Minerals

29 pages, 28833 KiB

Open AccessArticle

Mineralization Styles in the Orogenic (Quartz Vein) Gold Deposits of the Eastern Kazakhstan Gold Belt: Implications for Regional Prospecting

by Dmitry L. Konopelko, Valeriia S. Zhdanova, Sergei Y. Stepanov, Ekaterina S. Sidorova, Sergei V. Petrov, Aleksandr K. Kozin, Emil S. Aliyev, Vasiliy A. Saltanov, Mikhail A. Kalinin, Andrey V. Korneev and Reimar Seltmann

Minerals 2025, 15(8), 885; https://doi.org/10.3390/min15080885 - 21 Aug 2025

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Abstract

The Eastern Kazakhstan Gold Belt is a major black-shale-hosted gold province in Central Asia where the main types of deposits comprise mineralized zones with auriferous sulfides (micro- and nano-inclusions of gold and refractory gold) and quartz veins with visible gold. The quartz vein [...] Read more.

The Eastern Kazakhstan Gold Belt is a major black-shale-hosted gold province in Central Asia where the main types of deposits comprise mineralized zones with auriferous sulfides (micro- and nano-inclusions of gold and refractory gold) and quartz veins with visible gold. The quartz vein deposits are economically less important but may potentially represent the upper parts of bigger ore systems concealed at depth. In this work, the mineralogy of the quartz vein deposits and related wall rock alteration zones was studied using microscopy and SEM-EDS analysis, and the geochemical dispersion of the ore elements in primary alteration haloes was documented utilizing spatial distribution maps and statistical treatment methods. The studied auriferous quartz veins are classified as epizonal black-shale-hosted orogenic gold deposits. The veins generally have linear shapes with an average width of ca. 1 m and length up to 150 m and contain high-grade native gold with minor amounts of sulfides. In supergene oxidation zones, the native gold is closely associated with Fe-hydroxide minerals cementing brecciated zones within the veins. The auriferous quartz veins are usually enclosed by the wall rock alteration envelopes, where two types of alteration are distinguished. Proximal phyllic alteration (sericite-albite-pyrite ± chlorite, Fe-Mg-Ca carbonates, arsenopyrite, and pyrrhotite) develops as localized alteration envelopes, and pervasive carbonation accompanied by chlorite ± sericite and albite is the dominant process in the distal alteration zones. The rocks within the alteration zones are enriched in Au and chalcophile elements, and three groups of chemical elements showing significant positive mutual correlation have been identified: (1) an early geochemical assemblage includes V, P, and Co (±Ni), which are the chemical elements characteristic for black shale formations, (2) association of Au, As, and other chalcophile elements is distinctly overprinting, and manifests the main stage of sulfide-hosted Au mineralization, and (3) association of Bi and Hg (±Sb and U) includes the chemical elements that are mobile at low temperatures, and can be explained by activity of the late-stage hydrothermal or supergene fluids. The chalcophile elements show negative slopes from proximal to distal alteration zones and form overlapping positive anomalies on spatial distribution mono-elemental maps. Thus, the geochemical methods can provide useful tools to delineate the ore elemental associations and to outline reproducible anomalies for subsequent regional gold prospecting. Full article

(This article belongs to the Special Issue Structure and Origin of Gold Mineralization: From Primary to Placer Gold Deposits)

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20 pages, 3784 KiB

Open AccessArticle

Mineralogical Characterization and Provenance of Black Sand in the Xiahenan Area, Tarim Large Igneous Province

by Songqiu Zhang, Renyu Zeng, Shigang Duan, Jiayong Pan, Dong Liang, Jie Yan, Jianjun Wan, Qing Liu and You Zhang

Minerals 2025, 15(8), 884; https://doi.org/10.3390/min15080884 - 21 Aug 2025

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Abstract

The Tarim Large Igneous Province (TLIP) in NW China hosts abundant Fe–Ti–V oxide deposits associated with mafic–ultramafic intrusions. In the Xiahenan area, on the western margin of the TLIP, a distinct magnetic anomaly is linked to widespread surface accumulations of black sand. However, [...] Read more.

The Tarim Large Igneous Province (TLIP) in NW China hosts abundant Fe–Ti–V oxide deposits associated with mafic–ultramafic intrusions. In the Xiahenan area, on the western margin of the TLIP, a distinct magnetic anomaly is linked to widespread surface accumulations of black sand. However, the genesis and origin of these black sand grains remain unclear. Based on mineral assemblages, this study classifies the grains of the black sand into three types: (i) plagioclase (An_10–90)–ilmenite–olivine–magnetite assemblage (Sand I), (ii) plagioclase (An_0–10)-fine-grained magnetite assemblage (Sand II), and (iii) hornblende–magnetite highly complex assemblage (Sand III). Mineral geochemical studies demonstrate that magnetite in Sand I and Sand II is of magmatic origin, with protolith being basaltic magma. Magnetite in Sand III was eroded from veins formed by hydrothermal processes at 300–500 °C. Ilmenite in Sand I contains a high FeTiO₃ component, representing basaltic ilmenite. Olivine in Sand I has a low Fo content (43.86–47.27), belonging to hortonolite olivine. Research indicates that Sand I and Sand II share similar mineral assemblages and mineral geochemical characteristics with basalts in the Xiahenan area, suggesting they are weathering products of Xiahenan basalts or their cognate magmas. In contrast, the veined magnetite of Sand III formed during post-magmatic hydrothermal events. Full article

(This article belongs to the Special Issue Mineralization and Metallogeny of Iron Deposits)

18 pages, 2307 KiB

Open AccessArticle

Technological Properties Contrast of Galena, Sphalerite, Carbonaceous Material and Choice of Flotation Technology

by Akim Yergeshev, Rustam Tokpayev, Marina Karmeeva, Tamina Khavaza, Nazymarzu Yergesheva, Azhar Atchabarova, Mikhail Nauryzbayev and Vladislava Ignatkina

Minerals 2025, 15(8), 883; https://doi.org/10.3390/min15080883 - 21 Aug 2025

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Abstract

The presence of galena, sphalerite (cleiophane), and Carbonaceous Material (CM) in sulphide ore complicates the application of a direct-differential flotation flowsheet due to increased mutual interactions between both marketable concentrates and final tailings. Flotation tests, measurements of electrokinetic (zeta) potential, adsorption of sulphydric [...] Read more.

The presence of galena, sphalerite (cleiophane), and Carbonaceous Material (CM) in sulphide ore complicates the application of a direct-differential flotation flowsheet due to increased mutual interactions between both marketable concentrates and final tailings. Flotation tests, measurements of electrokinetic (zeta) potential, adsorption of sulphydric collectors, and colorimetric indicators were employed to elucidate the cause-and-effect relationships underlying the reduction in contrast of the flotation properties of galena and cleiophane surfaces. It was established that galena and cleiophane exhibit comparable flotation responses when using diesel oil within a pH range of 6–8. While high galena recovery is anticipated, the similar recovery of cleiophane is attributed to the ZnS zeta potential approaching zero in this pH interval. Experimental results demonstrated a distinct difference in the flotation behavior of galena and cleiophane, both with natural surface oxidation and following the removal of sulphoxy films. The application of Carbonaceous Material depressants derived from wood processing by-products (lignin-sulphonates) resulted in a significant decrease in sphalerite recovery. Although the flotation rate constant for Carbonaceous Material in the presence of lignin-sulphonate-based depressants decreases, the overall recovery to concentrate increases over time. The implementation of a bulk-differential flowsheet, involving the preliminary removal of CM prior to the bulk Pb-Zn flotation of lead-zinc sulphide ore, has been demonstrated to be effective. Full article

(This article belongs to the Special Issue Mineral Processing and Recycling Technologies for Sustainable Future)

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35 pages, 10915 KiB

Open AccessReview

Geochemistry of Mars with Laser-Induced Breakdown Spectroscopy (LIBS): ChemCam, SuperCam, and MarSCoDe

by Roger C. Wiens, Agnes Cousin, Samuel M. Clegg, Olivier Gasnault, Zhaopeng Chen, Sylvestre Maurice and Rong Shu

Minerals 2025, 15(8), 882; https://doi.org/10.3390/min15080882 - 21 Aug 2025

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Abstract

Laser-induced breakdown spectroscopy (LIBS) has been used to explore the chemistry of three regions of Mars on respective missions by NASA and CNSA, with CNES contributions. All three LIBS instruments use ~100 mm diameter telescopes projecting pulsed infrared laser beams of 10–14 mJ [...] Read more.

