Sulfide Minerals Research Articles

MINERAL PARAGENESIS OF EARLY BIOTITE VEINS AT THE KUH-E JANJA Cu-Au PORPHYRY DEPOSIT, SOUTHEASTERN IRAN: IMPORTANCE OF MICROTEXTURAL OBSERVATIONS IN STUDIES CONSTRAINING THE RELATIVE TIMING OF HYPOGENE Cu MINERALIZATION

Abstract Veins consisting primarily of biotite are the earliest stockwork vein type recognized at the Kuh-e Janja Cu-Au porphyry deposit in southeastern Iran. These early biotite veins may contain quartz and minor amounts of sulfide minerals such as chalcopyrite and pyrite. Observations at the hand-specimen scale do not provide reliable constraints on the paragenetic relationships, as the early biotite veins have been repeatedly overprinted during the evolution of the magmatic-hydrothermal system. Microscopic investigations show that the sulfide minerals in the early biotite veins are texturally late, providing evidence that sulfide deposition did not occur at the high temperatures of biotite formation and potassic alteration of the host rocks. Chalcopyrite primarily occurs along hairline fractures that crosscut or refracture the earlier biotite veins. Biotite in contact with the chalcopyrite can be apparently unaltered or is replaced by chlorite, depending on the degree of wall-rock buffering of the magmatic-hydrothermal fluids that caused hypogene Cu mineralization. The findings add to the growing body of evidence that Cu mineralization in this deposit type occurs at temperatures close to the transition from ductile to brittle conditions (<450°C) following a drop in the pressure regime from lithostatic to hydrostatic conditions.

Microbial community structure in an uranium-rich acid mine drainage site: implication for the biogeochemical release of uranium.

The generation of acid mine drainage (AMD) characterized by high acidity and elevated levels of toxic metals primarily results from the oxidation and dissolution of sulfide minerals facilitated by microbial catalysis. Although there has been significant research on microbial diversity and community composition in AMD, as well as the relationship between microbes and heavy metals, there remains a gap in understanding the microbial community structure in uranium-enriched AMD sites. In this paper, water samples with varying levels of uranium pollution were collected from an abandoned stone coal mine in Jiangxi Province, China during summer and winter, respectively. Geochemical and high-throughput sequencing analyses were conducted to characterize spatiotemporal variations in bacterial diversity and community composition along pollution groups. The results indicated that uranium was predominantly concentrated in the AMD of new pits with strong acid production capacity, reaching a peak concentration of 9,370 μg/L. This was accompanied by elevated acidity and concentrations of iron and total phosphorus, which were identified as significant drivers shaping the composition of bacterial communities, rather than fluctuations in seasonal conditions. In an extremely polluted environment (pH < 3), bacterial diversity was lowest, with a predominant presence of acidophilic iron-oxidizing bacteria (such as Ferrovum), and a portion of acidophilic heterotrophic bacteria synergistically coexisting. As pollution levels decreased, the microbial community gradually evolved to cohabitation of various pH-neutral heterotrophic species, ultimately reverting back to background level. The pH was the dominant factor determining biogeochemical release of uranium in AMD. Acidophilic and uranium-tolerant bacteria, including Ferrovum, Leptospirillum, Acidiphilium, and Metallibacterium, were identified as playing key roles in this process through mechanisms such as enhancing acid production rate and facilitating organic matter biodegradation.

Pullulan Polysaccharide as an Eco-Friendly Depressant for Flotation Separation of Chalcopyrite and Molybdenite.

It is difficult to separate molybdenite and chalcopyrite by froth flotation due to the good floatability of the two minerals. In this paper, the separation of copper-molybdenum sulfide minerals was realized by using pullulan polysaccharide (PU) as the depressant. The flotation test results showed that the copper concentrate grade increased from 16.24 to 29.86%, and the copper concentrate recovery reached 83.55% under low alkali conditions. The selective separation mechanism of the two minerals by PU was revealed through contact angle measurements, ζ-potential measurements, Fourier transform infrared (FTIR) spectroscopy analyses, and X-ray photoelectron spectroscopy (XPS) analyses. The ζ-potential and contact angle results showed that PU is more easily adsorbed on molybdenite to strengthen the hydrophilicity of molybdenite. The FTIR and XPS results showed that PU is adsorbed on molybdenite by physical interactions, and hydrophobic interactions and hydrogen bonding play a major role.

