In this study,Schwertmannite,Akaganéite and ammoniojarosite were biosynthesized by different bacteria and characterized.The results showed that bacteria are critical in mediating the mineral formation process:the...In this study,Schwertmannite,Akaganéite and ammoniojarosite were biosynthesized by different bacteria and characterized.The results showed that bacteria are critical in mediating the mineral formation process:the morphology,crystallinity,grain size and specific surface area of each mineral varied upon different bacteria and culturing conditions.In addition,the formed minerals’elemental composition and group disparity lead to different morphology,crystallinity and subsequent adsorption performance.In particular,adsorption difference existed in iron minerals biosynthesized by different bacteria.The maximal adsorption capacities of Akaganéite,Schwertmannite and ammoniojarosite were 26.6 mg/g,17.5 mg/g and 3.90 mg/g respectively.Cr(VI)adsorption on iron-minerals involves hydrogen bonding,electrostatic interaction,and ligand exchange.The adsorption only occurred on the surface of ammoniojarosite,while for Akaganéite and Schwertmannite,the tunnel structure greatly facilitated the adsorption process and improved adsorption capacity.Thus,the molecular structure is the primary determining factor for adsorption performance.Collectively,the results can provide useful information in selecting suitable bacteria for synthesizing heavy-metal scavenging minerals according to different environmental conditions.展开更多
Natural gas hydrates widely accumulate in submarine sediments composed of clay minerals.However,due to the complex physiochemistry and micron-sized particles of clay minerals,their effects on methane hydrate(MH)format...Natural gas hydrates widely accumulate in submarine sediments composed of clay minerals.However,due to the complex physiochemistry and micron-sized particles of clay minerals,their effects on methane hydrate(MH)formation and dissociation are still in controversy.In this study,montmorillonite and illite were separately mixed with quartz sand to investigate their effects on MH formation and dissociation.The microstructure of synthesized samples was observed by cryo-SEM innovatively to understand the effects of montmorillonite and illite on MH phase transition in micron scale.Results show that montmorillonite and illite both show the inhibition on MH formation kinetics and water-to-hydrate conversion,and illite shows a stronger inhibition.The 10 wt%montmorillonite addition significantly retards MH formation rate,and the 20 wt%montmorillonite has a less inhibition on the rate.The increase of illite mass ratio(0-20 wt%)retards the rate of MH formation.As the content of clay minerals increase,the water-to-hydrate conversion decreases.Cryo-SEM images presented that montmorillonite aggregates separate as individual clusters while illite particles pack as face-to-face configuration under the interaction with water.The surface-overlapped illite aggregates would make sediments pack tightly,hinder the contact between gas and water,and result in the more significant inhibition on MH formation kinetics.Under the depressurization method,the addition of clay minerals facilitates MH dissociation rate.Physicochemical properties of clay minerals and MH distribution in the pore space lead to the faster dissociation rate in clay-containing sediments.The results of this study would provide beneficial guides on geological investigations and optimizing strategies of natural gas production in marine hydrate-bearing sediments.展开更多
The effects of siderite,hematite,and goethite on pyrite reactions in sodium aluminate solution at high temperatures,based on the coexistence of pyrite and iron-bearing minerals in bauxite,were studied.The addition of ...The effects of siderite,hematite,and goethite on pyrite reactions in sodium aluminate solution at high temperatures,based on the coexistence of pyrite and iron-bearing minerals in bauxite,were studied.The addition of siderite,goethite,and hematite increases the concentrations of S_(2)O_(3)^(2−),SO_(3)^(2−)and SO_(4)^(2−),enhancing sulfur removal during desilication.Siderite and hematite facilitate nearly 100%magnetite formation from pyrite,whereas goethite leads to the formation of both hematite and magnetite from pyrite through a multiphase transformation process.Iron-bearing minerals significantly increase the iron content in residues and enhance iron recovery from the red mud.Siderite,goethite,and hematite produce a porous surface in the form of erosive holes due to electrochemical corrosion,improving reaction efficiency of pyrite.Additionally,electrochemical corrosion promotes the pyrite reaction in accordance with the Kröger and Ziegler models,controlled by interfacial diffusion and chemical reactions in the presence of siderite,hematite and magnetite.展开更多
Organic matter(OM)derived from the decomposition of crop residues plays a key role as a sorbent for cadmium(Cd)immobilization.Few studies have explored the straw decomposition processes with the presence of minerals,a...Organic matter(OM)derived from the decomposition of crop residues plays a key role as a sorbent for cadmium(Cd)immobilization.Few studies have explored the straw decomposition processes with the presence of minerals,and the effect of newly generated organomineral complexes on heavy metal adsorption.In this study,we investigated the variations in structure and composition during the rice straw decomposition with or without minerals(goethite and kaolinite),as well as the adsorption behavior and mechanisms by which straw decomposition affects Cd immobilization.The degree of humification of extracted straw organic matter was assessed using excitation-emission matrix(EEM)fluorescence and Ultraviolet-visible spectroscopy(UV-vis),while employing FTIR spectroscopy and XPS to characterize the adsorption mechanisms.The spectra analysis revealed the enrichment of highly aromatic and hydrophobic components,indicating that the degree of straw decomposition and humification were further intensified during incubation.Additionally,the existence of goethite(SG)accelerated the humification of OM.Sorption experiments revealed that the straw humification increased Cd adsorption capacity.Notably,SG exhibited significantly higher adsorption performance compared to the organic matter without minerals(RS)and the existence of kaolinite(SK).Further analysis using FT-IR spectroscopy and XPS verified that the primarymechanisms involved in Cd immobilization were complexion with—OH and—COOH,as well as the formation of Cd-πbinds with aromatic C=C on the surface of solid OMs.These findings will facilitate understanding the interactions of the rice straw decomposing with soil minerals and its remediation effect on Cd-contaminated farmland.展开更多
It has been shown that the age of minerals in which U±Th are a major(e.g.,uraninite,pitchblende and thorite)or minor(e.g.,monazite,xenotime)component can be calculated from the concentrations of U±Th and Pb ...It has been shown that the age of minerals in which U±Th are a major(e.g.,uraninite,pitchblende and thorite)or minor(e.g.,monazite,xenotime)component can be calculated from the concentrations of U±Th and Pb rather than their isotopes,and such ages are referred to as chemical ages.Although equations for calculating the chemical ages have been well established and various computation programs have been reported,there is a lack of software that can not only calculate the chemical ages of individual analytical points but also provide an evaluation of the errors of individual ages as well as the whole dataset.In this paper,we develop a software for calculating and assessing the chemical ages of uranium minerals(CAUM),an open-source Python-based program with a friendly Graphical User Interface(GUI).Electron probe microanalysis(EPMA)data of uranium minerals are first imported from Excel files and used to calculate the chemical ages and associated errors of individual analytical points.The age data are then visualized to aid evaluating if the dataset comprises one or multiple populations and whether or not there are meaningful correlations between the chemical ages and impurities.Actions can then be taken to evaluate the errors within individual populations and the significance of the correlations.The use of the software is demonstrated with examples from published data.展开更多