Laser-induced breakdown spectroscopy (LIBS) has been used to explore the chemistry of three regions of Mars on respective missions by NASA and CNSA, with CNES contributions. All three LIBS instruments use ~100 mm diameter telescopes projecting pulsed infrared laser beams of 10–14 mJ to enable LIBS at 2–10 m distances, eliminating the need to position the rover and instrument directly onto targets. Over 1.3 million LIBS spectra have been used to provide routine compositions for eight major elements and several minor and trace elements on >3000 targets on Mars. Onboard calibration targets common to all three instruments allow careful intercomparison of results. Operating over thirteen years, ChemCam on Curiosity has explored lacustrine sediments and diagenetic features in Gale crater, which was a long-lasting (>1 My) lake during Mars’ Hesperian period. SuperCam on Perseverance is exploring the ultramafic igneous floor, fluvial–deltaic features, and the rim of Jezero crater. MarSCoDe on the Zhurong rover investigated for one year the local blocks, soils, and transverse aeolian ridges of Utopia Planitia. The pioneering work of these three stand-off LIBS instruments paves the way for future space exploration with LIBS, where advantages of light-element (H, C, N, O) quantification can be used on icy regions. Full article

(This article belongs to the Special Issue Understanding Geological Processes through Laser-Induced Breakdown Spectroscopy Analysis)

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22 pages, 2291 KiB

Open AccessArticle

Heavy Metal Pollution Assessment and Survey of Rhizosphere Bacterial Communities from Saccharum spontaneum L. in a Rehabilitated Nickel-Laterite Mine in the Philippines

by Shiela W. Mainit, Carlito Baltazar Tabelin, Florifern C. Paglinawan, Jaime Q. Guihawan, Alissa Jane S. Mondejar, Vannie Joy T. Resabal, Maria Reina Suzette B. Madamba, Dennis Alonzo, Aileen H. Orbecido, Michael Angelo Promentilla, Joshua B. Zoleta, Dayle Tranz Daño, Ilhwan Park, Mayumi Ito, Takahiko Arima, Theerayut Phengsaart and Mylah Villacorte-Tabelin

Minerals 2025, 15(8), 881; https://doi.org/10.3390/min15080881 - 21 Aug 2025

Viewed by 399

Abstract

In this study, we assessed soil pollutants and surveyed the bacterial communities using 16S rRNA sequencing to better understand how to improve rehabilitation strategies for nickel-laterite mines in the Philippines. Representative soil samples and rhizospheres from Saccharum spontaneum L. in three post-mining sites [...] Read more.

In this study, we assessed soil pollutants and surveyed the bacterial communities using 16S rRNA sequencing to better understand how to improve rehabilitation strategies for nickel-laterite mines in the Philippines. Representative soil samples and rhizospheres from Saccharum spontaneum L. in three post-mining sites rehabilitated in 2015, 2017, and 2019 were collected and analyzed. X-ray diffraction (XRD) identified iron oxyhydroxides, silicates, and clays as major soil components. Based on the pollution load index and contamination degree, the 2015A and 2015B sites were classified as “pristine” and had a “low degree of pollution”, while the remaining sites (2017A, 2017B, 2019A, and 2019B) were considered “moderately contaminated” with nickel, chromium, cobalt, lead, zinc, and copper. An analysis of the bacterial community composition revealed that the phyla Proteobacteria and Actinobacteria, along with the genus Ralstonia, were the most abundant groups across both control and rehabilitated sites. Our results showed that the soil pH and organic matter contents were strongly linked to specific bacterial community composition. These taxa have potential for inoculation in nickel-laterite soils to promote the growth of hyperaccumulator plants. Our results also showed a significant correlation between the structure of the bacterial communities and nickel, chromium, and manganese soil contents, but not with rehabilitation time. Furthermore, we identified the genera Diaphorobacter as potential bioindicators because they are sensitive to nickel and chromium. This study provides valuable baseline data on heavy metal pollution and microbial diversity in a rehabilitated Ni-laterite mine site. Full article

(This article belongs to the Special Issue Sustainable Mining: Advancements, Challenges and Future Directions)

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16 pages, 5670 KiB

Open AccessArticle

Experimental Investigation on Spontaneous Combustion Characteristics of Sulfide Ores with Different Sulfur Content

by Qisong Huang, Bo Xu, Junjun Feng, Yugen Lu, Xiangyu Wang and Qinglang Liu

Minerals 2025, 15(8), 880; https://doi.org/10.3390/min15080880 - 21 Aug 2025

Viewed by 118

Abstract

The spontaneous combustion of sulfide ores (SOSC) is an extremely dangerous mining disaster that directly threatens safety production in mines and causes far-reaching negative impacts on the surrounding ecosystem. In this study, oxidation weight gain experiments, self-heating temperature and ignition temperature tests, and [...] Read more.

The spontaneous combustion of sulfide ores (SOSC) is an extremely dangerous mining disaster that directly threatens safety production in mines and causes far-reaching negative impacts on the surrounding ecosystem. In this study, oxidation weight gain experiments, self-heating temperature and ignition temperature tests, and thermogravimetric analysis (TGA) were conducted to detect the spontaneous combustion characteristics of sulfide ores with different sulfur contents (40.29%, 34.56%, 24.81%, and 14.2%). The results show that the sulfur content significantly affects the spontaneous combustion characteristics of sulfide ores. As the sulfur content decreased, the oxidized weight gain rate decreased overall, and the self-heating temperature (135, 152.5, 162.5, and 176.9 °C) and ignition temperature (425.3, 438.6, 455.4, and >500 °C) increased. The three combustion stages of the SOSC were divided based on the TG and DTG curves: low-temperature oxidation stage, combustion decomposition stage, and slow burnout stage. Furthermore, KAS and FWO methods were used to obtain the apparent activation energy in the combustion decomposition stage. The apparent activation energy decreased significantly with the increase in the sulfur content. The results of all experiments and analyses showed that sulfide ores with high sulfur content have a stronger tendency to undergo spontaneous combustion. The research results have important theoretical and practical implications for the prevention of SOSC. Full article

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

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16 pages, 7939 KiB

Open AccessArticle

Assessment of the Valorization Potential of Municipal Sewage Treatment Plant (STP) Sludge to Produce Red-Firing Wall Tiles

by Isabela Oliveira Rangel Areias, Felipe Sardinha Maciel and José Nilson França Holanda

Minerals 2025, 15(8), 879; https://doi.org/10.3390/min15080879 - 21 Aug 2025

Viewed by 165

Abstract

Municipal sewage treatment plants generate significant amounts of polluting sludge, which demands innovative valorization approaches to support its sustainable recycling. This work aimed to evaluate the valorization potential of sludge from a municipal sewage treatment plant (STP) as an alternative raw material to [...] Read more.

Municipal sewage treatment plants generate significant amounts of polluting sludge, which demands innovative valorization approaches to support its sustainable recycling. This work aimed to evaluate the valorization potential of sludge from a municipal sewage treatment plant (STP) as an alternative raw material to traditional limestone in red wall tile formulations. For this purpose, four red wall tile formulations were performed with 0%, 5%, 10%, and 15% weight of STP sludge replacing traditional limestone. The tile formulations prepared by the dry process were characterized to determine their chemical and mineral compositions, thermal analysis, and sintering behavior. The red wall tile pieces were manufactured by pressing and firing at temperatures ranging from 1150 °C to 1180 °C. The effects of STP sludge incorporation and firing temperature on the densification behavior and technological properties were investigated. The results indicated that the STP sludge exhibited good chemical compatibility for use in red wall tile formulations. Water absorption values varied between 16.52% and 19.70%, indicating compliance with the red wall tile production (BIII group). These findings demonstrate the valorization potential of STP sludge in red wall tiles, which offers a relevant recycling option for the sanitation sector and the circular economy. Full article

(This article belongs to the Special Issue From Clay Minerals to Ceramics: Progress and Challenges)

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13 pages, 7481 KiB

Open AccessArticle

Influence of Hydration on Shale Reservoirs: A Case Study of Gulong Shale Oil

by Feifei Fang, Ke Xu, Yu Zhang, Yu Wang, Zhimin Xu, Sijie He, Hui Huang, Hailong Wang, Weixiang Jin and Yue Gong

Minerals 2025, 15(8), 878; https://doi.org/10.3390/min15080878 - 21 Aug 2025

Viewed by 186

Abstract

In the process of the exploration and development of shale oil, the influence of hydration on shale reservoirs is complex, as it can not only improve porosity and permeability, but also lead to reservoir instability. At present, there is a lack of systematic [...] Read more.

