Antimony Mine Research Articles

Flavihumibacter stibioxidans sp. nov., an antimony-oxidizing bacterium isolated from antimony mine soil.

A Gram-stain-positive, strictly aerobic, non-motile and rod-shaped bacterial strain, designated YS-17T, was isolated from soil in the Lengshuijiang antimony mine, Hunan Province, China. Comparative 16S rRNA gene sequencing analysis clustered it with Flavihumibacter strains, and strain YS-17T was most closely related to Flavihumibacter cheonanensis WS16T (97.2 % similarity), Flavihumibacter petaseus T41T (96.6 %) and Flavihumibacter solisilvae 3-3T (96.5 %). The level of DNA-DNA relatedness between strain YS-17T and F. cheonanensis JCM 19322T was 35.5±0.1 % (n=2). The major respiratory quinone of strain YS-17T was menaquinone-7 and the major polar lipids were phosphatidylethanolamine, two unidentified lipids, two unidentified amino lipids and phospholipid. The major fatty acids (≥5 %) were iso-C15 : 0, iso-C15 : 1 G, unknown ECL 13.565, iso-C17 : 0 3-OH, C15 : 0, C16 : 1ω5c and anteiso-C15 : 0. The DNA G+C content was 47.8 mol%. Compared with other Flavihumibacter strains, strain YS-17T showed major biophysical and biochemical differences, with the ability to hydrolyse gelatin and to assimilate salicin and l-proline. The results demonstrated that strain YS-17T belongs to the genus Flavihumibacter and represents a novel species, for which the name Flavihumibacter stibioxidans sp. nov. is proposed. The type strain is YS-17T (=CCTCC AB 2016053T=KCTC 52205T).

Microbial Antimony Biogeochemistry: Enzymes, Regulation, and Related Metabolic Pathways.

Antimony (Sb) is a toxic metalloid that occurs widely at trace concentrations in soil, aquatic systems, and the atmosphere. Nowadays, with the development of its new industrial applications and the corresponding expansion of antimony mining activities, the phenomenon of antimony pollution has become an increasingly serious concern. In recent years, research interest in Sb has been growing and reflects a fundamental scientific concern regarding Sb in the environment. In this review, we summarize the recent research on bacterial antimony transformations, especially those regarding antimony uptake, efflux, antimonite oxidation, and antimonate reduction. We conclude that our current understanding of antimony biochemistry and biogeochemistry is roughly equivalent to where that of arsenic was some 20 years ago. This portends the possibility of future discoveries with regard to the ability of microorganisms to conserve energy for their growth from antimony redox reactions and the isolation of new species of "antimonotrophs."

Sources, migration and transformation of antimony contamination in the water environment of Xikuangshan, China: Evidence from geochemical and stable isotope (S, Sr) signatures

The Xikuangshan (XKS) mine in central China is the largest antimony (Sb) mine in the world. The mining activity has seriously contaminated the waters in the area. To determine the sources, migration and transformation of Sb contamination, 32 samples from groundwater (aquifer water), surface water and mine water were collected for water chemistry, trace element and SSO4 and Sr stable isotope analyses. The results showed that the groundwater and surface water were in an oxidized environment. The SSO4 and Sr isotope compositions in the water indicated that dissolved Sb and SO42 originated from sulfide mineral (Sb2S3) oxidation, whereas radiogenic Sr may have been sourced from silicified limestone and stibnite in the Shetianqiao aquifer. Furthermore, a positive correlation between δ34SSO4 and δ87Sr values revealed that the Sr, S and Sb in the waters had a common contamination source, i.e., silicified limestone and stibnite, whereas the Sr, S and Sb in rock and ore were sourced from Proterozoic basement clastics. The analysis also indicated that the isotope composition of dissolved SO42− had been influenced by slight bacterial SO4 reduction in the Magunao aquifer. Mining or rock collapse may have caused Shetianqiao aquifer water to contaminate the Magunao aquifer water via mixing. This study has demonstrated that the stable isotopes of 34SSO4 and 87Sr, combined with hydrochemical methods, are effective in tracking the sources, migration and transformation of Sb contamination.

Influence of reducing conditions on the release of antimony and arsenic from a tailings sediment

Purpose Burial treatment is a frequently used technology for contaminated solid materials, but little is known about the effect of redox changes on the mobility of metals and metalloids. Here, sediment contaminated by historical tailing slurry from an antimony (Sb) mine was incubated with sodium ascorbate solution (SAS), so as to gain insights into the remobilization of Sb and arsenic (As) under reducing conditions.

