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In this work, copper sulfide particles are synthesized with different Co doping concentrations such as 0, 1 and 5% at 80 °C by optimizing synthesis times from 1 to 3 h. Copper sulfide particles possess two structural phases of covellite CuS and digenite Cu9S5. The increase in synthesis time from 1 to 3 h increases the Cu9S5 phase growth and changes the morphology from flower to microsphere. The CuS synthesized with 0, 1 and 5% Co dopant concentrations demonstrate flower consisting of agglomerated nanosheets, microsphere and flower like microsphere. The elemental investigation substantiates Co ions presence in CuS microspheres. The A1g (LO) mode intensity is decreased with increase in Co dopant concentration confirming Co incorporation into CuS microsphere. The CuS synthesized with 0, 1, 5% Co dopants exhibit 322 mV, 305 mV and 289 mV to attain 100 mA/cm2 in 1 M KOH seawater. The CuS synthesized with 5% Co dopant demonstrates higher double layer capacitance (Cdl) of 173.9 mFcm−2 and lower charge transfer resistance (Rct) of 6.07 Ω with 78.84% retention after 10 h continuous stability than that of the other pristine (118.3 mFcm−2, 13.72 Ω) and 1% Co doped CuS microsphere (165.7 mFcm−2, 8.55 Ω) indicating more surface active site and rapid charge carrier transport, respectively.

Research subject. The mineral compositions of titanomagnetitic (apatite, titanomagnetite) and copper-titanomagnetitic (bornite, chalcopyrite, apatite, titanomagnetite) ores of the Volkovskoe Cu-Fe-Ti-V deposit (Middle Urals, Russia).Methods. The research was carried out using a Jeol JSM-6390LV scanning electron microscope and X-ray spectral microanalyzers JXA-5 (Jeol) at the Geoanalitik Collective Use Center of the IGG UB RAS. Results and conclusions.Native gold (with ≤ 0.3 wt % Pd, 0.2–0.4 wt % Cu; fneness 800–914 ‰), tellurides of Pd, Au and Ag (merenskyite, keithconnite, sylvanite, hessite) and Pt arsenide (sperrylite) were found in the copper-titanomagnetitic ores. For the frst time, two generations of native gold (fneness 1000 and 850–860 ‰) and palladium telluride (keithconnite Pd3-xTe) were detected in titanomagnetitic ores. The sequence of ore mineral formation and the features of their genesis were revealed. Native gold (fneness 1000‰) in the form of microinclusions in titanomagnetite was attributed to the magmatic stage. Noble metal minerals, intergrown with copper sulfdes (bornite, chalcopyrite, digenite) and associated with late hydroxyl-bearing minerals (amphibole, epidote, chlorite), are superimposed in relation to the magmatic minerals (pyroxene, plagioclase, hornblende, apatite, titanomagnetite, ilmenite, etc.) of these ores. Merenskyite, sperrylite, high fneness gold (800–914 ‰), as well as carrolite, cobaltite, copper-cobalt telluride and bismuth tellurium-selenide kawazulite Вi2Te2Se are syngenetic with copper sulfdes. The Au-Ag tellurides were deposited later than these minerals. It is shown that the high fugacity of tellurium, which binds Pd, Au, and Ag into tellurides, prevents the occurrence of native gold containing high concentrations of palladium and silver.

Copper sulfide nanoparticles represent a class of dual-functional materials whose optical properties are dominated by interband electronic transitions and intraband plasmon resonances, both of whic...

Kesterite Cu2ZnSnS4 (k-CZTS) nanocrystals have received attention for their tunable optoelectronic properties, as well as the earth abundance of their constituent atoms. However, the phase-pure synthesis of these quaternary NCs is challenging due to their polymorphism, as well as the undesired formation of related binary and ternary impurities. A general synthetic route to tackle this complexity is to pass through intermediate template nanocrystals that direct subsequent cation exchange toward the desired quaternary crystalline phase, particularly those that are thermodynamically disfavored or otherwise synthetically challenging. Here, working within this model multinary system, we achieve control over the formation of three binary copper sulfide polymorphs, cubic digenite (Cu1.8S), hexagonal covellite (CuS), and monoclinic djurleite (Cu1.94S). Controlled experiments with Cu0 seeds show that selected binary phases can be favored by the identity and stoichiometry of the sulfur precursor alone under otherwise comparable reaction conditions. We then demonstrate that the nature of the Cu2-xS template dictates the final polymorph of the CZTS nanocrystal products. Through digenite, the cation exchange reaction readily yields the k-CZTS phase due to its highly similar anion sublattice. Covellite nanocrystals template the k-CZTS phase but via major structural rearrangement to digenite that requires elevated temperatures in the absence of a strong reducing agent. In contrast, we show that independently synthesized djurleite nanorods template the formation of the wurtzite polymorph (w-CZTS) but with prominent stacking faults in the final product. Applying this refined understanding to the standard one-pot syntheses of k- and w-CZTS nanocrystals, we identify that these reactions are each effectively templated by binary intermediates formed in situ, harnessing their properties to guide the overall synthesis of phase-pure quaternary materials. Our results provide tools for the careful development of tailored nanocrystal syntheses in complex polymorphic systems.

The Tiegelongnan porphyry-epithermal deposit (2089 Mt @ 0.53% Cu, 0.08 g/t Au) is host to a large variety of Cu-sulfide minerals, mainly chalcopyrite, bornite, covellite, digenite, enargite, and tennantite. We used LA-ICP-MS to investigate the trace element geochemistry of the Tiegelongnan Cu-sulfides, as well as pyrite, to understand the correlation between sulfides and trace elements, gold in particular, in the porphyry and epithermal systems. Porphyry mineralization consists of stage 1 chalcopyrite-pyrite ± molybdenite, stage 2 chalcopyrite-bornite, and stage 3 covellite. Epithermal sulfides form stage 4 pyrite-alunite, stage 5 digenite-bornite-chalcopyrite, and stage 6 enargite-tennantite ± tetrahedrite. Stage 2 chalcopyrite (S2 Ccp, median = 9.7 ppm Au) is the primary porphyry Au host, and stage 6 tennantite in alunite veins (S6 Tnt-s, median = 98.0 ppm Au) is the major epithermal Au host. These Au-rich sulfides formed under higher oxidation conditions, suggesting that a high oxidation state favors the incorporation of Au in Cu-sulfides. Gold contents in coeval chalcopyrite and bornite are positively correlated to temperature, and Au is enriched in chalcopyrite over bornite at low temperatures (

