Search Results (240)

In recent years, an ion-adsorption type REE deposit has been discovered for the first time in the weathering crust of epimetamorphic rocks in Ningdu County, Jiangxi Province, which provides a new idea for the exploration of ion-adsorption-type REE deposits. However, most previous studies on the ore-forming parent rocks of ion-adsorption-type REE deposits have focused on granites and volcanic rocks, while studies on epimetamorphic rocks remain extremely scarce. In this paper, petrographic analysis of epimetamorphic rocks, LA-ICP-MS U–Pb dating and trace element analysis of zircon and apatite were conducted on the metamorphic tuff from the Kuli Formation in Ningdu County, Jiangxi Province, so as to constrain the formation age and tectonic dynamic setting of the rock mass, investigate the petrogenesis and material source of the rock mass, and reveal the metallogenic potential of the rock mass. The results of zircon and apatite U–Pb dating show that the protolith of the metamorphic tuff from the Kuli Formation formed at ca. 770 Ma, representing a product of mid-Neoproterozoic magmatic activity. The protolith restoration of metamorphic rocks suggests that the protolith of the metamorphic tuff from the Kuli Formation is magmatic rock. The estimated results of zircon Ti thermometry indicate that the magmatic crystallization temperature ranges from 623 to 723 °C, with an average value of approximately 696 °C, and the calculated zircon oxygen fugacity values vary from −18.7 to −9.4, with an average of −13.8, implying that the rock formed under conditions of relatively low temperature and high oxygen fugacity. The correlation diagrams of trace elements and element ratios in zircon and apatite reveal that the magmatic evolution involved extensive fractional crystallization of minerals such as zircon, monazite, apatite, titanite, rutile, and plagioclase during the formation of the rock mass. The discrimination diagrams of trace elements in zircon and apatite demonstrate that the metamorphic tuff from the Kuli Formation was formed in a continental margin arc or arc-related orogenic belt, and the magmatic source is characterized by crust–mantle mixing. Combined with previous research findings on regional tectonic-magmatic activities, it can be concluded that the metamorphic tuff from the Kuli Formation was formed in a tectonic setting of back-arc extension and intra-arc rifting caused by the rollback of the subducting oceanic slab. The upwelling of the asthenospheric mantle induced the partial melting of arc-derived sediments in the continental crust, which was subsequently mixed with mantle-derived magma, ultimately generating the parent magma of the metamorphic tuff. The metamorphic tuff from the Kuli Formation in Ningdu County, Jiangxi Province, has high REE abundance and relatively easily weathered REE mineral assemblages, which can provide sufficient material sources for ion-adsorption REE mineralization and have a great metallogenic potential for ion-adsorption REE deposits. Full article

The alkaline rocks located in the Hatu area of Dulan county in the middle section of the East Kunlun Orogenic Belt have a relatively high content of light rare earth elements (LREE). This study conducted scanning electron microscopy (SEM) petrographic methods, zircon U-Pb dating, and geochemical work on two REE-mineralized alkaline rock outcrops, providing support for further work and study in the mining area. The REE-mineralized alkaline rocks are composed of alkali feldspar syenite, hornblende alkali feldspar syenite, and quartz alkali feldspar syenite. SEM analysis indicates that the REE are mainly hosted in REE-bearing minerals such as chevkinite, parisite, allanite, and monazite. The alkali feldspar syenite and hornblende alkali feldspar are enriched in REE, with a content of 994 × 10⁻⁶~5054 × 10⁻⁶. The zircon U-Pb dating results show that the ages of the two REE-mineralized alkaline rock are 423.6 ± 2.7 Ma and 431.2 ± 5.3 Ma, respectively. Geochemical analysis indicates that the Hatu alkaline rocks can be classify as A-type granite, and are characterized by evidence of a mixture of materials from the crust and mantle. Considering the regional tectonic history, it is primarily inferred that the Hatu REE-mineralization alkaline rocks were formed after the closure of the Proto-Tethys Ocean Basin and the Eastern Kunlun region experienced extensional tectonic stage, resulting in the upwelling of asthenospheric material and heating of crustal material. This study provides theoretical support for regional geochemical research and further exploration efforts in the Hatu area. Full article