Antimony in the metallurgical industry: A review of its chemistry and environmental stabilization options

Antimony (Sb) is an impurity element that is increasingly encountered in the mineral processing/metallurgical industries of gold, copper and lead. Its occurrence in metallurgical feedstocks is in the form of various antimony minerals with stibnite, Sb2S3, being the most important one. During processing antimony is mobilized reporting to waste solid tailings or effluent streams. This becomes a matter of concern since antimony is similar to arsenic in many respects, both sharing similar chemical properties as well as toxicity and thus have negative environmental implications, especially in the context of industrial effluents and their treatment. This review summarizes the available literature on antimony in the environment and its removal with emphasis on effluent treatment. Antimony speciation as well as oxidation was presented at various conditions (pH, Eh, temperature, and concentration) to provide a basis of its aqueous behavior, an important foundation for industrial effluent treatment. For immobilizing antimony in the environment via precipitation from effluents several mineral candidates were identified of which schafarzikite, FeSb2O4, and tripuhyite, FeSbO4, were proposed as very attractive due to their very low antimony solubility (<1mgL−1).

PH-dependent release characteristics of antimony and arsenic from typical antimony-bearing ores

The pH-dependent leaching of antimony (Sb) and arsenic (As) from three typical Sb-bearing ores (Banxi, Muli and Tongkeng Antimony Mine) in China was assessed using a pH-static leaching experiment. The pH changes of the leached solutions and pH-dependent leaching of Sb and As occurred in different ways. For the Banxi and Muli Sb ores, alkaline conditions were more favorable for the release of Sb compared to neutral and acidic conditions, but the reverse was true for the pH-dependent release of As. For the Tongkeng Sb ore, unlike the previous two Sb-bearing ores, acidic conditions were more favorable for Sb release than neutral and alkaline conditions. The ores with lower Sb and As contents released higher percentages of their Sb and As after 16day leaching, suggesting that they are the largest potential sources of pollution. This work may provide key information on the geochemistry of Sb and As in the weathering zone.

Development of principles of selection of reagents for flotation of antimony and bismuth minerals

3D models of clusters of antimony and bismuth sulfides were constructed. For these models, the charges of individual atoms and the electron populations of s-Pop, p-Pop, and d-Pop orbitals were determined. Collector activity evaluation prediction (CAEP) was made for a number of proposed reagents attached to atoms of clusters of minerals. CAEP characterizes the activity of a collector: the lower CAEP, the more preferable the interaction of the collector and the more efficient the flotation reagent. For flotation of antimony and bismuth minerals, a number of promising collectors were recommended.

Treatment of antimony mine drainage: challenges and opportunities with special emphasis on mineral adsorption and sulfate reducing bacteria.

The present article summarizes antimony mine distribution, antimony mine drainage generation and environmental impacts, and critically analyses the remediation approach with special emphasis on iron oxidizing bacteria and sulfate reducing bacteria. Most recent research focuses on readily available low-cost adsorbents, such as minerals, wastes, and biosorbents. It is found that iron oxides prepared by chemical methods present superior adsorption ability for Sb(III) and Sb(V). However, this process is more costly and iron oxide activity can be inhibited by plenty of sulfate in antimony mine drainage. In the presence of sulfate reducing bacteria, sulfate can be reduced to sulfide and form Sb(2)S(3) precipitates. However, dissolved oxygen and lack of nutrient source in antimony mine drainage inhibit sulfate reducing bacteria activity. Biogenetic iron oxide minerals from iron corrosion by iron-oxidizing bacteria may prove promising for antimony adsorption, while the micro-environment generated from iron corrosion by iron oxidizing bacteria may provide better growth conditions for symbiotic sulfate reducing bacteria. Finally, based on biogenetic iron oxide adsorption and sulfate reducing bacteria followed by precipitation, the paper suggests an alternative treatment for antimony mine drainage that deserves exploration.