This study presents the results of experiments conducted on the granulation of copper sulfide (Cu2S) melt. The granulometric characteristics of the samples are calculated as a function of the melt temperature. An increase in the melt temperature to 1,350°C promotes the formation of particles with a particle size of –10.0 +5.0 mm, and a decrease in the melt temperature to 1,250°C promotes the formation of particles with smaller size grades (i.e., –1.6 +1.0, –1.0 +0.63, and –0.63 +0.063 mm). With an increase in temperature, the mean squared deviation of particle size from the average value and the degree of polydispersity decreases to some extent. This study also estimates the influence of the melt temperature on the shape of the granules. The cooling and spheroidization times of particles during granulation at the melt temperatures of 1,250°C, 1,300°C, and 1,350°C were calculated. In the temperature range under consideration for all of the investigated size grades of particles, the cooling time exceeded the spheroidization time, which contributed to the formation of spherical particles. The melt temperature did not significantly affect the chemical composition of Cu2S granules. The main phase component of the granules was chalcosine (Cu2S) with a monoclinic lattice of more than 80%. Chalcosine (Cu2S) with a hexagonal lattice of 8% to 9% and digenite (Cu1.78S) with 4% to 12% were also identified. Dispersed inclusions of metallic copper were also detected.

Among the most reliable techniques for exfoliation of two-dimensional (2D) layered materials, sonication-assisted liquid-phase exfoliation (LPE) is considered as a cost-effective and straightforward method for preparing graphene and its 2D inorganic counterparts at reasonable sizes and acceptable levels of defects. Although there were rapid advances in this field, the effect and outcome of the sonication frequency are poorly understood and often ignored, resulting in a low exfoliation efficiency. Here, we demonstrate that simple mild bath sonication at a higher frequency and low power positively contributes to the thickness, size, and quality of the final exfoliated products. We show that monolayer graphene flakes can be directly exfoliated from graphite using ethanol as a solvent by increasing the frequency of the bath sonication from 37 to 80 kHz. The statistical analysis shows that ∼77% of the measured graphene flakes have a thickness below three layers with an average lateral size of 13 μm. We demonstrate that this approach works for digenite (Cu9S5) and silver sulfide (Ag2S), thus indicating that this exfoliation technique can be applied to other inorganic 2D materials to obtain high-quality few-layered flakes. This simple and effective method facilitates the formation of monolayer/few layers of graphene and transition metal chalcogenides for a wide range of applications.

Author(s): Barkov, AY; Bindi, L; Tamura, N; Martin, RF; Ma, C; Winkler, B; Shvedov, GI; Morgenroth, W | Abstract: Fleetite, Cu2RhIrSb2, a new species of platinum-group mineral (PGM), was discovered intergrown with an Os–Ir–Ru alloy in the Miass Placer Zone (Au–PGE), southern Urals, Russia. A single grain 50 lm across was found. Osmium, ruthenium, and iridium are the main associated minerals; also present are Pt–Fe alloys, laurite, Sb-rich irarsite, Rh-rich tolovkite, kashinite, anduoite, ferronickelplatinum, heazlewoodite, PGE-bearing pentlandite and digenite, as well as micrometric inclusions of forsterite (Fo93.7), chromite–magnesiochromite, and Mg-rich edenite. In reflected light, fleetite is light gray; it is opaque, isotropic, non-pleochroic, and non-bireflectant. We report reflectance values measured in air. A mean of seven point-analyses (wavelength-dispersive spectrometry) gave Cu 13.93, Ni 8.60, Fe 0.10, Ir 28.07, Rh 7.91, Ru 1.96, Sb 39.28, total 99.85 wt.%, corresponding to (Cu1.41Ni0.58Fe0.01)R2.00(Rh0.49Ni0.36Ru0.12)R0.97Ir0.95Sb2.08 on the basis of six atoms per formula unit, taking into account the structural results. The calculated density is 10.83 g/cm3. Single-crystal X-ray studies show that fleetite is cubic, space group Fd3m (#227), a = 11.6682(8) A, V = 1588.59(19) A3, and Z = 16. A least-squares refinement of X-ray powder-diffraction data gave a = 11.6575(5) A and V = 1584.22(19) A3. The strongest five reflections in the powder pattern [d in A(I)(hkl)] are: 6.70(75)(111), 4.13(100)(220), 3.52(30)(311), 2.380(50)(422), 2.064(40)(440). Results of synchrotron micro-Laue diffraction experiments are consistent [a ¼ 11.66(2) A]. The crystal structure of fleetite was solved and refined to R ¼ 0.0340 based upon 153 reflections with Fo . 4r(Fo). It is isotypic with Pd11Bi2Se2 and best described as intermetallic, with all metal atoms in 12-fold coordination. Fleetite and other late exotic phases were formed by reaction of the associated alloy phases with a fluid phase enriched in Sb, As, and S in circulation in the cooling ophiolite source-rock. The mineral is named after Michael E. Fleet (1938–2017) in recognition of his significant contributions to the Earth Sciences.

For plasmonic copper-deficient Cu2-x S nanoparticles (NPs), accurate control of the crystal phase and morphology is highly desirable as both of which are known to determine the localized surface plasmon resonance (LSPR) wavelength and amplitude. Here, how the sulfur precursor reactivity in the synthesis of Cu2-x S NPs affects the resulting crystal phase and morphology is examined. Djurleite Cu1.94 S, roxbyite Cu1.8 S, digenite Cu1.8 S as well as covellite CuS nanodisks were synthesized by using 1-dodecanethiol, N,N-dibutylthiourea, and crystal sulfur 1-octadecene/oleylamine solutions and their crystal phase dependent LSPR properties were exhaustively discussed. In addition, crystal phase interconversion between covellite CuS and djurleite/roxbyite Cu2-x S was realized in the presence of the above sulfur precursors. On the other hand, djurleite Cu1.94 S nanorods rather than nanodisks were prepared by replacing 1-dodecanethiol with more reactive tert-dodecanethiol. The structural and morphological Cu2-x S NPs here holds great promise in the application of photothermal therapy, photocatalysis, surface-enhanced Raman scattering (SERS), and many others.

