Minerals

30 pages, 7272 KiB

Open AccessArticle

A Genetic Model for the Biggenden Gold-Bearing Fe Skarn Deposit, Queensland, Australia: Geology, Mineralogy, Isotope Geochemistry, and Fluid Inclusion Studies

by Mansour Edraki, Alireza K. Somarin and Paul M. Ashley

Minerals 2025, 15(1), 95; https://doi.org/10.3390/min15010095 - 20 Jan 2025

Viewed by 540

Abstract

The Biggenden gold-bearing Fe skarn deposit in southeast Queensland, Australia, is a calcic magnetite skarn that has been mined for Fe and gold (from the upper portion of the deposit). Skarn has replaced volcanic and sedimentary rocks of the Early Permian Gympie Group, [...] Read more.

The Biggenden gold-bearing Fe skarn deposit in southeast Queensland, Australia, is a calcic magnetite skarn that has been mined for Fe and gold (from the upper portion of the deposit). Skarn has replaced volcanic and sedimentary rocks of the Early Permian Gympie Group, which formed in different tectonic settings, including island arc, back arc, and mid-ocean ridge. This group has experienced a hornblende-hornfels grade of contact metamorphism due to the intrusion of the Late Triassic Degilbo Granite. The intrusion is a mildly oxidized I-type monzogranite that has geochemical characteristics intermediate between those of granitoids typically associated with Fe-Cu-Au and Sn-W-Mo skarn deposits. The skarn mineralogy indicates that there was an evolution from prograde to various retrograde assemblages. Prograde garnet (Adr_11-99Grs_1-78Alm_0-8Sps_0-11), clinopyroxene (Di_30-92Hd_7-65Jo_0-9), magnetite, and scapolite formed initially. Epidote and Cl-bearing amphibole (mainly ferropargasite) were the early retrograde minerals, followed by chlorite, calcite, actinolite, quartz, and sulfides. Late-stage retrograde reactions are indicated by the development of nontronite, calcite, and quartz. Gold is mainly associated with sulfide minerals in the retrograde sulfide stage. The fluids in equilibrium with the ore-stage calcites had δ¹³C and δ¹⁸O values that indicate deposition from magmatically derived fluids. The calculated δ¹⁸O values of the fluids in equilibrium with the skarn magnetite also suggest a magmatic origin. However, the fluids in equilibrium with epidote were a mixture of magmatic and meteoric water, and the fluids that deposited chlorite were at least partly meteoric. δD values for the retrograde amphibole and epidote fall within the common range for magmatic water. Late-stage chlorite was deposited from metasomatic fluids depleted in deuterium (D), implying a meteoric water origin. Sulfur isotopic compositions of the Biggenden sulfides are similar to other skarn deposits worldwide and indicate that sulfur was most probably derived from a magmatic source. Based on the strontium (⁸⁷Sr/⁸⁶Sr) and lead (²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb) isotope ratios, the volcanic and sedimentary rocks of the Gympie Group may have contributed part of the metals to the hydrothermal fluids. Lead isotope data are also consistent with a close age relationship between the mineralization at Biggenden and the crystallization of the Degilbo Granite. Microthermometric analysis indicates that there is an overall decrease in fluid temperature and salinity from the prograde skarn to retrograde alterations. Fluid inclusions in prograde skarn calcite and garnet yield homogenization temperatures of 500 to 600 °C and have salinities up to 45 equivalent wt % NaCl. Fluid inclusions in quartz and calcite from the retrograde sulfide-stage homogenized between 280 and 360 °C and have lower salinities (5–15 equivalent wt % NaCl). In a favored genetic model, hydrothermal fluids originated from the Degilbo Granite at depth and migrated through the shear zone, intrusive contact, and permeable Gympie Group rocks and leached extra Fe and Ca and deposited magnetite upon reaction with the adjacent marble and basalt. Full article

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

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22 pages, 9430 KiB

Open AccessArticle

Pyrite Textures, Trace Element Geochemistry and Galena Pb Isotopes of the Yanzhupo Gold Deposit in the Jiangnan Orogen, South China: Implications for Gold Mineralization Genesis

by Jia Liao, Xu Wang, Biao Chen, Buqing Wang, Zhenhua Zhu, Wentao Wang, Ding Peng, Qian Zhang, Zhuang Liu and Qiangqiang Xu

Minerals 2025, 15(1), 94; https://doi.org/10.3390/min15010094 - 20 Jan 2025

Viewed by 632

Abstract

The northeastern Hunan district in the Jiangnan Orogen (South China) holds significant gold resources, whose genesis remains perplexing, especially in terms of the gold source and mineralization process. Yanzhupo (2.50 t @ 2.52 g/t) is a newly discovered gold deposit in the northeastern [...] Read more.

The northeastern Hunan district in the Jiangnan Orogen (South China) holds significant gold resources, whose genesis remains perplexing, especially in terms of the gold source and mineralization process. Yanzhupo (2.50 t @ 2.52 g/t) is a newly discovered gold deposit in the northeastern Hunan district and is characterized by multiple generations of pyrite. Its alteration/mineralization can be divided into three stages: (I) quartz-ankerite-pyrite; (II) quartz-ankerite-chlorite-pyrite-gold; (III) quartz-ankerite-calcite-pyrite. Petrographic observations and back-scattered electron (BSE) imaging revealed six generations of pyrite: Cu-Au rich bright rims (Py1a) and porous cores (Py1b) in Stage I, Py2a with homogenous textures, Py2b with oscillatory zoning and Py2c with homogenous textures in Stage II and Py3 with homogenous textures in Stage III. Galena Pb isotopes, similar to the Wangu deposit, and pyrite chemical compositions show that the ore-forming materials of Yanzhupo came from deep magma, and some metal elements may be extracted from deep basement by fluid-mineral interactions during the upward migration of hydrothermal-magmatic fluid. The positive correlation between Cu and Au in pyrite reflects the oxidized ore-forming fluids. The enrichment of Cu and Au in Py1a reflects the precipitation of pyrite under high temperature fluid, forming the primary enrichment of Au. Porous Py1b is characterized by lower trace elements than Py1a, sharp reaction front and rich chalcopyrite and galena inclusions, indicating Py1b formed via coupled dissolution-reprecipitation (CDR) reactions of Py1a. The CDR reactions promoted by the oxidizing fluid itself re-release Au into the fluid. From Py2a to Py2c, the contents of As, Sb and Pb first increased and then decreased, which may reflect the increase of fluid pH caused by sulfidation of the wall rocks and the impoverishment of ore-forming fluids caused by the precipitation of a large number of elements. The sulfidation of the wall rocks in Stage II destroyed the stability of the Au(HS)₂⁻ and Au (HS)S₃⁻ complexes and led to the deposition of native gold. The barren ore-forming fluids precipitated homogenous Py3 in a stable environment. Therefore, we think that the Yanzhupo gold deposit may have been associated with magmatic-hydrothermal activity, and the mineralization mechanism may be CDR reactions and sulfidation of the wall rocks. Full article

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

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20 pages, 6276 KiB

Open AccessArticle

Critical Minerals in Tibetan Geothermal Systems: Their Distribution, Flux, Reserves, and Resource Effects

by Di Wang, Fei Xue, Lijian Ren, Xin Li, Songtao Wang and Xie Qibei Er

Minerals 2025, 15(1), 93; https://doi.org/10.3390/min15010093 - 20 Jan 2025

Viewed by 466

Abstract

Critical mineral resources (CMRs) are essential for emerging high-tech industries and are geopolitically significant, prompting countries to pursue resource exploration and development. Tibetan geothermal systems, recognized for their CMR potential, have not yet been systematically evaluated. This study presents a comprehensive investigation of [...] Read more.