The origin of Mesozoic granites associated with the Dahutang W-Cu-Mo orefield in northern Jiangxi, which hosts the world’s second-largest tungsten deposit, remains a compelling subject despite extensive geochemical and geochronological studies. In this contribution, we present wolframite mineral and whole-rock geochemistry, as well as monazite and zircon U-Pb ages, for the Mesozoic granites to constrain our understanding of the petrogenesis of these granites and their coupling relationship with the mineralization. The following two magmatic phases and four types of rocks in the study area are identified: the early stage (152–147 Ma) biotite (G1) granites and the late stage (144–130 Ma) two-mica (G2),muscovite (G3), and albite (G4) granite series. These two magmatic phases are temporally coincident with two mineralization stages (~150 Ma and 144–139 Ma). All the Mesozoic granites share the characteristics of high silica content, peraluminosity (A/CNK > 1.1), and low Zr + Nb + Ce + Y values (<200 ppm); they are derived from the partial melting of a Proterozoic crustal source and classified as S-type granites. Specifically, the G1 granites are characterized by relatively high MgO (~0.5%), CaO (~1%), and low P₂O₅ (0.13%–0.20%). They formed through a relatively high degree of partial melting at approximately 766 °C (zircon saturation temperatures), a process influenced by biotite dehydration reactions, with minor contributions from mantle-derived materials. In contrast, the G2–G4 granite series exhibits more typical peraluminous S-type granite features, such as high Al₂O₃, Na₂O, and P₂O₅ (mostly > 0.2%) contents, and low Sr and Ba contents. They are products of low-degree partial melting that occurred under conditions close to muscovite breakdown at ~726 °C. Additionally, fluid–melt interaction is recorded in both granites by distinctive geochemical signatures, including enrichment in Sn (>30 ppm), Cs (>35 ppm), Li (>250 ppm), F (>0.4%), and W (10–1000 ppm), coupled with low K/Rb (<150) and Nb/Ta (<5) ratios. The near-chondritic Zr/Hf (22.6–34.1) and Y/Ho (24.5–31.5) ratios of the G1 granites imply a relatively limited role of magmatic fluid–melt interaction during its evolution. For the G2–G4 granites, however, intense crystal fractionation and late-stage fluid–melt interaction are well-documented by their highly variable and low ratios of Y/Ho (14.8–41.4), Nb/Ta (0.89–5.57), Zr/Hf (8.84–41.67), and K/Rb (13.96–128.29). In the long-lived, reduced, and volatile-rich aqueous environment of the G2–G4 magmas, fractional crystallization and albitization collectively enhanced the solubility and hydrothermal transport capacity of W, Sn, Li, Nb, and Ta by multiple orders of magnitude. In contrast, in the earlier, more oxidized G1 magmas (which incorporated mantle materials), the exsolution and hydrothermal transport of Cu and Mo were associated with localized greisenization, but their capacity diminished with fractional crystallization. Historically, mineral exploration in the Dahutang mining area has focused primarily on W, Cu, and Mo. Based on this research, we conclude that there is significant mineral potential for rare metals (particularly Sn, Li, and Ta), and future exploration should prioritize areas adjacent to the evolved G2–G4 peraluminous leucogranites to search for new concealed mineral occurrences. Full article