This study employed convolutional neural networks(CNNs)for the classification of rock minerals based on 3179 RGB-scale original microstructural images of undisturbed broken surfaces.The image dataset covers 40 distinc...This study employed convolutional neural networks(CNNs)for the classification of rock minerals based on 3179 RGB-scale original microstructural images of undisturbed broken surfaces.The image dataset covers 40 distinct rock mineral-types.Three CNN architectures(Simple model,SqueezeNet,and Xception)were evaluated to compare their performance and feature extraction capabilities.Gradient-weighted Class Activation Mapping(Grad-CAM)was employed to visualize the features influencing model predictions,providing insights into how each model distinguishes between mineral classes.Key discriminative attributes included texture,grain size,pattern,and color variations.Texture and grain boundaries were identified as the most critical features,as they were strongly activated regions by the best model.Patterns such as banding and chromatic contrasts further enhanced classification accuracy.Performance analysis revealed that the Simple model had limited ability to isolate fine-grained details,producing broad and less specific activations(0.84 test accuracy).SqueezeNet demonstrated improved localization of discriminative features but occasionally missed finer textural details(0.95 test accuracy).The Xception model outperformed the others,achieving the highest classification accuracy(0.98 test accuracy)by exhibiting precise and tightly focused activations,capturing intricate textures and subtle chromatic variations.Its superior performance can be attributed to its deep architecture and efficient depth-wise separable convolutions,which enabled hierarchical and detailed feature extraction.Results underscores the importance of texture,pattern,and chromatic features in accurate mineral classification and highlights the suitability of deep,efficient architectures like Xception for such tasks.These findings demonstrate the potential of CNNs in geoscience research,offering a framework for automated mineral identification in industrial and scientific applications.展开更多
The Fengcheng Formation in the Hashan area,located on the northwestern margin of the Junggar Basin,represents a saline-alkaline lake facies with fine-grained mixed sedimentation.This formation is rich in alkaline mine...The Fengcheng Formation in the Hashan area,located on the northwestern margin of the Junggar Basin,represents a saline-alkaline lake facies with fine-grained mixed sedimentation.This formation is rich in alkaline minerals and serves as a high-quality source rock for hydrocarbon generation in alkaline lakes.However,its lithology is complex,and the origins of the salt minerals remain unclear.This study focuses on the salt minerals in the Fengcheng Formation of the Hashan area.Using core observation,thin section identification,scanning electron microscopy,electron probe micro-analysis,trace and rare earth element analysis,stable isotope analysis,fluid inclusion analysis,and zircon U-Pb dating,the sedimentary age of Fengcheng Formation and the mineralogical and geochemical characteristics of salt minerals were systematically studied.The salt minerals identified in the Fengcheng Formation include calcite,dolomite,eitelite,northupite,shortite,reedmergnerite,and Na-carbonate.According to the different types of salt minerals,the different contact relations between minerals,the different production positions and production styles of mineral combinations,the salt mineral assemblage in the study area is classified into three categories:The combination of calcite,dolomite,shortite,and reedmergnerite,The combination of Na-carbonates,eitelite,shortite,and reedmergnerite,The combination of dolomite,eitelite,shortite,and northupite.Two zircon U-Pb ages,307.8±2.7 Ma and 308.5±3.5 Ma,span the Carboniferous-Permian boundary,corresponding to an interglacial period within the Late Paleozoic Ice Age,aligning with the development of salt minerals.Salt minerals have the formation modes of sedimentation,replacement and hydrothermal transformation.Terrestrial weathering products,atmosphe ric,volcanic and hydrothermal processes,residual seawater,clay mineral transformation,thermal evolution of organic matter and tuffaceous alteration are material sources.The salt-forming fluid has the characteristics of weak acid-alkaline,medium-low temperature and high salinity,and is mainly driven by subduction zone high pressure,magmatic heat and gravity.The burial depth,temperature and CO_(2)concentration required for the formation of salt minerals were clarified,and the evolution sequence of salt-forming fluids from sedimentation to diagenesis and accompanied by hydrothermal(hot water)activities was summarized.The evolution model of salt minerals controlled by different genesis from the first member to the third member of Fengcheng Formation was established.The research findings are significant for understanding the paleoenvironment of the Fengcheng Formation,the formation mechanisms of high-salinity lakes,and the salt formation models.展开更多
To elucidate the adsorption characteristics and retention mechanisms of fracturing fluids in diverse clay minerals,we conducted on-line nuclear magnetic resonance(NMR)and atomic force microscopy(AFM)experiments.The de...To elucidate the adsorption characteristics and retention mechanisms of fracturing fluids in diverse clay minerals,we conducted on-line nuclear magnetic resonance(NMR)and atomic force microscopy(AFM)experiments.The depth and extent of solid phase damage are determined by the ratio between the size of fine fractions in fracturing fluid residue and the pore-throat size in experiments.Poor physical properties(K<0.5 mD)result in a more preferential flow pathway effect during flowback,and the stepwise incremental pressure differential proves to be more effective for the discharge of fracturing fluid in submicron pore throats.The permeability is significantly influenced by the differential distri-bution of retained fracturing fluid,as supported by direct experimental evidence.The presence of good physical properties(K>0.5 mD)combined with a scattered distribution of retained fracturing fluid is associated with high gas phase recovery permeability,whereas a continuous sheet-like distribution results in low recovery permeability.The expansive surface area and presence of filamentous illite minerals facilitate the multiple winding and adsorption of fracturing fluids,demonstrating strong hydrogen-bonding,multi-layering and multiple adsorption properties.The geological characteristics of the main gas formations exhibit significant variation,and the severity of damage caused by fracturing fluids occurs in diverse sequences.To address this issue,a differentiated strategy for optimizing frac-turing fluids has been proposed.展开更多
In this article,there were errors in Table 2 and Fig.5a which are corrected as below.In Table 2,the row headed alkali granite is incorrect.It should be alkaline granite.In Fig.5[a]the word alkali feldspar granite is i...In this article,there were errors in Table 2 and Fig.5a which are corrected as below.In Table 2,the row headed alkali granite is incorrect.It should be alkaline granite.In Fig.5[a]the word alkali feldspar granite is incor-rect,but should be alkaline granite;the Fig.5 should have appeared as shown below.The original article has been corrected.展开更多