The Dudica deposit is located in the southern part of the Republic of North Macedonia (RNM), not far from the border with Greece in the Kozuf–Aridean volcanic region. The deposit is genetically associated with the Neogene igneous event (≥6 Ma, K/Ar), which is manifested at the intersection of northeast trending faults with the northwest trending Vardar fault zone. The REE spectrum of volcanic rocks here is characterized by a weak negative Eu anomaly and enrichment in light REE (LREE) relative to heavy REE (HREE). Mineralization is found in veins, veinlets, and dissemination; Cu concentration is around 0.5%; Au, up to 1 g/t. The principal ore minerals are chalcopyrite, bornite, enargite, covellite, chalcocite, and digenite; pyrite, galena, sphalerite, marcasite, and native gold are less frequent. The δ34S isotope composition falls within a narrow interval of +1.00 to +2.50‰, indicative of the igneous origin. The data obtained suggest that the Dudica deposit belongs to the class of the high-sulfidation epithermal deposits.

Cation exchange reactions of colloidal copper sulfide nanoparticles are widely used to produce derivative nanoparticles having unique compositions, metastable crystal structures, and complex heterostructures. The copper sulfide crystal structure plays a key role in the mechanism by which cation exchange occurs and the product that forms. Here, we show that digenite copper sulfide nanoparticles undergo a spontaneous phase transition to tetragonal chalcocite in situ, prior to the onset of cation exchange. Room-temperature sonication of digenite (Cu1.8S) in trioctylphosphine, a Lewis base that drives cation exchange, extracts sulfur to produce tetragonal chalcocite (Cu2S). The subtle structural differences between digenite and tetragonal chalcocite are believed to influence the accessibility of cation diffusion channels and concomitantly the mechanism of cation exchange. Structural relationships in nanocrystal cation exchange are therefore dynamic, and intermediates generated in situ must be considered.

The limited literature data on gold-bearing albite–pyroxene rodingites are summarized for the Agardag ultramafic massif in southern Tuva. These data are supplemented by new mineralogical, geochemical, thermobarogeochemical, and isotopic–geochemical results in order to reveal the physicochemical mineral formation conditions and sources of ore matter and fluids on gold deposition in rodingites. Rodingites and associated schistose nephritoids are near-fault metasomatites and are confined to a latitudinal tectonic zone in antigorite serpentinites. They formed in two stages. Stage I minerals (pyroxene, albite, etc.) are rodingites and stage II minerals (Na-bearing actinolite, albite, etc.) are nephritoids and veinlets that intersect rodingites. Disseminated sulfides of the Cu–S series (chalcocite, digenite, etc.) and Au minerals (tetra-auricupride and electrum) were deposited during both stages. The temperature regime (500–250°C) and low amount of CO2 in fluid ( $${{{\text{X}}}_{{{\text{C}}{{{\text{O}}}_{{\text{2}}}}}}}$$ = 0.017–0.025) correspond to the formation conditions of typical bimetasomatic rodingites. The degree of oxidation of gas components in fluids CO2/(CO2 + Σreduced gases) increases from rodingites (0.189) to nephritoids (0.299) and antigorite serpentinites (0.738). The O isotopic composition of silicates and calculated O isotopic composition of the fluid during antigorite serpentinization (5.8 to 7.6‰ δ18Оfl and –66 to –69‰ δDfl) correspond to juvenile and magmatic water in contrast to metamorphic water during nephritization and rodingitization (6 to 9.9‰ δ18Оfl and –39 to –46‰ δDfl) with involvement of heavy oxygen that was subjected to the sedimentary cycle. It is suggested that the magmatic ore-bearing fluid (7.3–7.6 wt % NaCl-equiv) separated from gabbroic melts. The oxidized fluid was modified to a reduced fluid during interaction with ultramafic rocks. The mafic and ultramafic rocks were the source of Na, REE, Au, Ag, Cu, and Ni. Deformations with the formation of veins and filling of veinlets are favorable for a high local gold concentration.

In the urge of designing noble metal‐free and sustainable electrocatalysts for oxygen evolution reaction (OER), herein, a mineral Digenite Cu9S5 has been prepared from a molecular copper(I) precursor, [{(PyHS)2CuI(PyHS)}2](OTf)2 (1), and utilized as an anode material in electrocatalytic OER for the first time. A hot injection of 1 yielded a pure phase and highly crystalline Cu9S5, which was then electrophoretically deposited (EPD) on a highly conducting nickel foam (NF) substrate. When assessed as an electrode for OER, the Cu9S5/NF displayed an overpotential of merely 298±3 mV at a current density of 10 mA cm−2 in alkaline media. The overpotential recorded here supersedes the value obtained for the best reported Cu‐based as well as the benchmark precious‐metal‐based RuO2 and IrO2 electrocatalysts. In addition, the choronoamperometric OER indicated the superior stability of Cu9S5/NF, rendering its suitability as the sustainable anode material for practical feasibility. The excellent catalytic activity of Cu9S5 can be attributed to the formation of a crystalline CuO overlayer on the conductive Cu9S5 that behaves as active species to facilitate OER. This study delivers a distinct molecular precursor approach to produce highly active copper‐based catalysts that could be used as an efficient and durable OER electro(pre)catalysts relying on non‐precious metals., Copper as the topper. The Digenite mineral Cu9S5 phase has been produced from a molecular CuI 2S2 precursor complex and applied for efficient electrocatalytic alkaline oxygen evolution reaction, displaying competent catalytic activity and stability.

Copper sulfides have attracted great attention recently in the thermoelectric community due to the liquid-like behavior of Cu ions. Among the numerous copper sulfides, digenite Cu1.80S has a poorer thermoelectric performance but better stability than the state-of-the-art binary copper sulfide Cu1.97S. In this study, good stability and high thermoelectric performance were simultaneously obtained in Fe-doped Cu1.80S. Because Fe ions will not form a concentration gradient under an external field to change the critical voltage, Fe-doped Cu1.80S samples inherit the good stability of the pristine Cu1.80S. The critical voltage for Cu1.80Fe0.064S is 0.16 V at 750 K, which has been the largest value reported so far. Likewise, the Fe dopants can significantly improve the thermoelectric performance by suppressing the too high electrical conductivity of Cu1.80S. The peak dimensionless figure of merit (zT) for Cu1.80Fe0.064S is around 0.8 at 750 K, about four times that of Cu1.80S. The average zT for Cu1.80Fe0.064S is 0.40 in 300–750 K, which is amongst the highest values in reported thermoelectric sulfides. Combining the good stability and high thermoelectric performance, the present Cu1.80Fe0.064S has great potential to be used in the application of waste heat harvesting in the middle temperature range.