Critical mineral resources (CMRs) are essential for emerging high-tech industries and are geopolitically significant, prompting countries to pursue resource exploration and development. Tibetan geothermal systems, recognized for their CMR potential, have not yet been systematically evaluated. This study presents a comprehensive investigation of the spatial distributions, resource flux, reserves, and resource effects of CMRs, integrating and analyzing hydrochemical and discharge flow rate data. Geochemical findings reveal significant enrichment of lithium (Li), rubidium (Rb), cesium (Cs), and boron (B) in the spring waters and sediments, primarily located along the Yarlung Zangbo suture and north–south rift zones. Resource flux estimates include approximately 246 tons of Li, 54 tons of Rb, 233 tons of Cs, and 2747 tons of B per year, underscoring the mineral potential of the geothermal spring waters. Additionally, over 40,000 tons of Cs reserves are preserved in siliceous sinters in Tagejia, Gulu, and Semi. The Tibetan geothermal systems thus demonstrate considerable potential for CMRs, especially Cs, through stable discharge and widespread distribution, also serving as indicators for endogenous mineral exploration and providing potential sources for lithium in exogenous salt lakes. This study evaluates the CMR potential of the Tibetan geothermal systems, advancing CMR exploration while contributing to the future security of CMR supplies. Full article

(This article belongs to the Special Issue Critical Metal Minerals, 2nd Edition)

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25 pages, 36159 KiB

Open AccessArticle

Mineralogy and Geochemistry of Upper Cretaceous-Pliocene Sedimentary Rocks in the Yahşihan Basin, Central Anatolia, Türkiye: Provenance and Tectonic Implications

by Özgül Uyanık Sönmez, Abidin Temel, Muazzez Çelik Karakaya and Güllü Deniz Dogan-Kulahci

Minerals 2025, 15(1), 92; https://doi.org/10.3390/min15010092 - 19 Jan 2025

Viewed by 710

Abstract

The Yahşihan/Kırıkkale sedimentary basin, located in Central Anatolia within the İzmir-Ankara-Erzincan suture zone, mostly consists of Upper Cretaceous to Lower Pliocene sediments developed on the Ankara Melange, which is linked to the Northern Neo-Tethys Ocean. Although the stratigraphic, sedimentological, and tectono-stratigraphic characteristics of [...] Read more.

The Yahşihan/Kırıkkale sedimentary basin, located in Central Anatolia within the İzmir-Ankara-Erzincan suture zone, mostly consists of Upper Cretaceous to Lower Pliocene sediments developed on the Ankara Melange, which is linked to the Northern Neo-Tethys Ocean. Although the stratigraphic, sedimentological, and tectono-stratigraphic characteristics of the basin have been investigated by many researchers, its mineralogical and geochemical characteristics have not been studied extensively. In this study, the provenance, paleoclimatological properties, and tectonic structure of the sedimentary rocks were interpreted using detailed mineralogical and geochemical analysis data. Formations such as the Karadağ (Cenomanian-Campanian), Çiçekdağ (Santonian-Campanian), Samanlık (Maastrichtian), Dizilitaşlar (Paleocene-Early Eocene), Çayraz (Middle Eocene), İncik (Upper Eocene-Lower Miocene), Central Anatolia Group (Middle Miocene-Pliocene), and Quaternary alluvium were deposited in the basin. X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), and geochemical analyses were employed to determine the mineralogical and chemical composition of the units. Although highly oxic paleo-environmental conditions predominated in the basin, anoxic and suboxic conditions could also be present in the Dizilitaşlar and İncik formations. The units are primarily felsic with some mafic contributions, suggesting an oceanic island arc environment with varying paleoenvironmental conditions, reflecting seasonal changes between humid and arid periods. Full article

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

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20 pages, 10254 KiB

Open AccessFeature PaperArticle

Discernible Orientation for Tortuosity During Oxidative Precipitation of Fe(II) in Porous Media: Laboratory Experiment and Micro-CT Imaging

by Wenran Cao, Ekaterina Strounina, Harald Hofmann and Alexander Scheuermann

Minerals 2025, 15(1), 91; https://doi.org/10.3390/min15010091 - 19 Jan 2025

Viewed by 567

Abstract

In the mixing zone, where submarine groundwater carrying ferrous iron [Fe(II)] meets seawater with dissolved oxygen (DO), the oxidative precipitation of Fe(II) occurs at the pore scale (nm~μm), and the resulting Fe precipitation significantly influences the seepage properties at the Darcy scale (cm~m). [...] Read more.

In the mixing zone, where submarine groundwater carrying ferrous iron [Fe(II)] meets seawater with dissolved oxygen (DO), the oxidative precipitation of Fe(II) occurs at the pore scale (nm~μm), and the resulting Fe precipitation significantly influences the seepage properties at the Darcy scale (cm~m). Previous studies have presented a challenge in upscaling fluid dynamics from a small scale to a large scale, thereby constraining our understanding of the spatiotemporal variations in flow paths as porous media evolve. To address this limitation, this study simulated subsurface mixing by injecting Fe(II)-rich freshwater into a DO-rich saltwater flow within a custom-designed syringe packed with glass beads. Micro-computed tomography imaging at the representative elementary volume scale was utilized to track the development of Fe precipitates over time and space. Experimental observations revealed three distinct stages of Fe hydroxides and their effects on the flow dynamics. Initially, hydrous Fe precipitates were characterized by a low density and exhibited mobility, allowing temporarily clogged pathways to intermittently reopen. As precipitation progressed, the Fe precipitates accumulated, forming interparticle bonding structures that redirected the flow to bypass clogged pores and facilitated precipitate flushing near the syringe wall. In the final stage, a notable reduction in the macroscopic capillary number from 3.0 to 0.05 indicated a transition from a viscous- to capillary-dominated flow, which led to the construction of ramified, tortuous flow channels. This study highlights the critical role of high-resolution imaging techniques in bridging the gap between pore-scale and continuum-scale analyses of multiphase flows in hydrogeochemical processes, offering valuable insights into the complex groundwater–seawater mixing. Full article

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

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16 pages, 5907 KiB

Open AccessArticle

Investigation of the Possibility of Obtaining High-Purity Carbon Materials and Recovering Valuable Metals from Shungite Rocks

by Tatiana Aleksandrova, Anastasia Afanasova, Nadezhda Nikolaeva, Artyem Romashev, Valeriya Aburova and Evgeniya Prokhorova

Minerals 2025, 15(1), 90; https://doi.org/10.3390/min15010090 - 18 Jan 2025

Viewed by 533

Abstract

The increased consumption of strategic metals has led to the necessity to search for new and non-traditional sources of mineral raw materials. All this has resulted in the necessity to develop and justify new technological solutions for the integrated recovery of strategic metals [...] Read more.

The increased consumption of strategic metals has led to the necessity to search for new and non-traditional sources of mineral raw materials. All this has resulted in the necessity to develop and justify new technological solutions for the integrated recovery of strategic metals and the associated production of high-purity carbon materials. The purpose of this work was to substantiate the possibility of obtaining high-purity shungite carbon materials and metal-bearing concentrate containing valuable metals from shungite rocks using high-gradient magnetic separation and flotation with the use of an apolar collector emulsion in a frother solution. The conducted investigations using a complex of analysis methods allowed us to justify the obtaining of a metal-bearing concentrate containing iron, titanium, copper and zirconium and carbon material of high purity. By using high-gradient magnetic separation, we obtained a metal-bearing concentrate with a yield of 17.35% and a total metal content of 63.61% broken down as follows: Fe₂O₃ recovery of 87.66%, TiO₂ recovery of 56.03%, CuO recovery of 72.52% and ZrO₂ recovery of 54.42%. By using flotation, we obtained a shungite carbon concentrate with a yield of 31.41%, made of 88.15% carbon with a content and recovery of 88.09% and a sulphur content of 0.084%. The conducted studies showed the possibility of using classical beneficiation operations in the processing of non-traditional mineral raw materials to obtain commercial products. Full article

(This article belongs to the Special Issue Advances in Physical Separation of Gold, Iron Ore and Rare Earth Minerals)

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22 pages, 12695 KiB

Open AccessArticle

Simulation and Parameter Optimisation of Edge Effect in Ore Minerals Roll Crushing Process Based on Discrete Element Method

by Ruijie Gu, Wenzhe Wu, Shuaifeng Zhao, Hao Xing and Zhenzhong Qin

Minerals 2025, 15(1), 89; https://doi.org/10.3390/min15010089 - 18 Jan 2025

Viewed by 307

Abstract

The edge effect is caused by poor use of confinement systems, different roll aspect ratios, operating conditions and other factors, which result in uneven pressure distribution between the two crushing rolls along the roll width direction, affecting the overall roll crushing process. To [...] Read more.

