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Accurately determining the timing of hydrothermal mineralization for sediment-hosted disseminated gold (SHDG) deposits is difficult because of a lack of both suitable chronometers and in situ techniques with the required spatial resolution and precision. The lack of precise age determinations on gold deposits has hindered understanding of their genesis and relation to the geodynamic setting. The Qiuling-Jinlongshan deposit is a typical SHDG deposit located in the eastern South Qinling Orogen (SQO), with 109 t Au at an average grade of 6.17 g/t. Devonian and Carboniferous metasedimentary rocks host structurally controlled gold mineralization, which is associated with silica-carbonate alteration. Pyrite, arsenopyrite, and arsenian pyrite are major gold carriers, and gold also occurs as native gold grains and invisible gold in the sulfides. In this study, the well-defined hydrothermal overgrowth rims (~2 μm) of single monazite grains, associated with disseminated auriferous arsenian pyrite and arsenopyrite in low-grade metasedimentary rocks, yield U-Pb ages of239 ± 13 Ma (2σ) by high spatial resolution secondary ion mass spectrometry (SIMS). The hydrothermal monazites are cogenetic to the primary gold mineralization where they are closely associated with gold-bearing sulfides. This new age implies that the early to middle Triassic mineralization event in the eastern SQO was related to the Triassic tectonic transition from compression to transpression in the Qinling Orogen after the closure of the Mianlue Ocean. This study highlights the 2-μm high spatial resolution SIMS monazite U-Th-Pb dating method as a powerful tool for determining the timing of SHDG deposits worldwide. It is crucial to examine monazite textures and their link to hydrothermal alteration before carrying out the isotopic dating of monazite. [ABSTRACT FROM AUTHOR]

The Permian Cornubian granite batholith (295–275 Ma) in SW England includes seven major plutons and numerous smaller stocks extending for ∼250 km from the Isles of Scilly in the WSW to Dartmoor in the ENE. The granites are peraluminous and classified as crustal melt S-type, predominantly two-mica granites, and biotite or tourmaline monzo- and syenogranites, with subordinate minor topaz granite and lithium mica granite. The granites and their host rocks are pervasively mineralized with tin (cassiterite), tungsten (wolframite, ferberite), copper (chalcopyrite, chalcocite, bornite), arsenic (arsenopyrite), and zinc (sphalerite) mineralized lodes. Quartz-muscovite selvedges (greisen-bordered) also contain enrichment of lithophile elements such as boron (tourmaline), fluorine (fluorite), and lithium (lithium-micas such as lepidolite and zinnwaldite). They are derived from both muscovite and biotite dehydration melting of pelitic-psammitic rocks and intruded from a common source along the length of the batholith. Pressure estimates from andalusite and cordierite-bearing hornfels in the contact metamorphic aureole (150 ± 100 MPa) show that the granites intruded to 3 km depth. Cupolas around the Land’s End and Tregonning granites show aplite-pegmatite dikes and tourmaline + quartz + muscovite veins (greisen) that are frequently mineralized. Synchronous intrusions of lamprophyre dikes suggest an additional heat source for crustal melting may have been from underplating of alkaline magmas. The lack of significant erosion means that the source region is not exposed. In an accompanying paper (Part 2; Watts et al., 2024), gravity modeling reveals possible solutions for the shape and depth of the granite and the structure of the lower crust. We present a new model for the Land’s End, Tregonning, and Carnmenellis granites showing a mid-crustal source composed of amphibolite facies migmatites bounded by prominent seismic reflectors, with upward expanding dikes feeding inter-connected granite laccoliths that show inflated cupolas with shallow contact metamorphism. The Cornubian granites intruded >90 m.y. after obduction of the Lizard ophiolite complex, and after Upper Devonian–Carboniferous Variscan compressional, and later extensional, deformation of the surrounding Devonian country rocks. Comparisons are made between the Cornubian batholith and the Patagonian batholith in Chile, the Himalayan leucogranites, and the Baltoro granite batholith along the Karakoram range in northern Pakistan. [ABSTRACT FROM AUTHOR]

Carbonates have been traditionally regarded as post-ore minerals in hydrothermal deposits, but they can also occur in pre- and syn-ore stages. However, the genetic relationships between multistage carbonates and gold precipitation mechanisms remain unclear. The Jinshan gold deposit, the largest gold deposit in the eastern Jiangnan orogen, is characterized by the occurrence of abundant hydrothermal carbonates. The nature of the carbonates, especially their association with gold precipitation, was examined in this study through petrographic and geochemical analyses as well as geochemical modeling. Field and petrographic work recognized four paragenesis stages in the Jinshan deposit: (1) quartz (Q1)-carbonate, (2) pyritequartz (Q2), (3) gold-polysulfide-quartz (Q3)-carbonate, and (4) chlorite-quartz (Q4)-carbonate. Carbonates associated with gold mineralization are mainly present in the first and third stages. Among them, the first-stage carbonates are pre-ore ankerites (Ank1), which are generally crosscut by synore sulfides. Such carbonates mostly occur in altered host rocks that are characterized by bleaching. Mineralogical and geochemical analyses revealed that chlorite was consumed while ankerite was produced, and Fe contents of the host rocks remained generally unchanged during alteration. Consequently, ankerite (Ank1) is interpreted to have been generated by the interaction of CO2-bearing fluids and chlorite in the host rocks. Geochemical modeling revealed that both Fe-bearing chlorite and ankerite (Ank1) can lead to gold precipitation by triggering sulfidation, but ankerite has higher chemical reactivity and therefore is kinetically favorable for more efficient gold deposition. Synore carbonates were mainly formed in the third stage, primarily consisting of ankerite (Ank2) with minor calcite, and they were coprecipitated with native gold, galena, sphalerite, and chalcopyrite. Two stages of carbonates shared similar δ13CVPDB values and Pb, Zn, and Cu contents but different Ca, Mg, Mn, and Sr contents, indicating they formed at different stages of the same hydrothermal event. Geochemical modeling demonstrated that pH increases, as indicated by the formation of syn-ore carbonates, together with the consumption of S due to the precipitation of pyrite and arsenopyrite in the second stage, resulted in the decrease of Au, Pb, Zn, and Cu solubility in aqueous fluids. This would have led to the coprecipitation of native gold with galena, sphalerite, and chalcopyrite, forming the general small-scale but commonly occurring native gold–polysulfide veins in the hydrothermal gold deposits. Consequently, both pre- and syn-ore carbonates in the Jinshan deposit were genetically associated with efficient Au-polymetallic deposition through distinct mechanisms. Pre-ore carbonates caused the large-scale bleaching of the host rocks, while syn-ore carbonates were closely related to native gold–polysulfides, and they can both be used as exploration indicators for the Jinshan deposit and other similar hydrothermal gold deposits worldwide. [ABSTRACT FROM AUTHOR]

Jaszczakite is a new mineral discovered in the Nagybörzsöny gold deposit in Hungary. It is opaque, tin-white, and has a metallic luster. Jaszczakite is found in association with other minerals such as arsenopyrite, cosalite, bismuth, and quartz. It is a rare mineral and has only been found in one polished section so far. The mineral is named after Dr. John A. Jaszczak, a professor of physics and curator of the A. E. Seaman Mineral Museum, for his contributions to the field of mineralogy. [Extracted from the article]

Author affiliations *Corresponding authors Sulfur isotopes serve as critical tracers for understanding the material sources and cycling in earth science. The in situ sulfur isotope ratio analysis by laser ablation multiple-collector inductively coupled plasma-mass spectrometry (LA-MC-ICP-MS) has been a proven important technique, yet the precision and accuracy of measurement are limited by matrix-matched reference materials. In this study, we investigated three new potential reference materials (pyrite NWU-Py, gypsum NWU-Gy and arsenopyrite NWU-Apy) for sulfur isotope ratio analysis by LA-MC-ICP-MS. The ultra-fine powders of pyrite, gypsum and arsenopyrite were synthesized into a solid block using the fast-hot-pressing sintering method (FHP). The reliability of these reference materials was evaluated by large quantities of sulfur isotope measurements by LA-MC-ICP-MS, with mean δ34S values of 3.48 ± 0.26‰ (2SD, n = 787) for NWU-Py, 18.19 ± 0.32‰ (2SD, n = 290) for NWU-Gy, and -0.19 ± 0.32‰ (2SD, n = 383) for NWU-Apy, which are highly consistent with those obtained from isotope ratio mass spectrometry (IRMS). Furthermore, the F-testing and H-index indicate that the three materials have excellent homogeneity of sulfur isotope compositions. Therefore, NWU-Py, NWU-Gy, and NWU-Apy can serve as bracketing matrix-matched reference materials for in situ sulfur isotope measurement by LA-MC-ICP-MS. [ABSTRACT FROM AUTHOR]

