Search Results (37)

The Matra As–Sb deposit (Alpine Corsica, France) is hosted in the normal N–S trending Matra Fault. Sulfide minerals in ore consist of realgar, stibnite, and pyrite with minor orpiment and hörnesite. The gangue includes quartz, dolomite, and calcite. In this study, the microstructural analysis of selected ore samples has been combined with the geochemical characterization of the sulfides. The results depict a succession of events that record the evolution of the ore deposit related to fault movement. In the pre–ore stage, plumose, crustiform, jigsaw, and feathery textures of quartz testify to a short–lived boiling event. The mineral assemblage of the main–ore stage includes an Fe(–Zn) substage dominated by the formation of different textures of pyrite. In general, pyrite samples contain significant concentrations of As (≤32,231 ppm) and Sb (≤10,684 ppm), with lesser amounts of by Tl (≤1257 ppm) and Ni (≤174 ppm). This is followed by an Sb–As–Fe substage of pyrite–stibnite–realgar ±orpiment. The precipitation of the sulfides was mainly driven by changes in ƒS₂. The increasing level of oxidation is attributed to a progressive influx of meteoric water resulting from reactivation of the Matra Fault. Full article

Mineral characterization of gold-bearing metasomatites in the Khaptasynnakh ore zone of the Anabar Shield is provided in detail. The following ore formation sequence of mineral associations in the Khaptasynnakh zone was found: pyrite and pyrrhotite → gersdorffite and molybdenite → chalcopyrite, sphalerite, and galena → bornite and chalcocite → tellurides, native gold, stibnite, cinnabar, and native bismuth. Native gold is characterized by varying fineness (550 to 926‰) and Cu impurity (up to 7.87%) values. Most often, it forms symplectite intergrowths with Au telluride–calaverite. Native gold and Au tellurides showed inclusions of chalcocite, bornite, altaite, tellurobismuthite, rickardite, petzite, and clausthalite. A two-stage formation process of the examined gold is suggested: Low-fineness gold was introduced into the system during early potassium metasomatism, while higher-fineness gold related to silica metasomatism resulted from its additional mobilization by fluid during late-stage formation. The low-temperature gold–telluride association observed in the mineral paragenesis of ore-bearing rocks, as well as its inclusions in native gold, suggests epithermal gold–telluride mineralization. Mineral inclusions examined in placer gold validate a genetic relation between the examined ores and gold placers in the Khaptasynnakh ore zone. Full article

Active and abandoned mining sites are significant sources of heavy metals and metalloid pollution, leading to serious environmental issues. This study assessed the environmental risks posed by potentially toxic elements (PTEs), specifically arsenic (As) and antimony (Sb), in the Technosols (mining residues) of the former Pejão coal mine complex in Northern Portugal, a site impacted by forest wildfires in October 2017 that triggered underground combustion within the waste heaps. Our methodology involved determining the “pseudo-total” concentrations of As and Sb in the collected heap samples using microwave digestion with aqua regia (ISO 12914), followed by analysis using hydride generation-atomic absorption spectroscopy (HG-AAS). The concentrations of As an Sb ranging from 31.0 to 68.6 mg kg⁻¹ and 4.8 to 8.3 mg kg⁻¹, respectively, were found to be above the European background values reported in project FOREGS (11.6 mg kg⁻¹ for As and 1.04 mg kg⁻¹ for Sb) and Portuguese Environment Agency (APA) reference values for agricultural soils (11 mg kg⁻¹ for As and 7.5 mg kg⁻¹ for Sb), indicating significant enrichment of these PTEs. Based on average I_geo values, As contamination overall was classified as “unpolluted to moderately polluted” while Sb contamination was classified as “moderately polluted” in the waste pile samples and “unpolluted to moderately polluted” in the downhill soil samples. However, total PTE content alone is insufficient for a comprehensive environmental risk assessment. Therefore, further studies on As and Sb fractionation and speciation were conducted using the Shiowatana sequential extraction procedure (SEP). The results showed that As and Sb levels in the more mobile fractions were not significant. This suggests that the enrichment in the burned (BCW) and unburned (UCW) coal waste areas of the mine is likely due to the stockpiling of lithic fragments, primarily coals hosting arsenian pyrites and stibnite which largely traps these elements within its crystalline structure. The observed enrichment in downhill soils (DS) is attributed to mechanical weathering, rock fragment erosion, and transport processes. Given the strong association of these elements with solid phases, the risk of leaching into surface waters and aquifers is considered low. This work underscores the importance of a holistic approach to environmental risk assessment at former mining sites, contributing to the development of sustainable remediation strategies for long-term environmental protection. Full article