The edge effect is caused by poor use of confinement systems, different roll aspect ratios, operating conditions and other factors, which result in uneven pressure distribution between the two crushing rolls along the roll width direction, affecting the overall roll crushing process. To reduce the edge effect, this paper investigates the simulation of the edge effect and parameter optimisation in the roll-crushing process of ore materials based on the discrete element method (DEM). Firstly, the parameters of the iron ore crushing model are experimentally calibrated, and the working process of HPGR is simulated by DEM. Secondly, the effects of roll speed, roll gap, roll diameter and roll width on edge effect and crushing effect of HPGR are analysed by the one-factor experiment. Finally, the roll pressure optimisation model is established based on the Response Surface Methodology (RSM) to obtain the optimal roll pressure parameters. The results show that, with the roll speed and roll diameter increase, the edge effect also increases, the roll gap shows the opposite trend, and the roll width has less influence. The change in roll diameter has the greatest influence on the crushing effect, roll gap is second, and roll speed and roll width have less influence on the crushing effect. When the feed particles are iron ore with a particle size of 32 mm, the optimisation results show that the edge effect and crushing effect of HPGR are significantly improved when the roll speed is 1.25 rad/s, the roll gap is 38 mm, the roll diameter is 2000 mm and the roll width is 742 mm. Full article

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

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15 pages, 6633 KiB

Open AccessArticle

Nioboixiolite-(□),(Nb_0.8□0.2)⁴⁺O₂, a New Mineral Species from the Bayan Obo World-Class REE-Fe-Nb Deposit, Inner Mongolia, China

by Yike Li, Changhui Ke, Denghong Wang, Zidong Peng, Yonggang Zhao, Ruiping Li, Zhenyu Chen, Guowu Li, Hong Yu, Li Zhang, Bin Guo and Yupu Gao

Minerals 2025, 15(1), 88; https://doi.org/10.3390/min15010088 - 17 Jan 2025

Viewed by 369

Abstract

Nioboixiolite-(□) is a new mineral found in a carbonatite sill from the Bayan Obo mine, Baotou City, Inner Mongolia, China. It occurs as anhedral to subhedral grains (100 to 500 μm in diameter) that are disseminated in carbonatite rock composed of dolomite, calcite, [...] Read more.

Nioboixiolite-(□) is a new mineral found in a carbonatite sill from the Bayan Obo mine, Baotou City, Inner Mongolia, China. It occurs as anhedral to subhedral grains (100 to 500 μm in diameter) that are disseminated in carbonatite rock composed of dolomite, calcite, magnetite, apatite, biotite, actionlike, zircon, and columbite-(Fe). Most of these grains are highly serrated, with numerous inclusions of columbite-(Fe). The mineral is gray to deep black in color; is opaque, with a semi-metallic luster; has a black streak; and is brittle, with an uneven conchoidal splintery. The Mohs hardness is 6–6½, and the calculated density is 6.05 g/cm³. The reflection color is gray with a blue tone, and there is no double reflection color. The measured reflectivity of nioboixiolite-(□) is about 10.6%~12.1%, close to that of ixiolite (11%–13%). Nioboixiolite-(□) is non-fluorescent under 254 nm (short-wave) and 366 nm (long-wave) ultraviolet light. The average chemical analysis results (wt.%) of twelve electron microprobe analyses are F 0.01, MnO 0.12, MgO 0.15, BaO 0.62, PbO 0.91, SrO 1.49, CaO 2.76, Al₂O₃ 0.01, TREE₂O₃ 1.58, Fe₂O₃ 3.57, ThO₂ 0.11, SiO₂ 1.69, TiO₂ 3.68, Ta₂O₅ 13.95, Nb₂O₅ 47.04, and UO₃ 21.56, with a total of 99.25. The simplified formula is [Nb⁵⁺, Ta⁵⁺,Ti⁴⁺, Fe³⁺,□,]O₂. X-ray diffraction data show that nioboixiolite-(□) is orthorhombic, belonging to the space group Pbcn (#60). The refined unit cell parameters are a = 4.7071(5) Å, b = 5.7097(7) Å, c = 5.1111(6) Å, V = 138.31(3), and β = 90(1) °Å³ with Z = 4. In the crystal structure of nioboixiolite-(□), all cations occupy a single M1 site. In these minerals, edge-sharing M₁O₆ octahedra form chains along the c direction. In this direction, the chains are connected with each other via common vertices of the octahedra. The strongest measured X-ray powder diffraction lines are [d in Å, (I/I0), (hkl)]: 3.662(20) (110), 2.975(100) (111), 2.501(20) (021), 1.770(20) (122), 1.458(20) (023). A type specimen was deposited in the Geological Museum of China with catalogue number M16118, No. 15, Yangrou Hutong, Xisi, Beijing 100031, People’s Republic of China. Full article

(This article belongs to the Collection New Minerals)

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63 pages, 15760 KiB

Open AccessReview

Mineral Resources for the Ceramic Industry: Survey of Feldspathic Raw Materials in Italy

by Michele Dondi, Sonia Conte, Chiara Molinari and Chiara Zanelli

Minerals 2025, 15(1), 87; https://doi.org/10.3390/min15010087 - 17 Jan 2025

Viewed by 672

Abstract

Feldspars are essential components in the ceramic industry, and the increasing demand for high-grade fluxes has recently elevated their status as critical raw materials for the European Union. This survey aims to evaluate, for the first time, Italy’s mining potential for the production [...] Read more.

Feldspars are essential components in the ceramic industry, and the increasing demand for high-grade fluxes has recently elevated their status as critical raw materials for the European Union. This survey aims to evaluate, for the first time, Italy’s mining potential for the production of ceramic fluxes through a methodological approach that considers lithology, technological value, degree of alteration and potential for mining exploitation. The most promising resources are identified in the Alps, the Apennines, Sardinia and the Calabro–Peloritan Arc, based on the chemical composition of rocks without any beneficiation. Key parameters include the equivalent feldspar content and the sum of Fe₂O₃ + TiO₂. Factors that may influence the feasibility of exploitation are critically discussed for granitoids and syenites, acidic volcanics, aplites and pegmatites, albitites, felsic metamorphics, silica-saturated and silica-undersaturated volcanics, arkosic sandstones and rocks that have undergone epithermal alteration. All resources are compared with deposits currently under extraction and assessed against benchmarks or well-recognized raw materials used as market proxies. This review lays the groundwork for operational mining exploration by clearly defining Italy’s potential for feldspathic fluxes. The exploratory assessment approach to feldspathic resources can also be applied in other countries. Full article

(This article belongs to the Section Mineral Deposits)

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14 pages, 2619 KiB

Open AccessArticle

Temperature: An Influencing Factor on the Rheological and Energetic Parameters of Acid Pressure Technology Operations

by Gabriel Hernández-Ramírez, Antonio Bernardo-Sánchez, Aristides Alejandro Legrá-Lobaina, Laura Álvarez de Prado, Rodney Martínez-Rojas, Liudmila Pérez-García, Leonel Garcell-Puyáns, Jose Fernández-Ordás and Javier Menéndez

Minerals 2025, 15(1), 86; https://doi.org/10.3390/min15010086 - 17 Jan 2025

Viewed by 363

Abstract

In this work, a study was carried out on the effect of temperature as the main influencing factor on the rheological behavior of lateritic suspensions, raw material for the operations of pressurized acid technology (HPAL) used to obtain nickel and cobalt from of [...] Read more.

In this work, a study was carried out on the effect of temperature as the main influencing factor on the rheological behavior of lateritic suspensions, raw material for the operations of pressurized acid technology (HPAL) used to obtain nickel and cobalt from of oxidized ores. From studies of X-ray diffraction, X-ray fluorescence, particle size analyzer, and mathematical modeling, the behavior of the interactions and rheological characteristics of the analyzed samples were obtained. In this study, it was concluded that the use of mathematical models that relate the temperature up to 90 °C and the energy parameters of the pumping system of flows, loads, hydraulic losses, power, and efficiency would allow finding ways to increase and stabilize the flow of fed hydromixture with a flow rate of 1600 m³/h and a solids concentration of 48% (w/w) and guarantee the efficiency of the technological process. Full article

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

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16 pages, 6763 KiB

Open AccessArticle

Analyzing the Mechanism of Drilling Losses in the Zhengning Oilfield in the Ordos Basin

by Tuan Gu, Shugang Yang, Yunfeng Xiao, Linpeng Zhang, Fangquan Peng, Xu Su, Tao Fan, Haiyang Wang and Desheng Zhou

Minerals 2025, 15(1), 85; https://doi.org/10.3390/min15010085 - 17 Jan 2025

Viewed by 393

Abstract

Frequent wellbore loss incidents in the Mesozoic reservoirs of the Zhengning oilfield in the Ordos Basin, China, have severely impacted the development of tight oil and gas reservoirs in the basin. This study analyzed the mineral composition, microstructure, natural fracture distribution, and hydration–dispersion [...] Read more.