Abstract\nKEY POINTSThe Watershed scheelite deposit is located in an extinct fore-arc basin in the Mossman Orogen of North Queensland. This fore-arc region comprises multiply deformed, Ordovician–Silurian metasedimentary rocks of the Hodgkinson Formation, and it was intruded by Carboniferous–Permian granites of the Kennedy Igneous Association. At Watershed, the Hodgkinson Formation includes strongly deformed skarn-altered conglomerate, psammite and slate units, which record four deformation events that evolved from ductile (D1–3) to brittle–ductile (D4). Early, D1–2 scheelite mineralisation in Carboniferous monzonite and skarn-altered conglomerate formed during regional prograde metamorphism, which reached upper greenschist to lower amphibolite facies conditions. Permian, D4 scheelite mineralisation was deposited in transtensional, shear-related veins, vein haloes and skarn-altered conglomerate during retrograde, lower greenschist facies metamorphism. During D4, four stages of retrograde alteration (retrograde stages 1–4) affected the rocks. Fluid inclusion assemblages in retrograde stage 2, vein scheelite and quartz are characterised by a low-salinity H2O–NaCl ± CH4 fluid (XCH4 <0.01, 1.4–8.0 wt% NaCleq). The fluid inclusions show evidence for fluid mixing between a low (∼0 wt% NaCleq) and a medium (<8 wt% NaCleq) saline fluid. Scheelite mineralisation P–T conditions were determined at ∼300 °C and 1–1.8 kbar (i.e. a depth of 3.7–6.7 km), indicative of a high geothermal gradient (35–75 °C/km), which was likely caused by the heat from the Permian granites. The presence of pyrrhotite and arsenopyrite in D4 veins (retrograde stage 4), plus graphite and methane in the fluid inclusions in scheelite, indicates reduced mineralisation conditions. Oxygen isotope compositions (δ18OVSMOW) of retrograde stage 2 scheelite (+3.8 to +7.3‰), plagioclase (+7.0 to +11.8‰) and quartz (+12.6 to +15.5‰) indicate a fluid temperature of 306 ± 56 °C with δ18OVSMOW values between +4.7 and +8.3‰. Retrograde stage 3 muscovite δDVSMOW (−73.4 to −62.7‰) and δ18OVSMOW (+11.5 to +13.2‰) values were used to calculate the O–H isotopic compositions of the fluids in equilibrium with the minerals at various possible temperatures (250–300 °C). The results are consistent with a metamorphic origin for the mineralising fluid. Sulfur isotope compositions (δ34SCDT between −2.5 and +2.8‰) for vein-hosted, retrograde stage 4 sulfides indicate that sulfur could have come from seawater or seawater sulfate, which is consistent with the local geology, even though this range overlaps with magmatic sulfur isotope compositions. Metamorphic fluids probably originated from devolatilisation reactions in the Hodgkinson Formation during prograde metamorphism. Permian intrusions acted as heat source enhancing metamorphic fluid flow and metal transport.The main economic D4 scheelite mineralisation in veins occur at temperatures of 306 ± 56 °C and depths between 3.7 and 6.7 km.D4 scheelite mineralisation precipitated predominantly from a low- to medium-salinity metamorphic fluid, and with both H2O–NaCl and H2O–NaCl–CH4 compositions.The presence of methane (CH4) plus graphite in some fluid inclusions and the sulfide mineral phases indicates reduced mineralisation conditions.D4 scheelite mineralisation precipitated predominantly from a low- to medium-salinity metamorphic fluid, and with both H2O–NaCl and H2O–NaCl–CH4 compositions.The presence of methane (CH4) plus graphite in some fluid inclusions and the sulfide mineral phases indicates reduced mineralisation conditions. [ABSTRACT FROM AUTHOR]

Dharwar craton is located in southern India is part of the Dharwar-Singhbhum proto-continent and is known for its complex tectonic and structural controls. It's made up of two distinct parts, Western Dharwar Craton (WDC) and the Eastern Dharwar Craton (EDC) house several schist belts. Many of these schist belts, such as the Kolar schist belt, Hutti schist belt, Chitradurga schist belt and the Gadag schist belt, are auriferous. In such schist belts, gold occurs in association with sulphides such as pyrite, pyrrhotite, arsenopyrite and chalcopyrite. Gold mineralization in these belts is found to occur in different lithologies. The Gadag schist belt is composed dominantly of metabasalt in its western half and meta sediments in the eastern half. Quartz-carbonate veins are observed to cut across these lithologies as well as the Banded Iron Formations (BIFs). This paper aimed to study the gold mineralization in different lithologies of the Gadag schist belt and found that metabasalts and BIFs are the dominant rocks hosting gold. It is also observed that mineralization is strata-bound. Most of the places' auriferous sheared zones were observed in the study area. In Nagavi area, BIF hosted gold mineralization is observed, and major gold concentration varies from <21 to <26 ppb (parts per billion). Pyrite occurs as characteristic cubic crystals and as clusters of small grains. In carbonated sheared anorthosite, the rock is fine to medium-grained and in-equigranular. It consists of simple to polysynthetically twinned subhedral (100-200 by 400-600 µm) laths (~40-45%) set in a groundmass of irregular anhedral grains of secondary carbonate (~35-40%), chlorite (~8-10%), opaque (~5-7%) and accessory epidote and quartz. [ABSTRACT FROM AUTHOR]

The aim of the study was to compare the effects and mechanism of tetrasodium pyrophosphate (TSPP) and sodium tripolyphosphate (STPP) as dispersants on the selective flotation of arsenopyrite from muscovite. The results of single-mineral flotation showed that the recovery of arsenopyrite was 81.4% when no dispersant was added. The recovery of arsenopyrite slightly decreased with increasing dosage of TSPP. When the dosage of STPP was 6 × 10−5 mol/L, the recovery of arsenopyrite was only 28.6%. Neither of the dispersants had significant influence on the muscovite flotation (<10%). However, in a mixed-mineral system, the recovery of arsenopyrite dropped significantly, and then under the action of dispersants, its recovery back up. The RPM results showed that the dispersion effect of TSPP was superior to that of STPP. The electrokinetic potential showed that the potential change value of muscovite with TSPP was −17.37 mV, while that of muscovite with STPP was −8.33 mV (pH = 8). The adsorption of TSPP onto muscovite was stronger than that of STPP. FTIR and XPS analysis confirmed that dispersants exhibited chemical adsorption with the Al atoms on muscovite and that dispersant STPP exhibited stonger adsorption than TSPP on arsenopyrite, which was consistent with flotation experiments. [ABSTRACT FROM AUTHOR]

This study investigates the correlation between the electronic structure of the active sites on mineral surfaces and their adsorption capacity. Density functional theory (DFT) and flotation experiments are employed to examine the bonding behavior and adsorption enthalpy of ethylxanthate on pyrite (1 0 0) and arsenopyrite (0 0 1) surfaces. The results indicate that ethylxanthate adsorbs more significantly on pyrite than on arsenopyrite. The adsorption is chemical, primarily occurring through the orbitals of sulfur in the ethylxanthate and iron on the mineral surface. Compared to arsenopyrite, the d-band center of the iron atoms on the surface of pyrite is closer to the Fermi level; thus, the adsorption strength of ethylxanthate on the pyrite surface is greater than on arsenopyrite. The d-band centers of pyrite and arsenopyrite exhibit a direct relationship with their adsorption capacity. [ABSTRACT FROM AUTHOR]

The Mibei gold deposit, located in the southwestern part of the Xuefengshan uplift zone, the middle section of the Jiangnan orogenic belt in southern China, has estimated gold resources of approximately seven tons. This deposit is primarily a quartz vein‐type gold deposit, with ore bodies occurring mainly within Neoproterozoic metasediments. The main metallic minerals in the ore are pyrite, chalcopyrite, and arsenopyrite. In this study, the petrography and microthermometry of ore‐forming fluid inclusions, oxygen isotopes of gold‐bearing quartz, and sulfur isotopes of gold‐bearing sulfides and arsenopyrite were analyzed. Three types of fluid inclusions were identified: type Ia three‐phase inclusions comprising vapor and two phases of liquids (VCO2 + LCO2 + LH2O), type Ib two‐phase liquids (LCO2 + LH2O), type II two‐phase vapor‐rich inclusions (V/V + L > 50%), and type III pure liquid inclusions. Type I inclusions were heated uniformly to the liquid phase, type II inclusions were heated uniformly to the gas phase, and type III inclusions were heated without change. In general, the temperature range of homogenization to liquid phase of fluid inclusions in the Mibei gold deposit is 204–227°C. The salinity of the inclusion ranges from 4.6 to 12.2 wt% NaCl equiv. The δ18OSMOW of gold‐bearing quartz varies from 16.9‰ to 17.5‰. The δ18OH2O of gold‐bearing quartz are varied from 6.5‰ to 7.5‰. The δ34S values of gold‐bearing pyrite range from 1.7‰ to 6.8‰. The δ34S values of gold‐bearing arsenopyrite range from 5.6‰ to 5.9‰. The δ34S values of pyrite from wall rocks slate range from 6.4‰ to 11.6‰. This evidence implies that the ore‐forming fluids of the Mibei gold deposit originated from magmatic‐hydrothermal processes, mixing with minor S from the surrounding metasediments. Combined with the evolution of the Jiangnan orogenic belt, due to the magmatic and tectonic activities of the Xuefengshan uplift during the Caledonian period, the fault seal mechanism controlled the ore‐forming process. Overall, the Mibei gold deposit is more akin to a magmatic‐hydrothermal gold deposit. [ABSTRACT FROM AUTHOR]