In the process of the exploration and development of shale oil, the influence of hydration on shale reservoirs is complex, as it can not only improve porosity and permeability, but also lead to reservoir instability. At present, there is a lack of systematic understanding of the influence of hydration on the physical and chemical properties of shale oil reservoirs. Therefore, in this study, taking the Gulong shale oil reservoir in Songliao Basin as the research object, X-ray diffraction mineral composition analysis, electron microscope scanning, and micro-CT scanning were used to study the micro–macro-changes in shale caused by hydration, and the effects of different fracturing fluids on hydration were evaluated. The results show the following: (1) Hydration increases the porosity and permeability of Gulong shale through clay dispersion and dissolution pore formation, though these transient effects may compromise long-term reservoir stability due to pore-throat clogging. (2) Prolonged hydration significantly enhanced pore structure complexity, with tortuosity increasing by 64.7% (from 2.19 to 3.60) and the fractal dimension rising by 7.5% (from 1.99 to 2.14) with hydration time, and the proportion of larger pores (50–100 μm) increased significantly. (3) Hydration leads to crack propagation and new cracks, and the intersection of cracks reduces the core strength, which may eventually lead to macroscopic damage. (4) The influence of different fracturing fluids on the hydration reaction is obviously different. The higher the concentration, the stronger the hydration effect. Distilled water helps to increase porosity and permeability, but long-term effects may affect reservoir stability. The results of this paper reveal the changes in micro- and macro-characteristics of shale oil reservoirs under hydration, which is of great significance for analyzing the mechanism of hydration and provides theoretical support for improving shale oil recovery. 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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19 pages, 4176 KiB

Open AccessArticle

Identification of Mineral Pigments on Red- and Dark-Decorated Prehistoric Pottery from Bulgaria

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

Minerals 2025, 15(8), 877; https://doi.org/10.3390/min15080877 - 20 Aug 2025

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Abstract

Identifying the mineral pigments used in the decoration of prehistoric pottery is a significant step for understanding the evolution of the technological practices over time. On the Balkan Peninsula during late prehistory, the techniques used for red and dark-colored decorations underwent a significant [...] Read more.

Identifying the mineral pigments used in the decoration of prehistoric pottery is a significant step for understanding the evolution of the technological practices over time. On the Balkan Peninsula during late prehistory, the techniques used for red and dark-colored decorations underwent a significant transformation. In the Early Neolithic period, pottery was often decorated with dark-toned paints, ranging from deep red to brown. However, this approach declined noticeably during the Chalcolithic period, when red pigment pseudo-incrustation became the predominant decorative method. This study aims to identify the mineral pigments used in red and dark decorations on Neolithic and Chalcolithic pottery from Bulgaria and to trace possible technological, regional, or chronological variations in their composition. A total of 34 ceramic sherds, decorated in shades from red to brown and black, were analyzed using two complementary spectroscopic techniques: laser-induced breakdown spectroscopy (LIBS) and Fourier-transform infrared spectroscopy (FTIR). LIBS data were further evaluated using principal component analysis (PCA) to classify materials based on elemental composition. The results indicate that red decorations are consistently composed of hematite and remain compositionally stable regardless of the region, time period, or application technique. In contrast, dark decorations contain various combinations of iron oxides (magnetite and hematite) and manganese oxides, often including barium-rich manganese compounds—potentially indicating pigment provenance. Additionally, the dark decorations display regional differences. Full article

(This article belongs to the Special Issue Mineral Pigments: Properties Analysis and Applications)

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18 pages, 7705 KiB

Open AccessArticle

Mineral Liberation Analysis (MLA)-Based Characterization of Lithium Source: Biotite and Associated Minerals in Nepheline Syenites

by Zeynep Üçerler-Çamur, Ozgul Keles and Murat Olgaç Kangal

Minerals 2025, 15(8), 876; https://doi.org/10.3390/min15080876 - 20 Aug 2025

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Abstract

Due to the rapid advancement of technology, lithium carbonate has become a crucial raw material for battery storage applications. Brines remain the primary source, while lithium carbonate production from ores is limited. Therefore, expanding resources, identifying potential deposits, and characterizing existing sources are [...] Read more.

Due to the rapid advancement of technology, lithium carbonate has become a crucial raw material for battery storage applications. Brines remain the primary source, while lithium carbonate production from ores is limited. Therefore, expanding resources, identifying potential deposits, and characterizing existing sources are essential. Direct lithium detection via MLA is challenging due to its atomic number being below 6; however, it can be indirectly identified through lithium-bearing biotite. This study characterizes lithium-bearing biotite in nepheline syenite ore, considering biotite as the primary lithium source. Analytical methods included MLA, modal mineralogy, XRD, ICP-OES, XRF, SEM-BSE, and EDS. The ore contained 4% biotite, with a liberation degree exceeding 70% in particles finer than 500 µm. Biotite formed binary, ternary, and complex associations with K-feldspar, nepheline, and albite. Finer particle sizes increased biotite liberation while reducing associations; no binary biotite–nepheline associations were detected below 75 µm. EDS spectra confirmed biotite as the sole lithium-bearing mineral. Full article

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

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14 pages, 2536 KiB

Open AccessArticle

Geochemistry and Genetic Significance of Scheelite in the Nanwenhe Tungsten Deposit, Yunnan Province, Southwestern China

by Wei Wang, Shao-Yong Jiang, Kexin Wang, Yu-Ying Che and Shugang Xiao

Minerals 2025, 15(8), 875; https://doi.org/10.3390/min15080875 - 20 Aug 2025

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Abstract

The Nanwenhe tungsten deposit is located in the southeastern Yunnan Laojunshan mineral district and is hosted in the Paleoproterozoic Mengsong Group strata. It can be divided into two periods and four stages: skarn (early and late) and the vein type (feldspar–quartz–scheelite–tourmaline and calcite. [...] Read more.

The Nanwenhe tungsten deposit is located in the southeastern Yunnan Laojunshan mineral district and is hosted in the Paleoproterozoic Mengsong Group strata. It can be divided into two periods and four stages: skarn (early and late) and the vein type (feldspar–quartz–scheelite–tourmaline and calcite. There are two types of scheelite occurrences: one in skarn (Sch-1) and the other in feldspar–quartz–scheelite–tourmaline veins (Sch-2). The latter is further divided into two types: Sch-2a and Sch-2b. The REE content and Eu anomaly of skarn scheelite (Sch-1) are affected by early mineral crystallization; Sch-2a in feldspar–quartz–scheelite–tourmaline veins forms in a Na⁺-rich environment, and Eu²⁺ released into the fluid through hydrolysis may have largely entered tourmaline, resulting in the weak positive Eu anomaly of Sch-2a; the negative Eu anomaly of Sch-2b is likely inherited from the metamorphic fluid. The mineralization is likely closely related to the metamorphic fluid activity generated by the tensional structural environment at the end and after the regional uplift, forming ore by reducing fluids associated with regional metamorphism. The Laojunshan mineral district hosts several tungsten and tin polymetallic deposits and occurrences that share similar geological characteristics with the Nanwenhe tungsten deposit. No granite bodies related to mineralization have been identified within the mining area. Therefore, research on the genesis of the Nanwenhe tungsten deposit holds significant value for guiding exploration efforts. Full article

(This article belongs to the Special Issue Recent Developments in Rare Metal Mineral Deposits)

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18 pages, 5093 KiB

Open AccessArticle

Advancing Deep Ore Exploration with MobileMT: Rapid 2.5D Inversion of Broadband Airborne EM Data

by Alexander Prikhodko, Aamna Sirohey and Aleksei Philipovich

Minerals 2025, 15(8), 874; https://doi.org/10.3390/min15080874 - 19 Aug 2025

Viewed by 304

Abstract

The increasing demand for critical minerals is forcing the mineral exploration industry to search for deposits beneath deeper cover and over larger areas. MobileMT, an airborne passive, broadband, total-field AFMAG-class system, couples three-component measurements of airborne magnetic field variations with a remote electric-field [...] Read more.