Rare earth elements (REEs) hold great importance in the transition to a low-carbon economy. However, their increased exploitation, supply risks, low recyclability, and limited substitution by other elements have led to their classification as critical and strategic materials. The extraction of REEs from primary mining sources generates several negative environmental impacts, with greenhouse gas emissions being among the most significant. These emissions are quantified through Life Cycle Assessment (LCA) under the Global Warming Potential (GWP) category. Recycling REEs from secondary sources has emerged as a promising alternative to reduce mining dependence and environmental impacts. Nickel–metal hydride (NiMH) batteries contain approximately 5–10% REEs and represent a potential secondary source through urban mining. Our literature review presents a comparative analysis of the carbon footprint associated with the extraction of REEs from primary sources (bastnäsite and monazite), expressed per tonne of rare earth oxides (REO) produced, and with industrial-scale recycling processes of NiMH batteries, expressed per tonne of recovered REE mixture. The analysis indicates that CO₂ emissions associated with recycling processes (85–179 kg CO₂-eq per tonne of REO) are approximately 4 to 9 times higher than those reported for primary extraction routes; however, this comparison should be interpreted with cautiously, as recycling systems are multifunctional and involve the simultaneous recovery of additional metals such as Ni and Co, whereas primary mining operations are typically focused exclusively on REEs. Furthermore, differences in functional units, energy mixes, and geographical contexts limit the strict comparability of the results. Accordingly, a direct comparison based solely on REEs may overestimate the environmental burden of recycling. Consequently, the reported emission ranges provide an indicative perspective on relative magnitudes under current technological and regional conditions rather than a definitive comparative assessment. Despite the higher reported emissions, recycling should not be regarded as environmentally detrimental; it also plays a vital role in mitigating supply risks and reducing dependence on primary extraction. By diversifying supply sources, recycling enhances resource security and resilience. Full article

The Himalayan metallogenic belt is a globally significant province for leucogranites and pegmatites. Recent exploration has yielded major breakthroughs in the exploration of pegmatite-type Li-Be-Nb-Ta rare-metal deposits within its eastern segment. Discoveries such as the Qiongjiagang and Lhozhag deposits underscore the region’s substantial mineralization potential. In contrast, the western Himalayan segment remains comparatively underexplored. This study presents the geology and geochronology of the newly identified Zhaguopu Li-Be-Nb-Ta deposit in the Gyirong area, providing critical new insights. The deposit is centered on the Gyirong granite dome, which features a core of tourmaline-bearing leucogranite surrounded by a peripheral zone of beryl-bearing pegmatites and vein- to lens-shaped spodumene pegmatites, all hosted within metamorphosed sandstone, slate, and marble. The largest individual spodumene pegmatite vein exceeds 400 m in length, with thicknesses ranging from 0.5 to 4 m and a cumulative thickness surpassing 50 m. Principal ore minerals include spodumene, beryl, and columbite-group minerals. U-Pb geochronology of zircon, monazite, and columbite-group minerals from the leucogranite and pegmatite units constrains the rare-metal mineralization to a tight interval of 25–23 Ma, contemporaneous with the Qiongjiagang and Lhozhag deposits. Whole-rock geochemical data define a coherent fractional crystallization sequence from tourmaline granite through beryl pegmatite to spodumene pegmatite, characterized by increasing SiO₂ and peraluminosity, and extreme depletion in Ba, Sr, Eu and Nb/Ta ratios. This geochemical trend underscores the critical role of extreme magmatic differentiation in rare-metal enrichment. Field relationships and these coeval ages strongly support a genetic model in which the mineralized pegmatites originated from the extreme fractional crystallization of a common, cogenetic magmatic suite. The timing of this mineralization event correlates precisely with the post-collisional extension of the Himalayan orogen and the activity of the Southern Tibet Detachment System. We conclude that the interplay between this large-scale tectonism and magmatic differentiation is the fundamental driver for rare-metal enrichment. The discovery of the Zhaguopu deposit highlights the significant and previously underestimated potential for major pegmatite-type rare-metal deposits in the western Himalayan belt. Full article