The Xiling Gold Mine is a world-class giant monolithic gold deposit with an average gold content of 3.81 g/t, offering significant mining value. Utilizing techniques such as optical microscopy, scanning electron microscopy, and the mineral automatic analysis instrument(AMICS), the process mineralogical characteristics of the ore from the Xiling Gold Mine were analyzed, including an examination of mineral composition, dissemination grade, existence state of gold and its carrier minerals, and other pertinent features. The results indicate that gold in the ore primarily exists in the form of native gold and electrum. The majority of metal minerals are pyrite, accompanied by small quantities of sphalerite, chalcopyrite, galena, and arsenopyrite. Non-metallic minerals are predominantly quartz followed by muscovite, orthoclase, and potassium feldspar. Gold minerals within the ore mainly occurred in exposed gold form with a dissemination grain size concentrated above 10 µm. There is a close relationship between gold minerals and pyrite regarding their dissemination patterns; pyrite exhibits relatively coarse dissemination grain sizes, and the gold can be easily recovered under appropriate grinding fineness conditions at suitable reagent dosages during processing using full sulfide flotation technology. Based on the results of the process mineralogy analysis, the Xiling gold mine was processed using the full sulfide flotation process. The results of the closed -- circuit flow test show that under appropriate grinding fineness and reagent system conditions, the mineral processing indicators of Au 62.77 g/t with an Au recovery rate reaching 98. 89% can be achived. [ABSTRACT FROM AUTHOR]

In this paper, the effects of an ultrasonic power and the intensity of mechanical agitation for pulp on alkaline pretreatment of gold-bearing arsenopyrite were investigated. The effect of pulp temperature on leaching efficiency in alkaline pretreatment of arsenopyrite was investigated under ultrasound and non-ultrasound conditions. Pre-treatment was followed by gold leaching tests with a cyanide solution. Compared with the nonultrasound condition at the temperature of 60 ○C, arsenic extraction and gold extraction was increased 20 %, 14.4 %, respectively, in the presence of ultrasound at ambient temperature. The characteristics of the ultrasonic power level as a function of the intensity of mechanical agitation were evaluated by a numerical simulation with CFD software – Ansys Fluent. The simulation results demonstrated that the stronger intensity of mechanical agitation, the lower ultrasonic power level. These results were proved through leaching experiments at different rotation speeds of impeller and ultrasonic powers. The study results demonstrate that the ultrasound is an effective factor for pretreatment of gold bearing arsenopyrite and gold extraction is related to an ultrasonic power and the intensity of mechanical agitation. [ABSTRACT FROM AUTHOR]

Prospecting efforts to located Au mineralization within the Altai-Sayan fold area (ASFA) over previous decades have revealed that Devonian epithermal Au-Ag mineralization is more widespread than previously recognized. The preservation of this type of mineralization in Paleozoic rocks offers new prospects for the exploration of Au-Ag deposits in the underexplored region of Gornaya Shoria. The Kalarskoe epithermal Au-Ag occurrence represents Devonian epithermal mineralization within the Kaburchak cluster, Gornaya Shoria, Russia. This occurrence is confined to zones of argillic alteration that were superimposed on previously formed propylites. The argillic-altered rocks host quartz-sulfide veinlet zones. The mineralization of the Kalarskoe site is characterized by a high abundance of sulfide minerals: commonly, 5%–10%; often, up to 20%; and in some cases, up to 60%–70%. The ore minerals are represented by pyrite, arsenopyrite, sphalerite, galena, chalcopyrite, fahlores, native Au, and electrum, as well as by the sulfosalts Pb, Bi, Ag, Cu, and the tellurides of Au, Ag, and Pb. Based on mineralogical observations, at least four generations of sulfide mineral formations are distinguished within the ore occurrence. The mineralization of the Kalarskoe ore occurrence may be assigned to the intermediate sulfidation (IS) type. The results of the (U,Th)-He dating of pyrite from the pyrite-arsenopyrite massive body (pyr-3 and 4) revealed the protracted history of the mineralization in the intervals from ~399 to ~371 Ma. The obtained results substantially enhance the prospecting models for the exploration of epithermal Au-Ag deposits in the western part of the Altai-Sayan fold area (ASFA). [ABSTRACT FROM AUTHOR]

This document is an editorial for a special issue on "Valuable Metals Recovery by Mineral Processing and Hydrometallurgy." It emphasizes the importance of metals for society and the need for efficient techniques to process ores and extract metals. The recovery of metals from secondary sources, such as mining waste, is also highlighted. The editorial discusses various aspects and challenges of metal recovery, including the use of flotation in mineral beneficiation and the application of hydrometallurgical methods. It presents studies on grinding media, pulp oxidation-reduction potential, and the use of new reagents for metal recovery. The editorial also explores the extraction of metals from refractory ores and mining waste. Overall, the papers in this special issue demonstrate the potential for recovering valuable metals from various sources using modern techniques and theoretical frameworks. [Extracted from the article]

Zhengminghuaite, ideally Cu6Fe3As4S12, is a new Cu-Fe arsenosulfosalt found in the Zimudang Carlin-type gold deposit in southwestern Guizhou, China. It occurs as irregular, commonly fractured grains of several to a few tens of micrometers in the brecciated gold ores and is paragenetically associated with the late ore-stage mineral assemblage, including realgar, orpiment, pyrite, chalcopyrite, arsenopyrite, aktashite, christite, quartz, and calcite. Zhengminghuaite is opaque with a metallic luster and a conchoidal or uneven fracture. The Vickers microhardness (VHN10) is 219 kg/mm2 (range 192–247 kg/mm2), and the calculated density is 4.77(5) g/cm3. In reflected light, zhengminghuaite is whitish gray with weak bireflectance (whitish gray to pinkish tinted gray), very weak anisotropy, and no internal reflection. Electron microprobe analyses give the empirical formula (Cu5.92Hg0.08)Σ6.00 (Fe1.59Hg1.07Zn0.37)Σ3.03(As3.94Sb0.02)Σ3.96S11.93 on the basis of total cations = 13, with the simplified formula Cu6(Fe,Hg,Zn)3(As,Sb)4S12. Zhengminghuaite is trigonal, with space group R3. Unit-cell parameters determined from the single-crystal X-ray diffraction data are as follows: a = 13.5373(17) Å, c = 9.2354(13) Å, and V = 1465.7(4) Å3 (Z = 3). The eight strongest lines in the X-ray diffraction pattern are [d (Å) (I, %) (hkl)]: 3.0785 (67) (003), 3.0670 (100) (1 3 1), 2.6586 (89) (1 3 2), 1.8825 (97) (134), 1.8773 (82) (520), 1.6060 (89) (13 5), 1.6028 (81) (523), and 1.6012 (83) (26 1). The crystal structure of zhengminghuaite belongs to the nowackiite group and can be described as formed by (0001) layers composed of corner-sharing FeS4 and CuS4 tetrahedra that delimit two triangular cavities. Zhengminghuaite is the Fe-dominant analog at the divalent cations site of nowackiite (Cu6Zn3As4S12) and aktashite (Cu6Hg3As4S12). Paragenetic relationships indicate that zhengminghuaite and associated Hg- and Tl-sulfosalts precipitated in response to the increase in sulfidation state and decrease in temperature of the late-ore stage hydrothermal fluid. [ABSTRACT FROM AUTHOR]