Decomposition of Sulfide Phases and Subsequent Matte Collection in the Black Top of a Platinum Group Metal Smelter

ABSTRACT This study explored, on a laboratory scale, how matte separates from the gangue in the black top of a PGM smelter. Two PGM concentrates, one with high sulfide content (17.3 mass%, Platreef concentrate) and the other with low sulfide content (1.3 mass%, UG-2 concentrate), were studied in the temperature range of 800°C to 1480°C, which is the temperature gradient across the black top. The results showed that effective matte separation occurs at temperatures when the matte is completely molten, and a substantial amount of liquid silicate phase has formed. The main matte separation mechanism is the coalescence of sulfide prills and their gravitational settling through the continuous path created by the liquid silicate phase. Complete matte separation occurs at lower temperatures in Platreef concentrate (1400°C in Platreef concentrate vs. 1480°C in UG-2 concentrate), due to the higher concentration of liquid silicate phase of lower viscosity, as well as the higher amount of sulfide minerals in this concentrate. PGMs already dissolve and collect in a nickel-iron-based alloy associated with the matte at temperatures as low as 900°C.

Component separation and origin estimation of mining-influenced water based on fluoride ions and water isotopes in underground legacy mine, Central Japan

Study regionA legacy underground tungsten mine in a mountainous area, central Japan. Study focusWe analyzed mining-influenced water (MIW) from mine voids and surface water from rivers to determine the dissolved ion concentrations and water isotopes (δ18O and δ2H). The results were interpreted using principal components and cluster analyses, as well as Eh-pH (Pourbaix) diagram. By integrating the obtained analytical results with mine-related data, we conducted component separation of MIW and estimation of their origins. New hydrological insights for the regionThe MIW and part of surface water were characterized by the SO42− and F− generated via the dissolution of sulfide minerals and fluorite (CaF2) from the ore deposit. MIW components were successfully separated using these indicators and water isotopes. The results of component separation indicated that the MIW consisted of two components, namely infiltrating water that rapidly passes through upper mine voids to reach the mine void at ground level, and groundwater that undergoes some degree of residence time before flowing into the ground level void from shaft I.

The electrical structure of the lithosphere in the southeastern margin of the Amazonian craton: Contribution to West Gondwana tectonics

A high electrical conductivity belt near the southeastern margin of the Amazonian craton, known as Paraguay-Araguaia Conductivity Anomaly (PACA), has been discovered and mapped over a distance of more than 1,000 km by a large array of magnetometer measurements. To precisely determine the location and structure of the conductive anomaly, we conducted a 200-km-long magnetotelluric (MT) profile with typical site spacing of 8 km over the northern part of PACA and crossing the Goiás magmatic arc and Araguaia belt in Central Brazil. Three-dimensional resistivity models derived from this data indicate that the PACA is not a single conductor but comprises at least two contiguous bodies at the upper to middle crust. The enhanced conductivity of the northern part of PACA is likely due to sulfide minerals deposited in an inter-arc or back-arc basin that were deformed and subsequently emplaced tectonically beneath the western Goiás magmatic arc. The PACA is truncated to the west by a prominent sub-vertical resistor, attributed to the Transbrasiliano lineament (TBL), a continental-scale structural feature interpreted here as a mylonitic shear zone developed late in the Neoproterozoic to Cambrian tectonic history involving the collision between Amazonian craton and proto-West Gondwana. We cannot confirm the prevailing view of an east-dip subduction of oceanic lithosphere from the Amazonian plate under the Goiás arc terranes. Instead, our results probably represent the record of an oblique continental collision. Regardless of its origin, the PACA may serve as a proxy for the paleo border of the Amazonian plate. Therefore, additional geophysical mapping, especially in areas covered by thick Phanerozoic sediments, is essential to constrain the tectonic evolution of West Gondwana.