As a widely used fertilizer,urea significantly promotes the leaching of dissolved organic nitrogen(DON)in soils and aggravates nitrogen contamination in groundwater.Clayminerals are considered the most important facto...As a widely used fertilizer,urea significantly promotes the leaching of dissolved organic nitrogen(DON)in soils and aggravates nitrogen contamination in groundwater.Clayminerals are considered the most important factor in retaining DON.However,the effect of urea on the retention of DON with different molecular weights by clay minerals is unknown.In this study,the retention of both low-molecular weight DON(LMWD)and high-molecular weight DON(HMWD)by clay minerals in the presence of urea was investigated.For this purpose,batch adsorption and soil column leaching experiments,characterization analysis(Fourier transform infrared spectroscopy X-ray diffraction,and X-ray photoelectron spectroscopy),and molecular dynamics simulations were carried out.Urea had a positive effect on the adsorption of LMWD,whereas a competitive effect existed for the adsorption of HMWD.The dominant interactions among DON,urea,and clay minerals included H-bonding,ligand exchange,and cation exchange.The urea was preferentially adsorbed on clay minerals and formed a complex,which provided more adsorption sites to LMWD and only a few to HMWD.The presence of urea increased the retention of LMWD and decreased the retention of HMWD in clay minerals.The retention capacity of LMWD increased by 6.9%–12.8%,while that of HMWD decreased by 6.7%–53.1%.These findings suggest that LMWD tended to be trapped in soils,while HMWD was prone to be leached into groundwater,which can be used to evaluate the leaching of DON from soil to groundwater.展开更多
Gemini quaternary ammonium salt surfactants, butane-a, co-bis（dimethyl dodeculammonium bromide） （BDDA） ethane-a, fl-bis（dimethyl dodeculammonium bromide） （EDDA） were adopted to comparatively study the flotatio...Gemini quaternary ammonium salt surfactants, butane-a, co-bis（dimethyl dodeculammonium bromide） （BDDA） ethane-a, fl-bis（dimethyl dodeculammonium bromide） （EDDA） were adopted to comparatively study the flotation behaviors of kaolinite, pyrophyllite and illite. It was found that three silicate minerals all exhibited good floatability with Gemini cationic surfactants as collectors over a wide pH range, while BDDA showed a stronger collecting power than EDDA. FTIR spectra and zeta potential analysis indicated that the mechanism of adsorption of Gemini collector molecules on three silicate minerals surfaces was almost identical for the electronic attraction and hydrogen bonds effect. The theoretically obtained results of density functional theory （DFT） at B3LYP/6-31G （d） level demonstrated the stronger collecting power of BDDA presented in the floatation test and zeta potential measurement.展开更多
The formation and evolution of secondary minerals during bioleaching of chalcopyrite by thermoacidophilic Archaea Acidianus manzaensis were analyzed by combining synchrotron radiation X-ray diffraction（SR-XRD） and S...The formation and evolution of secondary minerals during bioleaching of chalcopyrite by thermoacidophilic Archaea Acidianus manzaensis were analyzed by combining synchrotron radiation X-ray diffraction（SR-XRD） and S, Fe and Cu Kα X-ray absorption near edge structure（XANES） spectroscopy. Leaching experiment showed that 82.4% of Cu2＋ was dissolved by A. manzaensis after 10 d. The surface of chalcopyrite was corroded apparently and covered with leaching products. During bioleaching, the formation and evolution of secondary minerals were as follows： 1） little elemental sulfur, jarosite, bornite and chalcocite were found at days 2 and 4; and 2） bornite and chalcocite disappeared, covellite formed, and jarosite gradually became the main component at days 6 and 10. These results indicated that metal-deficiency sulfides chalcocite and bornite were first formed with a low redox potential value（360-461 m V）, and then gradually transformed to covellite with a high redox potential value（461-531 m V）.展开更多
In order to uncover the intrinsic reasons for spontaneous combustion of sulfide minerals,representative samples were collected from typical metal mines to carry out the mechanical activation experiment.The structures ...In order to uncover the intrinsic reasons for spontaneous combustion of sulfide minerals,representative samples were collected from typical metal mines to carry out the mechanical activation experiment.The structures and heat behaviors of activated samples were characterized by scanning electron microscopy（SEM）,X-ray diffraction（XRD） analysis,and simultaneous thermal analysis（STA）.It is found that the sulfide minerals after mechanical activation show many changes with increased specific surface areas,aggregation phenomenon,decreased diffraction peak intensity,broadened diffraction peak,declined initial temperatures of heat release and self-ignition points.A new theory for explaining the spontaneous combustion of sulfide minerals is put forward：the chemical reaction activity of sulfide minerals is heightened by all kinds of mechanical forces during the mining,and the spontaneous combustion takes place finally under proper environment.展开更多
The similar floatabilities of calcium minerals and the huge difference between scheelite and wolframite have resulted in difficulties during their separation by flotation in Shizhuyuan Mine. In this study, novel colle...The similar floatabilities of calcium minerals and the huge difference between scheelite and wolframite have resulted in difficulties during their separation by flotation in Shizhuyuan Mine. In this study, novel collectors, lead complexes of benzohydroxamic acid（Pb-BHA）,were introduced to modify the surface properties of scheelite and wolframite, thereby effectively and selectively improving floatability. The Pb-BHA complexes are found to be selective for the separation of scheelite and calcium minerals with little use of depressants and enable the synchronous flotation of scheelite and wolframite.Hence, a novel flotation process was developed for the recovery of tungsten minerals. The process is simplified greatly, and the recovery is improved by almost 10%.Removing or decreasing the amount of water glass contributes to the improvement of tungsten and fluorite recovery and the circulation of water and reagents, which benefits the environment.展开更多
Several socio-environmental needs(medicine,industry,engineering,orogenesis,genesis,etc.)require minerals to be more precisly defined and characterised.The identification of minerals plays a crucial role for researcher...Several socio-environmental needs(medicine,industry,engineering,orogenesis,genesis,etc.)require minerals to be more precisly defined and characterised.The identification of minerals plays a crucial role for researchers and is becoming an essential aspect of geological analysis.However,traditional methods relied heavily on expert knowledge and specialised equipment,making them labour-intensive,costly and time-consuming.This depen-dence is often labour-intensive,not to mention costly and time-consuming.To address this issue,some re-searchers have opted for machine learning algorithms to quickly identify a single mineral in a microscopic image of rocks.However this approch does not correspond to patterns of mineral distribution,where minerals are typically found in associations.These associations make it difficult to accurately identify minerals using con-ventional machine learning algorithms.This paper introduces a deep neural learning model based on multi-label classification,utilizing the problem adaptation method to analyse microscopic images of rock thin sections.The model is based on the ResNet50 architecture,which is designed to analyse minerals and generates the probability of a mineral presence in an image.This method provides a solution to the dependence between associated minerals.Experiments on many test images showed a model confidence,achieving average precision,recall and F1_score 97.15%,96.25%and 96.69%,respectively.Visualisation of the class activation mapping using the Grad-CAM algorithm indicates that our model is likely to locate the identified minerals effectively.In this way,the importance of each pixel with the class of interest can be assessed using heat maps.The recorded results,in terms of both performance and pixel_level evaluation,demonstrate the promising potential of the model used.It can therefore be considered for multi-labels image classification,particulary for images representing rock minerals.This approach serves as a valuable support tool for geological studies.展开更多