Skarn and Fe-Zn-Pb mineralization at the Wondong deposit located in the Taebaeksan Basin of the central-eastern region of Korean Peninsula occurs along the contact between the Upper Cretaceous quartz-feldspar porphyry (QFP) and carbonate rocks of the Ordovician Makgol Formation. The QFP is relatively fresh and has a sharp contact with the garnet skarn. Skarn is dominant in the carbonate rocks but is rare in the QFP. It consists almost of grandite throughout the skarn but has mineralogical zonation of proximal garnet, intermediate pyroxene, and distal wollastonite with increasing distance from the contact between the QFP and garnet skarn. Garnet becomes Fe-rich, and pyroxene tends to be enriched in Fe and Mn toward the marble front. Massive Fe mineralization, replacing garnet skarn, is restricted proximal to the QFP. In contrast, although the Zn-Pb mineralization is found in all areas it mostly occurs in the carbonate rocks beyond the skarn. Zinc-Pb mineralization occurred as stockwork and vein in the QFP and the garnet skarn consists of sphalerite, galena, Al-rich garnet, and calcite with a minor quantity of arsenopyrite. In contrast, the carbonate replacement of the Zn-Pb mineralization beyond skarn consists of sphalerite, pyrrhotite, galena, diopsidic pyroxene, and calcite with minor minerals such as arsenopyrite, löellingite, and chalcopyrite. Sphalerite, principal ore mineral, becomes darker and Fe- (up to 34.4 mol% FeS) and Mn-rich (up to 1.5 mol% MnS) with increasing distance from the QFP. Arsenopyrite is closely associated with sphalerite tends to be decreased in As away from the QFP. All sulfide minerals from Zn-Pb mineralization in the Wondong deposit have δ34S values ranging from 2.9 to 5.9‰, which are attributed to the magmatic source. In addition, the narrow range and subtle variation of the δ34S values for all sulfides throughout the Wondong deposits are not interpreted to be involved in the mixing of multiple sulfur sources. Geological, petrographic, mineralogical, and isotopic geochemical investigations show that the early skarn was formed in an environment of high fluid: rock ratios at the contact between the QFP and Makgol Formation and it was dominated by grandite, indicating the oxidizing nature of the skarn-forming fluids. The ore deposition began after the formation of the main garnet dominated skarn. The ore-forming fluids responsible for Zn-Pb mineralization are characterized by a less oxidizing nature, as defined by comparatively Al-enriched garnet in vein type mineralization in and around the QFP. Farther, the fluids producing the carbonate replacement of the Zn-Pb mineralization are unlikely to be engaged in external effects such as mixing with multiple sulfur sources even though it travels over long distance. [ABSTRACT FROM AUTHOR]

Gold occurrence Maljavr is the first Archean conglomerate-hosted gold mineralization found in the Fennoscandian Shield. Gold-mineralized metasomatic rocks form a set of lenses within a 10 m thick linear zone, conformable to the bedding of host conglomerates. The lenses are up to 10 m long and up to 1 m thick and they clearly exhibit three alteration envelopes: the rock in the central part consists of garnet and quartz or garnet-only; biotite, garnet, and quartz make the intermediate biotite–garnet envelope; hornblende, hedenbergite, and quartz are the principal rock-forming minerals in the outer zone of the lenses. All metasomatic rocks contain sulfide mineralization up to 15–20 vol.% and up to 0.6 g/t Au. The main ore mineral is pyrrhotite, and the minor minerals are arsenopyrite, chalcopyrite, pentlandite, löllingite, and troilite. The age of zircon from biotite gneiss in the zone of alteration is 2664 ± 18 Ma, this is considered as the time of formation of lenses of metasomatic rocks. Biotite gneiss-conglomerate and metasomatic rocks were later intruded by tourmaline granite pegmatite 2508 ± 7 Ma. The injection of pegmatite caused re-crystallization of sulfides (mainly arsenopyrite and löllingite) and redistribution of gold. Visible gold in association with Bi minerals native bismuth, ehrigite, maldonite, bismuthinite, joseite-B, and hedleyite was found in inclusions in recrystallized arsenopyrite and löllingite. Au content in the rocks with recrystallized arsenopyrite and löllingite is >1 g/t, up to 30 g/t in hand samples. The 2508 Ma pegmatite is interpreted as synchronous with formation of gold mineralization in its present form. The linkage of gold mineralization with pegmatite and geochemical association Au-As-Se-Te-Bi in the mineralized rocks agree with characteristics of intrusion-related gold deposits worldwide. Biotite gneiss–metaconglomerate, hosting the mineralized altered rocks, was the probable primary source of arsenic and gold for mineralization. [ABSTRACT FROM AUTHOR]

In nature, arsenopyrite commonly acts as a companion mineral of chalcopyrite. As the arsenic in arsenopyrite easily exudes during the smelting process, arsenic will not only pollute the environment but also seriously affect human health once it flows into the nature, so it is important to realize the separation of arsenopyrite and chalcopyrite. Flotation is the most efficient and commonly used means to separate these two minerals. As the floatability of arsenopyrite is similar to that of chalcopyrite, the two are usually separated using depressants to suppress arsenic and float copper. The commonly used inorganic depressants in the separation process of copper and arsenic have drawbacks such as poor selectivity, strong toxicity, and environmental pollution. Therefore, the development of a clean, efficient and non-toxic inhibitor is the key to the separation of copper and arsenic. Ethylenediamine tetramethylene phosphoric acid (EDTMP) was developed as a novel depressant of arsenopyrite to achieve the separation of arsenopyrite and chalcopyrite. Micro-flotation experiments and artificial mixture flotation tests verified the flotation performance of EDTMP, and the mechanisms of EDTMP adsorbed on arsenopyrite and chalcopyrite surface were revealed by Zeta potential, FTIR spectrum, and XPS measurements. The flotation experiments revealed that EDTMP could effectively depress the flotation of arsenopyrite without affecting chalcopyrite at pH = 10 and SIBX concentration of 200 mg/L, and the results of zeta potential and FTIR spectrum indicated that EDTMP is preferred to adsorb on arsenopyrite, which hindered the adsorption between SIBX and arsenopyrite. XPS results showed that EDTMP chemisorbed on arsenopyrite surface in the form of P-O-Fe bonds, while EDTMP weakly physisorbed on chalcopyrite surface. EDTMP was a novel arsenopyrite depressant, which was highly efficient, clean, and environmentally friendly compared to traditional depressants. [ABSTRACT FROM AUTHOR]

A comprehensive study was conducted to investigate the geochemical characteristics of Sb, Pb, and Zn deposits in various regions of Chitral district. The primary objective was to identify the source and chemical composition of the metal-bearing fluids, which currently remain unidentified. Field research revealed the presence of stibnite (Sb), galena (Pb), and sphalerite (Zn) ores, accompanied by small amounts of chalcopyrite and pyrite. These deposits were found to be associated with the Reshun fault/shear zone, and secondary minerals such as quartz and calcite were observed. Ore petrography, in combination with SEM-BSE and SEM–EDS analysis, confirmed the presence of magnetite, chamosite, stibnite, fahlore, galena, litharge, sphalerite, arsenopyrite, zinkenite, chalcostibite, boulangenite, pyrite, as well as a few gangue minerals (specifically quartz and calcite). Atomic absorption spectroscopy (AAS) was employed on four cross-sections to determine the concentrations of the metal-bearing elements. The results revealed varying concentrations of Sb (ranging from 0.001 to 24%), Pb (ranging from 0.006 to 24.1%), Zn (ranging from 1.2 to 158,000 ppm), and Cu (ranging from 0.2 to 2730 ppm). Gold (Au) and silver (Ag) concentrations were predominantly below the detection limit (BDL), except for the Barum Ghari section, where gold concentrations ranged from 0.0 to 0.38 ppm. Integration of field observations, ore petrography, and SEM analysis suggested that the deposition of ores was influenced by metamorphic fluids generated during the progressive metamorphism of sedimentary layers. Furthermore, the AAS results demonstrated an increasing concentration of metal-bearing elements from the lower to the upper Chitral region. [ABSTRACT FROM AUTHOR]

The increasing presence of arsenic-containing impurities within Cu ores can adversely affect the smelting process and aggravate the environmental impact of slag tailing. This study investigates the geochemical, mineralogical, and chemical speciation characteristics to better understand the association and environmental stability of metal(loid)s in copper slag tailing. The results indicate that the predominant chemical compositions of the selected slag tailing are Fe2O3 (54.8%) and SiO2 (28.1%). These tailings exhibit potential for multi-elemental contamination due to elevated concentrations of environmentally sensitive elements. Mineral phases identified within the slag tailings include silicate (fayalite), oxides (magnetite and hematite), and sulfides (galena, sphalerite, arsenopyrite, and chalcopyrite). The consistent presence of silicate, iron, arsenic, and oxygen in the elemental distribution suggests the existence of arsenic within silicate minerals in the form of Si-Fe-As-O phases. Additionally, arsenic shows association with sulfide minerals and oxides. The percentages of arsenite (As(III)) and arsenate (As(V)) within the selected slag tailings are 59.4% and 40.6%, respectively. While the slag tailings are deemed non-hazardous due to the minimal amounts of toxic elements in leachates, proper disposal measures should be taken due to the elevated carbonate-bound levels of As and Cu present in these tailings. [ABSTRACT FROM AUTHOR]