Effect of lead ions treatment on the flotation behavior of lime-depressed pyrite in a butyl xanthate system

Pyrite is often found alongside other sulfide minerals and is typically suppressed by lime during industrial flotation to selectively enrich with other valuable minerals. Given the continuous depletion of mineral resources, recycling these suppressed resources has become necessary. Consequently, the reactivation of lime-depressed pyrite is crucial for its recovery via flotation. This study investigated the lead (Pb) nitrate to activate lime-depressed pyrite. Various analytical techniques, including micro-flotation tests, zeta potential measurements, contact angle measurements, ultraviolet–visible spectrophotometry, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM-EDS) were employed to investigate the activation mechanism of Pb2+ on lime-depressed pyrite. The treatment with Pb2+ resulted in a significant enhancement in the recovery of lime-depressed pyrite flotation, achieving a maximum recovery of 98.33 %. Analysis through zeta potential, XPS, and SEM-EDS revealed that Pb species reacted with lime-depressed pyrite surfaces to form Pb-S and Fe-O-Pb species. This reaction enhanced the active sites and adsorption of collectors on lime-depressed surfaces, consequently increasing the hydrophobicity of the pyrite particles.

Geothermal resources and deep tectonic in Leh Ladakh (NW Himalaya), India: Inference from magnetotelluric studies

The geothermal resources and their connectivity with the deep tectonic are meaningful to understand through their structural geometry in the NW Himalayas. Therefore, over the NW-SE profiles, 23 audio Magnetotelluric (AMT) sites and over the SW-NE profile, 15 broadband Magnetotelluric (BBMT) sites were carefully chosen to provide the detailed structure. The electrical models were produced from a 2-D inversion algorithm based on the non-linear conjugate gradient method. The Chumathang-Mahe and Puga-Sumdo regions offer excellent geothermal potential as heat/fluid passes through the Mahe Fault (MF), Zildat Fault (ZF) and Kiagor Tso Fault (KTF). These faults are well revealed in the electrical models beneath the subsurface. The Puga Valley has an excellent geothermal resource at shallow depth. A ∼1000 m thick sulfide mineral body is defined with high conductivity (∼1 Ω-m). The crustal structure shows a highly conductive mid-crust beneath the Ladakh batholiths with no manifestation roots. The signs of the Indus-Tsangpo Suture Zone (ITSZ) and Shyok Suture Zone (SSZ) are well represented in the crustal model and are associated with the steep-dipping faults. The Chumathang-Mahe and Puga-Sumdo geothermal regions are connected with low resistivity body (C1) at shallow depths in the crustal model along the SW-NE profile and offer a path for deep fluid flow. The frictional heat generated in the process of the Indian plate subducting beneath the Tibetan plateau and the collision zone between India and Asia carried to melt. The high heat surface flow indicates the thermal origin of low resistivity. Thus, a ∼10 sq. km low resistivity reservoir is identified beneath the Tso Morari dome in the crustal model that overlies a resistivity feature. The high conductivity at mid-crust determined at active tectonic fabric may be potential geothermal resources yielding high well-productivity.

On the Use of Styrene-Based Nanoparticles to Mitigate the Effect of Montmorillonite in Copper Sulfide Recovery by Flotation.

Clay minerals have different negative effects on the froth flotation process such as low adsorption of collectors on valuable minerals, increased pulp viscosity, and the reduction in recovery and grade concentrates of copper sulfides. This study aims to evaluate the use of polystyrene-based nanoparticles (NPs) for the froth flotation of chalcopyrite and their ability to mitigate the negative effect of montmorillonite on the recovery of this sulfide. The experimental stage consisted of preparing a type of polystyrene-based nanoparticle (St-CTAB-VI), which was analyzed by dynamic night scattering (DLS) to establish its hydrodynamic size. Then, the effect of NPs on chalcopyrite's angle's in the presence and absence of montmorillonite (15%) was evaluated and compared with the contact angle achieved using potassium amyl xanthate (PAX) and a mixture of PAX and NPs. In addition, zeta potential measurements were carried out to investigate the interactions between the chalcopyrite and the montmorillonite or the NPs under fixed concentrations and microflotation tests were performed employing different times to evaluate the chalcopyrite recovery in the presence of montmorillonite, using NPs and mixtures with PAX. Finally, turbidity analysis as a function of time was performed to evaluate the occurrence of sedimentation and flocculation phenomena in suspensions of 15% montmorillonite in the presence and absence of chalcopyrite, nanoparticles, and mixtures of NPs and PAX. The results indicated that the mixture of NPs and PAX contributed to increasing the contact angle of chalcopyrite in the presence of montmorillonite. This can be associated with the presence of molecular and nanometric collectors that generated a higher hydrophobicity on the chalcopyrite particles, contributing to reducing the presence of clay minerals on the mineral surface. In addition, the mixture of NPs and PAX promoted the generation of nanoparticles on the sulfide mineral surface, which helps to detach the slime and facilitate the bubble/mineral attachment step during flotation.