The Cu-Au deposit of Bor (Serbia) represents a continuum of mineralization styles, from porphyry-style ore occurring in quartz-magnetite-chalcopyrite veins and chalcopyrite disseminations to high-sulfidation epithermal Cu-Au ores in pyrite-chalcopyrite and anhydrite-sulfide veins. Decisive for the great economic importance of Bor is the presence of exceptionally rich high-sulfidation massive sulfide orebodies, composed of pyrite + covellite + chalcocite/digenite and minor anhydrite and enargite. They form irregular bodies measuring 0.5-10 million tons of ore grading up to 7% Cu, hosted by andesites and surrounded by intense argillic alteration. This study focuses on a small but rich underground orebody mined out recently, where limited drillcore is preserved for quantitative geochemical study. This paper documents the vein relationships within the deep porphyry-style orebody of Borska Reka, the transitional porphyry-epithermal veins, and the overlying and laterally surrounding epithermal massive sulfides of the Bor deposit. Geological observations indicate that the formation of massive sulfide orebodies concludes the ore formation. Mass balance calculations, recast into geologically realistic bulk fluid-rock reactions, confirm textural evidence that near-isovolumetric replacement of andesite host rocks is the dominant formation mechanism of massive sulfide orebodies at Bor, whereby all lithophile elements including Si are dissolved and only Ti stays relatively immobile. While net volume changes for individual mineralization styles within the massive sulfide orebody vary from - 16% volume loss to + 127% volume gain, overall volume change for the whole massive sulfide orebody was probably slightly negative. Brecciation is important only as means of creating channelways for reactive fluid that turns the andesite protolith into massive sulfide, whereas net breccia infill occurred only locally., Mineralium Deposita, 56 (8), ISSN:0026-4598, ISSN:1432-1866

The radionuclides 238U, 230Th, 226Ra, 210Pb and 210Po are present in copper flotation concentrates of IOCG-U deposits of South Australia. These radionuclides have been shown to be distributed across a range of different minerals. Their physical concentrations are so low that they cannot be measured, or location detected by conventional chemical or mineral analysis techniques. A diagnostic leaching approach has therefore been proposed to quantify the deportment of the radionuclides in the major mineral phase. The diagnostic leaching approach is based on the selective dissolution of the minerals from the samples and removal of the associated radionuclides. After each mineral was selectively dissolved, a resin-in-pulp (RIP) procedure was carried out to ensure that the chemically liberated radionuclides had been removed from the leaching residues. To develop the diagnostic leaching methodology, scoping tests were first undertaken to optimize the conditions for the selective dissolution of the major minerals. The effect of RIP process on the mineralogy of the residues and on the extraction of radionuclides was also investigated. These selective leaching and RIP tests results were used to develop a systematic diagnostic leaching approach for determining the amount of each radionuclide associated with each major mineral.The lixiviants and leaching conditions were selected to achieve the selective dissolution of the major minerals present in the copper flotation concentrates: digenite, bornite, chalcopyrite and hematite. The leach solutions used were acidic aqueous solutions containing sulphate or chloride with different redox reagents. Since copper sulphides require oxidative conditions to be dissolved, progressively more oxidizing conditions were defined in order to leach digenite; digenite and bornite; and digenite, bornite and chalcopyrite. The oxidizing agents used were ferric sulphate, sodium persulphate and ferric chloride. To increase the selectivity of the hematite solution, the concentrates were subjected to acid leaching under reducing conditions using sodium metabisulphite. Concentrated sulphuric acid leach (150 g/L) at temperatures of 60 °C and 90 °C were used to extract a large fraction of uranium and iron, with a minimal copper extraction.As a result of the selective leaches undertaken, in some cases, new product or intermediate phases were formed. Under oxidizing conditions, elemental sulphur was formed as an intermediate product of the dissolution of copper sulphides, while under non-oxidizing conditions, covellite and digenite were formed. In particular, the leaching of sulphuric acid at 90°C almost completely dissolved digenite, bornite and hematite, leaving chalcopyrite and covellite as the predominant minerals in the residue. Under most leaching conditions, 226Ra, 210Pb and 210Po achieved only limited extractions. However, in ferric chloride leaching, 210Pb and 210Po reached around 90% extraction, probably due to the increase in their solubility and the increase in the dissolution of chalcopyrite.The RIP procedure was carried out using solvent impregnated resin Lewatit VP OC 1026 in order to increase the extraction of radionuclides from the leach solution and leach residues. RIP significantly increased radionuclide extraction, particularly in the 210Pb and 210Po cases. In the case of 226Ra, its extraction did not show significant increases in any of the leaching conditions tested, while RIP had only a limited effect. To quantify the deportment, the radionuclides loads associated with each of the major minerals in the concentrates were calculated from the results of the selective mineral leaching and the radionuclide extraction stage.Although the concentrates on which the diagnostic leaching procedure was tested had similar mineralogy, the results of the radionuclide deportments were different in each case. This would indicate that the results of the diagnostic leaching vary according to the function of the material and depend not only on the mineralogy but also on the associations between them and the occurrence of the elements of interest. In other words, diagnostic leaching is a procedure that must be adjusted on a case-by-case basis.The diagnostic leaching procedure developed in this study allows quantifying the radionuclides apparent deportment the major minerals of the copper flotation concentrates. The accuracy of quantification depends on the selectivity of the leaching stages to dissolve the minerals and the efficiency of the washing stage to remove the elements of interest exposed in the leaching residues. Therefore, a thorough characterization of the major minerals, radionuclide hosts and their solubility under selective leaching conditions is required to be able to properly interpret deportment results.A generic five-step procedure was proposed to implement diagnostic leaching and quantify the deportment of elements of interest in any material composed of minerals. This procedure is based on a thorough knowledge of mineralogy, the occurrence of the elements of interest and their response to leaching conditions of the major minerals.