In anticipation of future demands, a comprehensive understanding of the chemical and mineralogical characteristics of nickel-bearing minerals is a prerequisite to devising effective nickel beneficiation methods. Of particular importance are markers in the mineralogy of the flotation concentrate that inform beneficiation strategies to improve concentrate grades, increasing both the marketability and cost of refining. In this work, a detailed characterization of a complex nickel sulfide flotation concentrate from a Western Australian deposit was carried out to determine the mode of occurrence and distribution of nickel and the associated gangue minerals, with the view of identifying prudent beneficiation strategies to improve concentrate grades. The concentrate was characterized via particle, chemical, and mineralogical techniques. Particle size analysis of the concentrate showed that it consisted predominantly of fine and ultra-fine particles (<20 μm), with the nickel value concentrated in the finer size fractions. Nickel mineralization in the ore (by quantitative X-ray diffraction) was found to be within pentlandite, violarite, millerite, and gersdorffite. The sulfide gangue was predominantly pyrrhotite, pyrite, chalcopyrite, sphalerite, arsenopyrite, and galena. Quantitative evaluation of minerals by scanning microscopy (QEMSCAN) analysis revealed that nickel minerals are at least 91% liberated, and the remaining portion (around 7%) is locked within binary iron (Fe) sulfides and 2% within complex minerals. Based on these findings, potential processing options, such as magnetic separation, gravity separation, and froth flotation, for recovering and upgrading nickel from this concentrate are discussed. Notably, with the significant presence of ultrafine/fine pyrrhotite content, averaging around 52% in the minus 38 µm fraction, novel flotation cells, including the Jameson cell, column flotation cells, and Reflux flotation cell (RFC), have been identified as potential candidates for fine/ultrafine pentlandite recovery. Overall, the characterization study conducted suggests that acquiring knowledge about the mineralogical characteristics of existing mineral concentrates can serve as a pathway to improving future concentrate grades. [ABSTRACT FROM AUTHOR]

The Santa María and Antares Zn-Pb(-Ag) skarn deposits in the Velardeña Mining District are located in central–NW Mexico. They lie 470 m apart along the contact between Oligocene felsic intrusions and Cretaceous limestones, and were developed during prograde, retrograde, post-ore (Santa María), and late stages. Firstly, the prograde stage was formed by fluids at ~ 600 °C and 15 wt% NaCl equiv., and consists of garnet + wollastonite ± clinopyroxene and biotite ± K-feldspar assemblages. Secondly, the retrograde/ore stage was formed by fluids at 300–500 °C with salinities of 20–30 wt% CaCl2 (Santa María) and > 40 wt% NaCl equiv. (Antares). It comprises assemblages of chlorite, amphibole, epidote, calcite, scapolite, quartz, sericite, adularia, fluorite, and muscovite associated with sphalerite, pyrite, galena, pyrrhotite, arsenopyrite, chalcopyrite, and Pb-Bi-Sb sulfosalts. Thirdly, the post-ore stage was formed by fluids at ~ 400 °C and 20–30 wt.% CaCl2 and comprises poorly mineralized calcite veins. Fourthly, the late stage was formed by fluids at < 300 °C and 20–30 wt.% CaCl2 (Santa María) and ~ 15 wt% NaCl equiv. (Antares), and crystallized tetrahedrite-group minerals and pyrite + marcasite. δ18Ofluid between ~ 14‰ and 23‰ at Santa María and between ~ 12‰ and 17‰ at Antares show a less-modified magmatic affinity for mineralizing fluids at Antares; δ13Cfluid between 0‰ and –6‰ register recycling of sedimentary C. Moreover, sulfides with δ34SVCDT between –3‰ and 2‰ reveal a magmatic source for S. Altogether, these data suggest that, at Santa María, magmatic-derived fluids actively interacted with the wall rocks, whereas at Antares the fluid-rock interaction was milder. In both deposits, metal deposition was triggered by the cooling and neutralization of ore-bearing fluids with carbonate rocks. Our 40Ar/39Ar dates for adularia of ca. 37.5 Ma place the deposits within the Eocene–early Miocene metallogenetic epoch of central–NW Mexico, during which other world-class skarn-epithermal systems were emplaced (e.g., Concepción del Oro and Mazapil-Peñasquito). [ABSTRACT FROM AUTHOR]

In order to further improve the recovery index of a refractory microfine-dissemination gold ore in Qinghai Province, a detailed process mineralogy study was conducted. The results showed that the main factors affecting gold recovery were the recovery of fine and micro-fine pyrite and arsenopyrite. Due to the difficulty of monomer dissociation of most fine and micro-fine pyrite and arsenopyrite during the grinding process, some gold minerals were lost. In addition, fine-grained gold inclusion by vein minerals was also an important form of gold mineral loss. It is suggested to use a flotation process with staged grinding and separation to improve gold recovery rate. [ABSTRACT FROM AUTHOR]

Arsenic is a common pollutant and impurity present in complex gold ores. In the pressure oxidation (POX) of refractory gold-bearing sulfides, a major environmental challenge is the treatment of the hazardous waste released from arsenic-bearing minerals during processing. While the bulk removal of arsenic from solution can occur during POX, the formation of stable arsenates relies on the operating conditions during POX and the subsequent curing stage. Herein, response surface methodology (RSM) and central composite design have been investigated as viable approaches for optimizing arsenic fixation during the curing of the POX product of arsenopyrite. Curing time (0–24 h) and temperature (60–120°C) were examined as the model variables for RSM optimization, and the performance was assessed via arsenic and iron precipitation, along with the change in free acid and sulfate concentrations. Experimental validation of the optimized model conditions demonstrated good agreement with the simulated outputs and provided a 10% increase in arsenic removal over the best model input. The formation of basic ferric arsenate sulfate and scorodite under these conditions was supported by RSM and confirmed via characterization. In the investigated system, the maximum arsenic removal occurs at a critical threshold temperature of 107°C, over which the scorodite formation decreases with temperature. Thermodynamic modeling revealed the preferable formation of soluble FeHAsO4+ complexes over scorodite above this threshold temperature, decreasing arsenic fixation at higher temperatures. [ABSTRACT FROM AUTHOR]

The Badran orogenic gold deposit is located in the Yana-Kolyma belt, Eastern Siberia; it has proven reserves of ~9.3 t of gold and an average grade of 7.8 ppm. The total gold production at the Badran deposit since 1984 amounts to ~34 t. Despite many years of study, the origin of the gold deposits of the Yana-Kolyma metallogenic belt, one of the world's largest belts, and the Badran deposit is controversial. Synthesis of regional geology and geology of the Badran deposit, fluid inclusion analysis, mineral and (S-O) isotope chemistry defines the genetic model, origin of fluids, and source of metals in the evolution of the ore-forming system, equivalent to other orogenic gold deposits on the margin of the Siberian craton. The deposit is localized in the Upper Triassic clastic rocks and is controlled by the NW-trending thrust. Polyphase mineralization occurs as disseminated arsenian pyrite and arsenopyrite ores with invisible gold, quartz veins with native gold and Fe, Pb, Zn, Cu sulfides and sulfosalts of orogenic type, and locally post-ore Ag, Sb-bearing minerals and Hg epithermal features. The quartz veins with native gold were formed from low-medium saline (1.5-10 wt% NaCl eq.) aqueous-carbonic fluids boiling at temperatures of 290°C to 210 °C and pressures of 300-250 to 125 bar. The δ34S values of pyrite and arsenopyrite vary from -1.1‰ to +2.4‰, with an average of +0.4‰; the δ18O of quartz from +15.1‰ to +17.5‰ at constant δ18OH2O about +7.5‰ (±1.0‰). High contents of As (up to 2.4 wt%) and Co/Ni ~from 0.3 to 9.9 in pyrite of proximal alteration are typical for hydrothermal systems. The results obtained confirm that the ore-forming fluids did not have a single origin, but were formed from a mixture of subcontinental lithospheric mantle and metamorphic sources. The subcrustal lithospheric mantle was fertilized in the time preceding mineralization (Late Jurassic) and was derived directly from the down-going subduction slab and overlying sediment wedge at the closure of the Oymyakon Ocean. [ABSTRACT FROM AUTHOR]

In mineral processing, arsenic-bearing minerals are particularly difficult to separate from their non-arsenic counterparts because they possess similar surface properties. Peptides are well known for their target specificity and can offer a 'green' alternative to traditional flotation reagents. However, the use of peptide technologies in mineral processing for developing novel flotation reagents has not been explored. Hence, this work aims to develop a screening method to identify mineral-binding peptides as potential reagent candidates. It is hypothesised that peptides can selectively adsorb onto mineral surfaces, and this method can efficiently identify mineral-binding peptides with high specificity toward the target minerals. The methodology presented involves a selection of peptide candidates from existing literature that show affinity toward arsenic species. These peptides were tested for their adsorption performance onto selected mineral surfaces to evaluate their mineral selectivity under flotation conditions. The study demonstrates that the screening method developed is effective in identifying peptides that have an affinity for target minerals, in this case, arsenic minerals. The screening method can be applied to other minerals, thus, unlocking the potential for developing new reagent chemistries for use in mineral processing. [ABSTRACT FROM AUTHOR]

Recently, preoxidation is an effective pretreatment method of refractory gold ore, which has been widely used due to the high desulfurization, arsenic removal, low environmental pollution, and rapid reaction rate. In this paper, we describe the thermodynamic considerations of preoxidation of pyrite and arsenopyrite, the main minerals of the refractory gold ore, and the effect of the pressure oxidation, one of the preoxidation processes on the chlorination leaching. The thermodynamic results indicated that arsenopyrite under acidic conditions is easier to oxidize compared to pyrite and the oxidation decomposition of pyrite and arsenopyrite-type gold ore can be considered mainly for pyrite. The experiment has shown that the arsenic removal rate was higher than the desulfurization rate; it is confirmed that the thermodynamic conclusion of the oxidation of pyrite and arsenopyrite was correct. Comparing the XRD, SEM, and EDX analyses of gold concentrate and pressurized oxidation residue, it can be seen that the surface of pressurized oxidation residue is a fine porous structure and the dense and durable structure of sulfide ore is mainly destroyed. [ABSTRACT FROM AUTHOR]