Profiling microbial community in a watershed heavily contaminated by an active antimony (Sb) mine in Southwest China

Located in Southwest China, the Chahe watershed has been severely contaminated by upstream active antimony (Sb) mines. The extremely high concentrations of Sb make the Chahe watershed an excellent model to elucidate the response of indigenous microbial activities within a severe Sb-contaminated environment. In this study, water and surface sediments from six locations in the Chahe watershed with different levels of Sb contamination were analyzed. Illumina sequencing of 16S rRNA amplicons revealed more than 40 phyla from the domain Bacteria and 2 phyla from the domain Archaea. Sequences assigned to the genera Flavobacterium, Sulfuricurvum, Halomonas, Shewanella, Lactobacillus, Acinetobacter, and Geobacter demonstrated high relative abundances in all sequencing libraries. Spearman's rank correlations indicated that a number of microbial phylotypes were positively correlated with different speciation of Sb, suggesting potential roles of these phylotypes in microbial Sb cycling. Canonical correspondence analysis further demonstrated that geochemical parameters, including water temperature, pH, total Fe, sulfate, aqueous Sb, and Eh, significantly structured the overall microbial community in Chahe watershed samples. Our findings offer a direct and reliable reference to the diversity of microbial communities in the presence of extremely high Sb concentrations, and may have potential implications for in situ bioremediation strategies of Sb contaminated sites.

The leaching characteristics and changes in the leached layer of antimony-bearing ores from China

China has the most abundant antimony (Sb) resources of any country in the world. Large quantities of Sb have been released from mining and smelting processes, causing serious Sb contamination in the mine or nearby areas. To understand the leaching characteristics of hazardous Sb, As, Pb and Cr from antimony minerals, 12 samples of antimony-bearing ores from eight large mines from China distributed in Hunan, Yunnan, Guizhou and Guangxi provinces were studied. The main compositions of these minerals are Sb2S3, SiO2 or CaCO3. The pH changes during the leaching indicated that some minerals themselves are alkaline, providing sufficient acid neutralizing capacity during leaching. However, some alkaline minerals release much more Sb, As, Pb and Cr than others. Inconsistencies between totals amounts and the released content of Sb, As, Pb and Cr were also found. The surface topography of an antimony sulfide mineral and the species changes of Sb and sulfur (S) on its leached surface were also characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. It is the oxidation dissolution of Sb2S3 that releases Sb. Sb(III) and S2− on the surface of the fresh mineral were oxidized to Sb(V) and S2O32− and SO42−, respectively, and finally, an equilibrium of dissolution was reached over time. The release of Sb, As, Pb and Cr from typical antimony ores is a source of Sb, As, Pb and Cr in the weathering zone; with this in mind, it is easier to understand the geochemical processes and the pollution accidents involving Sb and As within the mining areas and their surroundings.

Tuberculosis transmission and risk factors in a Chinese antimony mining community.

An antimony mine in Jiangxi Province, China. To investigate the incidence of tuberculosis (TB) transmission and associated risk factors in a Chinese antimony mining community. Retrospective cohort study The 15-locus mycobacterial interspersed repetitive unit-variable number of tandem repeats (MIRU-VNTR(15-China)) method was used to determine clustering of patients. A region of difference (RD105) deletion-targeted multiplex polymerase chain reaction was adopted to identify Beijing strains. Risk factors for clustering were assessed. Of 263 TB patients, 175 were distributed into 35 clusters. Estimated recent transmission of TB was 53.2% within the community. Patients who failed treatment were more likely to be in clusters (adjusted odds ratio [aOR] 0.03, 95%CI 2.12-6.89). Patients with multiresistant isolates were more likely to have failed treatment and to be in a cluster than those carrying a susceptible strain (aOR 0.001, 95%CI 4.89-29.7). Individuals who fail treatment are an important source of infection in TB transmission, and multiresistant isolates are mostly responsible for this. TB control plans need to focus on treatment failure cases in the community.

Spatial Variability and Distribution of the Metals in Surface Runoff in a Nonferrous Metal Mine.