Antimony is a chemical element with diverse uses that falls into the range of a critical raw material. Although it appears in nature as stibnite, the mining of this mineralogical species is rare or uncommon, and it is the element that is basically recovered as a secondary material in the processing of various elements (such as gold and copper). Another source for the recovery of this element is the recycling of Sb-bearing wastes such as batteries and alloys. Once dissolved and in order to recover it from the different leachates, adsorption processes are the ones that seem to have, at least for the scientific community, the highest acceptance. This work reviews the most recent advances (in 2024) in the recovery of antimony from different sources using not only adsorption processes but also other technologies of practical interest. Full article

Discovered within the North Himalayan Metallogenic Belt (NHMB), the Zhaxikang Pb–Zn–Ag–Sb deposit stands as the sole super-large scale ore deposit in the region. This deposit holds significant quantities of Pb and Zn (2.066 million tons at 6.38% average grade), Ag (2661 tons at an average of 101.64 g/t), and Sb (0.235 million tons at 1.14% average grade), making it one of China’s foremost Sb–polymetallic deposits. Stibnite represents the main carrier of Sb in this deposit and has been of great attention since its initial discovery. However, the trace element composition of stibnite in the Zhaxikang deposit has not yet been determined. This study carried out an analysis of the distribution patterns and substitution processes of trace elements within stibnite gathered from the Zhaxikang deposit, aiming to provide crucial information on ore-forming processes. Utilizing high-precision laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), we discovered that the studied stibnite is notably enriched in arsenic (~100 ppm) and lead (~10 ppm). Furthermore, the notably consistent time-resolved profiles suggest that elements such as Fe, Cu, As, In, Sn, Hg, and Pb predominantly exist as solid solutions within stibnite. Consequently, it is probable that the enrichment of Cu, Pb, and Sn in stibnite is due to isomorphic substitution reactions, including 3Pb²⁺↔2Sb³⁺, Cu⁺ + Pb²⁺↔Sb³⁺, and In³⁺ + Sn³⁺↔2Sb³⁺. Apart from that, Mn, Pb, and Hg with the spiky signals indicate their existence within stibnite as micro-inclusions. Overall, we found that the trace element substitutions in stibnite from the Zhaxikang Pb–Zn–Ag–Sb deposit are complicated. Incorporations of trace elements such as Pb, Cu, and In into stibnite are largely influenced by a variety of factors. The simple lattice structure and constant trace elements in studied stibnite indicate a low-temperature hydrothermal system and a relatively stable process for stibnite formation. Full article