A Comprehensive Review on Mine Tailings as a Raw Material in the Alkali Activation Process

The mining industry generates vast quantities of mine tailings on an annual basis. However, due to their limited economic value, a significant portion of these tailings are deposited close to mining sites, often underwater. The principal environmental apprehensions associated with mine tailings revolve around their elevated levels of heavy metals and sulfidic minerals. The oxidation of these sulfidic minerals can lead to the formation of acid mine drainage, which in turn releases heavy metals into nearby water systems. The effective management of tailing dams requires substantial financial investments for their construction and meticulous control. Consequently, a pressing need exists for stable, sustainable, and economically viable management approaches. One promising method for addressing mine tailings is through alkali activation, a technique that serves as a stabilization process. This approach yields robust, concrete-like structures by utilizing raw materials abundant in aluminum and silicon, which conveniently constitute the primary components of mining residues. This comprehensive review outlines the research on utilizing alkali activation for mine tailings. It delves into the reactivity and chemical attributes of diverse minerals. Numerous mine tailings exhibit an inadequate level of reactivity under alkaline conditions, so various pre-treatment methodologies and their impacts on mineralogy are meticulously explored.

Inhibition of acid rock drainage with iron-silicate or phosphate film: in rainy and submerged environments.

Iron phosphate-based coating and iron silicate-based coating were used to inhibit the oxidation of sulfide minerals in rainy and submerged environments. The inhibiting effectiveness of coating agents on the oxidation of iron sulfide minerals was investigated using pyrite and rock samples resulting from acid drainage. The film formed with both surface-coating agents was identified by pyrite surface analysis. It was also confirmed that the formation of coatings varies depending on the crystallographic orientation. The inhibitory effects under rainy and submerged conditions were investigated using column experiments. Submerged conditions accelerated deterioration compared to that under rainy conditions. Iron phosphate coating had a significantly better oxidation-inhibitory effect (84.86-98.70%) than iron silicate coating (56.80-92.36%), and at a concentration of 300mM, H+ elution was inhibited by more than 90% throughout the experiment. Furthermore, methods for effective film formation were investigated in terms of producing Fe3+; (1) application of coating agents mixed with oxidant (H2O2), (2) application of coating agent after the use of the oxidant. In a rainy environment, applying iron phosphate-based coating using the sequential method showed oxidation inhibition effects for cycles 1-9, whereas applying the mixed material showed effects for cycles 9-13. The use of a surface-coating agent after applying an oxidant did not inhibit oxidation. The surface coating agent and the oxidizing agent should be applied as a mixture to form a film.

Sulfide Copper‐Iron Isotopic Fractionation During Formation of the Kalatongke Magmatic Cu‐Ni Sulfide Deposit in the Central Asian Orogenic Belt

AbstractCopper and iron isotopic signatures in sulfide and silicate minerals are important genetic indicators in magmatic sulfide deposits. Kalatongke is a large‐scale magmatic Cu‐Ni sulfide deposit in the Central Asian Orogenic Belt, and one that experienced multiple stages of magmatism and contamination. It is an ideal deposit in which to study Cu‐Fe isotopic fractionation during multiple stages of magmatism and sulfide mineralization processes. The Kalatongke sulfide orebodies are hosted by three small mafic intrusions in which pyroxene and sulfides (pyrrhotite, pentlandite, and chalcopyrite) are the most common Fe‐rich minerals, and chalcopyrite is the dominant Cu‐rich mineral. Sulfide liquid and silicate melt ▵56FeSul‐Sil (0.03–0.19‰) and ▵65CuCcp‐Sil (−0.78–0.74‰) values are indicative of non‐equilibrium fractionation. Most of the Cu isotope compositions in the sulfide ores at Kalatongke can be modeled as subduction‐ metasomatized, oxidized mantle source‐derived silicate melt (initial δ57Fe = 0.15‰, δ65Cu = −0.07‰) that underwent lower crustal contamination, and then reacted with silicate melt, having an R factor of 100–1,000. Rapid silicate melt and sulfide liquid Fe isotope exchange and re‐equilibration between chalcopyrite and pyrrhotite in the massive ores is reflected in the similarity of their δ56Fe values. Sulfide in disseminated ores shows a range of Fe isotope ratios, influenced by the proportions of monosulfide solid solution (MSS) and intermediate solid solution (ISS) formed. Copper isotopes can be utilized to characterize crustal contamination and silicate melt‐sulfide liquid interaction, while the Fe isotope ratios of sulfide minerals record sulfide liquid segregation and evolution in magmatic sulfide deposits.