Frequent wellbore loss incidents in the Mesozoic reservoirs of the Zhengning oilfield in the Ordos Basin, China, have severely impacted the development of tight oil and gas reservoirs in the basin. This study analyzed the mineral composition, microstructure, natural fracture distribution, and hydration–dispersion characteristics of rocks in the loss-prone intervals of the Mesozoic reservoirs using a laboratory experimental system. The effects of natural fractures and drilling fluid immersion on the mechanical properties and failure behavior of the rocks were investigated, and the wellbore loss mechanisms in the Mesozoic reservoirs of the Zhengning oilfield were comprehensively analyzed. Experimental results show that the reservoir rocks in the loss-prone intervals are widely distributed, with natural fractures having a width of 0.2–0.3 mm, and the clay mineral content is generally above 40%. When the relative content of illite/smectite interstratification exceeds 80%, the rock exhibits strong hydration–dispersion behavior, with a thermal recovery rate of less than 85%. Drilling fluid immersion causes the rock mass to become unstable. The presence of natural fractures and the hydration–dispersion effect significantly weaken the strength of the surrounding rock mass, leading to enhanced rock plasticity. During drilling, the expansion and interconnection of natural fractures, combined with the hydration–dispersion effect, are the main causes of wellbore loss incidents. Our study clarifies the mechanisms underlying wellbore loss incidents in the Zhengning oilfield and provides reliable experimental evidence for preventing such incidents in this area. Full article

(This article belongs to the Special Issue Clay Minerals: Roles in Oil and Gas Generation, Drilling, and Enhanced Recovery)

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4 pages, 183 KiB

Open AccessEditorial

Editorial for the Special Issue of Minerals, “Advances in Low-Temperature Mineralogy and Geochemistry”

by Iuliu Bobos and Franck Bourdelle

Minerals 2025, 15(1), 84; https://doi.org/10.3390/min15010084 - 17 Jan 2025

Viewed by 343

Abstract

Low-temperature geochemical processes are ubiquitous in geological areas related to weathering, diagenesis, very low-grade metamorphism, and post-magmatic processes, and provide an explanation of the P–T–X history of the Earth’s crust [...] Full article

(This article belongs to the Special Issue Advances in Low-Temperature Mineralogy and Geochemistry)

24 pages, 6969 KiB

Open AccessFeature PaperArticle

The Short-Wave Infrared (SWIR) Spectral Exploration Identification and Indicative Significance of the Yixingzhai Gold Deposit, Shanxi Province

by Lifang Wang, Song Wu, Xiaodan Lai, Weili Yang, Rongliang Sun, Peng Liu, Yandong Yang and Yuxin Ren

Minerals 2025, 15(1), 83; https://doi.org/10.3390/min15010083 - 16 Jan 2025

Viewed by 401

Abstract

The Yixingzhai gold deposit is the largest gold deposit in Shanxi Province and develops three types of mineralization: porphyry, quartz vein, and breccia. Spectral characteristic parameters of muscovite are studied by short-wave infrared (SWIR) spectral, and the exploration significance is discussed. The Al-OH [...] Read more.

The Yixingzhai gold deposit is the largest gold deposit in Shanxi Province and develops three types of mineralization: porphyry, quartz vein, and breccia. Spectral characteristic parameters of muscovite are studied by short-wave infrared (SWIR) spectral, and the exploration significance is discussed. The Al-OH wavelength of muscovite associated with porphyry mineralization gradually becomes shorter from the periphery (>2206 nm) to the center (2201–2205 nm), and the crystallinity (>2.6) gradually increases. In quartz vein mineralization, the wavelength gradually increases from the periphery (<2203 nm) to the center (2210–2211 nm), while the crystallinity does not change significantly and in a small value (<1.5). The wavelength variation range of breccia mineralization is 2198~2214 nm and is concentrated in 2201~2204 nm near the center, while the overall crystallinity is lesser than 5.5 and concentrated around 1–2.2 near the center. The wavelength and crystallinity of muscovite are mainly affected by Tschermak substitution and temperature. When the contents of Si, Fe, and Mg are low and Al^VI is high, the wavelength tends toward the short-wave (SW) direction, while the opposite tends toward the long-wave (LW) direction. The high crystallinity (4.1–8.4) of muscovite can be used as an indicator of porphyry gold mineralization and also provides an important indicator to explore similar types of gold deposits. Full article

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

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13 pages, 2743 KiB

Open AccessArticle

Effects of Sodium Silicate on Flotation Separation of Sphalerite and Dolomite and Its Mechanism

by Longqian Ni, Jinfang Lv, Lingyu Kong and Longwei Qin

Minerals 2025, 15(1), 82; https://doi.org/10.3390/min15010082 - 16 Jan 2025

Viewed by 376

Abstract

Sphalerite often co-exists with dolomite, a carbonate mineral containing calcium and magnesium. In the flotation process of sphalerite, dolomite entering into the concentrate will have a considerable negative impact on the subsequent smelting. Therefore, the effects of sodium silicate on the flotation separation [...] Read more.

Sphalerite often co-exists with dolomite, a carbonate mineral containing calcium and magnesium. In the flotation process of sphalerite, dolomite entering into the concentrate will have a considerable negative impact on the subsequent smelting. Therefore, the effects of sodium silicate on the flotation separation of sphalerite and dolomite and its mechanism were investigated in this study. It was found that alkaline conditions and the addition of sodium silicate were conducive to the flotation separation of sphalerite and dolomite. Under alkaline conditions, sodium silicate improved the hydrophobicity of sphalerite and the slurry turbidity. The yield stress and apparent viscosity were significantly reduced when dolomite was present in slurry. In addition, the surface electrical properties of dolomite shifted from positive to negative with an increase in the dosage of sodium silicate at pH 11, leading to electrostatic repulsion between sphalerite and dolomite. EDLVO results indicated that the total interaction energy between dolomite and sphalerite particles was repulsive when sodium silicate was present. This study provided a theoretical basis for the flotation separation of sphalerite and dolomite. Full article

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

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14 pages, 2307 KiB

Open AccessArticle

Quantitative Analysis of Yield Stress and Its Evolution in Fiber-Reinforced Cemented Paste Backfill

by Shili Hu, Jingping Qiu, Qingsong Zhang, Zhenbang Guo and Chen Liu

Minerals 2025, 15(1), 81; https://doi.org/10.3390/min15010081 - 16 Jan 2025

Viewed by 369

Abstract

Fiber-reinforced cemented paste backfill (FR-CPB) has attracted considerable attention in modern mining applications due to its superior mechanical properties and adaptability. Despite its potential, understanding its rheological behavior remains limited, largely because of the absence of quantitative methods for assessing fiber packing behavior [...] Read more.

Fiber-reinforced cemented paste backfill (FR-CPB) has attracted considerable attention in modern mining applications due to its superior mechanical properties and adaptability. Despite its potential, understanding its rheological behavior remains limited, largely because of the absence of quantitative methods for assessing fiber packing behavior within CPB. This study develops a rheology-based approach to determine the maximum packing fraction of polypropylene fibers in fresh CPB, revealing that shorter fibers (3 mm) achieve a maximum packing fraction of 0.661, significantly higher than longer fibers (12 mm) with 0.534. Building on these findings, a quantitative model for the static yield stress of FR-CPB was developed, showing that under a high fiber content (0.9%) and with longer fibers (12 mm), the yield stress reached 274.34 kPa, a 40% increase compared to shorter fibers. Additionally, the study modeled the time-dependent evolution of yield stress, achieving a prediction accuracy with a correlation coefficient of 0.92. These advancements enable the optimization of FR-CPB composition, which can reduce material usage, enhance pipeline transport efficiency, and improve backfill stability in underground voids. By minimizing the risk of structural failure and optimizing resource allocation, this research provides a theoretical foundation for safer and more cost-effective mining operations. Full article

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

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31 pages, 15084 KiB

Open AccessArticle

Tempo-Spatial Tungsten Metallogeny in the Xing’an–Mongolia Orogenic Belt: Insights from the Early Cretaceous Shamai Tungsten Deposit Case Study in Northeastern China

by Zhenjiang Liu, Jianping Wang, Shaobo Cheng and Jiajun Liu

Minerals 2025, 15(1), 80; https://doi.org/10.3390/min15010080 - 16 Jan 2025

Viewed by 476

Abstract

The Xing’an–Mongolia Orogenic Belt (XMOB) is located in the eastern part of the Central Asian Orogenic Belt (CAOB). The region’s notable tectonic complexity and extensive tungsten mineralization offer a unique opportunity to explore metallogeny mechanisms in orogenic areas. This study focuses on the [...] Read more.