This study investigates the genesis of gold mineralization at the Rodruin prospect in the central Eastern Desert (CED) of Egypt, with the aim of constraining the relative contributions of metamorphic and magmatic fluids to ore formation. Gold mineralization at Rodruin is hosted by quartz–carbonate veins emplaced within a shear zone that transects low-grade metasedimentary sequences intruded by Ediacaran post-tectonic granitoids. It exhibits characteristics transitional between orogenic turbidite-hosted and polymetallic vein-type mineralization. Although metamorphic devolatilization is interpreted to have generated the dominant ore-forming fluids, adjacent granitoid intrusions acted primarily as a thermal engine, with only a limited direct input of magmatic-hydrothermal fluids. This interpretation is supported by the occurrence of magmatic-affiliated mineral inclusions (monazite, cassiterite, and zircon) coupled with generally low concentrations of trace elements typically enriched in granitic magmatic-hydrothermal fluids (Sb, Bi, Mo, W, Sn, Nb, and Ta), collectively indicating a subordinate magmatic contribution. Rare earth element (REE) patterns of the ore samples closely resemble those of the nearby granitoids, displaying LREE enrichment; however, a distinct positive Eu anomaly is restricted to the ore assemblages and is attributed to hydrothermal feldspar alteration supporting magmatic involvement in ore formation. Carbon and oxygen isotope compositions (δ¹³C = −6.6 to −2.36‰; δ¹⁸O = +15.7 to +19.7‰), together with REE signatures comparable to primitive mantle values and textural evidence for synchronous sulfide–carbonate precipitation, manifested by rhythmic banding of carbonates and sulfides unequivocally indicate a hydrothermal–metasomatic origin. Collectively, these lines of evidence support a hybrid metamorphic–magmatic model in which gold and associated base metals were predominantly transported by metamorphic fluids, whose mobilization and focusing were enhanced by the thermal influence of Younger granitic intrusions, whereas magmatic-hydrothermal fluids contributed only a minor proportion to the overall metal budget. Full article

The exploration of coastal placer deposits, often enriched in critical raw materials demanded by industry, is significantly challenged by the dynamic marine environment and by the limited research devoted to developing dedicated exploration methodologies. This study presents the first systematic integration of multi-source geospatial data in the Rías Baixas for placer mineral prediction in the initial exploratory stage of these deposits. The primary objective is to investigate the presence of Titanium (ilmenite, and rutile), Zirconium (zircon), and Rare Earth Element (REE)-bearing minerals (monazite, xenotime, allanite, and garnets) in Rías Baixas (NW Spain). The methodology includes a lithological reclassification and the generalization of coastal types. These features are then integrated with watershed, coastline dynamics, and mineral occurrence data. Validation includes existing semi-quantitative and qualitative mineral identification data, and new field observations of heavy mineral accumulations. This integration allowed us to identify nine potential and ten predictive areas with a high probability of hosting coastal placers. The validation process showed a 79% spatial correlation, confirming a significant heavy mineral accumulation in 15 areas. This work underscores the efficacy of integrated cartography in prioritizing potential and predictive areas during the crucial first stage of mineral exploration. The methodology can be further enhanced by incorporating additional data, such as stream sediment geochemistry and the application of remote sensing techniques. Full article

This study is carried out to investigate the radiological characteristics and mineralogical controls of natural radioisotopes (²³⁸U, ²²⁶Ra, ²³²Th, and ⁴⁰K) in granitic pegmatites from Abu Zawal Area (AZA) in the Eastern Desert of Egypt. The analyzed pegmatites, containing thorite, zircon, monazite, ferrocolumbite, and fergusonite, exhibit exceptionally high radioactivity concentrations of ²³⁸U ≤ 568; ²³²Th ≤ 674; ²²⁶Ra ≤ 170 (Bq kg⁻¹), significantly exceeding the world average permissible limits (35, 30, 30, and 400 Bq kg⁻¹ for ²³⁸U, ²²⁶Ra, ²³²Th, and ⁴⁰K, respectively). Comprehensive radiological assessment reveals severely elevated radiological impact associated with Ra_eq ≤ 1243 (Bq kg⁻¹) and hazard indices (H_ex≤ 3.36; ELCR ≤ 12.2 × 10⁻³) surpassing international safety thresholds (H_ex ≤ 1; ELCR ≤ 1 × 10⁻³). The observed disequilibrium between ²³⁸U and ²²⁶Ra (with ²²⁶Ra activities approximately half those of ²³⁸U) is attributed to the geochemical mobility of radium and potential selective leaching during late-stage hydrothermal alteration, while the overall enrichment of the uranium series over the thorium series is linked to the predominance of uranium-bearing minerals like zircon and fergusonite in these pegmatites. Mineralogical analysis demonstrates distinct radiation patterns: thorite and monazite dominate Th-derived gamma radiation and radon/thoron exhalation, while zircon and fergusonite control U enrichment and decay chain disequilibrium. Notably, nominally low-activity minerals like ferrocolumbite contribute to localized radiation hotspots through U/Th co-concentrations. The calculated absorbed dose rates ranged from 182 to 978 (nGy h⁻¹) and annual effective doses show extreme spatial variability correlated with Th-rich mineral assemblages. Full article