Geochemical and Isotopic Techniques Constraints on the Origin, Evolution, and Residence Time of Low‐enthalpy Geothermal Water in Western Wugongshan, SE China

AbstractGeothermal resources are increasingly gaining attention as a competitive, clean energy source to address the energy crisis and mitigate climate change. The Wugongshan area, situated in the southeast coast geothermal belt of China, is a typical geothermal anomaly and contains abundant medium‐ and low‐temperature geothermal resources. This study employed hydrogeochemical and isotopic techniques to explore the cyclic evolution of geothermal water in the western Wugongshan region, encompassing the recharge origin, water–rock interaction mechanisms, and residence time. The results show that the geothermal water in the western region of Wugongshan is weakly alkaline, with low enthalpy and mineralization levels. The hydrochemistry of geothermal waters is dominated by Na‐HCO3 and Na‐SO4, while the hydrochemistry types of cold springs are all Na‐HCO3. The hydrochemistry types of surface waters and rain waters are Na‐HCO3 or Ca‐HCO3. The δD and δ18O values reveal that the geothermal waters are recharged by atmospheric precipitation at an altitude between 550.0 and 1218.6 m. Molar ratios of major solutes and isotopic compositions of 87Sr/86Sr underscore the significant role of silicate weathering, dissolution, and cation exchange in controlling geothermal water chemistry. Additionally, geothermal waters experienced varying degrees of mixing with cold water during their ascent. The δ13C values suggest that the primary sources of carbon in the geothermal waters were biogenic and organic. The δ34S value suggests that the sulfates in geothermal water originate from sulfide minerals in the surrounding rock. Age dating using 3H and 14C isotopes suggests that geothermal waters have a residence time exceeding 1 kaBP and undergo a long‐distance cycling process.

Ore Remobilization History of the Metamorphosed Rävliden North Volcanogenic Massive Sulfide Deposit, Skellefte District, Sweden

Abstract The Skellefte district in northern Sweden hosts many volcanogenic massive sulfide (VMS) deposits and is considered one of the most important European mining districts for Cu, Zn, Pb, Ag, and Au. The volcanic and sedimentary rocks that the VMS deposits are hosted in were deformed during the Svecokarelian orogeny, with three documented regional deformation phases. These events imparted a distinct attitude and geometry to the deposits, their host succession, and discordant zones of synvolcanic hydrothermal alteration. Few studies have investigated the detailed deformation effects on the sulfide minerals. In this contribution, we document the structural characteristics and remobilization history of mineralization at the Rävliden North Zn-Pb-Cu-Ag deposit—one of the most important recent discoveries in the district consisting of 8.5 million tonnes (Mt) grading 1.01% Cu, 3.45% Zn, 0.53% Pb, 78.60 g/t Ag, and 0.23 g/t Au. At Rävliden, massive to semimassive sphalerite-rich mineralization with lesser pyrrhotite, galena, pyrite, and silver minerals occurs structurally above stringer-type mineralization dominated by chalcopyrite, pyrrhotite, and pyrite. These mineralization types exhibit evidence of deformation and remobilization such as (1) sulfide-alignment parallel to tectonic foliations; (2) rounded wall-rock tectonoclasts in a ductile deformed sulfide matrix (“ball ore” or durchbewegt ore); and (3) sulfides in tension gashes, strain shadows, piercement veins, and late, straight veinlets crosscutting tectonic fabrics. These features are attributed to polyphase deformation during the D1, D2, and D3 events at temperature ranging from 200° to 550°C. Remobilization of sulfides was mostly within the bounds of the main mineralization (i.e., 10–100 m), with few local external occurrences. A combination of solid-state and fluid-assisted remobilization processes are inferred. Rare brittle veinlets and zeolite-cemented breccias with sphalerite, galena, and silver minerals occur in the stratigraphic hanging wall, where they crosscut all Svecokarelian structures. This mineralization type is highly reminiscent of Phanerozoic low-T vein- and breccia-hosted Pb-Zn deposits of the Lycksele-Storuman area west of Rävliden North, which have been linked to far-field effects associated with the opening of the Iapetus Ocean (0.7–0.5 Ga). We suggest that this Zn-Pb mineralizing event led to the formation of the late sulfide-zeolite veinlets and breccias at Rävliden North, and that elements such as Ag and Sb within this mineralization were locally remobilized from Rävliden.