The Alattu–Päkylä gold occurrence is located in the Northern Lake Ladoga area, in the Raaha-Ladoga suprasubduction zone, at the Karelian Craton (AR)—Svecofennian foldbelt (PR₁) boundary. Its gold ore mineral associations are of two types of mineralization: (1) copper–molybdenum–porphyry with arsenopyrite and gold (intrusion-related) and (2) gold–arsenopyrite–sulfide in shear zones. Optical and scanning electron microscopy, X-ray fluorescence spectrometry, inductively coupled plasma mass spectrometry (ICP-MS), instrumental neutron activation analysis (INAA) and fire analysis with AAS finishing were used to study them. Type 1 was provoked by shallow-depth tonalite intrusion (~1.89 Ga) and type 2 by two stages of Svecofennian metamorphism (1.89–1.86 and 1.83–1.79 Ga) with the possible influence of the impactogenesis of the Janisjärvi astrobleme (age ~1 Ga). Intrusive and host rocks were subjected to shearing accompanied by the formation of ore-bearing metasomatic rocks of the propylite-beresite series (depending on substrate) and quartz–sericite, quartz and sericite–tourmaline veins and streaks. Ore mineralization is present as several consecutive mineral associations: pyritic–molybdenite with arsenopyrite and gold; gold–arsenopyrite; quartz–arsenopyrite with antimony sulfosalts of lead; gold–polysulfide with tetrahedrite –argentotetrahedrite series minerals and gold–antimony with Pb–Sb–S system minerals and native antimony. Arsenopyrite contains invisible (up to 234 ppm) and visible gold. Metamorphosed domains in arsenopyrite and rims with visible gold around it are usually enriched in As, indicating higher (up to >500 °C) temperatures of formations than original arsenopyrite with invisible gold (<500 °C). A paragenetic sequence associated with the deposition of invisible and visible gold established at the Alattu–Päkylä ore occurrence: pyrrhotite + unaltered arsenopyrite (with invisible gold) → altered arsenopyrite (As-enriched) + pyrite ± pyrrhotite + visible gold. Gold, associated with gudmundite, sphalerite and native antimony, seems to be due to cainotypic rhyodacitic porphyry cutting tonalite intrusion or with a retrograde stage in post-Svecofennian metamorphism. The isotopic composition of Pb and ²³⁸U/²⁰⁴Pb (9.4–9.75) for the feldspar of the tonalite intrusion and the pyrite of gold mineralization, εNd (−4 up to −5) for tonalites and ẟ³⁴S values of −2.10–+4.99 for arsenopyrite, indicate the formation of gold occurrence provoked by Svecofennian magmatic and tectono-thermal processes with the involvement of matter from a mantle-lower crustal reservoir into magma formation and mineralization. Full article

The Xujiashan Sb deposit located at the Mufushan fold thrust belt of the Yangtze block is one of the most important Sb deposits in this district. Stibnite in this deposit contains high and various contents of Se, but research on the distribution and enrichment of Se in stibnite remains limited. This paper conducts geochemical composition, C-H-O isotopic composition, and scanning electron microscopy morphology of the Xujiashan deposit to discuss the sources of ore-forming materials and fluid, as well as the distribution and enrichment mechanisms of selenium in stibnite. The results showed that the ores have trace element compositions comparable with the wall rocks, and Sb and Se contents are significantly higher than the average carbonate rocks. The δ¹³C_PDB values of calcite and quartz range from −12.8‰ to 5.5‰, the δ¹⁸O_SMOW values range from 20.4‰ to 24‰, and the δD_V-SMOW values range from −57.8‰ to −86.9‰. Trace element and isotope compositions indicate that the ore-forming materials were mainly derived from the wall rocks (sedimentary–metamorphic rocks) that S, Se, and Sb dissolved during fluid–rock interactions. The ore-forming fluids were metamorphic water produced by metamorphism, which had experienced multistage mixing with meteoric water and organic-rich fluids. Selenium substitutes for sulfur in the stibnite crystal lattice, causing rhythmically distributed Se contents in stibnite, which resulted from multistage physicochemical changes in ore-forming fluids during crystallization. The varied patterns of Se contents are the result of different cross-sections of the stibnite. Full article

The La’erma and Qiongmo Au–Se deposits are characterized by a paragenetic Au–Se association hosted in the siliceous formation of the Cambrian Taiyangding Group in the western Qinling Orogen, central China. The La’erma and Qiongmo Au–Se deposits, which are considered to be the Carlin gold deposits, comprise a variety of selenides, native gold, and stibnite coexisting with baryte. Four stages have been recognized: sage I comprises pyrite and quartz with minor stibnite; stage II is composed mainly of sulfides; stage III is composed mainly of selenides; and stage IV is dominated by quartz–baryte–dickite. Stages II and III are the main metallogenic stages. Based on changes in mineral assemblages, combined with fluid inclusions and thermodynamic data, we evaluated the physicochemical conditions of the main metallogenic stages. The logfS₂ values of ore-forming fluids at stage II ranged between −10.44 and −14.60 with logfSe₂ being less than −10.70. Comparably, during stage III, which is characterized by numerous selenides, the logfS₂ and logfSe₂ ranged from −7.13 to −12.20 and −13.98 to −8.82, respectively. The occurrence of baryte during the mineralization suggests a consistently oxidizing condition, which can effectively remove Au from fluids. More importantly, this study emphasizes that the oxidizing condition was only a fundamental prerequisite for the deposition of selenides, and a high ∑Se/S ratio of the fluid ultimately controlled the precipitation of selenides. In the La’erma and Qiongmo deposits, intense water–rock reactions occurred as ore-forming fluids flowed into the Se-rich siliceous formations, resulting in an increase in the ∑Se/S ratio of the fluid and in the precipitation of selenides. Full article