The horst and graben system in Western Anatolia lies on the eastern boundary of the Aegean extensional system, one of the most active extensional zones in the world. The Şahinali coal basin is located south of the Büyük Menderes Graben, which is part of this system. This study examines the rare earth elements and yttrium (REY) geochemistry, accumulation conditions, and economic potential of the Şahinali coals. Compared to world coals, the REE concentration in Şahinali coals (208.3 ppm) is quite high, and all REY groups are slightly enriched. Light REY (LREY) is dominant compared to medium REY (MREY) and heavy REY (HREY). The most abundant element in this group is Ce, reaching a concentration of 123.3 ppm. REY distribution patterns indicate H-type enrichment in most samples and, to a lesser extent, M-H-type enrichment. Element ratios (Al₂O₃/TiO₂, TiO₂/Zr, La/Sc, Co/Th) and REY anomalies (Ce, Eu, Gd) indicate that the sedimentary input is predominantly derived from felsic rocks, with limited intermediate to mafic contributions. SEM-EDS findings and correlation analyses indicate that REY are predominantly associated with aluminosilicate minerals. LREY-Th and MREY/HREY-Y relationships are supported by monazite and Y-rich illitic K-aluminosilicates. Paleoenvironmental indicators (V/Cr, Ni/Co, U/Th, Sr/Cu, Rb/Sr, Sr/Ba) indicate that the coal accumulated under oxic–suboxic, warm and humid conditions. The average REY oxide (REO) content slightly exceeds the commonly cited 1000 ppm screening threshold for coal ash. The majority of samples contain elevated proportions of critical REY (30.7%–54.3%) and show promising outlook coefficients (C_outl: 0.8–1.7). Together, these results indicate a favourable compositional signature for preliminary REY resource screening in the Şahinali coals, particularly with respect to elements relevant for high-technology applications. Full article

The Weishan rare earth element (REE) deposit, located in western Shandong, North China Block, is a typical carbonatite REE deposit and constitutes the third largest light REE resource in China. Its mineralization is closely related to the multi-stage evolution of a carbonatite magma–hydrothermal system. However, the mechanisms governing REE enrichment, migration, and precipitation remain insufficiently constrained from a mineralogical perspective, which hampers the understanding of the ore-forming processes and the establishment of predictive exploration models. Apatite is a pervasively developed REE phase in the Weishan deposit which occurs in multiple generations, and thus represents an ideal recorder of the magmatic–hydrothermal evolution. In this study, different generations of apatite hosted in carbonatite orebodies from the Weishan deposit were investigated using cathodoluminescence (CL), electron probe microanalysis (EPMA), and in situ LA-ICP-MS trace element analysis. Three types of apatite were identified. In paragenetic sequence, Ap-1 occurs as polycrystalline aggregates coexisting with calcite, is enriched in Na, Sr, and LREEs, and shows high (La/Yb)_N ratios, suggesting crystallization from an evolved carbonatite magma. Ap-2 and Ap-3 display typical replacement textures: both contain abundant dissolution pits and dissolution channels within the grains, which are filled by secondary minerals such as monazite and ancylite, and thus exhibit characteristic features of fluid-mediated dissolution–reprecipitation during the hydrothermal stage. Ap-2 is commonly associated with barite and strontianite, whereas Ap-3 is associated with pyrite and monazite and is characterized by relatively sharp grain boundaries with adjacent minerals. From Ap-1 to Ap-3, total REE contents decrease systematically, whereas Na, Sr, and P contents increase. All three apatite types lack Eu anomalies but display positive Ce anomalies. Discrimination diagrams involving LREE-Sr/Y and log(Ce)-log(Eu/Y) indicate that apatite in the Weishan REE deposit formed during the magmatic to hydrothermal evolution of a carbonatite, and that the dissolution of early magmatic apatite, followed by element remobilization and mineral reprecipitation, effectively records the progressive evolution of the ore-forming fluid. Full article