The increasing demand for critical minerals is forcing the mineral exploration industry to search for deposits beneath deeper cover and over larger areas. MobileMT, an airborne passive, broadband, total-field AFMAG-class system, couples three-component measurements of airborne magnetic field variations with a remote electric-field base station to image electrical resistivity from the surface to depths of >1–2 km. We present a workflow that integrates MobileMT data with the parallelized, adaptive finite-element 2.5D open-source inversion code MARE2DEM, accompanied by automated mesh generation procedures, to create a rapid and scalable workflow for deep ore exploration. Using this software on two field trials, we demonstrate that (i) high-frequency (>4 kHz) data are essential for recovering not only shallow geology but also, when combined with low frequencies, for refining deep structures and targets and that (ii) base station effects modify the shape of the apparent conductivity curve but have negligible impact on the inverted sections. The proposed workflow is a reliable and effective approach for identifying mineralization-related features and refining geologic models based on data from extensive airborne geophysical surveys. Full article

(This article belongs to the Special Issue Electromagnetic Inversion for Deep Ore Explorations)

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19 pages, 10525 KiB

Open AccessArticle

Exploring Smoothing and Interpolation in Thellier-Type Paleointensity Determinations

by Lluís Casas, Marc Ortiz and Roberta Di Febo

Minerals 2025, 15(8), 873; https://doi.org/10.3390/min15080873 - 19 Aug 2025

Viewed by 116

Abstract

Smoothing and interpolation of zero-field (Z) and infield (I) heating steps in Thellier-type paleointensity determinations have been tested. Paleomagnetic samples of different materials were artificially magnetized with an applied field of 50 µT. Six samples were measured following the standard double-heating Coe-variation experimental [...] Read more.

Smoothing and interpolation of zero-field (Z) and infield (I) heating steps in Thellier-type paleointensity determinations have been tested. Paleomagnetic samples of different materials were artificially magnetized with an applied field of 50 µT. Six samples were measured following the standard double-heating Coe-variation experimental protocol, and the obtained results were used to test several mathematical functions to smooth the experimental data. The best smoothed results were obtained using a Five Parameters Logistic (5PL) function that resulted in field estimates of good quality, although not better than those obtained experimentally. Therefore, the smoothing of de- and remagnetization data appears unnecessary. In addition to smoothing, the tested functions can be used to interpolate additional Z and, indirectly, also I steps. Interpolation using cubic Hermite splines (without any smoothing) displays a better performance than interpolation (and smoothing) using the 5PL function. A new single-step heating method is presented, combining experimental and interpolated de- and remagnetization steps. The new method would not be applicable for retrieving reliable ancient field intensities on its own, but it could save measuring time under some circumstances. Full article

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16 pages, 8282 KiB

Open AccessArticle

Petrographic, Geochemical, and Geochronological Characteristics of the Granite in Yunnan and Its Constraints on Ion-Adsorption Rare Earth Element Mineralization

by Bin Zhang, Haobin Niu, Linkui Zhang, Binhui Zhang, Xiangping Zhu, Rudong Gao, Yongfei Yang and Yinggui Zou

Minerals 2025, 15(8), 872; https://doi.org/10.3390/min15080872 - 19 Aug 2025

Viewed by 133

Abstract

The TuguanZhai rare earth deposit in Tengchong, along with the Longan and Yingpanshan deposits in Longchuan, is a significant ion-adsorption type rare earth (iREE) deposit in Yunnan, China. Previous studies mainly focused on the geochemistry of residual regolith or the migration and enrichment [...] Read more.

The TuguanZhai rare earth deposit in Tengchong, along with the Longan and Yingpanshan deposits in Longchuan, is a significant ion-adsorption type rare earth (iREE) deposit in Yunnan, China. Previous studies mainly focused on the geochemistry of residual regolith or the migration and enrichment mechanism of rare earth elements (REEs), but lacked systematic analysis of the protoliths. To constrain this deposit and its protolith rock, called Tuguanzhai granite, we systematically integrate petrology features, petrogeochemistry, zircon U-Pb date, and artificial heavy mineral separation (AHMS). Specifically, iREE-host granites include two main periods in this area: the Early Cretaceous (112.13 ± 0.75 Ma) and the Paleocene–Eocene (52.78 ± 0.28 Ma, 48.56 ± 0.19 Ma). The former includes three types of biotite monzogranite with different grain sizes, and the latter is mainly medium-grained biotite monzogranite with local mylonitization. Geochemical features show that these granites generally share high alkalinity compositions (w(K₂O + Na₂O): 7.15 to 12.75 wt%) and potassium contents (w(K₂O): 3.89 to 8.36 wt%). The mineralized granites exhibit significantly higher concentrations of the total REEs than non-mineralized granites, along with a strong enrichment of light REEs. Moreover, the results of AHMS reveal that the REE contents of apatite, allanite, and titanite in mineralized granites are 4.98, 1.29, and 1.90 times more abundant than in non-mineralized granites, respectively. Due to REEs being released from these REE-rich minerals in humid environments, there exists significant potential for iREE formation and exploration in the Early Cretaceous granites in western Yunnan. We innovatively propose the “abundance of easily leachable minerals” as a key indicator for iREE mineralization and exploration, having found it to be better than the traditional total REE contents. Full article

(This article belongs to the Special Issue Recent Developments in Rare Metal Mineral Deposits)

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33 pages, 8120 KiB

Open AccessArticle

Origin of the World-Class Eagle, Eagle East, and Tamarack Ni-Cu-PGE Deposits

by Robert Nowak, Chad Deering and Espree Essig

Minerals 2025, 15(8), 871; https://doi.org/10.3390/min15080871 - 18 Aug 2025

Viewed by 321

Abstract

The 1.1 Ga Mesoproterozoic Midcontinent rift hosts the Eagle, Eagle East, and Tamarack Ni-Cu-PGE deposits and Embayment Prospect. These deposits are hosted by ultramafic igneous rocks and have some of the highest Ni-Cu grades on Earth. We use new bulk-rock data and published [...] Read more.

The 1.1 Ga Mesoproterozoic Midcontinent rift hosts the Eagle, Eagle East, and Tamarack Ni-Cu-PGE deposits and Embayment Prospect. These deposits are hosted by ultramafic igneous rocks and have some of the highest Ni-Cu grades on Earth. We use new bulk-rock data and published datasets (bulk-rock, mineral chemistry, and isotopic analyses) to examine major, minor, and trace element trends of both Midcontinent rift-related alkaline and tholeiitic intrusions. In addition, we compare the geochemical data to local kimberlite-hosted lower-crustal xenoliths and local igneous (Archean) and sedimentary (Paleoproterozoic) country rocks. We found the peridotite magma compositions dominantly consist of primitive mantle compositions with varying abundances of subduction-related components, alkaline-transitional melts, and local country rock contaminates (e.g., Baraga and Animikie Basin sediments). The subduction-related components are interpreted to be derived from previous Archean and Paleoproterozoic subduction events and likely hosted within the sub-continental lithospheric mantle. Importantly, these subduction-related components are also interpreted to have acted as oxidizing agents within the melt, stabilizing sulfate (+2 FMQ (fayalite–magnetite–quartz) to FMQ) while inhibiting sulfide crystallization as the magma ascended through ~50 km of the Superior craton. This study largely corroborates the previous findings with respect to the contribution of local country rock contamination to the Eagle–Tamarack peridotite host rocks, which is estimated to be minimal (<5%). However, the incorporation of <5% reductive pelitic siltstone contamination results in strong shifts in the oxygen fugacity of the peridotite melt, from +2 FMQ to slightly below FMQ, as determined from spinel Fe³⁺/∑Fe ratios. This shift in oxygen fugacity resulted in the transition from total sulfate (+2 FMQ) to sulfate + sulfide (<+2 FMQ to FMQ) to total sulfide (<FMQ). This shift in oxygen fugacity is a key contributor to the formation of Ni-Cu-PGE-rich massive sulfides within the Eagle peridotite. This study presents an expanded geochemical interpretation for the exploration of Midcontinent rift-related Ni-Cu-PGE deposits to include peridotites with subduction-like signatures and contaminated via <5% reductive sedimentary country rocks. Full article

(This article belongs to the Special Issue Critical Mineral Exploration: Innovations, Challenges and Future Directions)

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16 pages, 2065 KiB

Open AccessArticle

Selective Recovery of Zinc from Oxide Ores Using Monosodium Glutamate as a Green Lixiviant

by Yasemin Ozturk

Minerals 2025, 15(8), 870; https://doi.org/10.3390/min15080870 - 18 Aug 2025

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Abstract

This study aims to develop an environmentally friendly hydrometallurgical process for the recovery of zinc from zinc oxide ores. The process includes monosodium glutamate (MSG) leaching, followed by zinc recovery from the pregnant leach solution via electrowinning, and the recirculation of the spent [...] Read more.

