 19 Nov 2024

Abstract

The gypsum crystals (CaSO₄·2H₂O) crystallizes in a low symmetry system (monoclinic) and shows a marked layered structure along with a perfect cleavage parallel to the {010} faces. Owing to its widespread occurrence, as a single or twinned crystal, here [...] Read more.

The gypsum crystals (CaSO₄·2H₂O) crystallizes in a low symmetry system (monoclinic) and shows a marked layered structure along with a perfect cleavage parallel to the {010} faces. Owing to its widespread occurrence, as a single or twinned crystal, here the gypsum equilibrium (E.S.) and growth shapes (G.S.) have been re-visited. In making the distinction among E.S. and G.S., in the present work, the basic difference between epitaxy and homo-taxy is clearly evidenced. Gypsum has also been a fruitful occasion to recollect the general rules concerning either contact or penetration twins, for free growing and for twinned crystals nucleating onto pre-existing substrates. Both geometric and crystal growth aspects have been considered as well, by unifying theory and experiments of crystallography and crystal growth through the intervention of

β_{adh}

, the physical quantity representing the specific adhesion energy between gypsum and other phases. Hence, the adhesion energy allowed us to systematically use the Dupré’s formula. In the final part of the paper, peculiar attention has been paid to sediments (or solution growth) where the crystal size is very small, in order to offer a new simple way to afford classical (CNT) and non-classical nucleation (NCNT) theories, both ruling two quantities commonly used in the industrial crystallization: the total induction times (

t_{i n d}^{t o t a l}

) and crystal size distribution (CSD). 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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20 pages, 12316 KiB

Open AccessArticle

Effect of Selective Milling on the Concentration Process of Critical Raw Materials from MSW Incinerator Bottom Ash

by Ida B. G. S. Adhiwiguna, S. Humaira Sahbudin, Winfried Ruhkamp, Ragnar Warnecke and Rüdiger Deike

Minerals 2024, 14(11), 1174; https://doi.org/10.3390/min14111174 - 19 Nov 2024

Abstract

This research introduces selective milling as a reliable and effective initial concentration process to enable efficient separation and ensure high recovery rates of valuable and critical materials (minerals and metals) from processed incinerator bottom ash (pr.IBA), a treated mineral fraction originating from the [...] Read more.

This research introduces selective milling as a reliable and effective initial concentration process to enable efficient separation and ensure high recovery rates of valuable and critical materials (minerals and metals) from processed incinerator bottom ash (pr.IBA), a treated mineral fraction originating from the conventional municipal solid waste (MSW) incinerator bottom ash (IBA) processing steps. Four different types of pr.IBA (each sample weighing up to three tons) were selectively milled using a demonstration-scale vertical roller mill to produce three distinct products: fine, middle, and coarse fractions. Chemical analysis demonstrated that a concentration step after selective milling could be reliably achieved regardless of the variation in the sources and qualities of the input materials. Specifically, calcium-containing compounds can be enriched in the fine fraction, potentially containing Ca₂SiO₄, CaSO₄, and CaCO₃. Complementary to its particle size equivalent to the raw mix, this calcium segregation could be valuable as an alternative material in cement clinker production. Conversely, the segregation of metal-bearing substances, particularly iron and copper, was detected in the coarse fraction. Such segregation is comparable to specific ore grades and enhances the possibility of metal recovery from pr.IBA. Full article

(This article belongs to the Special Issue Recent Advances in Separation Techniques for Critical Minerals/Metals, Circular Economy, and Sustainability)

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24 pages, 10810 KiB

Open AccessArticle

Petrogenesis of the Shibaogou Mo-W-Associated Porphyritic Granite, West Henan, China: Constrains from Geochemistry, Zircon U-Pb Chronology, and Sr-Nd-Pb Isotopes

by Zhiwei Qiu, Zhenju Zhou, Nan Qi, Pocheng Huang, Junming Yao, Yantao Feng and Yanjing Chen

Minerals 2024, 14(11), 1173; https://doi.org/10.3390/min14111173 - 19 Nov 2024

Abstract

The Shibaogou pluton, located in the Luanchuan orefield of western Henan Province in China, is a typical porphyritic granite within the Yanshanian “Dabie-type” Mo metallogenic system. It is mainly composed of porphyritic monzogranite and porphyritic syenogranite. Zircon U-Pb dating results indicate emplacement ages [...] Read more.