The Xing’an–Mongolia Orogenic Belt (XMOB) is located in the eastern part of the Central Asian Orogenic Belt (CAOB). The region’s notable tectonic complexity and extensive tungsten mineralization offer a unique opportunity to explore metallogeny mechanisms in orogenic areas. This study focuses on the Shamai tungsten deposit as a case study, presenting results from LA–ICP–MS U–Pb dating of fine-grained, medium-grained, and porphyritic biotite monzogranite samples from the deposit, along with in situ zircon Hf isotopic and plagioclase Pb isotopic analyses. The fine-grained, medium-grained, and porphyritic biotite monzogranite were emplaced at 142.5, 141.9, and 140.2 Ma, respectively. These samples contain zircons with εHf(t) values ranging from 3.2 to 7.9 and 4.2 to 7.6, respectively, yielding T_DM2 model ages from 996 to 692 Ma and 923 to 708 Ma. These findings suggest that the magmas in the Shamai deposit were produced by partial melting of juvenile crustal material mixed with mantle-derived components. The tungsten mineralization periods in the Eastern XMOB region can be divided into three stages: Early Paleozoic (ca. 520–475 Ma), Triassic (ca. 250–200 Ma), and Jurassic to Early Cretaceous (ca. 190–130 Ma). The highest concentration of tungsten mineralization in the XMOB occurs within the Xing’an Block during the Jurassic to Early Cretaceous period. Yanshanian magmatism and the most significant tungsten metallogenic events are likely influenced by an extensional setting and oceanic slab rollback, shaped by the tectonic evolution of the Mongol-Okhotsk Ocean and the Paleo-Pacific Ocean. Full article

(This article belongs to the Section Mineral Deposits)

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12 pages, 1674 KiB

Open AccessArticle

Effect of Manganese Oxide Mineralogy and Surface Mo Coverage on Mo Isotope Fractionation During the Adsorption Process

by Akihiro Okuyama, Teruhiko Kashiwabara, Minako Kurisu, Yoshio Takahashi and Keisuke Fukushi

Minerals 2025, 15(1), 79; https://doi.org/10.3390/min15010079 - 16 Jan 2025

Viewed by 761

Abstract

The large molybdenum (Mo) isotope fractionation from seawater is caused by the adsorption of Mo on manganese oxides. However, the effects of the manganese oxide mineralogy (crystal structure) and surface Mo coverage on Mo isotope fractionation have not been investigated. In this study, [...] Read more.

The large molybdenum (Mo) isotope fractionation from seawater is caused by the adsorption of Mo on manganese oxides. However, the effects of the manganese oxide mineralogy (crystal structure) and surface Mo coverage on Mo isotope fractionation have not been investigated. In this study, the isotope fractionation of Mo by adsorption on synthetic todorokite, birnessite, and δMnO₂ was investigated under a wide range of surface Mo coverages. The Mo isotope fractionation changed from Δ^98/95Mo = 2.18 ± 0.05‰ to 2.61 ± 0.06‰ for todorokite; from 1.25 ± 0.05‰ to 2.10 ± 0.05‰ for birnessite; and from 2.19 ± 0.07‰ to 2.73 ± 0.08‰ for δMnO₂. The Mo isotope fractionations of the three manganese oxides were negatively correlated with surface coverage normalized to the specific surface area. The independence of the obtained correlation of the manganese oxide species indicates that the Mo isotope fractionation depends on the surface coverage but not on the mineralogy of the manganese oxides. The experimentally observed Mo isotope fractionation (<2.7‰) in manganese oxides generally underestimates the isotope fractionation in natural ferromanganese oxides (~3‰). According to the dependency of the Mo isotope fractionation on the surface coverage, the underestimation relative to previous experimental studies can be attributed to the lower Mo surface coverage of natural ferromanganese oxides. Full article

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

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13 pages, 3439 KiB

Open AccessArticle

New Insights for Improving Low-Rank Coal Flotation Performance via Tetrahydrofurfuryl Ester Collectors

by Xin Wang, Rui Ding, Xinyu Cui, Yonghong Qin, Gan Cheng, George Abaka-Wood and Enze Li

Minerals 2025, 15(1), 78; https://doi.org/10.3390/min15010078 - 15 Jan 2025

Viewed by 477

Abstract

With the advancement of large-scale coal development and utilization, low-rank coal (LRC) is increasingly gaining prominence in the energy sector. Upgrading and ash reduction are key to the clean utilization of LRC. Flotation technology based on gas/liquid/solid interfacial interactions remains an effective way [...] Read more.

With the advancement of large-scale coal development and utilization, low-rank coal (LRC) is increasingly gaining prominence in the energy sector. Upgrading and ash reduction are key to the clean utilization of LRC. Flotation technology based on gas/liquid/solid interfacial interactions remains an effective way to recover combustible materials and realize the clean utilization of coal. The traditional collector, kerosene, has demonstrated its inefficiency and environmental toxicity in the flotation of LRC. In this study, four eco-friendly tetrahydrofuran ester compounds (THF-series) were investigated as novel collectors to improve the flotation performance of LRC. The flotation results showed that THF-series collectors were more effective than kerosene in enhancing the LRC flotation. Among these, tetrahydrofurfuryl butyrate (THFB) exhibited the best performance, with combustible material recovery and flotation perfection factors 79.79% and 15.05% higher than those of kerosene, respectively, at a dosage of 1.2 kg/t. Characterization results indicated that THF-series collectors rapidly adsorbed onto the LRC surface via hydrogen bonding, resulting in stronger hydrophobicity and higher electronegativity. High-speed camera and particle image velocimeter (PIV) observation further demonstrated that THFB dispersed more evenly in the flotation system, reducing the lateral movement of bubbles during their ascent, lowering the impact of bubble wakes on coal particles, and promoting the stable adhesion of bubbles to the LRC surface within a shorter time (16.65 ms), thereby preventing entrainment effects. This study provides new insights and options for the green and efficient flotation of LRC. Full article

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

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25 pages, 8369 KiB

Open AccessArticle

Origin of Diorites and Coeval Mafic Microgranular Enclaves in the Liuba Region, South Qinling Orogen, Central China: Insights from Petrography, Zircon U-Pb Geochronology and Geochemistry

by Shan Gao, Xianzhi Pei, Lei Pei, Zuochen Li, Ruibao Li, Shaowei Zhao, Mao Wang, Li Qin and Xiao Wang

Minerals 2025, 15(1), 77; https://doi.org/10.3390/min15010077 - 15 Jan 2025

Viewed by 471

Abstract

The formation of early Mesozoic granitoid plutons in the Qinling Orogen is widely regarded as a result of the collision and accretion between the Yangtze Block and the South Qinling Block during the early Mesozoic, but the specific magmatic process, source composition, tectonic [...] Read more.

The formation of early Mesozoic granitoid plutons in the Qinling Orogen is widely regarded as a result of the collision and accretion between the Yangtze Block and the South Qinling Block during the early Mesozoic, but the specific magmatic process, source composition, tectonic environment and deep dynamic background remain controversial. This study reports the petrology, zircon U–Pb geochronology, and whole-rock geochemistry of diorites from the Liuba and Qingyangyi plutons in the South Qinling, to provide new evidence for understanding the final collision tectonic evolution process of Qinling Orogenic belt. The Liuba and Qingyangyi plutons, located in the central part of the South Qinling region, are primarily composed of quartz diorite and quartz monzodiorite, respectively. The results indicate that the weighted mean crystallization ages of the quartz diorite in the Liuba pluton range from 216.1 ± 0.8 Ma to 217.1 ± 1.3 Ma, with the weighted mean crystallization ages of its MMEs being 215.4 ± 1.0 Ma. The crystallization ages of the quartz monzodiorite in the Qingyangyi pluton range from 214.6 ± 0.9 Ma to 215.4 ± 0.9 Ma, suggesting that both plutons were formed in the late Triassic. The investigated plutons are characterized as right-leaning and have weak negative Eu anomalies on the chondrite-normalized REE patterns diagram. The large ion lithophile elements (LILE) Rb, Ba, Th and K are relatively enriched, while high-field strength elements (HFSE) Nb, Ta, Ti and P are strongly depleted. The formation of numerous MMEs in the Liuba pluton is the product of magmatic mixing. The Liuba and Qingyangyi plutons are the results of crust thickening and partial melting of lower crust caused by the comprehensive late Triassic collision between the Yangtze Block and the North China Block (NCB), and are the manifestation of magmatic intrusion along the South Qinling tectonic belt in the late Triassic period. 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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19 pages, 5574 KiB

Open AccessFeature PaperArticle

Investigation of Interfacial Characteristics as a Key Aspect of the Justification of the Reagent Regime for Coal Flotation

by Tatyana N. Aleksandrova, Valentin V. Kuznetsov and Evgeniya O. Prokhorova

Minerals 2025, 15(1), 76; https://doi.org/10.3390/min15010076 - 14 Jan 2025

Viewed by 443

Abstract

This work presents a comprehensive approach for the justification of the reagent regime of coal flotation by investigating the interfacial characteristics of flotation phases with various techniques. For the energy characterization of the surface processes in flotation systems, a method of establishing the [...] Read more.