This study aims to develop an environmentally friendly hydrometallurgical process for the recovery of zinc from zinc oxide ores. The process includes monosodium glutamate (MSG) leaching, followed by zinc recovery from the pregnant leach solution via electrowinning, and the recirculation of the spent solution to the leaching stage. The study investigated the effects of key leaching parameters and identified the optimal conditions as a pH of 9.5, temperature of 70 °C, 5 h leaching time, solid-to-liquid ratio of 50 g/L, particle size of d₈₀ = 115 µm, and initial MSG concentration of 1.0 M. Under these conditions, 82.3 ± 0.05% of the zinc was extracted with minimal co-dissolution of impurities. Subsequent electrowinning at 100 A/m² for 150 min yielded 74.97 ± 2.43% zinc recovery with 96.4 ± 0.76% purity. The process achieved a current efficiency of 87.08%, while the specific energy consumption was calculated to be 3.98 kWh per kilogram of zinc recovered. The reusability of MSG was examined by recirculating spent electrowinning solution back to the leaching stage. Zinc extraction decreased from 82.2% to 28.5% over three electrowinning–leaching cycles, due to MSG degradation during electrowinning. The results of this study demonstrated that MSG is a selective and effective lixiviant for zinc recovery, while underlining the limitations of its reuse. Full article

(This article belongs to the Special Issue Mineral Processing and Extractive Metallurgy of Sulfide Ores, 2nd Edition)

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22 pages, 7632 KiB

Open AccessArticle

REY Spatial Distribution and Mineral Association in Coal, Carbonaceous Shale and Siltstone: Implications for REE Enrichment Mechanisms

by Laura Wilcock, Lauren P. Birgenheier, Emma A. Morris, Peyton D. Fausett, Haley H. Coe, Diego P. Fernandez, Ryan D. Gall and Michael D. Vanden Berg

Minerals 2025, 15(8), 869; https://doi.org/10.3390/min15080869 - 18 Aug 2025

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Abstract

Rare earth elements (REYs) are crucial components of billions of products worldwide. Transitioning from foreign to domestic REY sources requires utilizing both primary (i.e., carbonatites, alkaline igneous rocks, pegmatites, skarn deposits) and secondary (unconventional) sources (i.e., ion-adsorption clays, placer deposits, weathered rock, black [...] Read more.

Rare earth elements (REYs) are crucial components of billions of products worldwide. Transitioning from foreign to domestic REY sources requires utilizing both primary (i.e., carbonatites, alkaline igneous rocks, pegmatites, skarn deposits) and secondary (unconventional) sources (i.e., ion-adsorption clays, placer deposits, weathered rock, black and/or oil shales). Coal and coal-bearing strata, promising secondary REY resources, are the focus of this study. Understanding REY mineral associations in unconventional resources is essential to quantifying resource volume and identifying viable mineral separation and processing techniques. Highly REY-enriched (>750 ppm) coal or mudstone samples from the Uinta Region, Utah, USA, were selected for scanning electron microscopy (SEM) analysis. Energy dispersive X-ray spectroscopy (EDS)-determined REY enrichment occurs in: (1) a silt-size fraction (5–30 μm) of monazite and xenotime REY-enriched grains, (2) a clay-size fraction (2–5 μm) of monazite REY-enriched grains dispersed in the clay-rich matrix, and (3) organically confined REY domains < 2 μm. Findings suggest possible REY enrichment from multiple sources, including: (1) detrital silt-size grains, (2) volcanic ash fall, largely in clay-size grains, and (3) organic REY uptake in the peat swamp depositional environment. Full article

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

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24 pages, 1738 KiB

Open AccessReview

Biomineralization Mediated by Iron-Oxidizing Microorganisms: Implication for the Immobilization and Transformation of Heavy Metals in AMD

by Siyu Li, Chengcheng Li, Xubo Gao, Mengyun Zhu, Huihui Li and Xue Wang

Minerals 2025, 15(8), 868; https://doi.org/10.3390/min15080868 - 17 Aug 2025

Viewed by 181

Abstract

Iron, an essential element for virtually all known organisms, serves not only as a micronutrient but also as an energy source for bacteria. Iron-oxidizing microorganisms mediate Fe(II) oxidation under diverse redox conditions, yielding amorphous iron (hydr)oxides or crystalline iron minerals. This globally significant [...] Read more.

Iron, an essential element for virtually all known organisms, serves not only as a micronutrient but also as an energy source for bacteria. Iron-oxidizing microorganisms mediate Fe(II) oxidation under diverse redox conditions, yielding amorphous iron (hydr)oxides or crystalline iron minerals. This globally significant biogeochemical process drives modern iron cycling across terrestrial and aquatic ecosystems. The resulting biomineralization not only produces secondary minerals but also effectively immobilizes heavy metals, offering a sustainable strategy for environmental remediation. This review systematically examines (1) the biogeochemical mechanisms and mineralogical signatures of Fe(II) oxidation by four distinct iron oxidizers: acidophilic aerobes (e.g., Acidithiobacillus), neutrophilic microaerophiles (e.g., Gallionella), nitrate-reducing anaerobes (e.g., Acidovorax), and anoxygenic phototrophs (e.g., Rhodobacter); (2) research advances in heavy metal immobilization by biogenic iron minerals: adsorption, coprecipitation, and structural incorporation; and (3) the impact of pH, temperature, organic matter, and coexisting ions on Fe(II) oxidation efficiency and iron mineral formation by iron-oxidizing bacteria. By characterizing iron-oxidizing bacterial species and their functional processes under varying pH and redox conditions, this study provides critical insights into microbial behaviors driving the evolution of acid mine drainage (AMD). Full article

(This article belongs to the Special Issue Challenges of Groundwater Quality Degradation in the Past Decades: Clues from Water–Minerals Interaction, 2nd Edition)

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23 pages, 12244 KiB

Open AccessArticle

The Petrology of Tuffisite in a Trachytic Diatreme from the Kızılcaören Alkaline Silicate–Carbonatite Complex, NW Anatolia

by Yalçın E. Ersoy, Hikmet Yavuz, İbrahim Uysal, Martin R. Palmer and Dirk Müller

Minerals 2025, 15(8), 867; https://doi.org/10.3390/min15080867 - 17 Aug 2025

Viewed by 333

Abstract

The Kızılcaören alkaline silicate–carbonatite complex, located in the Sivrihisar (Eskişehir, NW Anatolia) region, includes phonolite, trachyte, carbonatite, pyroclastics, and REE mineralization (bastnäsite as a critical REE mineral). The emplacement and origin of this complex are poorly constrained, as previous studies mostly concentrated on [...] Read more.

The Kızılcaören alkaline silicate–carbonatite complex, located in the Sivrihisar (Eskişehir, NW Anatolia) region, includes phonolite, trachyte, carbonatite, pyroclastics, and REE mineralization (bastnäsite as a critical REE mineral). The emplacement and origin of this complex are poorly constrained, as previous studies mostly concentrated on the petrology of the alkaline rocks, carbonatite, and REE-mineralization, and little attention has been paid to the texture, composition, and origin of the pyroclastic rocks. The pyroclastic rocks in the region contain both rounded and angular-shaped cognate and wall-rock xenoliths derived from syenitic/trachytic hypabyssal rocks and carbonatites, as well as juvenile components such as carbonatite droplets and pelletal lapilli. The syenitic/trachytic hypabyssal rock fragments contain sanidine with high BaO (up to 3.3 wt.%) contents, amphibole (magnesio-fluoro-arfvedsonite), and apatite. Some clasts seem to have reacted with carbonatitic material, including high-SrO (up to 0.6 wt.%) calcite, dolomite, baryte, benstonite, fluorapatite. The carbonatite rock fragments are composed of calcite, baryte, fluorite, and bastnäsite. The carbonatite droplets have a spinifex-like texture and contain rhombohedral Mg-Fe-Ca carbonate admixtures, baryte, potassic-richterite, and parisite embedded in larger crystals of high-SrO (up to 0.7 wt.%) calcite. The spherical–elliptical pelletal lapilli (2–3 mm) contain a lithic center mantled by flow-aligned prismatic sanidine (with BaO up to 3.5 wt.%) microphenocrysts settled in a high-SrO (up to 0.7 wt.%) cryptocrystalline CaCO₃ matrix. All these components are embedded in an ultra-fine-grained matrix. The EPMA results from the matrix reveal that, chemically, it consists largely of BaO-rich sanidine, with minor carbonate, baryte and Fe-Ti oxide. The presence of pelletal lapilli, which is one of the most common and characteristic features of diatreme fillings in alkaline silicate–carbonatite complexes, reveals that the pyroclastic rocks in the region represent a tuffisite formed by intrusive fragmentation and fluidization processes in the presence of excess volatile components consisting mainly of CO₂ and F. Full article

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

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15 pages, 4750 KiB

Open AccessArticle

Analysis of Occurrence States of Rare Earth Elements in the Carbonatite Deposits in China

by Zuopei Jiang, Ni He, Liang Hu, Yayuan Liu, Jingyi Gong and Hongbo Zhao

Minerals 2025, 15(8), 866; https://doi.org/10.3390/min15080866 - 16 Aug 2025

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Abstract

Rare earth elements (REEs), as necessary elements in many industries, have driven increased demand for mineral exploitation. However, understanding the occurrence states of REEs is crucial for their extraction. Therefore, this work primarily investigated the differences in the occurrence states of REEs and [...] Read more.