The spatial variation and distribution features of the metals tested in the surface runoff in Xikuangshan Bao Daxing miming area were analyzed by combining statistical methods with a geographic information system (GIS). The results showed that the maximum concentrations of those five kinds of the metals (Sb, Zn, Cu, Pb, and Cd) in the surface runoff of the antimony mining area were lower than the standard value except the concentration of metal Ni. Their concentrations were 497.1, 2.0, 1.8, 22.2, and 22.1 times larger than the standard value, respectively. This metal pollution was mainly concentrated in local areas, which were seriously polluted. The variation coefficient of Sb, Zn, Cu, Ni, Pb, and Cd was between 0.4 to 0.6, wherein the Sb's spatial variability coefficient is 50.56%, indicating a strong variability. Variation coefficients of the rest of metals were less than 50%, suggesting a moderate variability. The spatial structure analysis showed that the squared correlation coefficient (R 2) of the models fitting for Sb, Zn, Cu, Ni, Pb, and Cd was between 0.721 and 0.976; the ratio of the nugget value (C 0) to the abutment value (C + C 0) was between 0.0767 and 0.559; the semivariogram of Sb, Zn, Ni, and Pb was in agreement with a spherical model, while semivariogram of Cu and Cd was in agreement with Gaussian model, and both had a strong spatial correlation. The trend and spatial distribution indicated that those pollution distributions resulting from Ni, Pb, and Cd are similar, mainly concentrated in both ends of north and south in eastern part. The main reasons for the pollution were attributed to the residents living, transportation, and industrial activities; the Sb distribution was concentrated mainly in the central part, of which the pollution was assigned to the mining and the industrial activity; the pollution distributions of Zn and Cu were similar, mainly concentrated in both ends of north and south as well as in west; the sources of the metals were widely distributed.

Growth, photosynthesis, and defense mechanism of antimony (Sb)-contaminated Boehmeria nivea L.

Ramie (Boehmeria nivea L.) is the oldest cash fiber crop in China and is widely grown in antimony (Sb) mining areas. To evaluate the extent of Sb resistance and tolerance, the growth, tolerance index (TI), Sb content in plant parts and in Hoagland solution, bioaccumulation factor (BF), photosynthesis, and physiological changes in Sb-contaminated B. nivea (20, 40, 80, and 200mgL(-1) Sb) grown hydroponically were investigated. The Sb tolerance and resistance of ramie were clearly revealed by growth inhibition, a TI between 13 and 99%, non-significant changes in the maximum quantum efficiency of photosystem (F v /F m ), energy-harvesting efficiency (photosystem II (PSII)) and single-photon avalanche diode (SPAD) value, a significant increase in Sb in plant parts, BF >1, and an increase in catalase (CAT) and malondialdehyde (MDA) at 200mgL(-1) Sb. Under increasing Sb stress, nearly the same non-significant decline in the maximum quantum efficiency of photosystem (F v /F m ), energy-harvesting efficiency (PSII), relative quantum yield of photosystem II (φPSII), and photochemical quenching (qP), except for F v /F m at 20mgL(-1) Sb, were recorded. SPAD values for chlorophyll under Sb stress showed an increasing trend, except for a slight decrease, i.e., <2%, than the control SPAD value at 200mgL(-1) Sb. With a continuous increase in MDA, superoxide dismutase (SOD), peroxidase (POD), and CAT activities were suppressed under Sb addition up to 40mgL(-1) Sb and the addition of Sb enhanced enzyme production at 80 and 200mgL(-1) Sb. A continuous decrease in SOD, POD, and CAT up to 40mgL(-1) Sb and enhancements at ≥80mgL(-1), along with the continuous enhancement of MDA activity and inhibited biomass production, clearly reveal the roles of these enzymes in detoxifying Sb stress and the defense mechanism of ramie at 80mgL(-1) Sb. Thus, B. nivea constitutes a promising candidate for Sb phytoremediation at mining sites.

Characterizing the accumulation of various heavy metals in native plants growing around an old antimony mine

ABSTRACTThe objective of this study was to explore potential plant candidates to act as phytoremediators around the Xikuangshan mine, Hunan Province, China. Native plants including Imperata cylindrical (L), Rumex patientia L., Fagopyrum dibotrys (D.Don), Fagopyrum dibotrys (D.Don), Phytolacca americana L., Dryopteris erytbrosora, Pteriduum aquilinum var. latiusculum (Desv), Nephrolepiscordifolia (L) Presl, Oplismenus undulatifolius (A) Bea, Erigeron annuus (L) Pers, and soils samples were collected. As, Sb, Hg, Cd, Cr, Pb, and Zn levels were measured in soil and plant samples. The concentrations of As, Sb, Hg, and Cd in soils were above the corresponding background values for Hunan province. R. Patienti, P. aquilinum, and P. americana had large bioconcentration factors (BAFs) and high translocation factors (TFs) for Sb; and the same showed in D. erytbrosora for Hg, P. vittata for Cd, I. cylindrical for Cr, and D. erytbrosora for Pb and Zn. In general, perennial plants showed high heavy metal contents in roots, and TFs greater than 1 were only observed for Sb in E. annuus and Cr in O. undulatifolius. These results demonstrate that several native plants growing around Xikuangshan are potential phytoremediators for metal and metalloid contaminated soils.