The Suizhou meteorite is a heavily shock-met-amorphosed L6 chondrite which contains thin shock melt veins.So far,26 high-pressure phases have been identified from the meteorite.Among the high-pressure phases,ten of th...The Suizhou meteorite is a heavily shock-met-amorphosed L6 chondrite which contains thin shock melt veins.So far,26 high-pressure phases have been identified from the meteorite.Among the high-pressure phases,ten of them were approved as new minerals which include tuite,xieite,wangdaodeite,chenmingite,hemleyite,poirierite,asimowite,hiroseite,elgoresyite,and ohtaniite,by the Commission on New Minerals,Nomenclature and Classification of the International Mineralogical Association.Other high-pressure phases identified from the meteorite are ahrensite,akimotoite,bridgmanite,lingunite,magnesiowüstite,majorite,majorite-pyrope_(ss),maskelynite,riesite,ringwoodite,wadsleyite,and 5 other phases including phase A,vitrified phase B and phase C,phase D(Ca-rich majorite),and partly inverted ringwoodite.The occurrence and abundance of high-pressure phases makes this meteorite the one with the richest variety of high-pressure minerals to date.展开更多
Latin American countries possess rich resources of critical minerals,which have long underpinned their economic growth and social advancement.Meanwhile,however,these countries are grappling with excessive external dep...Latin American countries possess rich resources of critical minerals,which have long underpinned their economic growth and social advancement.Meanwhile,however,these countries are grappling with excessive external dependency,underdeveloped industrial chains,low value-added exports,and weak international discourse power.In recent years,due to various external and internal factors,such as the restructuring of the global supply chains,the intensification of major-country rivalry,the transformation of regional development patterns,and the resurgence of resource nationalism,Latin American countries have been more aware of the strategic value and security attribute of critical minerals.Increasingly,they have strengthened the strategic governance of these resources from the national security perspective to defend national sovereignty over resources,enhance the resilience of their supply chains,improve industrial independence,and protect ecological security.Towards these ends,Latin American countries have been actively exploring and developing critical minerals strategies that align with global geopolitical changes and regional transformation needs.In practice,Latin American countries have tightened their control over critical minerals,considered both short-term economic gains and long-term development interests,balanced environmental protection and social responsibility,and conducted international mining cooperation based on the principles of diversity and balance.They are striving to maximize their security and development interests by seeking high-level security and high-quality development of critical mineral resources.展开更多
Coupled dissolution-precipitation is one of the critical processes influencing the mineralogical and geochemical evolution of pegmatites.This mechanism involves the simultaneous dissolution of primary mineral phases a...Coupled dissolution-precipitation is one of the critical processes influencing the mineralogical and geochemical evolution of pegmatites.This mechanism involves the simultaneous dissolution of primary mineral phases and the precipitation of secondary phases,driven by changes in the chemical environment,often mediated by hydrothermal fluids.The Bailongshan Li deposit,located in the West Kunlun region of northwest China,is a significant geological formation known for its rich lithium content and associated rare metals such as tantalum,niobium,and tin.This study investigates the coupled dissolution-precipitation processes that have played a crucial role in the mineralization of this deposit,focusing on key minerals,including cassiterite(Cst),columbite-group minerals(CGM),and elbaite(Elb).Using a combination of petrographic analysis,back-scattered electron(BSE)imaging,cathodoluminescence(CL)imaging,and micro X-ray fluorescence(XRF)mapping,we examined the textural and chemical characteristics of these minerals.Our findings reveal intricate patchy zoning patterns and element distributions(indicated by the Nb,Ta,W,Mn,Fe,Hf,Ti for CGM;Hf,Ti Rb,W,Nb,Ta for Cst;Ti,Zn,Fe,W,Hf,Mn,K for Elb)that indicate multiple stages of mineral alteration driven by fluid-mediated processes.The coupled dissolution-precipitation mechanisms observed in the Bailongshan deposit have resulted in significant redistribution and enrichment of economically valuable elements.The study highlights the importance of hydrothermal fluids in altering primary mineral phases and precipitating secondary phases with distinct compositions.These processes not only modified the mineralogical makeup of the pegmatite but also enhanced its economic potential by concentrating rare metals.Signatures of coupled dissolutionprecipitation processes can serve as an essential tool for mineral exploration,guiding the search for high-grade zones within similar pegmatitic formations.展开更多
With rapid progress in the global green transition over recent years,the sustained and stable supply of critical minerals essential for the green transition has garnered increased attention.As the largest country by l...With rapid progress in the global green transition over recent years,the sustained and stable supply of critical minerals essential for the green transition has garnered increased attention.As the largest country by landmass,Russia has a wealth of natural resources,particularly fossil fuels and critical minerals.In the current context of major-country rivalries,geopolitical conf licts,Western sanctions,and the green transition,Russia hopes to reduce excessive dependency on the oil and gas industry and diversify its sources of revenue.More importantly,it intends to use critical minerals as a new strategic tool for a long-term confrontation with the West and effectively ensure its national security and development interests.Towards this end,Russia has formulated strategic plans,encouraged import substitution,increased policy support,promoted geological study and exploration,and accelerated Arctic development.However,Russia faces many constraints in critical mineral development.Whether Russia can consolidate its status as a resource power in the future depends not only on the intensity,depth,and breadth of Western sanctions but also on its ability to break through the Western blockade,sustain the import of necessary equipment and technologies,develop alternative technologies,and gradually transform itself to adapt to the new circumstances.展开更多
基金Project(42277256)supported by the National Natural Science Foundation of ChinaProjects(HBKT-2021011,HBKT-2021014)supported by the Hunan Province Environmental Protection Research Program,ChinaProject(CDSKY-2023-05)supported by the Scientific Research of Project Hunan Provincial Urban Geological Survey and Monitoring Institute,China。
文摘In this study,Schwertmannite,Akaganéite and ammoniojarosite were biosynthesized by different bacteria and characterized.The results showed that bacteria are critical in mediating the mineral formation process:the morphology,crystallinity,grain size and specific surface area of each mineral varied upon different bacteria and culturing conditions.In addition,the formed minerals’elemental composition and group disparity lead to different morphology,crystallinity and subsequent adsorption performance.In particular,adsorption difference existed in iron minerals biosynthesized by different bacteria.The maximal adsorption capacities of Akaganéite,Schwertmannite and ammoniojarosite were 26.6 mg/g,17.5 mg/g and 3.90 mg/g respectively.Cr(VI)adsorption on iron-minerals involves hydrogen bonding,electrostatic interaction,and ligand exchange.The adsorption only occurred on the surface of ammoniojarosite,while for Akaganéite and Schwertmannite,the tunnel structure greatly facilitated the adsorption process and improved adsorption capacity.Thus,the molecular structure is the primary determining factor for adsorption performance.Collectively,the results can provide useful information in selecting suitable bacteria for synthesizing heavy-metal scavenging minerals according to different environmental conditions.