Rare earth elements (REEs), as necessary elements in many industries, have driven increased demand for mineral exploitation. However, understanding the occurrence states of REEs is crucial for their extraction. Therefore, this work primarily investigated the differences in the occurrence states of REEs and the thermal decomposition behavior of carbonatite rare earth deposits in China using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray powder diffraction, and X-ray photoelectron spectroscopy. The results showed that the bastnaesite concentrate from the M deposit in southwestern China (referred to herein as B-ore), contained REEs accounting for 53.59%, and was associated with small amounts of wulfenite, barite, and iron ore. In contrast, the contents of REEs in the raw ores of N deposit in northern China (referred to herein as R-ore) was relatively low (3.71%), but were also enriched in Fe. R-ore consisted of small particle, with 32.44% sized between 0.075 and 0.11 mm, and 26.38% below 0.075 mm. The contents of Fe, La, and Ce in these smaller particles were higher than those of larger particles. Fe might be substituted with Ce, La, and other REEs in magnetite crystals, forming isomorphic structures. This research was expected to provide assistance in the efficient extraction of REEs from carbonatite deposits. Full article

(This article belongs to the Special Issue Mineral Processing and Extractive Metallurgy of Sulfide Ores, 2nd Edition)

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23 pages, 7080 KiB

Open AccessArticle

Phase and Composition Study of 18th Century Qallaline Tiles, Tunis

by Philippe Colomban, Gulsu Simsek-Franci, Xavier Gallet, Anh-Tu Ngo, Wided Melliti-Chemi and Naceur Ayed

Minerals 2025, 15(8), 865; https://doi.org/10.3390/min15080865 - 15 Aug 2025

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Abstract

The potters of Qallaline (or Kallaline, from qallāl, meaning “potters” in Arabic), a district of Tunis (Tunisia) near the now-vanished Bab Kartâjanna gate, produced tiles from the 16th century until the end of the 19th century, with peak activity in the 18th [...] Read more.

The potters of Qallaline (or Kallaline, from qallāl, meaning “potters” in Arabic), a district of Tunis (Tunisia) near the now-vanished Bab Kartâjanna gate, produced tiles from the 16th century until the end of the 19th century, with peak activity in the 18th century. These tiles, made from local clay, feature decorations influenced by Hafsid art, the Castilian Renaissance, the Spanish Baroque of the Valencia region, and Ottoman styles. Their characteristic color palette combines green, blue, and ochre. Representative sherds from various 18th-century sites were analyzed using SEM-EDS, portable XRF (pXRF), and Raman microspectroscopy. The results were compared with tiles from earlier (16th-century Iznik, Türkiye), contemporary (18th-century Tekfur Palace, Istanbul, Türkiye), and later (19th-century Naples, Italy) productions used for similar purposes. The chemical signature of the different cobalt ores used appears to depend primarily on the production period. The pastes used in Iznik, Tekfur, and Qallaline ceramics exhibit different compositions. Qallaline potters employed three types of pastes, varying in calcium content, which were used either separately or together within the same tile. In some cases, tin was also present in association with lead. The cobalts used at Qallaline originate from different sources than those used contemporaneously in Meissen (Saxony), as well as from those used in the decoration of Iznik tiles one or two centuries earlier, which are themselves comparable to the cobalt used in Persian mīnā’ī. The As, Ni, and Mn contents are similar to those of the cobalt employed at the Royal Manufacture of Sèvres, believed to have come from the Giftain Valley in Catalonia. Full article

(This article belongs to the Special Issue Characterization of Archaeological Materials Employing Geochemical and Analytical Methods)

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46 pages, 9391 KiB

Open AccessArticle

Multifactorial Controls on Carbonate–Clastic Sedimentation in Rift Basins: Integrated Foraminiferal, Sequence Stratigraphic, and Petrophysical Analysis, Gulf of Suez, Egypt

by Haitham M. Ayyad, Hatem E. Semary, Mohamed Fathy, Ahmed Hassan Ismail Hassan, Anis Ben Ghorbal and Mohamed Reda

Minerals 2025, 15(8), 864; https://doi.org/10.3390/min15080864 - 15 Aug 2025

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Abstract

The lithological dichotomy in the Hammam Faraun Member (Gulf of Suez, Egypt) reveals a stable western flank with Nullipore carbonate deposits, contrasting with the clastic-prone eastern margin influenced by tectonic activity. This study aims to decipher multifactorial controls on spatial lithological variability and [...] Read more.

The lithological dichotomy in the Hammam Faraun Member (Gulf of Suez, Egypt) reveals a stable western flank with Nullipore carbonate deposits, contrasting with the clastic-prone eastern margin influenced by tectonic activity. This study aims to decipher multifactorial controls on spatial lithological variability and reservoir implications through (1) foraminiferal-based paleoenvironmental reconstruction; (2) integrated sequence stratigraphic–petrophysical analysis for sweet spot identification; and (3) synthesis of lateral facies controls. This study uniquely integrates foraminiferal paleoenvironmental proxies, sequence stratigraphy, and petrophysical analyses to understand the multifactorial controls on spatial variability and its implications for reservoir characterization. Middle Miocene sea surface temperatures, reconstructed between 19.2 and 21.2 °C, align with warm conditions favorable for carbonate production across the basin. Foraminiferal data indicate consistent bathyal depths (611–1238 m) in the eastern region, further inhibited in photic depths by clastic influx from the nearby Nubian Shield, increasing turbidity and limiting carbonate factory growth. Conversely, the western shelf, at depths of less than 100 m, supports thriving carbonate platforms. In the sequence stratigraphy analysis, we identify two primary sequences: LA.SQ1 (15.12–14.99 Ma), characterized by evaporitic Feiran Member deposits, and LA.SQ2 (14.99–14.78 Ma), dominated by clastic deposits. The primary reservoir comprises highstand systems tract (HST) sandstones with effective porosity ranging from 17% to 22% (calculated via shale-corrected neutron density cross-plots) and hydrocarbon saturation of 33%–55% (computed using Archie’s equation). These values, validated in Wells 112-58 (ϕe = 19%, S_hc = 55%) and 113M-81 (ϕe = 17%, S_hc = 33%), demonstrate the primary reservoir potential. Authigenic dolomite cement and clay content reduce permeability in argillaceous intervals, while quartz dissolution in clean sands enhances porosity. This research emphasizes that bathymetry, sediment availability, and syn-sedimentary tectonics, rather than climate, govern carbonate depletion in the eastern region, providing predictive parameters for identifying reservoir sweet spots in clastic-dominated rift basins. Full article

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

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35 pages, 17908 KiB

Open AccessArticle

Chemical and Textural Variability of Zircon from Slightly Peralkaline Madeira Albite Granite, Pitinga Magmatic Province, Brazil

by Karel Breiter, Hilton Tulio Costi, Zuzana Korbelová and Marek Dosbaba

Minerals 2025, 15(8), 863; https://doi.org/10.3390/min15080863 - 15 Aug 2025

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Abstract

Zircon is one of the most common accessory minerals in all types of granitoids. Due to its resistance to secondary processes, it preserves information about the composition of magma and conditions at the time of crystallization. Madeira albite granite, Brazil, offers optimum conditions [...] Read more.