Nowadays, research on promoting the dissolution of chalcopyrite is important. As a natural symbiotic mineral of chalcopyrite, arsenopyrite will have an impact on the dissolution of chalcopyrite. This paper shows the influence of arsenopyrite on the dissolution of chalcopyrite in an acidic culture medium. The leaching results showed that adding arsenopyrite increased the leaching concentration of copper by 332 mg/L. The residues showed a decrease in sulfur through X-ray diffraction analysis (XRD) and an increase in dissolution degree through scanning electron microscope (SEM). Electrochemical experiments have shown that the rest potential of arsenopyrite is higher than that of chalcopyrite, so there is a galvanic interaction, and the impact on chalcopyrite is greater than that of arsenopyrite. The polarization curve also proves this. Under the interaction of galvanic couples, the reduction of S0 production and the enhancement of Cu2+ release can promote the dissolution of chalcopyrite. In addition, X-ray photoelectron spectrometer (XPS) analysis under the action of galvanic coupling indicates that more SO42− is generated on the surface of chalcopyrite, replacing Sn2−/S0, and SEM shows a stronger corrosion morphology. All results confirm that the electrochemical effect between arsenopyrite and chalcopyrite promotes the dissolution of chalcopyrite in the acidic culture medium. [ABSTRACT FROM AUTHOR]

Petrochronology of monazite in volcanic rocks of the Hutti deposit in the Eastern Dharwar Craton (India) has been studied to understand the magmatic and hydrothermal events that have affected the area. The volcanic rocks occurring in the Hutti greenstone belt are bimodal in nature and contain both felsic and metabasalt. The felsic volcanic rocks in the area preserve accessory minerals like monazite, allanite, and apatite, whereas the same is absent in metabasalts. Petrographic observation of felsic volcanic rock shows corona growth of allanite and apatite (in addition to huttonite) clustering around monazite grains. This corona texture, termed allanite cluster, occurs parallel to the shear planes (C‐plane) of the felsic volcanic rock and characterizes late‐stage hydrothermal activity in the area. Texturally, monazite in the felsic volcanic rock occurs included within arsenopyrite (<1 μm), and in association with apatite, allanite, and occasionally with huttonite/thorite (~10–40 μm), in which monazite grains preserve geochemical heterogeneity in both intra‐ and inter‐grains. The U–Th–PbTotal dating of monazite associated with the allanite cluster shows two age peaks (both from intra‐ and inter‐grains) at 2658 ± 17 Ma (older) and 2534 ± 38 Ma (younger), in which the older age represents the magmatic/crystallization age of the studied felsic volcanic rock overprinted by a later hydrothermal event in the study area. Based on monazite geochemistry‐geochronology, the present study deduces two texturally constrained events related to the primary crystallization of monazite (~2.65 Ga) and subsequent alteration of the same during a later hydrothermal event (ca. 2.53 Ga) that has affected the felsic volcanic rock in the Hutti gold deposit. [ABSTRACT FROM AUTHOR]

There are many lode gold deposits and occurrences in the Kalamaili area of the East Junggar, northwestern China. However, little is known about the specifics of ore geology and geochemistry of these gold deposits because of very limited exploration and research work in this region. Field geology, fluid inclusions, stable isotopes, trace elements in quartz, and hydrothermal zircon U-Pb dating are combined in this study to constrain the nature and source of ore fluids, the timing of mineralization, and the mechanism of gold precipitation in Kalamaili. The gold deposits are confined to a narrow zone between two regional NW- to NWW-trending shear zones and are structurally controlled by secondary, high-angle faults of the shears. The orebodies occur in the Middle Devonian and Lower Carboniferous, zeolite to lower greenschist facies clastic sedimentary and pyroclastic rocks. Gold mineralization occurs as auriferous quartz-sulfide ± tourmaline veins/veinlets and disseminated ores in the immediate altered wall rocks. The ore mineralogy is relatively simple and dominated by quartz with minor to trace amounts of sulfides (pyrite and arsenopyrite), sericite, calcite, and native gold. Quartz of various generations contains three types of fluid inclusions, including predominant H2O-CO2-NaCl inclusions and subordinate H2O-NaCl inclusions and CO2 ± CH4 ± N2 inclusions. The mineralizing fluid is uniformly characterized by a medium to high homogenization temperature (mostly 240-330 °C), low salinity (typically <6 wt% NaCl equivalent), reduced, and CO2-rich-H2O-NaCl ± CH4 fluid. The hydrogen and oxygen isotope data (δ18OH2O = +5.6‰ to +14.3‰, δDH2O = -99‰ to -62‰) indicate a metamorphic origin for the mineralizing fluid. The majority of sulfide δ34S values range between 0‰ and +10‰, indicative of a largely sedimentary rock reservoir of sulfur in the ore-forming fluids. Geochemically, the auriferous quartz is characterized by low concentrations of most trace elements including Ti, Al, Li, Ge, and Sb. Laser ablation--inductively coupled plasma--mass spectrometry U-Pb isotope dating of hydrothermal zircons from the auriferous quartz vein yielded a weighted mean 206Pb/238U age of ca. 313 Ma. Phase separation of ore fluids and fluid-rock interaction are suggested as key mechanisms for the gold precipitation. Integrated geological and geochemical evidence indicates that formation of the orogenic gold system in Kalamaili is related to the transition from compressional to transcurrent deformation during the Late Carboniferous. Target gold exploration in this region should focus on the northeast side of the Kalamaili fault zone, where there exist suitable structural and stratigraphic trap sites with high fluid flux and potential gold mineralization. [ABSTRACT FROM AUTHOR]

Purpose. In this paper, we discuss the genetic model and emphasize many pending issues on the carbonate replacement textures of the Amensif Zn-Pb-Cu-Ag±Au-Bi deposit (the Western High Atlas, Morocco), the source of metal and the possible contribution of the Azegour granite to this ore genesis. Methods. This study is based on geological mapping, drill core and petrography analysis in combination with ICP-AES, XRD, and SEM data. Findings. The detailed mineralogy consists mainly of sulfides and sulfosalts. The main ore minerals include arsenopyrite, pyrite, sphalerite, chalcopyrite, galena and bismuthinite. Mineral inclusions related to isomorphic sulfosalts are found in galena and/or chalcopyrite. They include matildite, galenobismutite, pavonite, cosalite, schirmerite, krupkaite, ramdohrite, wittichenite, emplectite, luzonite, gustavite, hedleyite, krennerite, wittite, freibergite, tetrahedrite, tennantite and native bismuth. The supergene minerals are anglesite, covellite, malachite, azurite and goethite. In addition, specific replacements are observed between dolomites and sulfides, indicating an interaction between hydrothermal fluid and host rocks. Four ore stages have been identified based on the relationship between mineral phases and ore-forming conditions. The results of this study indicate that Ag and Au precipitation is controlled by the Bi-Te-Pb-S system, while enrichment in Bi, Te and Se sulfosalts and Bitelluride indicates a magmatic source of the ore-forming fluid. Originality. The study delves into the genetic model of the Amensif Zn-Pb-Cu-Ag±Au-Bi deposit in the Western High Atlas, Moroc-co, with a focus on carbonate replacement textures, while also exploring its classification as either a carbonate replacement deposit or a skarn deposit. Practical implications. Mineral textures are indicators of the replacement process in the Amensif Zn-Pb-Cu-Bi-Ag±Au carbonate replacement deposit (the Western High Atlas, Morocco). The results obtained from this research paper can be used as a powerful tool in mineral exploration of the Western High Atlas. [ABSTRACT FROM AUTHOR]