Detection of Sulfur Oxidizing Bacteria to Oxidize Hydrogen Sulfide in Biogas from Pig Farm by NGS and DNA Microarray Technique

A high concentration of hydrogen sulfide (H2S) released from pig farming is one of the major environmental problems affecting surrounding communities. In modern pig farms, the bioscrubber is used to eliminate H2S, which is found to be driven mainly by the sulfur-oxidizing bacteria (SOB) community. Therefore, in this study, molecular biology techniques such as next-generation sequencing (NGS) and DNA microarray are proposed to study the linkage between enzyme activity and the abundance of the SOB community. The starting sludge (SFP1) and recirculating sludge (SFP2) samples were collected from the bioscrubber reactor in the pig farm. The abundance of microbial populations between the two sampling sites was considered together with the gene expression results of both soxABXYZ and fccAB. Based on the NGS analysis, the members of phylum Proteobacteria such as Halothiobacillus, Acidithiobacillus, Thiothrix, Novosphingobium, Sulfuricurvum, Sulfurovum, Sulfurimonas, Acinetobacter, Thiobacillus, Magnetospirillum, Arcobacter, and Paracoccus were predominantly found in SFP2. The presence of Cyanobacteria in SFP pig farms is associated with increased biogas yields. The microarray results showed that the expression of soxAXBYZ and fccAB genes involved in the oxidation of sulfide to sulfate was increased in Halothiobacillus, Paracoccus, Acidithiobacillus, Magnetospirillum, Sphingobium, Thiobacillus, Sulfuricurvum, Sulfuricurvum, Arcobacter, and Thiothrix. Both NGS and DNA microarray data supported the functional roles of SOB in odor elimination and the oxidation of H2S through the function of soxABXYZ and fccAB. The results also identified the key microbes for H2S odor treatment, which can be utilized to monitor the stability of biological treatment systems and the toxicity of sulfide minerals by oxidation.

Deciphering ore genesis with oxygen and sulfur isotope signatures: A case study from the Singhbhum Shear Zone, Eastern India

The importance of light-stable isotopes and their mass-dependent fractionations in understanding past geological processes is enormous. The present research delivers precise, high-resolution, in-situ oxygen (18/16O) and triple sulfur (32/33/34S) isotope ratios from quartz and sulfide minerals found in the CuAu Kendadih deposit located along the Mesoproterozoic (∼1.6 Ga) Singhbhum Shear Zone (SSZ) in eastern India. Oxygen and sulfur isotope analyses were carried out on quartz and pyrite-chalcopyrite pairs that are in textural equilibrium, using the most advanced Large Geometry-Secondary Ion Mass Spectrometer (LG-SIMS; CAMECA IMS-1300HR3). The results show restricted ranges for δ18Oquartz (+6 to +7.7‰; average: 6.9 ± 0.9‰, n = 50) and δ34Schalcopyrite-pyrite (+11.4 to +11.9‰; average: 11.79 ± 0.2‰, n = 62). This isotopic homogeneity suggests a single, uniform fluid source for the ore-forming metals. The combined oxygen, sulfur isotope ratios, and fluid inclusion data are consistent with a hydrothermal fluid derived from an “I-type” granitic melt. This study incorporates existing fluid inclusion, stable, and radiogenic isotope data from temporally similar deposits within the shear zone, reevaluating their implications in light of the new findings. It proposes that, around 1.6 billion years ago, underplating the Singhbhum Craton by the Dalma Plume resulted in the remelting of the lower crust. This remelting is attributed to the plume's introduction of a significantly elevated thermal perturbation. The process is hypothesized to have led to the generation of second-order granitic melts. Upon emplacement in the lower crust, these granitic melts became the potential source for essential metals, ligands, and hydrothermal fluids, contributing to mineralization within the deep-seated Singhbhum Shear Zone. This research attempts to comprehensively describe the “source-to-sink” ore genesis model by proposing potential magma chamber processes that concentrate metals and ligands at the roof zone, followed by the separation of metal-rich hydrothermal fluids, fluid-rock interaction, and the physicochemical conditions governing the deposition of the extensive polymetallic deposit. This work offers novel insights into the Mesoproterozoic metallogenesis along the Singhbhum Shear Zone, challenging existing paradigms that favored evaporite or seawater brine sources. Furthermore, it sheds light on the Mesoproterozoic sub-crustal processes beneath the Indian Craton in this region.