Zircon is one of the most common accessory minerals in all types of granitoids. Due to its resistance to secondary processes, it preserves information about the composition of magma and conditions at the time of crystallization. Madeira albite granite, Brazil, offers optimum conditions for the study of chemistry and shape of zircon and the relation between the contents of particular trace elements in magma vs. in crystallizing zircon. Textural and chemical zircon data obtained using scanning electron microscopy (BSE) and cathodoluminescence (CL) imaging, automated mineralogy by TESCAN Integrated Mineral Analyzer (TIMA), and electron probe microanalyses (EPMA) enabled us to define four albite granite facies containing zircons of specific structures and chemistry. Zircon in the Madeira albite granite was formed during several, largely temporally and spatially independent episodes. During the crystallization of the common facies, occupying most of the intrusion volume, Zr/Hf value in zircon decreased from 40 to 20. This zircon, in some episodes, incorporated a higher amount of Th, which was later unmixed in the form of thorite inclusions. The pegmatoidal facies, representing crystallization of residual magma, contains zircon without thorite inclusions with a Zr/Hf value from 35 to 5. The Th/U and Y/Yb values during this evolution scattered but generally evolved to Th, Yb-enriched compositions (Th/U up to >10, Y/Yb down to 0.1). The Li-poor facies, located in the center of the stock near the cryolite deposit, contains zircon with comparatively high Zr/Hf = 45–70 and higher U and Y contents. Later, part of the common facies was hydrothermally altered to border facies, but zircon did not change noticeably during this process. The contents of minor elements in all zircon varieties are generally low (U + Th + Y + REE ˂ 0.05 apfu); Y and REE are incorporated exclusively in the xenotime component. Many crystals have low analytical totals, down to 95 wt%, and are enriched in Al, Fe, Mn, Ca, and F but this process does not influence the primary Zr/Hf, Th/U, and Y/Yb ratios. Zircons from other Madeira granite facies, including the neighboring Europa pluton, differ mainly in much higher Y/Yb values and in having (Y + REE) >> P, indicating a different than xenotime substitution mechanism. Zircon from the Madeira albite granite differs from zircons from many metaluminous rare-metal granites in low contents of minor elements and a common assemblage with thorite, instead of forming Zrn–Thr–Xnt solid solutions. Full article

(This article belongs to the Special Issue Tectono-Magmatic Evolution of the Amazonian and São Francisco Cratons: Insights from Thermochronological and Geochronological Data)

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13 pages, 2780 KiB

Open AccessArticle

Enhancement on KCl Flotation at Low Temperature by a Novel Amine-Alcohol Compound Collector: Experiment and Molecular Dynamic Simulation

by Bo Wang, Jintai Tian, Biao Fan, Xin Wang and Enze Li

Minerals 2025, 15(8), 862; https://doi.org/10.3390/min15080862 - 15 Aug 2025

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Abstract

To address the challenges of low KCl recovery and high collector consumption during flotation at low temperature, a novel approach with utilizing a compound collector consisting of octadecylamine hydrochloride (ODA) and alcohols (butanol, octanol, and dodecanol) to enhance low-temperature KCl flotation recovery was [...] Read more.

To address the challenges of low KCl recovery and high collector consumption during flotation at low temperature, a novel approach with utilizing a compound collector consisting of octadecylamine hydrochloride (ODA) and alcohols (butanol, octanol, and dodecanol) to enhance low-temperature KCl flotation recovery was proposed in this study. The flotation performance and underlying mechanisms of this novel amine–alcohol compound collector were investigated through combination of micro-flotation tests, contact angle measurements, and molecular dynamics simulations. The results revealed that KCl flotation recovery decreased with declining temperature using single ODA as the collector, and the maximum KCl flotation recovery was approximately 40% with an ODA concentration of 1 × 10⁻⁵ mol/L at the temperature of 0 °C. Moreover, amine–alcohol compound collector shows different KCl flotation recovery; among them, dodecanol (DOD) presents the best performance at 25 °C with an ODA concentration of 3 × 10⁻⁶ mol/L. The KCl flotation recovery initially increased and then gradually decreased with increasing the DOD concentration, and 90% KCl recovery was achieved with a DOD concentration of 1.5 × 10⁻⁵ mol/L (DOD:ODA = 5:1 in mole) under 25 °C. Furthermore, this compound collector exhibited high selectivity for KCl/NaCl flotation. Mechanism studies indicated that the trend in contact angle changes on the KCl crystal surface closely mirrored the trend in flotation recovery. Molecular dynamics simulations demonstrated that at 0 °C, the presence of DOD resulted in a higher diffusion coefficient for ODA molecules compared to the system without DOD. Additionally, the water molecules in System 3 exhibited a lower diffusion coefficient and a greater number of hydrogen bonds. This novel compound collector offers a potential solution for improving KCl recovery and reducing ODA consumption during low-temperature flotation. It holds significant theoretical and practical implications for advancing low-temperature KCl flotation technology. Full article

(This article belongs to the Special Issue Extraction of Valuable Elements from Salt Lake Brine)

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18 pages, 2498 KiB

Open AccessArticle

Table Olive Wastewater Treatment Using the Clay Mineral Palygorskite as Adsorbent

by Christina Vasiliki Lazaratou and John Rosoglou

Minerals 2025, 15(8), 861; https://doi.org/10.3390/min15080861 - 15 Aug 2025

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Abstract

This study investigated the effectiveness of palygorskite (Pal) as an adsorbent for removing total phenolic content (TPC), dissolved chemical oxygen demand (d-COD), and color from treated olive wastewater (TOW). Experiments were conducted to evaluate the impact of varying Pal dosages (2.5–20 g/L), initial [...] Read more.

This study investigated the effectiveness of palygorskite (Pal) as an adsorbent for removing total phenolic content (TPC), dissolved chemical oxygen demand (d-COD), and color from treated olive wastewater (TOW). Experiments were conducted to evaluate the impact of varying Pal dosages (2.5–20 g/L), initial TPC concentrations (80–400 mg/L), and pH (2–9). The results showed that increasing the Pal dosage improved the removal efficiency of TPC and d-COD, though there were diminishing returns beyond 10 g L⁻¹, which indicates equilibrium adsorption behavior. The maximum TPC and d-COD removal reached 68% and 55%, respectively, while color removal exceeded 95% regardless of dosage. Adsorption was most efficient at lower TPC concentrations and an acidic pH (2–3), with up to 85% TPC removal. This suggests that pH-dependent phenolic ionization enhances Pal adsorption. Color removal remained consistently high across all conditions, highlighting palygorskite’s mesoporosity and affinity for chromophoric compounds. These findings affirm the potential of Pal as a cost-effective and versatile adsorbent for TOW treatment. Full article

(This article belongs to the Special Issue Applications of Clay Minerals and Engineered Materials in Water and Wastewater Treatment)

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21 pages, 62661 KiB

Open AccessArticle

Petrography, Fluid Inclusions and Isotopic Analysis of Ordovician Carbonate Reservoirs in the Central Ordos Basin, NW China

by Xiaoli Wu, Ping Wang, Haijian Jiang, Hexin Huang, Tong Chen, Lei Chen, Dongxing Wang and Junnian Chen

Minerals 2025, 15(8), 860; https://doi.org/10.3390/min15080860 - 15 Aug 2025

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Abstract

Deep carbonate reservoirs have garnered significant attention and demonstrated great potential for oil and gas exploration in recent years. The Majiagou Formation in the Ordos Basin has received much attention for its deep oil and gas deposits recently. However, the issue of fluid [...] Read more.

Deep carbonate reservoirs have garnered significant attention and demonstrated great potential for oil and gas exploration in recent years. The Majiagou Formation in the Ordos Basin has received much attention for its deep oil and gas deposits recently. However, the issue of fluid evolution within the great depth has been overlooked, and the relationship between fluid flow and the gas accumulation process remains unclear. This paper aims to explore the fluid evolution and its relationship with the gas accumulation, which poses a challenge for further petroleum exploration. To achieve this, petrological studies on dolomite samples were carried out and four types of secondary cements were identified: early gypsum-moldic pore-filling calcite, late gypsum-moldic pore-filling calcite, dissolution pore-filling calcite and fracture-filling calcite. Subsequently, an interdisciplinary approach that integrates petrography observation, microthermometry, laser Raman analysis of fluid inclusions, and carbon and oxygen isotope tests on these types of cements is employed to elucidate the fluid flow evolution. These investigations revealed that four different stages of inorganic fluid activity were coeval with two stages of organic fluid activity. The two stages of organic fluid flows were significantly important for petroleum accumulation. In the late Triassic to early Jurassic, there was small-scale liquid oil accumulation, which was associated with the second stage of fluids. In the early Cretaceous, there was large-scale gas accumulation, which was associated with the fourth stage of fluids. This research is crucial for understanding the fluid flow process and its relationship with hydrocarbon accumulation in deeply buried carbonate formations. Full article

(This article belongs to the Special Issue Natural and Induced Diagenesis in Clastic Rock)

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25 pages, 4376 KiB

Open AccessReview

Manganese Resources in China: An Overview of Resource Status and Recent Advances in Metallogenic Models and Exploration

by Erke Peng, Jianguang Yang, Zhilin Wang, Dong Li, Yuanxing Gao, Danyang Yan, Yanfei Chen and Xueyi Guo

Minerals 2025, 15(8), 859; https://doi.org/10.3390/min15080859 - 15 Aug 2025

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Abstract

Manganese is a critical metal for modern industry, essential in steelmaking and increasingly important for the production of advanced battery materials. As one of the world’s leading consumers and importers of manganese, China faces a persistent supply–demand imbalance, primarily due to the predominance [...] Read more.