Pure-phase Cu2−xS (x = 1, 0.2) nanoparticles have been synthesized by the thermal decomposition of copper(II) dithiocarbamate as a single-source precursor in oleylamine as a capping agent. The compositions of the Cu2−xS nanocrystals varied from CuS (covellite) through the mixture of phases (CuS and Cu7.2S4) to Cu9S5 (digenite) by simply varying the temperature of synthesis. The crystallinity and morphology of the copper sulfides were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), which showed pure phases at low (120 °C) and high (220 °C) temperatures and a mixture of phases at intermediate temperatures (150 and 180 °C). Covellite was of a spherical morphology, while digenite was rod shaped. The optical properties of these nanocrystals were characterized by UV−vis–NIR and photoluminescence spectroscopies. Both samples had very similar absorption spectra but distinguishable fluorescence properties and exhibited a blue shift in their band gap energies compared to bulk Cu2−xS. The pure phases were used as catalysts for the photocatalytic degradation of tetracycline (TC) under visible-light irradiation. The results demonstrated that the photocatalytic activity of the digenite phase exhibited higher catalytic degradation of 98.5% compared to the covellite phase, which showed 88% degradation within the 120 min reaction time using 80 mg of the catalysts. The higher degradation efficiency achieved with the digenite phase was attributed to its higher absorption of the visible light compared to covellite.

The Gadir Au-Ag-Cu-Pb-Zn deposit, located in the western part of Azerbaijan, was extensively occurred in quartz porphyry, and rarely in the contact of the hornfelsed andesite and quartz porphyry. The hydrothermal alterations associated with mineralization are quartz-adularia±sericite and propylitic alterations. The Gadir deposit is mainly composed of native gold, hessite, chalcopyrite, sphalerite, galena, pyrite, minor arsenopyrite, marcasite, digenite, barite, and adularia. The Gadir deposit is mainly composed of Au, Ag, Cu, Pb, and Zn which maximum quantities are 10.3 ppm, 1133 ppm, 23780 ppm, 59811 ppm, and 424770 ppm, respectively. The δ34SH2S values (−2.2 to 4.4 ‰) of sulfides (chalcopyrite, pyrite, and sphalerite) from the Gadir Au-Ag-Cu-Pb-Zn deposit indicate a magmatic origin for the ore-forming fluids. The geological, mineralogical, geochemical, and isotopic data for Gadir deposit suggest an epithermal deposit associated with the porphyry system.

In this research work we have synthesized copper sulfide (Cu2−xS) nanostructures by the hydrothermal method. The post-sulfurization was performed by using tube furnace to reduce sulfur deficiency and to minimize impurities present in the crystal-lattice. The samples were synthesized by various pH values of precursor solution. The samples were characterized by XRD, RAMAN spectroscopy, SEM, Hall measurements and Seebeck effect. XRD analysis revealed the formation of hexagonal covellite (CuS) and chalcocite (Cu2S) phases of copper sulfide. Despite these phases XRD data also showed the dominating hexagonal digenite (Cu1.8S) phase of copper sulfide. We observed a decreasing trend in average crystalline size with the increasing pH values of the samples from the XRD data. We have found maximum average crystalline size of 39.1679 nm at pH value of 4. The formation of LO mode of hexagonal covellite phase of copper sulfide was observed from RAMAN analysis. The SEM images revealed the formation of flower-like nanostructures at the lowest pH value. It strengthened our argument that the crystallinity of nanostructures is inversely proportional to the pH value. We have achieved maximum values of Seebeck coefficient and conductivity at room temperature as 73.920 µV/K and 0.909 S/cm, respectively. The Seebeck coefficient and conductivity graphs showed an increasing trend due to the energy filtering effect in mesoporous structure. The maximum value of power factor was 4.91 × 10–7 Wm−1 K−2.

Nielsenite, a rare intermetallide of palladium and copper, was described previously as a late-magmatic formation. A different genetic type of nielsenite was studied in the layered ultrabasite–basite Yoko-Dovyren intrusive. The maximum concentrations of Pd, Pt, Au, and Ag minerals are confined to crosscutting bodies of pegmatoid sulfide-bearing anorthosites within the contact zone between the troctolites and overlapping gabbro-norites strata in this intrusive. Postmagmatic pneumatolytic (fluid-metasomatic) Pd, Pt, Au, and Ag minerals, such as kotulskite, moncheite, michenerite, zvyagintsevite, telargpalite, paolovite, electrum, and sperrillite, compose metasomes in Fe–Ni–Cu sulfides and in the silicate matrix nearby. The Yoko-Dovyren intrusive is tectonized and tilted, crossed by inclined faults with streamlined serpentinized rocks, which contain lizardite, antigorite, clinozoisite, chlorite, actinolite, prehnite, pectolite, and hydrogarnet and are often transformed into rodingites of a prehnite–pumpellyite facies. The serpentinization process is younger than the intrusive rocks by 55 million years. In metamorphosed anorthosites, chalcopyrite is replaced by bornite, chalcocite, digenite, and magnetite; pentlandite is replaced with violarite, heazlewoodite, …; pyrrhotine is replaced by magnetite, …; moncheite is replaced with cuproplatinum–tulameenite; the veins of clinozoisite and pectolite with chlorite inclusions of chalcosine and native copper are well developed. Curved veins of nielsenite in brecciated chalcopyrite occasionally extend such veins. The size of the veins of metamorphogenic-hydrothermal nielsenite reaches up to 200 × 10 microns. Nielsenite metasomes up to 12 microns in diameter are developed nearby. The composition of the Yoko-Dovyren nielsenite is stable and close to stoichiometric with the formula Pd1.01Cu2,81Fe0,17Ni0,01. The Yoko-Dovyren nielsenite differs from the holotype of nielsenite of the Skergaard intrusive by the absence of Pt and Au impurities and a significant impurity of Fe. Yoko-Dovyren nielsenite was likely to appear under conditions of the prehnite–pumpellyite metamorphism facies at a high fugacity of О2 and at an extremely low fugacity of sulfide sulfur (log f S2 < –24 at ≈300°C).