This work presents a comprehensive approach for the justification of the reagent regime of coal flotation by investigating the interfacial characteristics of flotation phases with various techniques. For the energy characterization of the surface processes in flotation systems, a method of establishing the components of the specific surface Gibbs energy on the basis of a numerical estimation of surface free energy change during the adsorption of flotation reagents using the Owens–Wendt–Rabel–Kaelble technique was proposed. Using the developed approach, the features of the kinetics of n-hexane sorption on the surface of coal samples were established. The substantiation of differences in the potential mechanisms of the fixation of strictly apolar and aromatic reagents is based on the results of the quantum–chemical modeling of the states of the coal–adsorbate system using the software packages Avogadro and Orca. The simulation shows the possibility of aliphatic and aromatic reagents’ synergetic effects on coal surface hydrophobization. Based on the results of quantum–chemical modeling, it was found that for the physical adsorption of an oxyethylated nonyl-phenol molecule on a molecular fragment of the coal surface, according to the Weiser model, the decrease in the energy of the system was 0.05562 eV, which indicates the high thermodynamic probability of the physical sorption of this compound. The parameters of the Langmuir monomolecular model for the sorption of oxyethylated nonyl-phenol on the surface of the studied coal samples were established. The criterion characterizing the interphase phenomena in the flotation system based on the results of potentiometric studies of the interfacial characteristics, E_f, was proposed. It was found that for the studied values of the flow rate of oxyethylated nonyl-phenol, the highest value of E_f was achieved when the value of the sorption of the reagent equaled 63.99% of the limiting sorption capacity. The performance of the proposed reagents for coal flotation was confirmed by flotation tests. Full article

(This article belongs to the Special Issue Harnessing Surface Chemistry for Enhanced Mineral Recovery)

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29 pages, 43098 KiB

Open AccessArticle

Sedimentary Characteristics of Shallow Water Delta: A Case Study from the Paleogene Funing Formation in the Haian Sag of the Subei Basin, China

by Zhao Ma, Guiyu Dong, Tianwei Wang, Yongfeng Qiu, Tianzhuo Bi and Ziyi Yang

Minerals 2025, 15(1), 75; https://doi.org/10.3390/min15010075 - 14 Jan 2025

Viewed by 469

Abstract

Haian Depression is one of the key areas for oil and gas resource replacement in Jiangsu Oilfield. Since the 13th cycle of the Five Year Plan, with the continuous improvement in the exploration level of the Taizhou Formation (K₂t), the difficulty [...] Read more.

Haian Depression is one of the key areas for oil and gas resource replacement in Jiangsu Oilfield. Since the 13th cycle of the Five Year Plan, with the continuous improvement in the exploration level of the Taizhou Formation (K₂t), the difficulty of tapping potential has gradually increased. It is urgent to change our thinking and expand new exploration layers. From the perspective of oil and gas display frequency in different layers of the Haian Depression, except for K₂t, the oil and gas systems with the Fusan Member (E₁f₃) as the main reservoir have good oil and gas display frequency, demonstrating great exploration potential. This study of sedimentary characteristics is the basis of analyzing the sedimentary environment and lithofacies paleogeographic conditions and is of great significance for determining the distribution range of subtle oil and gas reservoirs. Based on this understanding, this study was specially established to systematically analyze the logging curves of forty-three wells in the research area, combined with core observations of eighteen coring wells and the analysis of eight seismic profiles. The results show that the low slope, warm and humid climate, sufficient provenance, and frequent lake level rise and fall cycles during the deposition period of the E₁f₃ member of the Haian Sag provide a favorable depositional background for the development of shallow water delta in the study area. There are many gullies in the research area, mainly consisting of U-shaped gullies and W-shaped gullies. Slope breaks are mainly affected by structural factors leading to fractures, and the types are mostly fault terrbreakslope breaks. In the study area, the shallow water delta deposits during the deposition period of the four key sand groups in the Fu3 Formation are dominated by the shallow water delta front and shallow water prodelta. The shallow water delta plain subfacies are not significantly developed because of erosion. The sand bodies are mainly distributed in the Sunjiawa Subdepression, and the Fuan Subdepression in the north of the depression, and the sand bodies in the plane show the filling characteristics of the strip. Based on the above research, a sedimentary model of shallow water delta during the E₁f₃ section of the Haian Depression was established, providing a geological basis for the design of exploration and development plans for hidden oil and gas reservoirs in the next step. Full article

(This article belongs to the Special Issue Sedimentary Basins: Sedimentation, Stratigraphy, Petrology and Tectonics)

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21 pages, 3535 KiB

Open AccessReview

Coal-Hosted Al-Ga-Li-REE Deposits in China: A Review

by Yanbo Zhang, Xiangyang Liu and Wei Zhao

Minerals 2025, 15(1), 74; https://doi.org/10.3390/min15010074 - 14 Jan 2025

Viewed by 531

Abstract

Investigation of the critical metal elements in coal and coal-bearing strata has become one of the hottest research topics in coal geology and coal industry. Coal-hosted Ga-Al-Li-REE deposits have been discovered in the Jungar and Daqingshan Coalfields of Inner Mongolia, China. Gallium, Al, [...] Read more.

Investigation of the critical metal elements in coal and coal-bearing strata has become one of the hottest research topics in coal geology and coal industry. Coal-hosted Ga-Al-Li-REE deposits have been discovered in the Jungar and Daqingshan Coalfields of Inner Mongolia, China. Gallium, Al, and Li in the Jungar coals have been successfully extracted and utilized. This paper reviews the discovery history of coal-hosted Ga-Al-Li-REE deposits, including contents, modes of occurrence, and enrichment origin of critical metals in each coal mine, including Heidaigou, Harewusu, and Guanbanwusu Mines in the Jungar Coalfield and the Adaohai Coal Mine in the Daqingshan Coalfield, as well as the recently reported Lao Sangou Mine. Gallium and Al in the coals investigated mainly occur in kaolinite, boehmite, diaspore, and gorceixite; REEs are mainly hosted by gorceixite and kaolinite; and Li is mainly hosted by cholorite. Gallium, Al, and REEs are mainly derived from the sediment-source region, i.e., weathered bauxite in the Benxi Formation. In addition, REE enrichment is also attributed to the intra-seam parting leaching by groundwater. Lithium enrichment in the coals is of hydrothermal fluid input. The content of Al₂O₃ and Ga in coal combustions (e.g., fly ash) is higher than 50% and ~100 µg/g, respectively; concentrations of Li in these coals also reach the cut-off grade for industrial recovery (for example, Li concentration in the Haerwusu coals is ~116 µg/g). Investigations of the content, distribution, and mineralization of critical elements in coal not only provide important references for the potential discovery of similar deposits but also offer significant coal geochemical and coal mineralogical evidence for revealing the geological genesis of coal seams, coal seam correlation, the formation and post-depositional modification of coal basins, regional geological evolution, and geological events. Meanwhile, such investigation also has an important practical significance for the economic circular development of the coal industry, environmental protection during coal utilization, and the security of critical metal resources. Full article

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

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24 pages, 4166 KiB

Open AccessArticle

Reconstruction of the Temperature Conditions of Burial-Related Pressure Solution by Clumped Isotopes Validates the Analysis of Sedimentary Stylolites Roughness as a Reliable Depth Gauge

by Nicolas E. Beaudoin, Daniel Koehn, Einat Aharonov, Andrea Billi, Matthieu Daeron and Adrian Boyce

Minerals 2025, 15(1), 73; https://doi.org/10.3390/min15010073 - 14 Jan 2025

Viewed by 529

Abstract

Rough surfaces known as stylolites are common geological features that are developed by pressure solution, especially in carbonate rocks, where they are used as strain markers and as stress gauges. As applications are developing in various geological settings, questions arise regarding the uncertainties [...] Read more.