Pyrite, the most common sulfide mineral, is a ubiquitous component of many hydrothermal gold deposits. Geochemical patterns within the refractory pyrite structure represent a valuable repository of information that can help constrain the sources of ore-forming materials, and the evolution of ore-forming processes over time. However, there are still a lot of debates on the mechanisms of physico-chemical processes in ore-forming fluid controlling trace element and sulfur isotope distributions in pyrite during growth. In our manuscript, we use cutting-edge complementary microanalytical methods to understand the origin and evolution of zoned gold-bearing pyrite in samples from the largest gold deposit in the Ailaoshan gold belt, SW China, Zhenyuan (exceeding 100t Au, average grade: 5.3 g/t). Pyrite, arsenopyrite, chalcopyrite, and stibnite are the most abundant sulfide minerals in most orebodies. Of these, pyrite is dominant and is also the most important host for gold. Two types of pyrite can be clearly distinguished: framboidal pyrite and hydrothermal pyrite. Gold is most commonly hosted by hydrothermal pyrite. Framboidal pyrite, mainly hosted by carbonaceous slate, hosts negligible Au, and features low δ34S values ranging from − 35.0 (± 0.9) to − 25.6 (± 1.0)‰. Hydrothermal pyrite is characterized by complex intra-grain zoned textures with alternating As-rich and As-poor bands readily recognizable on backscattered electron images. Scanning electron microscopy and trace-element analyses show that both visible and invisible gold occur only in the As-rich bands. Compared to the As-poor bands (72.1% of Au concentration data < 1.96 ppm, n = 43), the As-rich bands are characterized by far higher concentrations of Au (up to 1420 ppm), Cu, Ag, Sb, and Tl, but lower concentrations of Co and Ni. In-situ sulfur isotope analysis indicates that the δ34S values of As-rich zones range from − 7.3 (± 0.6) to 2.9 (± 0.6)‰ and are similar to those of As-poor zones (from − 6.9 (± 0.7) to 2.8 (± 0.6)‰), but distinct from the framboidal pyrite. Combined with published fluid inclusion data and a probable age for the magmatic event associated with mineralization, these data suggest that magmatic–hydrothermal fluids contributed most ore-forming materials and that periodic boiling led to formation of the rhythmic As-rich and As-poor bands in pyrite. Our data for pyrite constrain the evolution of ore-forming processes and provide new insights into the formation of zoned pyrite, with the conclusions having broad implications for analogous hydrothermal gold deposits worldwide. [ABSTRACT FROM AUTHOR]

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The paper presents the first results of mineralogical studies of gold-bearing quartz–carbonate–sericite metasomatites of the Kutyn deposit in Khabarovsk krai. The mineral assemblages with native gold and variations in its morphology, size, and chemical composition are studied. It is established that native gold with a fineness of 650–780‰ is associated with Sb-bearing arsenopyrite, pyrite, fahlores, galena, and hessite. Native gold with higher fineness (810–850‰) fills fractures in arsenopyrite. The fineness of native gold from quartz veinlets is 730–770‰. The Te minerals include hessite, altaite, petzite, stützite, telluranthimonite, and coloradoite. Successive pyrite–arsenopyrite, native gold–tetrahedrite–arsenopyrite, native gold–pyrite, and telluride ore assemblages of the hydrothermal–metasomatic stage are distinguished on the basis of the analysis of the composition of minerals and their morphology, interrelations, and trace-element composition of pyrite (up to 6.9 wt % As) and arsenopyrite (up to 2.8 wt % Sb and up to 5.4 wt % Te), which are ubiquitous minerals of this system. The supergene stage led to the formation of a goethite–arsenate assemblage with ultrafine native gold inclusions, which formed during oxidation of gold-bearing pyrite and arsenopyrite. Based on a chlorite geothermometer (Cathelineau and Nieva, 1985), the estimated temperature of early metasomatic process is 229–278°C. According to a stability diagram of the Au–Ag–Te system (Bortnikov et al., 1988), the formation temperature of native gold–tetrahedrite–arsenopyrite assemblage could not be lower than 170°C. The narrow variations in values of S (logS2 from –16.8 to –15.0) and Te (logTe2 from –16.5 to –15.2) fugacity at 200°C are estimated for the first time, which correspond to the formation of the studied native gold–tetrahedrite–arsenopyrite assemblage. [ABSTRACT FROM AUTHOR]

Arsenopyrite dissolution is an important source of arsenic's environmental occurrence and is well-studied under oxidative conditions. However, little is known of anoxic leaching of arsenopyrite by water, though it is probably one of the dominant abiotic processes controlling arsenic mobility in oxygen-limited environments such as groundwaters and paddy fields. The present study attempts to probe the mechanism of arsenopyrite-water interaction in anoxic environment through examining the pH dependence of dissolution kinetics and stoichiometry, as well as speciation changes both on the surface and in solution. Batch and flow-through experiments were first carried out to measure dissolution rates and the results showed alkaline pH mildly encourages As release. Furthermore, the dissolution was found to be near stoichiometric with respect to As and S but not with Fe/As or Fe/S, and the non-stoichiometry exhibited a negative dependence on pH. Combining speciation analyses that revealed the presence of H 2 O 2 , SO 4 2− and S 2 O 3 2− in solutions and a positive correlation of surface species Fe(III)-O, S(-II), and As(I), As(III), As(V), and As(-III) to solution pH, we interpreted the anoxic dissolution behavior of arsenopyrite through a mechanism that combines surface complexation and interfacial redox reactions. The kinetic measurements came to be concerning as data indicates arsenopyrite dissolution in anoxic environment can lead to water having arsenic concentrations above the 10 ppb WHO guideline value in one day at the experimental conditions. The observed H 2 O 2 production indicated the dissolution is associated with or initiated by electron transfer despite the anoxic condition, further suggesting that a more comprehensive theory other than surface complexation model may be needed to better understand the geochemical behavior of As and possibly S in the context of sulfide mineral–water interactions. [ABSTRACT FROM AUTHOR]

The objective of this research was applying air Micronanobubbles to reduce Arsenic present in an effluent generated at the laboratory level. In this research, an effluent with arsenic metal was used from a mixture of minerals with the presence of arsenopyrite with 19% As content. This mixture of minerals was stirred in a hot alkaline leaching medium at a temperature of 80 °C, with Na2S (1.5 M) and NaOH (1.0 M), then it was diluted with distilled water to obtain a volume of 100 L with a concentration of 150 ppm As. This effluent was treated with the air micronanobubble (MNB) generator equipment patented by Dr. Jhonny Valverde Flores. The variables of the pressure and the insufflation time of air as MNB in the effluent with content of the arsenic element were analyzed. A 40% decrease of As was obtained in the effluent. The results indicate that the use of MNB is promising in terms of the reduction of arsenic in solutions with concentrations of the same. [ABSTRACT FROM AUTHOR]

Geological observations and U–Pb dating of zircons from intrusions of the Yana–Kolyma gold province constrain the age of orogenic gold deposits to the time interval between 150 ± 3Ma and 108 ± 1 Ma. The Natalka deposit is the largest key deposit in the gold province. We determined the age of mineralization as the Valanzhinian (136 ± 1 to 132 ± 2 Ma) by 40Ar/39Ar dating of muscovite and by Re–Os dating of arsenopyrite and native gold. There are no known manifestations of magmatism of this age in the province, therefore, we conclude that the formation of gold–quartz mineralization is very likely related to metamorphism and metasomatism triggered by regional-scale shear deformations. [ABSTRACT FROM AUTHOR]

The Tamilouw-Haya orogenic gold deposit is located in the southern arm of Seram Island, Indonesia, occupying Tehoru Metamorphic Complex. Gold mineralization is predominantly in the form of veins, stockwork, and breccia, although minor dissemination is slightly appeared in the rock float samples. Ore-mineral assemblages are dominated by native gold, pyrite, chalcopyrite, sphalerite, tetrahedrite-tennantite (sulfosalt), galena, pyrrhotite, marcasite, realgar, kalininite, and arsenopyrite. Covellite, hematite, goethite, and malachite appear as supergene minerals. High-grade gold ores in this area are generally found in quartz-carbonate veins with the main alteration processes involving silicification, carbonatization, and sericitic. The P-T history of the mineralization was revealed by fluid inclusions, and this study implies the depth of ore deposit and its evolution during mineralization. The primary fluid inclusions from three different types of quartz/quartz-carbonate veins in Tamilouw-Haya crystallized at the homogenization temperature (Th) of 240 °C to 340 °C, with a fluid salinity from 3.87 to 0.70 wt. % NaCl equivalent, and melting temperature (Tm) of -0.4 to -2.3 oC. The ore-forming fluids consist mainly of two-phase (VCO2+LH2O) liquid-rich aqueous inclusions, characterized by low to rich CO2, low salinity, and moderate temperature. There are three vein types as the ore-bearing fluids with precious metals and anomalous high basemetal contents. Quartz type 1-veins (V1); concordant veins, formed at a temperature of 240-307 oC with an average salinity of 1.8 wt. % NaCl equivalent. Quartz type 2-veins (V2) tend to cut the rock foliation which are formed at temperature range from 293-336 oC with the average salinity that shows a value of 2.4 wt. % NaCl equivalent. Meanwhile, type 3 quartz-carbonate veins (V3) are formed at the temperature range of 240-340 oC and the average salinity of 2.72 wt. % NaCl equivalent. These quartz-carbonate veins cut the wall-rock foliation, which is identified as the late stage and associated with ore deposition in Tamilouw-Haya. The gold deposit in Tamilouw-Haya is formed at a depth of about 5.5-9 km of paleosurface, and the pressure between 1.7-2.4 Kbar in epizonal to mesozonal zones. [ABSTRACT FROM AUTHOR]