When valuable digenite is heavily oxidized, it may not respond to the flotation process and remain largely in the tailing with the pyrite. This is problematic because the recovery of digenite from heavily oxidized Cu-S ore is of great significance. In this study, the effect of sodium sulfide on the selective flotation separation of heavily oxidized digenite and pyrite was investigated. The micro-flotation results showed that the floatability of digenite could be effectively restored with the addition of sodium sulfide and sodium butyl xanthate (SBX). However, pyrite showed a poor floatability under the same conditions. Based on this, the flotation separation of artificially mixed minerals was carried out, and a satisfactory result with 51.4% Cu grade and 93.1% Cu recovery could be obtained in the optimized flotation conditions. Then, the sulfidization mechanism of heavily oxidized digenite was discussed in detail through an examination of zeta potential measurements, adsorption measurements, contact angle measurements, and X-ray photoelectron spectroscopy (XPS) analyses. The results indicated that the negatively charged SH− could adsorb on the surface of digenite through chemisorption, and lower the quantity of hydrophilic copper sulfate and oxides/hydroxides on the digenite surface in the presence of SBX, thus significantly increasing the surface contact angle, decreasing the amount of SBX adsorbed to the value observed for unoxidized digenite, and promoting the flotation of heavily oxidized digenite.

The aim of this study was to determine the structural, compositional, and mineralogical composition of carbonatitic copper sulfide concentrator plant streams. Three samples, each from a different stream (run of mine (ROM), concentrate, and tailings) of a copper concentrator were characterized using various techniques, including stereomicroscopy, X-ray fluorescence, X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) in conjunction with energy-dispersive X-ray spectroscopy (EDS), and optical microscopy. The results reveal that each stream possesses its own unique compositional features. Carbonate minerals associated with calcite and dolomite, followed by quartz, remain the major minerals in both the ROM and tails streams. In the ROM stream, chalcopyrite appears to occur as veins within the carbonatite-hosting ore body. Mineral phase mutation was discovered in the tails stream because magnetite formerly identified in the ROM as the primary iron oxide had evolved into hematite. This metamorphosis was likely promoted by the concentration process. The concentration process was effective, upgrading the chalcopyrite content from 2wt% in the ROM stream to 58wt% in the concentrate stream; it was accompanied by bornite (4wt%), anilite (3wt%), and digenite (2.5wt%). In addition, the concentrate stream exhibited properties distinctive from those of the other streams. The FTIR analysis showed the existence of a sulfide group related to the chalcopyrite mineral. Free chalcopyrite grains were observed in the concentrate by SEM analysis, and their mineral presence was supported by the EDS analysis results. All characterization techniques corresponded well with each other regarding the structure, chemistry, and composition of the samples.

The Lar porphyry Cu-Mo deposit is located 20 km northeast of Zahedan in the Sistan Suture Zone (SSZ), in the southeastern part of Iran. Lar is a sub-economic porphyry Cu-Mo deposit with average grades of 0.16% Cu, 0.01% Mo, and 0.66 ppb Au. The Cu-Mo mineralization developed in post-collisional shoshonitic syenitic to monzonitic intrusions in an Oligocene igneous complex known as the Lar Igneous Complex (LIC). The host and country rocks have undergone variable degrees of supergene and hypogene alteration including silicic, potassic, propylitic, phyllic, and argillic alteration. The Cu-Mo mineralization is mainly controlled by NNW striking faults and fractures, and occurs as quartz veins and veinlets, disseminated sulfides, and stockworks. The mineralization can be divided into two types: hypogene and supergene. Hypogene mineralization is characterized by chalcopyrite, pyrite, bornite, molybdenite and magnetite, whereas supergene mineralization is characterized by enargite, covellite, chalcocite, digenite, malachite, azurite, and iron hydroxides. Sulfur isotope values for hypogene sulfides range from 0.28 to −1.76‰ and suggest an igneous source/or mantle-derived origin for sulfur. The δ18O values for quartz in mineralized quartz veins range from 9.6 to 11.5‰. These values would be in equilibrium with waters having calculated δ18OH2O values of 9.3–11.2‰, suggesting magmatic water. Re-Os dating of two molybdenite samples from two different drill holes yields dates of 29.72 ± 0.11 and 31.95 ± 0.11, suggesting that the system was active for at least 2.0 m.y.

MINERALIZATION OF THE ZECHSTEIN LOWER ANHYDRITE IN THE FORE-SUDETIC MONOCLINE Abstract. The paper presents the characteristics of ore mineralization of the Lower Anhydrite in the Fore-Sudetic Monocline. Both reduced and oxidized (Rote Faule) rocks have been investigated. Reduced anhydrites are characterized by significant variability of metal concentrations and sulphide minerals. The most intensely mineralized anhydrites occur above the oxidized bottom part of the Lower Anhydrite. Mineralization in this part is dominated by copper sulphides (chalcocite, digenite, covellite, bornite and chalcopyrite) which are accompanied by galena and sphalerite. Further away from the oxidized zone, zinc and lead sulphides predominate over copper sulphides, and pyrite mineralization is also observed. Complex intergrowths and replacement textures of sulphides, as well as intergrowths of the ore minerals with sulphates and carbonates are considered to have formed after lithification of the enclosing sediments, and indicate that the original associations of sulphides were overprinted by superimposed later mineralization. Oxidized anhydrites generally have no significant concentrations of metals like Cu, Pb and Zn. The relict mineralization there is represented by remnants of tiny grains of copper sulphides (mainly covellite, digenite and chalcocite) and pyrite, profoundly altered as a result of their partial replacement by hematite. This mineralization present in the oxidized anhydrites indicates that hematite emplacement overlapped deposition of the original sulphides and extended oxidation up into the Lower Anhydrite. Position of the reduced and oxidized areas of anhydrites enriched in metals indicates centres of the most intense activity of the ascending mineralizing fluids.