Rough surfaces known as stylolites are common geological features that are developed by pressure solution, especially in carbonate rocks, where they are used as strain markers and as stress gauges. As applications are developing in various geological settings, questions arise regarding the uncertainties associated with quantitative estimates of paleostress using stylolite roughness. This contribution reports for the first time a measurement of the temperature at which pressure solution was active by applying clumped isotopes thermometry to calcite cement found in jogs linking the tips of the stylolites. This authigenic calcite formed as a redistribution of the surrounding dissolved material by the same dissolution processes that formed the extensive stylolite network. We compare the depth derived from these temperatures to the depth calculated from the vertical stress inversion of a bedding parallel stylolite population documented on a slab of the Calcare Massiccio formation (early Jurassic) formerly collected in the Umbria-Marches Arcuate Ridge (Northern Apennines, Italy). We further validate the coevality between the jog development and the pressure solution by simulating the stress field around the stylolite tip. Calcite clumped isotopes constrain crystallization to temperatures between 35 and 40 °C from a common fluid with a δ¹⁸O signature around −1.3‰ SMOW. Additional δ¹⁸O isotopes on numerous jogs allows the range of precipitation temperature to be extended to from 25 to 53 °C, corresponding to a depth range of 650 to 1900 m. This may be directly compared to the results of stylolite roughness inversion for stress, which predict a range of vertical stress from 14 to 46 MPa, corresponding to depths from 400 to 2000 m. The overall correlation between these two independent depth estimates suggests that sedimentary stylolites can reliably be used as a depth gauge, independently of the thermal gradient. Beyond the method validation, our study also reveals some mechanisms of pressure solution and the associated p,T conditions favouring their development in carbonates. Full article

(This article belongs to the Special Issue Stylolites: Development, Properties, Inversion and Scaling)

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20 pages, 4860 KiB

Open AccessArticle

Influence and Mechanism of Structural Characteristics of Limestone on Quicklime Reaction Activity

by Zehao Yang, Jing Wu, Zhiqin Huang, Yong Zhu, Weikang Liang and Minjie Zhu

Minerals 2025, 15(1), 72; https://doi.org/10.3390/min15010072 - 13 Jan 2025

Viewed by 632

Abstract

Quicklime (CaO) is extensively used in metallurgy, chemical engineering, materials science, and greenhouse gas reduction due to its high reactivity, low energy consumption, and environmental benefits. It is considered as one of the most promising raw materials for nanomaterial synthesis and carbon dioxide [...] Read more.

Quicklime (CaO) is extensively used in metallurgy, chemical engineering, materials science, and greenhouse gas reduction due to its high reactivity, low energy consumption, and environmental benefits. It is considered as one of the most promising raw materials for nanomaterial synthesis and carbon dioxide capture. Previous studies have predominantly focused on the impact of limestone composition and calcination condition. Recent research, however, suggests that the structural characteristics of limestone also play a crucial role in determining the reactivity of quicklime. This study investigates the effect of limestone structure on quicklime reactivity and provides a mechanistic analysis. Three types of limestone with varying structures—clastic-structured, transitional-crystalline-structured, and crystalline-structured—were selected for experiments under different calcination times. The results indicate that quicklime produced from clastic-structured limestone exhibits the highest reactivity. The observed differences in quicklime reactivity can primarily be attributed to the following factors: (1) Clastic-structured limestone possesses larger pore volume and specific surface area, which enhance heat conduction and ensure the uniform decomposition of calcite across various regions. (2) The rock-forming calcite particles are fine and small, allowing for the simultaneous decomposition of the outer shell, middle, and core during heating. This prevents “overburning” of the shell or “underfiring” of the core, thereby improving the overall reactivity. Based on these findings, we propose that fine-grained, high-purity clastic-structured limestone is more favorable for producing high-activity quicklime. Full article

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17 pages, 7198 KiB

Open AccessArticle

DCGAN-Based Feature Augmentation: A Novel Approach for Efficient Mineralization Prediction Through Data Generation

by Soran Qaderi, Abbas Maghsoudi, Amin Beiranvand Pour, Abdorrahman Rajabi and Mahyar Yousefi

Minerals 2025, 15(1), 71; https://doi.org/10.3390/min15010071 - 13 Jan 2025

Viewed by 669

Abstract

This study aims to improve the efficiency of mineral exploration by introducing a novel application of Deep Convolutional Generative Adversarial Networks (DCGANs) to augment geological evidence layers. By training a DCGAN model with existing geological, geochemical, and remote sensing data, we have synthesized [...] Read more.

This study aims to improve the efficiency of mineral exploration by introducing a novel application of Deep Convolutional Generative Adversarial Networks (DCGANs) to augment geological evidence layers. By training a DCGAN model with existing geological, geochemical, and remote sensing data, we have synthesized new, plausible layers of evidence that reveal unrecognized patterns and correlations. This approach deepens the understanding of the controlling factors in the formation of mineral deposits. The implications of this research are significant and could improve the efficiency and success rate of mineral exploration projects by providing more reliable and comprehensive data for decision-making. The predictive map created using the proposed feature augmentation technique covered all known deposits in only 18% of the study area. Full article

(This article belongs to the Special Issue Advancements in Mineral Resource Characterization Using Machine Learning)

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17 pages, 3835 KiB

Open AccessArticle

U-Pb and Hf Isotopic Analyses for Detrital Zircon of the Danzhou Group in the Western Jiangnan Orogenic Belt and Tectonic Implications

by Jingna Liu, Xianglin Huang, Xiyue Xia and Xiuping Li

Minerals 2025, 15(1), 70; https://doi.org/10.3390/min15010070 - 13 Jan 2025

Viewed by 430

Abstract

In order to better constrain the specific depositional age and provenance of the Danzhou Group and understand the geological evolution of the Jiangnan Orogenic Belt, we conducted a combined U-Pb and Hf-isotope analysis of detrital zircons from the Gongdong and Hetong formations of [...] Read more.

In order to better constrain the specific depositional age and provenance of the Danzhou Group and understand the geological evolution of the Jiangnan Orogenic Belt, we conducted a combined U-Pb and Hf-isotope analysis of detrital zircons from the Gongdong and Hetong formations of the Danzhou Group in the Longsheng area of the Western Jiangnan Orogenic Belt. Detrital zircons from the Gongdong Formation yield three age populations of 2658–2517 Ma, 2427–1678 Ma and 891–781 Ma, and the youngest ages suggest that the sedimentation began after ca. 783 Ma. U-Pb ages of detrital zircons from the Hetong Formation yield major populations at 2769–2502 Ma, 2492–2100 Ma, and 991–731 Ma, and the youngest ages redefine the maximum depositional age of this unit is 760 Ma, much younger than previously considered. Thus, the upper part of the Hetong Formation in the Longsheng area is newly subdivided into the Sanmenjie Formation, which is characterized by a large amount of 765–761 Ma volcanic rocks. The dominant 991–731 Ma detrital zircons for all samples were likely sourced from the Neoproterozoic igneous rocks of the southeast margin of the Yangtze Block. The subordinate 2494–1678 Ma detrital zircons were probably sourced from the Cathaysia Block. Minor amounts of 2769–2502 Ma detrital zircons may have been sourced from the Yangtze Block. Detrital zircons from the Gongdong Formation have mainly negative εHf (t) values (−1.1 to 21.8, 90%), suggesting that the detritus of the Gongdong Formation is dominated by the recycling of old crustal materials. The εHf (t) values of detrital zircons from the Hetong Formation have a large spread of −22.2 to +9.7, indicating that the source material of the Hetong Formation includes both the juvenile crustal materials and the recycled ancient crustal materials. The above age populations and Hf isotopic characteristics are consistent with the magmatic rocks in the Jiangnan Orogenic Belt and the Southeast Yangtze Block. Taking into account the lithostratigraphic features, provenances, and depositional ages, the Danzhou Group in the Western Jiangnan Orogenic Belt was deposited in a back-arc basin. Full article

(This article belongs to the Special Issue Tracing Precambrian Pathways: Neoproterozoic Rocks and Their Global Context)

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14 pages, 6053 KiB

Open AccessArticle

The Source and Significance of Silicon in the Late Permian Dalong Formation, Northeastern Sichuan Basin

by Xiaotong Ge, Xun Ge, Daizhao Chen, Yali Liu, Ruyue Wang and Min Li

Minerals 2025, 15(1), 69; https://doi.org/10.3390/min15010069 - 13 Jan 2025

Viewed by 384

Abstract

The Late Permian was a critical interval in geological history, during which dramatic changes occurred in the Earth’s surface system, and a set of black rock series rich in organic matter and silicon, the Dalong Formation, was deposited in the northeastern Sichuan Basin. [...] Read more.