Post-collisional Cu-Au-Ni-Co-Pt-Pd-Sc porphyry [Duck Creek porphyry system (DCPS)] with overlying Au-Te-Bi-W-HRE epithermal mineralisation [Highway epithermal system (HES)] has been discovered in the core of the Mitakoodi anticline, southwest of Cloncurry. Xenotime and monazite geochronology indicate mineralisation occurred between ~1490 and 1530 Ma. Host rock lithologies show widespread potassic and/or propylitic to phyllic alteration. Paragenesis of porphyry sulphides indicates early crystallisation of pyrite, followed by chalcopyrite, with bornite forming by hydrothermal alteration of chalcopyrite. Cu sulphides also show the effect of supergene oxidation alteration with rims of covellite, digenite and chalcocite. Redox conditions deduced from the V/Sc systematics indicate that the DCPS contains both highly oxidised (typical of porphyries) and reduced lithologies, typical of plume-generated tholeiitic and alkaline suites. Ni/Te and Cu/Te systematics plot within the fields defined by epithermal and porphyry deposits. Duck Creek chalcophile and highly siderophile element (Cu, MgO and Pd) systematics resemble data from porphyry mineral systems, at Cadia, Bingham Canyon, Grasberg, Skouries, Kalmakyr, Elaisite, Assarel and Medet. SAM geophysical inversion models suggest the presence of an extensive porphyry system below the HES. A progressive increase in molar Cu/Au ratios with depth from the HES to the DCPS supports this conclusion. Three metal sources contributed to the linked DCPS-HES viz., tholeiitic ferrogabbro, potassic ultramafic to mafic system and an Fe and Ca-rich alkaline system. The latter two imparted non-crustal superchondritic Nb/Ta ratios that are characteristic of many deposits in the eastern Mount Isa Block. The associated tholeiite and alkaline magmatism reflect mantle plume upwelling through a palaeo-slab window that had accreted below the eastern flank of the North Australian craton following west-verging collision by the Numil Terrane. Discovery of this linked mineral system provides a new paradigm for mineral exploration in the region. Full article

There exists an east–west trending albitite (breccia) zone, approximately 400 km in length, closely related to gold mineralization, in Devonian strata in the South Qinling tectonic belt. The genesis and formation age of these albitite (breccia) are of great significance for understanding gold enrichment mechanisms and guiding future exploration. Past studies have mainly focused on the Fengxian–Taibai area in the western segment of the albitite (breccia) zone, whereas the eastern segment remains significantly understudied. In this study, a systematic field investigation, as well as petrology, geochemistry, and accessory-mineral geochronology studies were conducted on albitites and albitite breccias in the Shangnan area, the eastern segment of the albitite (breccia) zone. The results show that the albitites are interlayered with or occur as lenses within Devonian clastic rocks. The albitite breccias are mostly enclosed in albitite and Devonian strata, and the clasts within are subangular, uniform in type, and exhibit minimal displacement. Both albitites and albitite breccias exhibit similar trace-element characteristics and detrital zircon age spectra to those of Devonian clastic rocks. Abundant hydrothermal monazites with U–Pb ages ranging from 260 to 252 Ma are present in both albitites and albitite breccias but absent in Devonian clastic rocks. Collectively, these results indicate that the albitites in the Shangnan area are of hydrothermal metasomatic origin, while the albitite breccias record hydraulic fracturing and cementation, and both are products of the same fluid activity event in the Late Permian. We propose that albitite (breccia) zones in the South Qinling tectonic belt were formed under distinct tectonic settings during different evolution stages of the Late Paleozoic Mianlüe Ocean. Specifically, the albitites (breccias) in the Shangnan area are products of thorough metasomatism, local fracturing, and cementation of Devonian clastic rocks by mixed fluids, which ascended along the Fengzhen–Shanyang Fault coeval with the emplacement of magmatic rocks related to subduction of the Mianlüe Ocean. In contrast, the albitite breccias in the Fengxian–Taibai area are the result of fluid activity during the transition from regional compression to extension after the closure of the Mianlüe Ocean. Full article