Manganese is a critical metal for modern industry, essential in steelmaking and increasingly important for the production of advanced battery materials. As one of the world’s leading consumers and importers of manganese, China faces a persistent supply–demand imbalance, primarily due to the predominance of low-grade domestic resources that are highly impure and are further characterized by complex mineral textures and assemblages. This challenge is further exacerbated by surging demand from emerging sectors, particularly green energy technologies. This review systematically summarizes the current status of China’s manganese resources, focusing on their geological characteristics, genetic classifications, temporal and spatial distributions, and metallogenic belts. Recent advances in ore-forming theory and major breakthroughs in exploration over the past decade are critically reviewed, with emphasis on their implications for prospecting strategies and metallogenic models. The findings aim to guide future research directions and support strategic resource planning and industrial upgrading. Full article

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

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15 pages, 33094 KiB

Open AccessArticle

The Shallow Structure of the Jalisco Block (Western Trans-Mexican Volcanic Belt) Inferred from Aeromagnetic Data—Implications for Mineral Deposits

by Héctor López Loera, José Rosas-Elguera and Avto Goguitchaichvili

Minerals 2025, 15(8), 858; https://doi.org/10.3390/min15080858 - 14 Aug 2025

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Abstract

The complex geology of southwestern Mexico results from prolonged interaction between the North American and Farallon plates along an active subduction zone. This process led to crustal growth via oceanic lithosphere consumption, island arc accretion and batholith exhumation, forming great geological features like [...] Read more.

The complex geology of southwestern Mexico results from prolonged interaction between the North American and Farallon plates along an active subduction zone. This process led to crustal growth via oceanic lithosphere consumption, island arc accretion and batholith exhumation, forming great geological features like the Guerrero composite terrane. On the other hand, the Zihuatanejo subterrane, evolved into the Jalisco Block is now bounded by major grabens. Aeromagnetic data from the Mexican Geological Service (1962–2016) were used to map geological structures and contribute to the mineral exploration. Advanced magnetic processing and 3D modeling (VOXI Magnetic Vector Inversion) revealed the Jalisco Block’s complex structure, including Triassic basement, Jurassic–Cretaceous volcanics, and plutonic bodies such as the Puerto Vallarta batholith. Magnetic anomalies are related to intrusive bodies and mineralized zones, notably Peña Colorada (Fe), El Barqueño (Au), and La Huerta. Iron deposits are linked to intrusive volcanic–sedimentary contacts, while gold aligns with intrusive zones and observed magnetic maxima. A notable NW–SE magnetic low at 20 km depth suggests a reactivated back-arc basin and crustal fracture zone. These findings underscore aeromagnetic surveys’ value in both mineral exploration and geological interpretation. Full article

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

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19 pages, 6660 KiB

Open AccessArticle

Chemistry, Raman Spectroscopy and Micro-Textures of Theophrastite and Other Ni-Minerals from the Vermion Fe-Ni-Laterites, Greece: Genetic Significance

by Maria Economou-Eliopoulos, Christos Kanellopoulos, Angeliki Papoutsa, Theodoros Markopoulos, Federica Zaccarini and Maria Perraki

Minerals 2025, 15(8), 857; https://doi.org/10.3390/min15080857 - 14 Aug 2025

Viewed by 706

Abstract

A small, strongly schistose Ni-laterite occurrence at the Vermion ophiolite (40°26′ Ν, 22°10′ Ε), Northen Greece, along a strong shear zone, is characterized by relatively high Ni, Co and Mn contents, magnetite as the dominant mineral, garnet (grossularite), theophrastite [β-Ni(OH)₂], otwayite-like [...] Read more.

A small, strongly schistose Ni-laterite occurrence at the Vermion ophiolite (40°26′ Ν, 22°10′ Ε), Northen Greece, along a strong shear zone, is characterized by relatively high Ni, Co and Mn contents, magnetite as the dominant mineral, garnet (grossularite), theophrastite [β-Ni(OH)₂], otwayite-like phase (ideally Ni₂CO₃(OH)₂.H₂O), (Ni, Co, Mn)-hydroxides, and Ni-phyllosilicates. New analytical data, including black-white and color back-scattered electron images (BSEIs), elemental mapping and scanning, and Raman Spectroscopy, alongside silicates and hydroxides revealed the presence of varying silica content (less than 1 to 29 wt.%) in theophrastite and in (Ni, Co, Mn ± Fe)-hydroxides, although the X-ray powder diffraction data correspond to those of pure hydroxides. The gradual stacking of fine fibrous otwayite-like crystals to the boundaries of successive thin layers and within layers themselves, results in porous mineral phases of varying density shifting towards more compact mineral with increasing residence time. The presented data suggest that a potential explanation of the presence of Si in theophrastite may be the precipitation of Si after initial Ni-hydroxyl-carbonate fine crystals deposition. A potential sequence of the stability of Ni-minerals at Vermion may be as follows: Hydroxyl-carbonates < [β-Ni(OH)₂] (theophrastite) < (Ni, Co, Mn)(OH)₂ < Ni-phyllosilicates; this may be a significant factor for Ni-exploration in Ni-larerite deposits. Full article

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

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25 pages, 16018 KiB

Open AccessArticle

Textures and Inclusions in Mengyin Diamonds: Insights on Their Formation Within the Southeastern North China Craton

by Yu-Meng Sun, Yi-Qi Wang, Liang Zhang, Li-Qiang Yang, Zhi-Yuan Chu and Hao-Shuai Wang

Minerals 2025, 15(8), 856; https://doi.org/10.3390/min15080856 - 14 Aug 2025

Viewed by 304

Abstract

Beyond its renowned gemological value, diamond serves as a vital economic mineral and a unique messenger from Earth’s deep interior, preserving invaluable geological information. Since the Mengyin region is the source of China’s greatest diamond deposits, research on the diamonds there not only [...] Read more.

Beyond its renowned gemological value, diamond serves as a vital economic mineral and a unique messenger from Earth’s deep interior, preserving invaluable geological information. Since the Mengyin region is the source of China’s greatest diamond deposits, research on the diamonds there not only adds to our understanding of their origins but also offers an essential glimpse into the development of the North China Craton’s mantle lithosphere. In this article, 50 diamond samples from Mengyin were investigated using gemological microscopy, Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, DiamondView™, and X-ray micro-computed tomography (CT) scanning technologies. The types of Mengyin diamonds are mainly Type IaAB, Type IaB, and Type IIa, and the impurity elements are N and H. Inclusions in diamonds serve as direct indicators of mantle-derived components, providing crucial constraints on the pressure–temperature (P–T) conditions during their crystallization. Mengyin diamonds have both eclogite-type and peridotite-type inclusions. It formed at depths ranging from 147 to 176 km, which corresponds to source pressures of approximately 4.45–5.35 GPa, as determined by the Raman shifts of olivine inclusions. The discovery of coesite provides key mineralogical evidence for subduction of an ancient oceanic plate in the source region. The surface morphology of diamonds varies when they are reabsorbed by melts from the mantle, reflecting distinctive features that record subsequent geological events. Distinctive surface features observed on Mengyin diamonds include fusion pits, tile-like etch patterns, and growth steps. Specifically, regular flat-bottomed negative trigons are mainly formed during diamond resorption in kimberlite melts with a low CO₂ (X_CO2 < ~0.5) and high H₂O content. The samples exhibit varying fluorescence under DiamondView™, displaying blue, green, and a combination of blue and green colors. This diversity indicates that the diamonds have undergone a complex process of non-uniform growth. The nitrogen content of the melt composition also varies significantly throughout the different growth stages. The N3 center is responsible for the blue fluorescence, suggesting that it originated in a long-term, hot, high-nitrogen craton, and the varied ring band structure reveals localized, episodic environmental variations. Radiation and medium-temperature annealing produce H3 centers, which depict stagnation throughout the ascent of kimberlite magma and are responsible for the green fluorescence. Full article

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

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Minerals, Volume 15, Issue 8 (August 2025) – 120 articles

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