The Late Permian was a critical interval in geological history, during which dramatic changes occurred in the Earth’s surface system, and a set of black rock series rich in organic matter and silicon, the Dalong Formation, was deposited in the northeastern Sichuan Basin. We conducted a detailed sedimentological and petrological investigation integrated with (major and trace) element contents in the deep-water sequence of the Xibeixiang and Jianfeng sections. It demonstrates the source of silicon, tectonic background, and sedimentary environment of the Dalong Formation, and explores the influence of hydrothermal activities on organic matter enrichment. The results show that the upper part of the Dalong Formation contained more radiolarians in the Xibeixiang section compared to the Jianfeng section. Hydrothermal proxies such as Eu/Eu*, Al-Fe-Mn diagram, Al/(Al + Fe + Mn), and Lu_N/La_N suggest a biotic origin for the chert in the Dalong Formation in the Xibeixiang and Jianfeng sections, while the Xibeixiang section was slightly affected by hydrothermal activities. The La-Th-Sc diagram and the La/Sc and Ti/Zr crossplots point to a continental island arc and active continental margin origins for the Xibeixiang and Jianfeng sections. Combined with previous research, the silicon of the Dalong Formation in the northeastern Sichuan Basin is mainly derived from biological sources. The Xibeixiang section was affected by a small amount of hydrothermal fluid due to its proximity to the Paleo-Tethys Ocean and continental island arcs. Furthermore, the enrichment of organic matter was predominantly driven by high productivity, with minimal impact from hydrothermal activities. These insights hold significant research value and practical implications for shale gas exploration in the Sichuan Basin. Full article

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

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21 pages, 4425 KiB

Open AccessFeature PaperArticle

Transition of CO₂ from Emissions to Sequestration During Chemical Weathering of Ultramafic and Mafic Mine Tailings

by Xiaolin Zhang, Long-Fei Gou, Liang Tang, Shen Liu, Tim T. Werner, Feng Jiang, Yinger Deng and Amogh Mudbhatkal

Minerals 2025, 15(1), 68; https://doi.org/10.3390/min15010068 - 12 Jan 2025

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Abstract

Weather-enhanced sulphide oxidation accelerates CO₂ release into the atmosphere. However, over extended geological timescales, ultramafic and mafic magmatic minerals may transition from being sources of CO₂ emissions to reservoirs for carbon sequestration. Ultramafic and mafic mine tailings present a unique opportunity [...] Read more.

Weather-enhanced sulphide oxidation accelerates CO₂ release into the atmosphere. However, over extended geological timescales, ultramafic and mafic magmatic minerals may transition from being sources of CO₂ emissions to reservoirs for carbon sequestration. Ultramafic and mafic mine tailings present a unique opportunity to monitor carbon balance processes, as mine waste undergoes instantaneous and rapid chemical weathering, which shortens the duration between CO₂ release and absorption. In this study, we analysed 30 vanadium-titanium magnetite mine tailings ponds with varying closure times in the Panxi region of China, where ~60 years of mineral excavation and dressing have produced significant outcrops of mega-mine waste. Our analysis of anions, cations, saturation simulations, and ⁸⁷Sr/⁸⁶Sr; δ¹³C and δ³⁴S isotopic fingerprints from mine tailings filtrates reveals that the dissolution load of mine tailings may depend significantly on early-stage sulphide oxidation. Despite the abundance of ultramafic and mafic minerals in tailings, dolomite dominates chemical weathering, accounting for ~79.2% of the cationic load. Additionally, due to sulphuric-carbonate weathering, the filtrates undergo deacidification along with sulphide depletion. The data in this study suggest that pristine V-Ti-Fe tailings ponds undergo CO₂ emissions in the first two years but subsequently begin to absorb atmospheric CO₂ along with the filtrates. Our results provide valuable insights into monitoring weathering transitions and carbon balance in ultramafic and mafic rocks. Full article

(This article belongs to the Special Issue CO2 Mineralization and Utilization)

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27 pages, 13692 KiB

Open AccessArticle

Evolution of the Hydrothermal Fluids Inferred from the Occurrence and Isotope Characteristics of the Carbonate Minerals at the Pogo Gold Deposit, Alaska, USA

by Yuichi Morishita and Jamie R. Rogers

Minerals 2025, 15(1), 67; https://doi.org/10.3390/min15010067 - 12 Jan 2025

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Abstract

Pogo is identified as a deep-seated, intrusion-related gold deposit. Carbonate minerals have a close spatial relationship to hydrothermal gold mineralization in all of its principal ore zones. The carbon and oxygen isotopic ratios of carbonate minerals (siderite, ankerite, and calcite) present within the [...] Read more.

Pogo is identified as a deep-seated, intrusion-related gold deposit. Carbonate minerals have a close spatial relationship to hydrothermal gold mineralization in all of its principal ore zones. The carbon and oxygen isotopic ratios of carbonate minerals (siderite, ankerite, and calcite) present within the deposit illustrate the isotopic evolution of the ore-forming fluid. The initial hydrothermal fluid phase is interpreted to be magmatic in origin. The fluid evolution was characterized by a gradual decrease in δ¹⁸O and a slight increase in δ¹³C with decreasing temperature. The dominant carbon-bearing species was CO₂, with methane introduced sporadically. Siderite is associated with early-stage mineralization and occurs with ankerite in main-stage ore assemblages. Calcite is recognized in the later stages of mineralization. Gold in the Pogo deposit occurs as native gold, Au-Bi-Te minerals, inclusions in sulfide minerals, or as “invisible gold”. The latter is found in pyrite, chalcopyrite, arsenopyrite, and quartz, based on ion microprobe analysis. The presence of invisible gold in these minerals has significant metallurgical implications for gold processing at the Pogo mine. Full article

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

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16 pages, 22557 KiB

Open AccessArticle

HRTEM Study of Desulfurization of Pt- and Pd-Rich Sulfides from New Caledonia Ophiolite

by Néstor Cano, José M. González-Jiménez, Fernando Gervilla and Thomas N. Kerestedjian

Minerals 2025, 15(1), 66; https://doi.org/10.3390/min15010066 - 12 Jan 2025

Viewed by 493

Abstract

Oxygen-bearing platinum group minerals (O-bearing PGMs) are intergrown with base metal sulfides (BMS, e.g., pentlandite–[NiFe]₉S₈) within fractures in chromite grains from chromitite bodies on Ouen Island, New Caledonia. These PGMs are hosted in chlorite and serpentine, which formed during [...] Read more.

Oxygen-bearing platinum group minerals (O-bearing PGMs) are intergrown with base metal sulfides (BMS, e.g., pentlandite–[NiFe]₉S₈) within fractures in chromite grains from chromitite bodies on Ouen Island, New Caledonia. These PGMs are hosted in chlorite and serpentine, which formed during serpentinization of olivine and pyroxene. The O-bearing PGM grains are polygonal, show microfracturing (indicating volume loss), and contain Pt-Pd-rich sulfide remnants, suggesting pseudomorphic replacement of primary (magmatic) sulfides. They display chemical zonation, with Pt(-Pd-Ni-Fe) relict sulfide cores replaced by Pt-Fe-Ni oxidized alloy mantles and Pt-Cu-Fe(-Pd) alloy rims (tulameenite), indicating desulfurization. The core and mantle show a nanoporous structure, interpreted as the result of coupled dissolution–reprecipitation reactions between magmatic sulfides and low fO₂–fS₂ serpentinite-related fluids, probably formed during olivine transformation to serpentine + magnetite (early stages of serpentinization). This fluid infiltrated magmatic sulfides (PGE-rich and BMS), degrading them to secondary products and releasing S and metals that were accommodated in the mantle and rim of O-bearing PGMs. Upon olivine exhaustion, an increase in fO₂ might have stabilized Pt-Fe-O compounds (likely Pt⁰/Pt-Fe + Fe oxyhydroxides) alongside Ni-Fe alloys. Our results show that post-magmatic desulfurization of primary sulfides produces complex nano-scale intergrowths, mainly driven by changes in the fluid’s physicochemical properties during serpentinization. Full article

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

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