基金supported by the Key Research Program of the Institute of Geology&Geophysics,CAS(Grant No.IGGCAS-201903).
文摘Natural gas hydrates widely accumulate in submarine sediments composed of clay minerals.However,due to the complex physiochemistry and micron-sized particles of clay minerals,their effects on methane hydrate(MH)formation and dissociation are still in controversy.In this study,montmorillonite and illite were separately mixed with quartz sand to investigate their effects on MH formation and dissociation.The microstructure of synthesized samples was observed by cryo-SEM innovatively to understand the effects of montmorillonite and illite on MH phase transition in micron scale.Results show that montmorillonite and illite both show the inhibition on MH formation kinetics and water-to-hydrate conversion,and illite shows a stronger inhibition.The 10 wt%montmorillonite addition significantly retards MH formation rate,and the 20 wt%montmorillonite has a less inhibition on the rate.The increase of illite mass ratio(0-20 wt%)retards the rate of MH formation.As the content of clay minerals increase,the water-to-hydrate conversion decreases.Cryo-SEM images presented that montmorillonite aggregates separate as individual clusters while illite particles pack as face-to-face configuration under the interaction with water.The surface-overlapped illite aggregates would make sediments pack tightly,hinder the contact between gas and water,and result in the more significant inhibition on MH formation kinetics.Under the depressurization method,the addition of clay minerals facilitates MH dissociation rate.Physicochemical properties of clay minerals and MH distribution in the pore space lead to the faster dissociation rate in clay-containing sediments.The results of this study would provide beneficial guides on geological investigations and optimizing strategies of natural gas production in marine hydrate-bearing sediments.
基金the National Key R&D Program of China(No.2022YFC2904404).
文摘The effects of siderite,hematite,and goethite on pyrite reactions in sodium aluminate solution at high temperatures,based on the coexistence of pyrite and iron-bearing minerals in bauxite,were studied.The addition of siderite,goethite,and hematite increases the concentrations of S_(2)O_(3)^(2−),SO_(3)^(2−)and SO_(4)^(2−),enhancing sulfur removal during desilication.Siderite and hematite facilitate nearly 100%magnetite formation from pyrite,whereas goethite leads to the formation of both hematite and magnetite from pyrite through a multiphase transformation process.Iron-bearing minerals significantly increase the iron content in residues and enhance iron recovery from the red mud.Siderite,goethite,and hematite produce a porous surface in the form of erosive holes due to electrochemical corrosion,improving reaction efficiency of pyrite.Additionally,electrochemical corrosion promotes the pyrite reaction in accordance with the Kröger and Ziegler models,controlled by interfacial diffusion and chemical reactions in the presence of siderite,hematite and magnetite.
基金supported by the National Key Research and Development Program of China(No.2022YFD1700102)the National Natural Science Foundation of China(No.U20A20108)the Hunan Provincial Natural Science Foundation of China(No.2021JJ30357).
文摘Organic matter(OM)derived from the decomposition of crop residues plays a key role as a sorbent for cadmium(Cd)immobilization.Few studies have explored the straw decomposition processes with the presence of minerals,and the effect of newly generated organomineral complexes on heavy metal adsorption.In this study,we investigated the variations in structure and composition during the rice straw decomposition with or without minerals(goethite and kaolinite),as well as the adsorption behavior and mechanisms by which straw decomposition affects Cd immobilization.The degree of humification of extracted straw organic matter was assessed using excitation-emission matrix(EEM)fluorescence and Ultraviolet-visible spectroscopy(UV-vis),while employing FTIR spectroscopy and XPS to characterize the adsorption mechanisms.The spectra analysis revealed the enrichment of highly aromatic and hydrophobic components,indicating that the degree of straw decomposition and humification were further intensified during incubation.Additionally,the existence of goethite(SG)accelerated the humification of OM.Sorption experiments revealed that the straw humification increased Cd adsorption capacity.Notably,SG exhibited significantly higher adsorption performance compared to the organic matter without minerals(RS)and the existence of kaolinite(SK).Further analysis using FT-IR spectroscopy and XPS verified that the primarymechanisms involved in Cd immobilization were complexion with—OH and—COOH,as well as the formation of Cd-πbinds with aromatic C=C on the surface of solid OMs.These findings will facilitate understanding the interactions of the rice straw decomposing with soil minerals and its remediation effect on Cd-contaminated farmland.
基金supported by the Natural Science Foundation Program of China(42173072,41503037,U1967207)Postgraduate Innovative Cultivation Program(CDUT2023BJCX013)Uranium Resources Exploration and Exploitation Innovation Center&and Everest Scientific Research Program(CDUT).