Microbially assisted bio-oxidation of sulfide concentrates in stirred-tank reactors (stirred-tank reactor bio-oxidation (STRB)) and acid pressure oxidation (POX) are widely used to pretreat refractory sulfide concentrates and increase gold extraction via cyanidation. Continuous STRB requires a comparatively long residence time; however, in some cases, it cannot effectively oxidize some sulfide minerals. POX enables oxidation in a short residence time. At the same time, if a processed concentrate contains a large amount of sulfur, it decreases the ratio of the solid mineral phase to liquid (pulp density) during POX and limits its economic attractiveness. In the present work, experiments were performed to investigate the problems associated with both processing methods for refractory sulfide concentrates. The experiments combined both treatments (STRB and POX) based on the example of a pyrite–arsenopyrite gold-bearing concentrate. The gold recovery from the untreated concentrate via cyanidation reached 58%. Continuous STRB for 2, 4, and 6 days oxidized 43, 74, and 79% of the sulfide sulfur (Ss), respectively. The gold recovery rates from the bio-oxidation residues were 68, 82, and 88%, respectively. The pressure oxidation of both the concentrate and STRB residues increased Ss oxidation by 97–99% and gold recovery by 96–97%. For 2 days, STRB decreased the Ss content and increased the possible liquid-to-solid ratio for POX. The combined processes result in a new promising direction because the POX stage allows high gold recovery, whereas combining STRB and POX provides products for further POX in terms of Ss content and increases POX productivity. [ABSTRACT FROM AUTHOR]

This is an essay in the field of mineral processing engineering. Pyrite and arsenopyrite are common associated sulfides. Because their crystal structures and surface properties are very similar, their flotation separation has been an important research topic. In the flotation process of arsenic and sulfur minerals, the oxidation reaction is easy to occur in different degrees. The oxidation treatment technology is used to strengthen the oxidation difference between the two minerals and to change the inherent flotation behavior of the minerals, the separation of arsenopyrite from pyrite can be realized. Based on the self-crystal structure and surface properties of pyrite and arsenopyrite, the research status and progress of separation technology and mechanism of pyrite and arsenopyrite in oxidative flotation are introduced in detail, the research direction is analyzed and prospected, and it is hoped to provide some reference for the green and efficient flotation separation of arsenic and sulfur minerals.

This study investigates the correlation between the electronic structure of the active sites on mineral surfaces and their adsorption capacity. Density functional theory (DFT) and flotation experiments are employed to examine the bonding behavior and adsorption enthalpy of ethylxanthate on pyrite (1 0 0) and arsenopyrite (0 0 1) surfaces. The results indicate that ethylxanthate adsorbs more significantly on pyrite than on arsenopyrite. The adsorption is chemical, primarily occurring through the orbitals of sulfur in the ethylxanthate and iron on the mineral surface. Compared to arsenopyrite, the d-band center of the iron atoms on the surface of pyrite is closer to the Fermi level; thus, the adsorption strength of ethylxanthate on the pyrite surface is greater than on arsenopyrite. The d-band centers of pyrite and arsenopyrite exhibit a direct relationship with their adsorption capacity.

A small and isolated hydrothermal vein-type Sb deposit is hosted by a lamprophyre dike which penetrated Neoproterozoic to early Cambrian volcanosedimentary successions near Chříč in the Teplá-Barrandian Unit, Czech Republic. Hydrothermal minerals were formed in several consecutive mineralization stages, separated by long pauses in hydrothermal fluid flow. Early Stage I is characterized by the formation of carbonates of dolomite-ankerite series (Carb I) and arsenopyrite with an imprecise Re-Os age of ~570 to 510 Ma. Stage I was followed by tectonic movements and brecciation. The second mineralization stage (Stage II) is characterized by the precipitation of quartz (Qtz I) and Sb minerals (predominantly stibnite) while the third stage (Stage III) is marked by the presence of carbonates of dolomite-ankerite series (Carb II) and quartz (Qtz II) along with Cu, Zn, Pb, Ag and Fe sulfides. Lead isotope data of galena indicate a Variscan age of Stages II-III. These stages were followed by precipitation of another generation of carbonate of dolomite-ankerite series (Carb III, Stage IV), quartz (Qtz III, Stage V) and formation of Sb supergene minerals. The earlier reported occurrence of gold was not confirmed in the studied rock samples but three types of gold particles of variable fineness, with one of them indicating a local origin, were found in the heavy mineral concentrate from a local creek. Elevated Au concentrations were found in arsenopyrite and pyrite. The ore-forming hydrothermal fluid of the mineralization stage III was of H2O-CO2 type with minor CH4 admixture, medium salinity, and temperatures in the range of 258-350 °C with an observed temperature decrease from Stage II to Stage V. Oxygen isotope data of Carb II correspond to high d18Ofluid values (~ +7.5 = VSMOW) with a decrease in the fluid d18O to later stages. An important part of the carbonate carbon was derived from decomposition of organic matter or its high-temperature reaction with hydrothermal fluid. Considering the wide variation in d34S values of sulfides and elevated Sb contents in the TBU black shales, we anticipate that the origin of the Chříč mineralization is closely associated with a metal and carbon-sulfur remobilization from the TBU volcanosedimentary successions in response to Cadomian and Variscan tectonothermal events. [ABSTRACT FROM AUTHOR]

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Gold mineralization in the El-Barramiya region of the Eastern Desert, Egypt, is connected to the post-accretionary stage throughout the Central Eastern Desert. It is represented by quartz, quartz-carbonate veins and disseminations in listvenite rocks. The thrust contact between rock units in El-Barramiya area played an imperative part in gold mineralization where the obduction of ophiolitic rocks over the metasediments and metavolcanics caused shear zones. Mineralization in the study area formed along shear zones and the gold mineralization prefers to precipitate along the transition zone between low-grade regional metamorphic area which is represented by metasediments and high grade which is represented by actinolite schist. The gold mineralization lode of El-Barramiya gold mine area is situated in E–W trending quartz and quartz-carbonate veins along a shear zone located in the intersections between faults trend in NE–SW (Najd fault), NW–SE and thrust faults trend in NEE–SWW in metavolcanic and metasedimentary host rocks. Porphyry granite in the mine area played an important role in hydrothermal alteration process where it represents the source of K, listvenite formed when fluids rich in CO2 and bearing-K permeate and alter the previously altered ultramafic rocks, usually serpentinites of the ophiolitic mélange rocks. The listvenitization process includes silicification and carbonatization metasomatic processes, tectonized serpentinites are altered to listvenite as the carbonatization becomes more intense close to dipping transpressive faults. Geochemical studies of listvenite and mineralized veins helped to determine the ultramafic genesis of listvenite and gold transformed as gold bisulfide. The whole rock geochemical data from El-Barramiya and elsewhere indicate that the transformation of serpentinite into listvenite involves profound metasomatic modification of the bulk-rock geochemistry. The chemical changes during alteration of serpentinite to listvenite are dominated by the addition of CO2, the removal of H2O, and the redistribution of SiO2, MgO and CaO as carbonate minerals and silica replace serpentine. All listvenites at El-Barramiya lode gold deposit are enriched in CaO, Fe2O3 and K2O, but depleted in MgO compared with associated serpentinite that is presumed to represent their protoliths. The chemical changes during alteration of serpentinite to listvenite are dominated by the addition of CO2, the removal of H2O, and the redistribution of SiO2, MgO and CaO as carbonate minerals and silica replace serpentine. Alteration also caused redistribution of trace elements, with some being locally remobilized within the rock, some being added from a fluid phase, and others being leached out of the rock. Petrographic investigation and geochemical studies show different types of alterations (carbonatization and silicification) and mineralization. Mineralizations are represented by gold and sulfides (pyrite, arsenopyrite and smaller quantities of chalcopyrite, sphalerite, galena, tetrahedrite and gersdorffite) found in auriferous quartz veins and disseminated in listvenite. The area exposed to brittle–ductile deformation in addition to different types of structures such as faults and fractures controlling on the formation of mineralization and act as hydrothermal channels ways for fluid flow. Fluid inclusions studies revealed that gold mineralization was formed from heterogeneous trapping of H2O–CO2 fluids at a temperature of 280–340 °C and pressure within the range of 1.5–1.9 kbar, which is consistent with the mesothermal conditions. [ABSTRACT FROM AUTHOR]

The Tanzania Archaean Kavirondian Group conglomerates are primarily distributed in the Nzega region of central Tanzania, with a small amount also found in the Lupa region to the southwest. This rock formation, which extends approximately 50 km in length and 0.5-3 km in width in a near EW and NW direction, is characterized by widespread gold mineralization. The main mineralization features include silicification and pyrite mineralization, followed by arsenopyrite mineralization and pyrrhotite mineralization. The study findings are as follows: Induced polarization anomalies exhibit distinct relatively low resistivity and high polarization characteristics. Soil geochemical measurements show significant Au anomalies with well-defined concentration centers and zones. Gold mineralization is strictly controlled by rock layers and is confined to the conglomerate zones. The gold mineralization is extensive, with mineralized bodies ranging from 5 m to 20 m in width. The gold grades within the mineralized bodies are relatively low, ranging from 0.2 g/t to 1.0 g/t, but local enrichment zones can reach 2 g/t to 3 g/t. [ABSTRACT FROM AUTHOR]