In Situ Sulfur Isotope Geochemistry Using Secondary Ion Mass Spectrometry of Sulfides in the ABM Replacement-Style Volcanogenic Massive Sulfide Deposit, Finlayson Lake District, Yukon, Canada

Abstract The ABM deposit is a bimodal-felsic, replacement-style volcanogenic massive sulfide deposit located in the Finlayson Lake district, Yukon, Canada, that is hosted by back-arc-affinity felsic volcanic rocks of the Yukon-Tanana terrane. Massive sulfide mineralization occurs as a series of stacked and stratabound lenses subparallel to the volcanic stratigraphy, surrounded by an envelope of pervasive white mica and chlorite alteration. Three major mineral assemblages occur: (1) a pyrite-sphalerite assemblage enriched in Zn-Pb-As-Sb-Ag-Au that formed at temperatures ∼200–270 °C, (2) a pyrite-chalcopyrite-magnetite-pyrrhotite assemblage enriched in Cu-Bi-Se-Co that formed at temperatures ∼300–350 °C, and (3) a chalcopyrite-pyrrhotite-pyrite stringer assemblage formed at temperatures &amp;gt;300 °C. In situ analysis of the sulfur isotopic ratios (δ34S) using secondary ion mass spectrometry has been performed on sulfides (pyrite, pyrrhotite, chalcopyrite, galena, and arsenopyrite) from samples representative of the major mineral assemblages. The δ34S results range between +4.0 and +12.5‰. The pyrite-sphalerite assemblage has an average δ34S value of +6.6 ± 1.8‰ (n = 31), whereas the higher temperature assemblages have an average δ34S value of +9.9 ± 1.4‰ (n = 59). Examination of the δ34S values of adjacent mineral pairs shows that the sulfides were formed under disequilibrium conditions and were not significantly altered or re-equilibrated by greenschist facies metamorphism that affected the ABM deposit post-volcanogenic massive sulfide formation. The observed range of δ34S values suggests that H2S derived from thermochemical sulfate reduction of seawater sulfate and/or an igneous sulfur source as the likeliest sources of S for the sulfides in the ABM deposit. Modeling of thermochemical sulfate reduction of contemporaneous Late Devonian seawater sulfate (δ34S ∼ +25‰) at temperatures estimated for the fluids forming the ABM deposit mineral assemblages (200–350 °C) shows that the reduction of 5–30% of the seawater sulfate would result in isotopic signatures similar to those observed at the ABM deposit. This model also explains the distribution of δ34S values across the mineral assemblages, as thermochemical sulfate reduction at higher temperatures (350 °C) results in more isotopically positive δ34S values. Modeling of mixing lines between thermochemical sulfate reduction at different temperatures and an igneous sulfur source suggests that leaching of magmatic/volcanic rocks also acted as a source of sulfur and was a likely a major contributor (70–95%) to the hydrothermal fluid system at the ABM deposit.