Determination of Carbonate Minerals Responsible for Alkaline Mine Drainage at Xikuangshan Antimony Mine, China: Using Thermodynamic Chemical Equilibrium Model

Minerals responsible for mine water quality at the Xikuangshan antimony mine were identified and characterized by a computer-assisted thermodynamic chemical equilibrium model. A total of 30 samples were collected and analyzed for major cations and anions. The Eh-pH diagrams identified Fe2O3 as the dominant iron species, while SO42- was the dominant sulfide species, which indicates acid production. The major acid producing minerals undergoing oxidation were identified to be pyrite, pyrrhotite, arsenopyrite and siderite. Other secondary sulfide minerals that contributed to SO42- concentration in the groundwater were gypsum and epsomite. Calcite and dolomite were the main buffering carbonate minerals. Identification of the specific acid producing and consuming minerals occurred in the mine area is critical to determine an effective water management plan.

Structures, mineralogy, and fluid regime of ore formation in the polygenetic Malo-Taryn gold field, Northeast Russia

Detailed structural study of ore zones and deformations in host rocks reveals the multistage tectonic evolution of the Malo-Taryn ore field. Gold–quartz mineralization is confined to the interstratal and longitudinal thrust faults, where vein–stringer bodies are systematically oriented relative to the structures of the thrust stage. Antimony mineralization is superposed on gold–quartz mineralization in the same structures, being associated with veins formed during the shear stage of deformations. It is determined that the types of mineralization were formed in the following sequence: gold–bismuth, low-sulfide gold–quartz, berthierite–antimonite, and silver–antimony. Data on mineral assemblages and typomorphic features of minerals are reported. The isotope composition of minerals, temperature conditions, and composition of orebearing fluids are studied. It is established that the same minerals ascribed to different types of mineralization sharply differ in typomorphic features, which is caused by the different composition and genesis of the hydrothermal fluids. The superposition of different types of mineralization on one another within repeatedly activated tectonic structures that were fluid-permeable for a long time is an important indication of large-scale deposits.

Adsorption of methylantimony and methylarsenic on soils, sediments, and mine tailings from antimony mine area

Biogeochemical processes of antimony (Sb) – a chemically similar element as arsenic (As) – in a variety of environment is largely unexplored. Soil and sediment environment are known to control the geochemical fate of several contaminants via a multitude of processes, primarily adsorption. Here adsorption of organic Sb/As on soils, sediments, and mine tailings was investigated. Sorption studies showed that the methylarsenic sorption capacity and rate were greater than methylantimony sorption. For TMSb, MMA, and DMA sorption samples, the highest sorption capacity occurred in the Ferralsol, which contained the highest amount of Fe/Al-oxyhydroxides. The sorption capacity was proportional to the Fe/Al concentration in the environmental matrices (TMSb-Fe: R2=0.52, TMSb-Al: R2=0.69; MMA-Fe: R2=0.61, MMA-Al: R2=0.76; DMA-Fe: R2=0.42, DMA-Al: R2=0.59). The highest amount of TMSb, MMA, and DMA sorption rate was also observed for the Ferralsol with 82%, 97%, and 87%, respectively and that of the lowest values were the mine tailings. The other samples had similar amounts of TMSb/MMA/DMA sorption rate ranging from 5 to 60% of initially added organic species.

Mobility of antimony, arsenic and lead at a former antimony mine, Glendinning, Scotland

Elevated concentrations of antimony (Sb), arsenic (As) and lead (Pb) in upland organic-rich soils have resulted from past Sb mining activities at Glendinning, southern Scotland. Transfer of these elements into soil porewaters was linked to the production and leaching of dissolved organic matter and to leaching of spoil material. Sb was predominantly present in truly dissolved (<3kDa) forms whilst As and Pb were more commonly associated with large Fe-rich/organic colloids. The distinctive porewater behaviour of Sb accounts for its loss from deeper sections of certain cores and its transport over greater distances down steeper sections of the catchment. Although Sb and As concentrations decreased with increasing distance down a steep gully from the main spoil heap, elevated concentrations (~6-8 and 13-20μgL−1, respectively) were detected in receiving streamwaters. Thus, only partial attenuation occurs in steeply sloping sections of mining-impacted upland organic-rich soils and so spoil-derived contamination of surface waters may continue over time periods of decades to centuries. Capsule abstractProduction and leaching of dissolved organic matter led to the concomitant transfer of truly dissolved Sb to soil porewaters. Leaching of spoil-derived Sb impacted on the quality of receiving stream waters.