文摘It has been shown that the age of minerals in which U±Th are a major(e.g.,uraninite,pitchblende and thorite)or minor(e.g.,monazite,xenotime)component can be calculated from the concentrations of U±Th and Pb rather than their isotopes,and such ages are referred to as chemical ages.Although equations for calculating the chemical ages have been well established and various computation programs have been reported,there is a lack of software that can not only calculate the chemical ages of individual analytical points but also provide an evaluation of the errors of individual ages as well as the whole dataset.In this paper,we develop a software for calculating and assessing the chemical ages of uranium minerals(CAUM),an open-source Python-based program with a friendly Graphical User Interface(GUI).Electron probe microanalysis(EPMA)data of uranium minerals are first imported from Excel files and used to calculate the chemical ages and associated errors of individual analytical points.The age data are then visualized to aid evaluating if the dataset comprises one or multiple populations and whether or not there are meaningful correlations between the chemical ages and impurities.Actions can then be taken to evaluate the errors within individual populations and the significance of the correlations.The use of the software is demonstrated with examples from published data.
基金support provided by Imam Abdulrah-man Bin Faisal University,Dammam,KSA,in carrying out this research.
文摘This study employed convolutional neural networks(CNNs)for the classification of rock minerals based on 3179 RGB-scale original microstructural images of undisturbed broken surfaces.The image dataset covers 40 distinct rock mineral-types.Three CNN architectures(Simple model,SqueezeNet,and Xception)were evaluated to compare their performance and feature extraction capabilities.Gradient-weighted Class Activation Mapping(Grad-CAM)was employed to visualize the features influencing model predictions,providing insights into how each model distinguishes between mineral classes.Key discriminative attributes included texture,grain size,pattern,and color variations.Texture and grain boundaries were identified as the most critical features,as they were strongly activated regions by the best model.Patterns such as banding and chromatic contrasts further enhanced classification accuracy.Performance analysis revealed that the Simple model had limited ability to isolate fine-grained details,producing broad and less specific activations(0.84 test accuracy).SqueezeNet demonstrated improved localization of discriminative features but occasionally missed finer textural details(0.95 test accuracy).The Xception model outperformed the others,achieving the highest classification accuracy(0.98 test accuracy)by exhibiting precise and tightly focused activations,capturing intricate textures and subtle chromatic variations.Its superior performance can be attributed to its deep architecture and efficient depth-wise separable convolutions,which enabled hierarchical and detailed feature extraction.Results underscores the importance of texture,pattern,and chromatic features in accurate mineral classification and highlights the suitability of deep,efficient architectures like Xception for such tasks.These findings demonstrate the potential of CNNs in geoscience research,offering a framework for automated mineral identification in industrial and scientific applications.
基金funded by National Natural Science Foundation of China(Grant Nos.42172153)。
文摘The Fengcheng Formation in the Hashan area,located on the northwestern margin of the Junggar Basin,represents a saline-alkaline lake facies with fine-grained mixed sedimentation.This formation is rich in alkaline minerals and serves as a high-quality source rock for hydrocarbon generation in alkaline lakes.However,its lithology is complex,and the origins of the salt minerals remain unclear.This study focuses on the salt minerals in the Fengcheng Formation of the Hashan area.Using core observation,thin section identification,scanning electron microscopy,electron probe micro-analysis,trace and rare earth element analysis,stable isotope analysis,fluid inclusion analysis,and zircon U-Pb dating,the sedimentary age of Fengcheng Formation and the mineralogical and geochemical characteristics of salt minerals were systematically studied.The salt minerals identified in the Fengcheng Formation include calcite,dolomite,eitelite,northupite,shortite,reedmergnerite,and Na-carbonate.According to the different types of salt minerals,the different contact relations between minerals,the different production positions and production styles of mineral combinations,the salt mineral assemblage in the study area is classified into three categories:The combination of calcite,dolomite,shortite,and reedmergnerite,The combination of Na-carbonates,eitelite,shortite,and reedmergnerite,The combination of dolomite,eitelite,shortite,and northupite.Two zircon U-Pb ages,307.8±2.7 Ma and 308.5±3.5 Ma,span the Carboniferous-Permian boundary,corresponding to an interglacial period within the Late Paleozoic Ice Age,aligning with the development of salt minerals.Salt minerals have the formation modes of sedimentation,replacement and hydrothermal transformation.Terrestrial weathering products,atmosphe ric,volcanic and hydrothermal processes,residual seawater,clay mineral transformation,thermal evolution of organic matter and tuffaceous alteration are material sources.The salt-forming fluid has the characteristics of weak acid-alkaline,medium-low temperature and high salinity,and is mainly driven by subduction zone high pressure,magmatic heat and gravity.The burial depth,temperature and CO_(2)concentration required for the formation of salt minerals were clarified,and the evolution sequence of salt-forming fluids from sedimentation to diagenesis and accompanied by hydrothermal(hot water)activities was summarized.The evolution model of salt minerals controlled by different genesis from the first member to the third member of Fengcheng Formation was established.The research findings are significant for understanding the paleoenvironment of the Fengcheng Formation,the formation mechanisms of high-salinity lakes,and the salt formation models.
基金supported by the Sichuan Youth Science and Technology Innovation Research Team Project(No.2021JDTDO017)the open Fund(PLN2022-11)of State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(Southwest Petroleum University)+1 种基金Southwest Petroleum University Graduate Innovation Fund(No.2022KYCX021)Jian Tian would like to acknowledge the funding from the National Natural Science Foundation of China(52404023).
文摘To elucidate the adsorption characteristics and retention mechanisms of fracturing fluids in diverse clay minerals,we conducted on-line nuclear magnetic resonance(NMR)and atomic force microscopy(AFM)experiments.The depth and extent of solid phase damage are determined by the ratio between the size of fine fractions in fracturing fluid residue and the pore-throat size in experiments.Poor physical properties(K<0.5 mD)result in a more preferential flow pathway effect during flowback,and the stepwise incremental pressure differential proves to be more effective for the discharge of fracturing fluid in submicron pore throats.The permeability is significantly influenced by the differential distri-bution of retained fracturing fluid,as supported by direct experimental evidence.The presence of good physical properties(K>0.5 mD)combined with a scattered distribution of retained fracturing fluid is associated with high gas phase recovery permeability,whereas a continuous sheet-like distribution results in low recovery permeability.The expansive surface area and presence of filamentous illite minerals facilitate the multiple winding and adsorption of fracturing fluids,demonstrating strong hydrogen-bonding,multi-layering and multiple adsorption properties.The geological characteristics of the main gas formations exhibit significant variation,and the severity of damage caused by fracturing fluids occurs in diverse sequences.To address this issue,a differentiated strategy for optimizing frac-turing fluids has been proposed.
文摘In this article,there were errors in Table 2 and Fig.5a which are corrected as below.In Table 2,the row headed alkali granite is incorrect.It should be alkaline granite.In Fig.5[a]the word alkali feldspar granite is incor-rect,but should be alkaline granite;the Fig.5 should have appeared as shown below.The original article has been corrected.