Digenite fine particles are easily oxidized and ferric ions (Fe3+) commonly exist in the flotation pulp of digenite. This study investigated the effect of Fe3+ on the sulfidization flotation of oxidized digenite fine particles using sodium butyl xanthate (SBX) as a collector. The results of microflotation experiments show that the flotation rate and recovery of oxidized digenite fine particles can be improved by adding Na2S and SBX, whereas the existence of large amounts of Fe3+ is not beneficial for the sulfidization flotation of digenite. The results of Fe3+ adsorption, zeta potential, and contact angle measurements indicate that Fe3+ can be adsorbed on the digenite surface mainly in the form of Fe(OH)3, which hinders the adsorption of SBX and significantly reduces the surface hydrophobicity of digenite. X-ray photoelectron spectroscopy analysis further suggests that the poor surface hydrophobicity of digenite in the presence of Fe3+ is due to the production of large amounts of hydrophilic iron and copper oxides/hydroxides on the surface. Furthermore, optical microscopy analysis shows that these hydrophilic species effectively disperse digenite fine particles in the pulp, which eventually leads to the poor floatability of digenite. Therefore, it is necessary to reduce the amount of Fe3+ present in the pulp and adsorbed on digenite surface before sulfidization to realize effective separation of oxidized digenite fine particles and iron sulfide minerals.

Industrial magnetic resonance spectrometers are used for on-line, bulk, quantitative analysis of minerals. These analysers are used to rapidly detect the grade of ore which can assist ore-sorting and advanced ore management to overcome declining mine productivity due to the gradual reduction in mined ore grade. Magnetic resonance is well suited to these bulk sensing applications. The technique provides high levels of mineral discrimination as it is highly sensitive to subtle changes in electric, magnetic, and crystallographic environment of copper in target minerals. Being a radio spectroscopy, it also delivers significant advantages in bulk measurement of ore materials due to the penetrating nature of radio excitation. On-line mineralogical characterisation can be achieved without the use of extremely high magnetic fields associated with conventional nuclear magnetic resonance. The two sub-classes of interest in so-called “zero-field” nuclear magnetic resonance (ZFNMR) are nuclear quadrupole resonance (NQR) and antiferromagnetic NMR (AFNMR). This thesis provides a detailed theoretical summary of these resonances. Three economically important copper minerals, covellite (CuS), bornite (Cu_5FeS_4) and digenite (Cu_9S_5), were analysed with these techniques. Covellite was the exemplar for an alternative magnetic resonance pulse sequence that provides significant signals at low peak power. The sequence used is a single long pulse applied in the regime of large inhomogeneous broadening and short transverse and longitudinal decay times. Extensive experiments and modelling of Bloch equations provided a detailed description of the pulse sequence performance. The work has a practical application in that large-scale magnetic resonance instrumentation has limited peak power required to satisfactorily excite large volumes encountered in industrial applications. Single long pulses are observed to produce on-resonance signals at much lower powers than that is required for typical hard pulse sequences, providing an efficient alternative. A low temperature search for bornite was conducted to determine whether it was amenable to room temperature zero-field magnetic resonance. A spectrum was observed at 10 K and had multiple overlapped and broadened resonances over a 12 MHz frequency range. An attempt to model the spectra using the density functional theory was performed. The spectrum is interpreted as a result of complex mineral structure potentially relating to superstructures and magnetic ordering. Experiments at higher temperatures were not successful leading to the conclusion that room temperature resonances are unlikely to be observable. Digenite was studied in order to develop capability of room temperature measurement of this important mineral. Measurements were performed at 260 K and 280 K with the successful observation of resonances. The transverse decay times in digenite are very short. The technique of T_2 enhancement was attempted in order to lengthen the transverse decay times and provide a subsequent improvement of signal magnitude. The enhancement is produced by the application of a relatively weak static magnetic field to a pure quadrupole system. This improvement was observed in digenite however, room temperature observations were not possible due to the vary rapid reduction in decay time observed near room temperature. The experimental results in this thesis were obtained using an optimised home-built laboratory magnetic resonance spectrometer. Specific modifications for each of the experiments included probe construction for cryogenic applications, spectrometer electronics to allow detection over a very wide frequency band and inclusion of a weak static electromagnetic field with auxiliary coils. Overall, this work produced results that increased the knowledge, capability, and practical implementation for detection of resonances in the targeted copper minerals. Translation of the studied techniques into large scale analysers would enhance bulk mineral characterisation in mining and industrial applications.

The copper-containing agates of the Avacha Bay (Eastern Kamchatka, Russia) have been investigated in this study. Optical microscopy, scanning electron microscopy, electron microprobe analysis, X-ray powder diffraction, Raman spectroscopy, and fluid inclusions were used to investigate the samples. It was found that copper mineralization in agates is represented by native copper, copper sulphides (chalcocite, djurleite, digenite, anilite, yarrowite, rarely chalcopyrite) and cuprite. In addition to copper minerals, sphalerite and native silver were also found in the agates. Native copper is localized in a siliceous matrix in the form of inclusions usually less than 100 microns in size&mdash, rarely up to 1 mm&mdash, forming dendrites and crystals of a cubic system. Copper sulphides are found in the interstices of chalcedony often cementing the marginal parts of spherule aggregates of silica. In addition, they fill the micro veins, which occupy a cross-cutting position with respect to the concentric bands of chalcedony. The idiomorphic appearance of native copper crystals and clear boundaries with the silica matrix suggest their simultaneous crystallization. Copper sulphides, cuprite, and barite micro veins indicate a later deposition. Raman spectroscopy and X-ray powder diffraction results demonstrated that the Avacha Bay agates contained cristobalite in addition to quartz and moganite. The fluid inclusions study shows that the crystalline quartz in the center of the nodule in agates was formed with the participation of solutions containing a very low salt concentration (&lt, 0.3 wt.% NaCl equivalent) at the temperature range 110&ndash, 50 &deg, C and below. The main salt components were CaCl2 and NaCl, with a probable admixture of MgCl2. The copper mineralization in the agates of the Avacha Bay established in the volcanic strata can serve as a direct sign of their metallogenic specialization.