Accurate identification and understanding of various metallic minerals are crucial for deciphering geological formations, structures, and ages. Giving their pivotal role as essential natural resources, a microscopic exploration of metallic minerals becomes imperative. Traditional analytical methods, while helpful, exhibit certain limitations. However, terahertz time-domain spectroscopy, distinguished by its high signal-to-noise ratio, expansive frequency band, and low incident wave energy, is a promising complement to conventional techniques in characterizing metallic minerals. This study employs terahertz time-domain spectroscopy to examine samples of Stibnite, Sphalerite, Galena, and Pyrite originating from diverse geological conditions. The vibrations of molecules within these metallic minerals induce discernible changes in the terahertz spectra. Our findings untiate the extensive potential of terahertz time-domain spectroscopy in the characterization of metallic minerals, affirming its considerable practical value in mineral resource exploration. Full article

Antimony is widely acknowledged as a critical raw material of worldwide significance, based on its recognition by many countries. According to current projections, there is an anticipated increase in the demand for antimony in the forthcoming years. An issue of significant concern within the supply chain, which poses a substantial obstacle to sustainable development, is the global unequal allocation of abundant antimony resources. Most nations exhibited a high degree of dependence on a few countries for their net imports of antimony, resulting in a notable disruption and raising concerns regarding the supply chain. In most countries, antimony exploration and exploitation have been paused for a long period due to financial constraints associated with operations and environmental concerns. Nowadays, identifying additional antimony reserves, particularly in countries that heavily rely on new technologies and use significant amounts of antimony, is imperative and presents a pressing endeavor. Greece is recognized as one of the European Union member states with identified antimony deposits and a historical record of antimony exploitation. A thorough description, examination, and re-assessment of all existing data on the deposits and occurrences of antimony in Greece is presented. Most of Greece’s antimony deposits are related to hydrothermal processes, controlled by specific tectonic structures, and associated with Cenozoic magmatism. They are classified either as simple Sb-deposits, where the primary ore is a stibnite mineral, or complex polymetallic deposits with varying contents that include antimony minerals. Full article

The superlarge Huaaobaote Ag–Pb–Zn deposit is located on the western slope of the southern Great Xing’an Range (SGXR). The deposit includes four ore blocks, namely, ore blocks I, II, III, and V. Except for the no. I orebody of ore block I, which is hosted in the contact zone between the Carboniferous serpentinized harzburgite and the Permian siltstone, the other orebodies all occur as veins controlled by faults. The mineralization process at the deposit can be divided into four stages: cassiterite–arsenopyrite–pyrite–quartz stage (stage I), cassiterite–chalcopyrite–pyrite–freibergite–arsenopyrite–pyrrhotite–quartz stage (stage II), sphalerite–galena–jamesonite–stibnite–freibergite–silver mineral–quartz–calcite–chlorite stage (stage III), and argentite–pyrargyrite–pyrite–quartz–calcite (stage IV). Cassiterite U–Pb dating of the Huaaobaote deposit yielded ages of 136.3–134.3 Ma, indicating that the deposit formed in the Early Cretaceous period. Two types of fluid inclusions (FIs), including liquid-rich and gas-rich FIs, have been distinguished in the quartz vein and sphalerite. The homogenization temperature during the four stages gradually decreases, with temperatures of 302–340 °C for stage I, 267–304 °C for stage II, 186–273 °C for stage III, and 166–199 °C for stage IV, respectively. The salinity (wt% NaCl eqv.) at stages I, II, III, and IV is 3.7–6.6, 0.2–4.5, 0.2–5.0, and 0.4–1.6, respectively, indicating that the ore-forming fluid is characterized by low salinity. The δ¹⁸O_water and δD values of the ore-forming fluid range from −11.9‰ to 7.9‰ and −168‰ to −76‰, respectively, indicating that the ore-forming fluid was dominantly derived from a mixture of magmatic and meteoric water. The calculated δ³⁴S_H2S values range from −3.6‰ to 1.2‰, indicating that the sulfur mainly came from granitic magma. The ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb, and ²⁰⁸Pb/²⁰⁴Pb ratios of sulfides are in the ranges of 18.195–18.317, 15.509–15.667, and 37.965–38.475, respectively, implying that the ore-forming material was mainly derived from felsic magma that may be formed by the partial melting of orogenic materials. Fluid mixing, cooling, and immiscibility were the three primary mechanisms for mineral precipitation in the Huaaobaote deposit. Full article