基金supported by the National Natural Science Foundation of China(No.42107052)Beijing Natural Science Foundation(No.JQ21031).
文摘As a widely used fertilizer,urea significantly promotes the leaching of dissolved organic nitrogen(DON)in soils and aggravates nitrogen contamination in groundwater.Clayminerals are considered the most important factor in retaining DON.However,the effect of urea on the retention of DON with different molecular weights by clay minerals is unknown.In this study,the retention of both low-molecular weight DON(LMWD)and high-molecular weight DON(HMWD)by clay minerals in the presence of urea was investigated.For this purpose,batch adsorption and soil column leaching experiments,characterization analysis(Fourier transform infrared spectroscopy X-ray diffraction,and X-ray photoelectron spectroscopy),and molecular dynamics simulations were carried out.Urea had a positive effect on the adsorption of LMWD,whereas a competitive effect existed for the adsorption of HMWD.The dominant interactions among DON,urea,and clay minerals included H-bonding,ligand exchange,and cation exchange.The urea was preferentially adsorbed on clay minerals and formed a complex,which provided more adsorption sites to LMWD and only a few to HMWD.The presence of urea increased the retention of LMWD and decreased the retention of HMWD in clay minerals.The retention capacity of LMWD increased by 6.9%–12.8%,while that of HMWD decreased by 6.7%–53.1%.These findings suggest that LMWD tended to be trapped in soils,while HMWD was prone to be leached into groundwater,which can be used to evaluate the leaching of DON from soil to groundwater.
基金Project(2013AA064102)supported by the High-tech Research and Development Program of ChinaProject(51004114)supported by the National Natural Science Foundation of China+1 种基金Project(2007B52)supported by the Foundation for the Author of National Excellent Doctoral Dissertation of ChinaProject(NCEP-08-0568)supported by the Program for New Century Excellent Talents in Chinese University
文摘Gemini quaternary ammonium salt surfactants, butane-a, co-bis（dimethyl dodeculammonium bromide） （BDDA） ethane-a, fl-bis（dimethyl dodeculammonium bromide） （EDDA） were adopted to comparatively study the flotation behaviors of kaolinite, pyrophyllite and illite. It was found that three silicate minerals all exhibited good floatability with Gemini cationic surfactants as collectors over a wide pH range, while BDDA showed a stronger collecting power than EDDA. FTIR spectra and zeta potential analysis indicated that the mechanism of adsorption of Gemini collector molecules on three silicate minerals surfaces was almost identical for the electronic attraction and hydrogen bonds effect. The theoretically obtained results of density functional theory （DFT） at B3LYP/6-31G （d） level demonstrated the stronger collecting power of BDDA presented in the floatation test and zeta potential measurement.
基金Project(U1232103)supported by the Joint Funds of National Natural Science Foundation of China and Large Scientific Facility Foundation of Chinese Academy of SciencesProject(51274257)supported by the National Natural Science Foundation of China+2 种基金Project(CX2014B092)supported by Hunan Provincial Innovation Foundation For Postgraduate,ChinaProject(VR-12419)supported by Beijing Synchrotron Radiation Facility Public User Program,ChinaProjects(13SRBL15U13024,13SRBL14B13023)supported by the Open Funds of Shanghai Synchrotron Radiation Facility,China
文摘The formation and evolution of secondary minerals during bioleaching of chalcopyrite by thermoacidophilic Archaea Acidianus manzaensis were analyzed by combining synchrotron radiation X-ray diffraction（SR-XRD） and S, Fe and Cu Kα X-ray absorption near edge structure（XANES） spectroscopy. Leaching experiment showed that 82.4% of Cu2＋ was dissolved by A. manzaensis after 10 d. The surface of chalcopyrite was corroded apparently and covered with leaching products. During bioleaching, the formation and evolution of secondary minerals were as follows： 1） little elemental sulfur, jarosite, bornite and chalcocite were found at days 2 and 4; and 2） bornite and chalcocite disappeared, covellite formed, and jarosite gradually became the main component at days 6 and 10. These results indicated that metal-deficiency sulfides chalcocite and bornite were first formed with a low redox potential value（360-461 m V）, and then gradually transformed to covellite with a high redox potential value（461-531 m V）.
基金Project(2012J05088) supported by the Natural Science Foundation of Fujian Province,ChinaProject(022409) supported by the School Talent Foundation of Fuzhou University,China
文摘In order to uncover the intrinsic reasons for spontaneous combustion of sulfide minerals,representative samples were collected from typical metal mines to carry out the mechanical activation experiment.The structures and heat behaviors of activated samples were characterized by scanning electron microscopy（SEM）,X-ray diffraction（XRD） analysis,and simultaneous thermal analysis（STA）.It is found that the sulfide minerals after mechanical activation show many changes with increased specific surface areas,aggregation phenomenon,decreased diffraction peak intensity,broadened diffraction peak,declined initial temperatures of heat release and self-ignition points.A new theory for explaining the spontaneous combustion of sulfide minerals is put forward：the chemical reaction activity of sulfide minerals is heightened by all kinds of mechanical forces during the mining,and the spontaneous combustion takes place finally under proper environment.
基金financially supported by the National Natural Science Foundation of China (No.51634009)the Institutions of Higher Learning Discipline Innovation Conference Program (111 Project) (No.B14034)the Collaborative Innovation Center for Clean and Efficient Utilization of Strategic Metal Mineral Resources Innovation Driven Plan of Central South University (No.2015CX005)
文摘The similar floatabilities of calcium minerals and the huge difference between scheelite and wolframite have resulted in difficulties during their separation by flotation in Shizhuyuan Mine. In this study, novel collectors, lead complexes of benzohydroxamic acid（Pb-BHA）,were introduced to modify the surface properties of scheelite and wolframite, thereby effectively and selectively improving floatability. The Pb-BHA complexes are found to be selective for the separation of scheelite and calcium minerals with little use of depressants and enable the synchronous flotation of scheelite and wolframite.Hence, a novel flotation process was developed for the recovery of tungsten minerals. The process is simplified greatly, and the recovery is improved by almost 10%.Removing or decreasing the amount of water glass contributes to the improvement of tungsten and fluorite recovery and the circulation of water and reagents, which benefits the environment.