The Shibaogou pluton, located in the Luanchuan orefield of western Henan Province in China, is a typical porphyritic granite within the Yanshanian “Dabie-type” Mo metallogenic system. It is mainly composed of porphyritic monzogranite and porphyritic syenogranite. Zircon U-Pb dating results indicate emplacement ages of 150.1 ± 1.3 Ma and 151.0 ± 1.1 Ma for the monzogranite and 148.1 ± 1.0 Ma and 148.5 ± 1.3 Ma for the syenogranite. The pluton is characterized by geochemical features of high silicon, metaluminous, and high-K calc-alkaline compositions, enriched in Rb, U, Th, and Pb, and exhibits high Sr/Y (18.53–58.82), high (La/Yb)_N (9.01–35.51), and weak Eu anomalies. These features indicate a source region from a thickened lower crust with garnet and rutile as residual phases at depths of approximately 40–60 km. Sr-Nd-Pb isotopic analyses suggest that the magmatic source is mainly derived from the Taihua and Xiong’er Groups of the Huaxiong Block, mixed with juvenile crustal rocks from the Kuanping and Erlangping Groups of the North Qinling Accretion Belt. Combined with geological and isotopic characteristics, it is concluded that the Shibaogou pluton formed during the compression–extension transition period associated with the collision between the Yangtze Block and the North China Craton, reflecting the complex partial melting processes in the thickened lower crust. The present study reveals that the magmatic–hydrothermal activity at Shibaogou lasted approximately 5 Ma, showing multi-phase characteristics, further demonstrating the close relationship between the pluton and the Mo-W mineralization. Full article

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

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26 pages, 9981 KiB

Open AccessArticle

Ore Formation and Mineralogy of the Alattu–Päkylä Gold Occurrence, Ladoga Karelia, Russia

by Vasily I. Ivashchenko

Minerals 2024, 14(11), 1172; https://doi.org/10.3390/min14111172 - 18 Nov 2024

Abstract

The Alattu–Päkylä gold occurrence is located in the Northern Lake Ladoga area, in the Raaha-Ladoga suprasubduction zone, at the Karelian Craton (AR)—Svecofennian foldbelt (PR₁) boundary. Its gold ore mineral associations are of two types of mineralization: (1) copper–molybdenum–porphyry with arsenopyrite and [...] Read more.

The Alattu–Päkylä gold occurrence is located in the Northern Lake Ladoga area, in the Raaha-Ladoga suprasubduction zone, at the Karelian Craton (AR)—Svecofennian foldbelt (PR₁) boundary. Its gold ore mineral associations are of two types of mineralization: (1) copper–molybdenum–porphyry with arsenopyrite and gold (intrusion-related) and (2) gold–arsenopyrite–sulfide in shear zones. Optical and scanning electron microscopy, X-ray fluorescence spectrometry, inductively coupled plasma mass spectrometry (ICP-MS), instrumental neutron activation analysis (INAA) and fire analysis with AAS finishing were used to study them. Type 1 was provoked by shallow-depth tonalite intrusion (~1.89 Ga) and type 2 by two stages of Svecofennian metamorphism (1.89–1.86 and 1.83–1.79 Ga) with the possible influence of the impactogenesis of the Janisjärvi astrobleme (age ~1 Ga). Intrusive and host rocks were subjected to shearing accompanied by the formation of ore-bearing metasomatic rocks of the propylite-beresite series (depending on substrate) and quartz–sericite, quartz and sericite–tourmaline veins and streaks. Ore mineralization is present as several consecutive mineral associations: pyritic–molybdenite with arsenopyrite and gold; gold–arsenopyrite; quartz–arsenopyrite with antimony sulfosalts of lead; gold–polysulfide with tetrahedrite –argentotetrahedrite series minerals and gold–antimony with Pb–Sb–S system minerals and native antimony. Arsenopyrite contains invisible (up to 234 ppm) and visible gold. Metamorphosed domains in arsenopyrite and rims with visible gold around it are usually enriched in As, indicating higher (up to >500 °C) temperatures of formations than original arsenopyrite with invisible gold (<500 °C). A paragenetic sequence associated with the deposition of invisible and visible gold established at the Alattu–Päkylä ore occurrence: pyrrhotite + unaltered arsenopyrite (with invisible gold) → altered arsenopyrite (As-enriched) + pyrite ± pyrrhotite + visible gold. Gold, associated with gudmundite, sphalerite and native antimony, seems to be due to cainotypic rhyodacitic porphyry cutting tonalite intrusion or with a retrograde stage in post-Svecofennian metamorphism. The isotopic composition of Pb and ²³⁸U/²⁰⁴Pb (9.4–9.75) for the feldspar of the tonalite intrusion and the pyrite of gold mineralization, εNd (−4 up to −5) for tonalites and ẟ³⁴S values of −2.10–+4.99 for arsenopyrite, indicate the formation of gold occurrence provoked by Svecofennian magmatic and tectono-thermal processes with the involvement of matter from a mantle-lower crustal reservoir into magma formation and mineralization. Full article