Hydrogeochemical Characteristics of Groundwater at the Xikuangshan Antimony Mine in South China

The hydrogeochemical influence of the Xikuangshan antimony mine on groundwater quality was investigated by analyzing groundwater from 24 springs in the area for major and trace elements. The samples had a pH of 7.6–8.5; total dissolved solids ranged from 125 to 607 mg/L. The groundwater was dominated by alkaline earths (Ca2+ + Mg2+) over the alkalies (Na+ + K+), and weak acids $$\left( {{\text{HCO}}_{ 3}^{ - } } \right)$$ over strong acids $$\left( {{\text{SO}}_{4}^{2 - } + {\text{Cl}}^{ - } } \right)$$ . Calcite was generally supersaturated and gypsum was always undersaturated, while dolomite was undersaturated in 34 % of the samples. Iron was negatively correlated with Ca2+, Mg2+, and $${\text{SO}}_{ 4}^{ 2- }$$ , which is consistent with Fe removal during acid buffering. Scatter diagrams and correlation coefficients between the major ions indicate dissolution of carbonates and gypsum as major processes, which could promote calcite precipitation.

Spatial-temporal and genetic relationships between gold and antimony mineralization at gold-sulfide deposits of the Ob-Zaisan folded zone

The Ob-Zaisan folded zone is a fragment of a single structure composed of Paleozoic sedimentary and volcanogenic rocks (mainly black shale), which was formed at the margin of the Siberian continent and features a common set of magmatic complexes and mineral systems. However, there are some differences that determine the specific geological and metallogenic features of the Irtysh-Zaisan and Kolyvan-Tomsk fragments of the Ob-Zaisan folded zone. In the gold deposits of the West Kalba and Kolyvan-Tomsk auriferous belt, the main gold-sulfide mineralization is controlled by zones of shearing and dynamic metamorphism in carbonaceous carbonate-terrigenous rocks. This type of mineralization was formed in tectonic blocks in a compressional setting. Antimony mineralization is characterized by brecciated textures and the vein-like morphology of ore bodies, reflecting extensional tectonics. At some deposits (Zherek, Mirazh, Dalny), Sb mineralization is spatially separated from the main gold-sulfide ores and shows cross-cutting relations to the principal ore-controlling structures. In other gold deposits, stibnite is spatially associated with disseminated gold-sulfide ores and forms mineral assemblages with Ni, Co, Au, Pb, and Fe (Alimbet, Zhanan, Legostaevskoe, Semiluzhenskoe, and Kamenskoe deposits). This study reveals no direct correlation between Au and Sb in gold-sulfide ores of these deposits. SEM analysis indicated the absence of free gold in stibnite veins. However, atomic absorption and electron microprobe analysis indicated the presence of “invisible gold” from a few ppm to several tens of ppm in the stibnite. High gold contents in the gold-sulfide ores overprinted by antimony mineralization (Suzdalskoe, Zhanan, and Legostaevskoe deposits) can be explained by the processes of regeneration and redeposition. The results of microstructural observations, isotope geochronology, studies of mineral assemblages and fluid inclusions in the ores from gold deposits of the Ob-Zaisan folded zone suggest that antimony mineralization was formed at gold-polysulfide stage, which was separated from the early ore pyrite-arsenopyrite stage by a 30 Ma time gap. It can be assumed that the essentially stibnite mineralization was formed at a separate stage and was separated from the gold-polysulfide mineralization by a 7 Ma interval of tectonic activity. Our Ar-Ar data on sericite from ore samples, combined with U-Pb data on zircons from igneous rocks and previous data from the literature show that there were two major stages of ore formation: the Early Permian (282-270 Ma) and the Early Triassic (250-240 Ma). Most researchers suggest that these stages of mineralization can be related to the epochs of intraplate magmatism that led to the formation of the Tarim (280 Ma) and Siberian (250 Ma) large igneous provinces. These global geological events are generally connected with the influence of Tarim and Siberian mantle plumes.