文摘Several socio-environmental needs(medicine,industry,engineering,orogenesis,genesis,etc.)require minerals to be more precisly defined and characterised.The identification of minerals plays a crucial role for researchers and is becoming an essential aspect of geological analysis.However,traditional methods relied heavily on expert knowledge and specialised equipment,making them labour-intensive,costly and time-consuming.This depen-dence is often labour-intensive,not to mention costly and time-consuming.To address this issue,some re-searchers have opted for machine learning algorithms to quickly identify a single mineral in a microscopic image of rocks.However this approch does not correspond to patterns of mineral distribution,where minerals are typically found in associations.These associations make it difficult to accurately identify minerals using con-ventional machine learning algorithms.This paper introduces a deep neural learning model based on multi-label classification,utilizing the problem adaptation method to analyse microscopic images of rock thin sections.The model is based on the ResNet50 architecture,which is designed to analyse minerals and generates the probability of a mineral presence in an image.This method provides a solution to the dependence between associated minerals.Experiments on many test images showed a model confidence,achieving average precision,recall and F1_score 97.15%,96.25%and 96.69%,respectively.Visualisation of the class activation mapping using the Grad-CAM algorithm indicates that our model is likely to locate the identified minerals effectively.In this way,the importance of each pixel with the class of interest can be assessed using heat maps.The recorded results,in terms of both performance and pixel_level evaluation,demonstrate the promising potential of the model used.It can therefore be considered for multi-labels image classification,particulary for images representing rock minerals.This approach serves as a valuable support tool for geological studies.
基金Science and Technology Planning Project of Guangdong Province(2023B1212060048).
文摘The Suizhou meteorite is a heavily shock-met-amorphosed L6 chondrite which contains thin shock melt veins.So far,26 high-pressure phases have been identified from the meteorite.Among the high-pressure phases,ten of them were approved as new minerals which include tuite,xieite,wangdaodeite,chenmingite,hemleyite,poirierite,asimowite,hiroseite,elgoresyite,and ohtaniite,by the Commission on New Minerals,Nomenclature and Classification of the International Mineralogical Association.Other high-pressure phases identified from the meteorite are ahrensite,akimotoite,bridgmanite,lingunite,magnesiowüstite,majorite,majorite-pyrope_(ss),maskelynite,riesite,ringwoodite,wadsleyite,and 5 other phases including phase A,vitrified phase B and phase C,phase D(Ca-rich majorite),and partly inverted ringwoodite.The occurrence and abundance of high-pressure phases makes this meteorite the one with the richest variety of high-pressure minerals to date.
文摘Latin American countries possess rich resources of critical minerals,which have long underpinned their economic growth and social advancement.Meanwhile,however,these countries are grappling with excessive external dependency,underdeveloped industrial chains,low value-added exports,and weak international discourse power.In recent years,due to various external and internal factors,such as the restructuring of the global supply chains,the intensification of major-country rivalry,the transformation of regional development patterns,and the resurgence of resource nationalism,Latin American countries have been more aware of the strategic value and security attribute of critical minerals.Increasingly,they have strengthened the strategic governance of these resources from the national security perspective to defend national sovereignty over resources,enhance the resilience of their supply chains,improve industrial independence,and protect ecological security.Towards these ends,Latin American countries have been actively exploring and developing critical minerals strategies that align with global geopolitical changes and regional transformation needs.In practice,Latin American countries have tightened their control over critical minerals,considered both short-term economic gains and long-term development interests,balanced environmental protection and social responsibility,and conducted international mining cooperation based on the principles of diversity and balance.They are striving to maximize their security and development interests by seeking high-level security and high-quality development of critical mineral resources.
基金jointly supported by the National Natural Science Foundation of China(Nos.42250202,92162323,42272075)the Fundamental Research Funds for the Central Universities,Sun Yat-sen University(No.24lgqb001)+1 种基金the Natural Science Foundation Project of Guangdong Province(No.2022A1515010003)the Guangdong Province Introduced Innovative R&D Team of Big Data—Mathematical Earth Sciences and Extreme Geological Events Team(No.2021ZT09H399)。
文摘Coupled dissolution-precipitation is one of the critical processes influencing the mineralogical and geochemical evolution of pegmatites.This mechanism involves the simultaneous dissolution of primary mineral phases and the precipitation of secondary phases,driven by changes in the chemical environment,often mediated by hydrothermal fluids.The Bailongshan Li deposit,located in the West Kunlun region of northwest China,is a significant geological formation known for its rich lithium content and associated rare metals such as tantalum,niobium,and tin.This study investigates the coupled dissolution-precipitation processes that have played a crucial role in the mineralization of this deposit,focusing on key minerals,including cassiterite(Cst),columbite-group minerals(CGM),and elbaite(Elb).Using a combination of petrographic analysis,back-scattered electron(BSE)imaging,cathodoluminescence(CL)imaging,and micro X-ray fluorescence(XRF)mapping,we examined the textural and chemical characteristics of these minerals.Our findings reveal intricate patchy zoning patterns and element distributions(indicated by the Nb,Ta,W,Mn,Fe,Hf,Ti for CGM;Hf,Ti Rb,W,Nb,Ta for Cst;Ti,Zn,Fe,W,Hf,Mn,K for Elb)that indicate multiple stages of mineral alteration driven by fluid-mediated processes.The coupled dissolution-precipitation mechanisms observed in the Bailongshan deposit have resulted in significant redistribution and enrichment of economically valuable elements.The study highlights the importance of hydrothermal fluids in altering primary mineral phases and precipitating secondary phases with distinct compositions.These processes not only modified the mineralogical makeup of the pegmatite but also enhanced its economic potential by concentrating rare metals.Signatures of coupled dissolutionprecipitation processes can serve as an essential tool for mineral exploration,guiding the search for high-grade zones within similar pegmatitic formations.
文摘With rapid progress in the global green transition over recent years,the sustained and stable supply of critical minerals essential for the green transition has garnered increased attention.As the largest country by landmass,Russia has a wealth of natural resources,particularly fossil fuels and critical minerals.In the current context of major-country rivalries,geopolitical conf licts,Western sanctions,and the green transition,Russia hopes to reduce excessive dependency on the oil and gas industry and diversify its sources of revenue.More importantly,it intends to use critical minerals as a new strategic tool for a long-term confrontation with the West and effectively ensure its national security and development interests.Towards this end,Russia has formulated strategic plans,encouraged import substitution,increased policy support,promoted geological study and exploration,and accelerated Arctic development.However,Russia faces many constraints in critical mineral development.Whether Russia can consolidate its status as a resource power in the future depends not only on the intensity,depth,and breadth of Western sanctions but also on its ability to break through the Western blockade,sustain the import of necessary equipment and technologies,develop alternative technologies,and gradually transform itself to adapt to the new circumstances.