(This article belongs to the Special Issue Genesis and Metallogeny of Non-ferrous and Precious Metal Deposits, 2nd Edition)

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18 pages, 7145 KiB

Open AccessReview

Evolution of Auriferous Fluids in the Kraaipan-Amalia Greenstone Belts: Evidence from Mineralogical and Isotopic Constraints

by Kofi Adomako-Ansah, Napoleon Q. Hammond, Yuichi Morishita and Daizo Ishiyama

Minerals 2024, 14(11), 1171; https://doi.org/10.3390/min14111171 - 18 Nov 2024

Abstract

The Kraaipan and Amalia greenstone belts in South Africa occur in the western part of the Kaapvaal Craton. The two belts stretch discontinuously in an approximately north–south orientation over a distance of about 250 km from southern Botswana in the north to the [...] Read more.

The Kraaipan and Amalia greenstone belts in South Africa occur in the western part of the Kaapvaal Craton. The two belts stretch discontinuously in an approximately north–south orientation over a distance of about 250 km from southern Botswana in the north to the Vaal River near Christiana in the south and are separated by a distance of about 90 km. Gold mineralization is hosted in banded iron formation at both the Kalahari Goldridge deposit (Kalgold) in the Kraaipan greenstone belt in the north and the Amalia deposit in the Amalia greenstone belt in the south, with the mineralization associated with quartz–carbonate veins. The footwalls of these deposits are generally composed of mafic volcanic schist and the hanging walls consisting of graywackes, schist and shale units. The Kalgold and Amalia gold deposits show some variation in the redox condition of the mineralizing system and fluid chemistry. The ore mineral assemblage is characterized by magnetite–pyrrhotite–pyrite at Kalgold, which is indicative of reducing conditions, and a magnetite–hematite–pyrite assemblage at Amalia that suggests a relatively oxidizing environment. Average mineralizing temperatures determined from chlorite geothermometry were relatively higher at the Kalahari Goldridge deposit ranging from 350 to 400 °C compared to the slightly cooler range of 330 to 390 °C at Amalia. The composition of the fluids derived from fluid inclusions is indicative of low salinity H₂O--CO₂±CH₄-rich fluids at Kalgold against relatively H₂O-CO₂-rich fluids at Amalia. Evidence from strontium–carbon–oxygen isotopic ratios from carbonates suggests that differences in redox conditions in the deposits could be attributed to different flow pathways by an evolving fluid from a common source (with minimum ⁸⁷Sr/⁸⁶Sr = 0.70354) to the sites of gold deposition, with a significant ore fluid interaction with a thick sequence of carbonaceous meta-pelitic rock units at the Kalahari Goldridge deposit that is absent in the Amalia deposit. Full article

(This article belongs to the Special Issue Geochemistry and Genesis of Hydrothermal Ore Deposits)

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