The stibnite mineralization at Rizana (Kilkis ore district; Serbo-Macedonian metallogenic province; northern Greece) occurs along a NE–SW-trending brittle shear-zone, which transects a two-mica and an augen-gneiss of the Vertiskos Unit. Barren Triassic A-type granites and satellite pegmatites and aplites, as well as Oligocene-Miocene plutonic, subvolcanic and volcanic rocks that are variably hydrothermally altered and mineralized, outcrop in the broader region. The mineralization appears as veins, discordant lodes and disseminations. Veins and discordant lodes exhibit massive and brecciated textures. Historic underground mining (1930s–1950s) produced 9000 t of stibnite ore, grading 40% Sb on average. The main ore mineral assemblage includes stibnite + berthierite + sphalerite + pyrite + chalcopyrite + native antimony and traces of wolframite, galena, tetrahedrite, marcasite, pyrrhotite, arsenopyrite, realgar, native arsenic and native gold. Quartz, minor barite and ankerite are the gangue minerals. Sericitization and silicification developed along the shear-zone, forming hydrothermal halos of moderate intensity in the two-mica gneiss. Locally, valentinite, goethite and claudetite are present due to the supergene oxidation of the stibnite mineralization. Bulk ore geochemistry shows enrichments in specific elements including As, Au, Cd, Se, Tl and W. Fluid inclusion microthermometry showed that the mineralization was formed under a limited range of temperatures and salinities. The fluids had low to slightly moderate salinities (6.6–8.1 wt% equiv. NaCl) with low homogenization temperatures (217–254 °C, with a maximum at 220 °C). Full article

The Daocaowan antimony (Sb) deposit is a newly discovered Sb deposit located outside the northeast Xikuangshan ore field. In the absence of geochemical data, the metallogenic mechanism of the Daocaowan Sb deposit and its relationship with the Xikuangshan ore field remains unclear. Using high-resolution LA-ICP-MS technique, this study quantitatively determined the in-situ S isotope values and trace element composition of stibnite from the Daocaowan Sb deposit in South China to investigate the source of ore-forming materials and genesis of this deposit. The trace element compositions of stibnite from the Daocaowan Sb deposit revealed the form of occurrence and substitution mechanism of trace elements in stibnite, providing new constraints for explaining the genesis of Sb deposits. The relatively smooth LA-ICP-MS profiles indicate that As, Cu, Hg, and Pb primarily occur as solid solutions in stibnite. Therefore, we speculate that the substitution 3Sb³⁺↔As³⁺ + 2Cu⁺ + Hg²⁺ + Pb²⁺ may be the reason for the enrichment of As, Cu, Hg, and Pb in stibnite. A comparison with the Xikuangshan Sb deposit reveals the metallogenic mechanism of the Daocaowan Sb deposit, and the relationship between the two. With the exception of higher content of Fe in Stibnite from the Daocaowan deposit as compared to the Xikuangshan deposit, other trace elements are similar between the two deposits. The results show that the Daocaowan and Xikuangshan Sb deposits may have the same source of ore-forming fluids. We propose that the ore-forming fluid flowed through the Xikuangshan Sb deposit along the F₇₅ fault and dissolved pyrite in the wall rock. Subsequently this fluid containing a high concentration of Fe precipitated and mineralized at Daocaowan. Meanwhile, the S isotope value of the Daocaowan Sb deposit (+6.65 to +9.29‰) is consistent with that of the Xikuangshan, proving that the ore-forming materials of the two deposits are from the same source, probably the basement strata. We propose that the Daocaowan Sb deposit is part of the Xikuangshan ore field, indicating a great prospecting potential in the northeast of the Xikuangshan ore field. Full article