Arsenic-poor fluids promote strong As partitioning into pyrite

Pyrite is a ubiquitous sulfide mineral found in diverse geological settings and holds great significance in the formation of Au deposits as well as the safe utilization of groundwater due to its remarkable ability to incorporate substantial amounts of As. However, despite its importance, there remains a dearth of fundamental data on the partitioning of As between pyrite and fluid, which is key for accurately modeling the As distribution in these environments.Here, we present new insights into the partitioning behavior of As between pyrite and fluid at conditions that mimic natural fluid systems. Pyrite was synthesized by replacement of natural siderite in hydrothermal experiments at 200 °C and pH 5 applying a wide range of fluid As concentrations, spanning from 0.001 to 100 µg/g. The As distribution and concentration in synthetic pyrite was analyzed by quantitative LA-ICP-MS mapping providing a high spatial resolution and sensitivity at 2–3 µm image pixel size at a detection limit of ∼1 µg/g at the single pixel scale. Pyrite-fluid partitioning coefficients (DAs(py/fluid)) between synthetic pyrite and experimental fluid agree with previously published data for high fluid As concentrations of 1 µg/g to 100 µg/g (DAs < 2000). However, at low As concentrations in the experimental fluid (<1 µg/g), a steep increase in the DAs(py/fluid) values of up to ∼30,000 was detected, demonstrating even stronger As partitioning into pyrite. This is confirmed by the analyses of natural pyrite that precipitated from As-poor fluids (0.3–0.4 ng/g) within a deep anoxic aquifer in SE Sweden. The discovery holds significant implications for the mobility and scavenging of As, which in turn is important for understanding the formation and fingerprinting of mineral deposits as well as for the secure utilization of groundwater resources.

Influence of Mineralogy and Mineralogy Approach to Optimize Processing: A Case Study of Tin–Copper Polymetallic Ore

Tin-Copper polymetallic ore is a type of typical ore that cassiterite is closely associated with sulfide minerals. In mineral processing of tin–copper polymetallic ore, flotation is generally used to recover valuable sulfide minerals, while gravity separation is used to recover cassiterite. A mine in Yunnan, China, uses the traditional “flotation–gravity separation” process to recover copper and tin but faces several problems during processing, such as an insufficient copper grade in Cu concentrate, a much higher grade of As in S concentrate, and a grade of S in Sn concentrate that exceeds the standard. A process mineralogy study was conducted, with a focus on Cu–S mixed concentrate, S concentrate, and Sn rough concentrate. It was determined that the main cause of these problems is not the liberation or size distribution of valuable minerals but the superstructure of pyrrhotite, which represents one of the most abundant minerals in the products. Based on EMPA, SEM-EDS, and XRD data, both monoclinic pyrrhotite and hexagonal pyrrhotite occurred in all samples. The abundance of different superstructures of pyrrhotite in one sample was determined by means of particle extraction and area calculation from microscopic images, and the distribution characteristics of monoclinic pyrrhotite and hexagonal pyrrhotite in the whole process were clarified. This process mineralogy study indicates that the strong magnetic hexagonal pyrrhotite mainly affects the copper recovery during flotation, and the hexagonal pyrrhotite mainly affects the recovery of cassiterite during gravity separation. Strong magnetic monoclinic pyrrhotite and weak magnetic hexagonal pyrrhotite should be fully considered in the optimization of mineral processing, and the magnetic separation of pyrrhotite should be adopted to optimize the overall environment of copper flotation and tin gravity separation.

Copper sulfide mineral performs non-enzymatic anaerobic ammonium oxidation through a hydrazine intermediate.

Anaerobic ammonium oxidation (anammox)-the biological process that activates ammonium with nitrite-is responsible for a significant fraction of N2 production in marine environments. Despite decades of biochemical research, however, no synthetic models capable of anammox have been identified. Here we report that a copper sulfide mineral replicates the entire biological anammox pathway catalysed by three metalloenzymes. We identified a copper-nitrosonium {CuNO}10 complex, formed by nitrite reduction, as the oxidant for ammonium oxidation that leads to heterolytic N-N bond formation from nitrite and ammonium. Similar to the biological process, N2 production was mediated by the highly reactive intermediate hydrazine, one of the most potent reductants in nature. We also found another pathway involving N-N bond heterocoupling for the formation of hybrid N2O, a potent greenhouse gas with a unique isotope composition. Our study represents a rare example of non-enzymatic anammox reaction that interconnects six redox states in the abiotic nitrogen cycle.