The mineral matter in coal has great significance for geological evolution, and clean and fractional utilization. The Laochang mining area is one of the largest anthracite coal production bases in Southern China, and the most important coal energy base in Yunnan province, China. This study investigates the composition and mode of occurrence of mineral matter in the Laochang coals to reveal the sediment provenance, sedimentary environment, and hydrothermal fluids. The predominant minerals in the Laochang coals include oxide (quartz, anatase), clay (kaolinite, illite/smectite mixed layer), sulfide (pyrite, sphalerite), phosphate (xenotime, monazite, goyazite–gorceixite), and carbonate (calcite, dolomite, sideroplesite, siderite). The minerals in the Laochang coals are dominated by quartz (2.4~54.8%) and kaolinite (3.4~39.2%), followed by illite, smectite, muscovite, calcite, pyrite, and anatase. Quartz and dolomite in SB-7+8 coal have the highest proportions, reaching 54.8% and 17.3%. The modes of occurrence of minerals reflect that the Laochang coals are affected by the epigenetic hydrothermal fluids and seawater. The chalcophile elements Hg, Pb, Se, and Cr, and lithophile elements Li, Nb, Ta, Zr, Hf, and REY are slightly enriched in XB-3 coal, which is attributed to the intrusion of seawater and the supply of terrestrial detrital materials, respectively. REY is dominated by LREY, followed by MREY, and a lower level of HREY in the Laochang coals, which have a high fractionation degree. The REY enrichment H-type is influenced by the hydrothermal fluids. Based on the relationship between Al₂O₃ and TiO₂, Al₂O₃/TiO₂ and Nb/Yb, and the negative anomaly Eu, the detrital material in the erosion source area of the Laochang coal is derived from the Emeishan Large Igneous Province basalt and felsic–intermediate rocks. Full article

Placer deposits constitute important secondary resources for economically valuable minerals, including rare earth elements (REEs) and heavy minerals such as zircon, rutile, and ilmenite. In this study, representative samples from the Hantepe placer deposit (Çanakkale, Türkiye) were processed to investigate the occurrence, distribution, and beneficiation potential of REE-bearing minerals. The ore was subjected to size classification, followed by gravity concentration on a shaking table and subsequent magnetic separation using a low-intensity disc separator. The resulting products were characterized by X-ray diffraction and X-ray fluorescence. The dominant REE-host minerals were identified as titanite, zircon, apatite, monazite and, allanite, accompanied by magnetite, hematite, quartz, and feldspar as gangue constituents. The non-magnetic final concentrate achieved substantial upgrading of critical elements, with Ce increasing from 868 g/t to 5716 g/t, Nd from 308 g/t to 2308 g/t, and Zr from 1435 g/t to 9748 g/t. Additionally, the magnetic concentrate (7.0 wt.%) was strongly enriched in Fe₂O₃ (70.26%) and V (2359 g/t), indicating its potential suitability as an Fe–V source. Overall, the results demonstrate that combined gravity and magnetic separation constitutes an effective beneficiation strategy for critical mineral recovery from placer systems. These findings establish a strong basis for future pilot-scale studies and the techno-economic evaluation of the Hantepe deposit as an emerging source of strategic and industrially relevant heavy minerals. Full article

The increasing emphasis on green chemistry has led numerous researchers to focus on environmentally friendly solvents for mineral extraction. Among them, deep eutectic solvents (DESs) have garnered significant attention due to their eco-friendly, non-toxic, and biodegradable properties. These solvents possess comparable physicochemical properties to conventional ionic liquids but are more cost-effective and environmentally friendly. While DESs have been widely studied for extracting metals from synthetic minerals and end-of-life products, its use with primary ores and associated wastes remains relatively unexplored. This study aims to bridge that gap by assessing the effectiveness of choline chloride- and ethylene glycol-based DESs in extracting rare earth elements from primary feedstocks with varied grades and mineralogy, including sub-economic ores, monazite flotation tailings, and acid-crack and leach residue. The study also examines the practical challenges in preparing DES and assesses the applicability of the solvents for primary materials. By examining both solvent preparation challenges and the variable responses of different feed materials, this work provides a high-level scoping analysis to better understand the suitability and limitations of DES for primary resource extraction. This study highlights the challenges with physical properties and mineral breakdown in using DES. Full article