The Wulonggou Gold Field is one of the giant gold fields in the East Kunlun Orogenic Belt, northwestern China. Previous studies mainly focused on elementary mineral isotopic studies, fluid inclusions, and geological features in the Wulonggou Gold Field. In this study, we report some research on the precise age and the specific ore-forming process of the WGF: the hydrothermal monazite U–Pb ages; the way of gold precipitation; the composition, evolution, and source of ore-forming fluids of the Wulonggou Gold Field. Finally, we demonstrate a link between two-stage hydrothermal events and sequential episodes of crust-derived magmas, with implications for gold metallogeny in the East Kunlun Orogenic Belt. There are four hydrothermal stages that are recognized: a quartz–pyrite stage (stage 1), a quartz–pyrite–arsenopyrite–chalcopyrite stage (stage 2), a quartz–galena–sphalerite–pyrite stage (stage 3) and a quartz–stibnite–carbonate stage (stage 4). The monazite U–Pb ages of the Huanglonggou and Hongqigou deposits in the Wulonggou Gold Field were 422.2 ± 2.4 Ma and 236.7 ± 3.7 Ma, respectively, which support the opinion of two epochs of mineralization. Stages 1 and 2 are the main gold mineralization stages, wherein Au and As have a close genetic relationship. The Hongqigou and Huanglonggou deposits seem to have been formed in different metallogenic events due to the contrast on the trace element compositions in pyrite. The sources of the ore-forming materials and fluids of the Hongqigou and Huanglonggou deposits show apparent characteristics of orogenic gold deposit, and the magmatic events during Paleozoic and Mesozoic have an important contribution to the formation of the gold deposits. The gold deposits in the Wulonggou Gold Field can be interpreted as an orogenic gold system related to two-epoch tectonic–magmatic events. Full article

The Xikuangshan antimony (Sb) deposit is the world’s largest known Sb deposit. Due to the lack of suitable minerals for reliable high-precision radiometric dating, it remains difficult to determine the exact age of Sb mineralization in this deposit. Here, we report the first LA-MC-ICP-MS U-Pb ages of syn-stibnite calcite from this deposit. The dating results indicate the presence of at least two stages of Sb mineralization in the Xikuangshan ore district. The calcite-stibnite veins in the Daocaowan ore block probably formed during the Paleocene (58.1 ± 0.9 Ma), representing an early stage of Sb mineralization, while the quartz-stibnite vein in the Feishuiyan ore block probably formed during the Eocene (50.4 ± 4.4 Ma, 50.4 ± 5.0 Ma, and 51.9 ± 1.6 Ma), representing a late stage of Sb mineralization. The new calcite U-Pb ages are significantly younger than the calcite Sm-Nd ages (124.1 ± 3.7 Ma, 155.5 ± 1.1 Ma) reported by previous researchers. We suggest that Sb mineralization of the South China antimony metallogenic belt may be related to tectono-thermal events during Paleogene, possibly linked to high heat flow during the subduction (ca. 60–40 Ma) of the Pacific Plate beneath the Eurasian Plate and/or the Indo–Asian Collision (began at ca. 61 Ma). The young in situ U-Pb ages of calcite challenge the idea of late Mesozoic Sb mineralization in the South China antimony metallogenic belt, suggesting the requirement for more high-precision dating studies. Full article