Ethyl isobutyl xanthogenic acetate (EIBXAC) was used as a novel collector in the flotation of secondary copper sulfide minerals owing to its ability to separate copper and sulfur. The collectivity and selectivity mechanisms of this novel collector were investigated using single-mineral and artificial mixed-mineral tests, combined with adsorption tests, fourier transform infrared spectroscopy (FTIR) tests, and density functional theory (DFT) calculations. The results of the flotation indicated that EIBXAC had a better collecting effect than ammonium dibutyl dithiophosphate (ADD) on covellite and digenite, which had an insignificant effect on pyrite. The artificial mixed-mineral experiment indicated that EIBXAC could improve the grade of the copper concentrate while maintaining the same recovery, it had higher efficiency and selectivity. Based on the results of the adsorption and FTIR tests, the adsorption capacities of EIBXAC on the surfaces of covellite, digenite, and pyrite were quite different: Cu-S bonds were formed on covellite and digenite, and Fe-O bonds were formed on pyrite, which was also verified that EIBXAC was chemically adsorbed on the mineral surface. DFT calculations indicated that the adsorption capacity of EIBXAC for covellite and digenite was stronger than that of ADD, which had a weaker adsorption capacity for pyrite. This study can provide theoretical guidance for the application of EIBXAC.

This study performed a series of comparable experiments (with or without column chromatography) to evaluate whether non-deviated Cu isotope ratios can be obtained directly by Nu Plasma II multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS) using standard-sample bracketing with Ga as internal mass bias correction model (C-SSBIN) without column chromatography. Twelve Cu-dominated minerals (copper plate, native copper, chalcopyrite, bornite, chalcocite, digenite, covellite, tetrahedrite, azurite, malachite, atacamite, and cyanotrichite) displayed little drift in δ65Cu values compared with those of minerals with column chromatography, with Δδ65Cuwithout−with ranging from −0.04 to +0.02‰. This means that Cu isotope ratios in Cu-dominated minerals can be achieved without column chromatography, due to the simple matrix and the stability of the machine by using C-SSBIN mode. The acidity and internal standard concentration mismatch effects, as well as the matrix effect, were strictly assessed by Nu Plasma II MC-ICP-MS in a wet-plasma mode in the State Key Laboratory of Continental Dynamics (SKLCD). Finally, a long-term reproducibility of better than ±0.03‰ [n = 38, 2 standard deviations (2s)] were achieved by repeatedly measuring chalcopyrite without column chromatography over 4 months.

We report the preparation of copper sulphide nanoparticles from copper(II) piperidine dithiocarbamate. Powder XRD patterns confirmed covellite copper sulphide (CuS) for nanoparticles obtained at 120 °C while nanoparticles prepared at 180 and 220 °C exist in digenite copper sulphide (Cu9S5) crystalline phases. TEM micrographs showed CuS obtained at 120 °C have mixture of hexagonal, triangular, and spherical shapes with no agglomeration with crystallite sizes in the range 4.9–51.4 nm. Copper sulphide obtained at 180 °C have particle sizes in the range 31.3–44.0 nm while agglomerated particles were obtained at 220 °C with particle sizes of 74.4–125.4 nm. The results confirmed that the particle sizes of the as-prepared copper sulphide nanoparticles are temperature dependent. Optical studies of the copper sulphide nanoparticles indicates the absorption band edges are blue shifted due to decreased crystallite sizes of the nanoparticles compared to bulk copper sulphide.

Porphyry-type deposits are crucial reserves of Cu and Mo. They are associated with large haloes of hydrothermal alteration that host particular mineral assemblages. Portable X-ray fluorescence analysis (pXRF) is an increasingly common tool used by mineral prospectors to make judgments in the field during mapping or core logging. A total of 31 samples from 13 porphyry copper deposits of the Western Cordillera were examined. Whole-rock composition was estimated over three points of analysis by pXRF. This approach attempts to capture the rapid and sometimes haphazard application of pXRF in mineral exploration. Modes determined by optical petrography were converted into bulk rock compositions and compared with those determined by pXRF. The elements S, Si, Ca, and K all were underestimated by optical mineralogy, and the elements Cu, Mo, Al, Fe, Mg, and Ti were overestimated by optical mineralogy when compared with pXRF results. Most of these porphyry samples occur in veined porphyritic quartz monzonite that is characteristic of these deposits. Sulfide and silicate vein stockworks are pervasive in most of the samples as well as dissemination of sulfides outwards from veinlets. Ore minerals present include chalcopyrite and molybdenite with lesser bornite. Chalcocite, digenite, and covellite are secondary. Potential sources of analytical bias are discussed.

Covellite is a secondary copper sulfide, and it is not abundant. There are few investigations on this mineral in spite of it being formed during the leaching of chalcocite or digenite, the other investigations on covellite are with the use of mineraloids, copper concentrates, and synthetic covellite. The present investigation applied the surface optimization methodology using a central composite face design to evaluate the effect of leaching time, chloride concentration, and sulfuric acid concentration on the level of copper extraction from covellite (84.3% of purity). Copper is dissolved from a sample of pure covellite without the application of temperature or pressure, the importance of its purity is that the behavior of the parameters is analyzed, isolating the impurities that affect leaching. The chloride came from NaCl, and it was effectuated in a size range from &ndash, 150 to +106 &mu, m. An ANOVA indicated that the leaching time and chloride concentration have the most significant influence, while the copper extraction was independent of sulfuric acid concentration. The experimental data were described by a highly representative quadratic model obtained by linear regression (R2 = 0.99).

Studying the dissolution of chalcocite allows to understand the behavior of the most abundant secondary sulfide ore in copper deposits, while digenite (Cu1.8S) and other intermediate sulfides (Cu2&minus, xS) are often associated with chalcocite. The most common mechanism of dissolution is by two stages, and chloride ions benefit the kinetics of dissolution. In this study, a pure chalcocite mineral (99.9% according to XRD (X-Ray Diffraction) analysis) is leached in chloride media using NaCl and wastewater as the sources of chloride. Magnetic leaching tests are performed at 65, 75, and 95 &deg, C, using a particle size between &minus, 150 and + 106 &mu, m. Chloride concentration and leaching time are the main variables. A substantial dissolution of chalcocite was obtained with 0.5 M H2SO4, 100 g/L of chloride and a leaching time of 3 h. The apparent activation energy (Ea) derived from the slopes of the Arrhenius plots was 36 kJ/mol. The XRD analysis proves the presence of elemental sulfur (S0) as the main component in the leaching residue. No significant differences in copper extraction were detected when using 100 g/L of chloride ion or wastewater (39 g/L).

Digenite (Cu1.8S) has attracted extensive attention as candidate for use in thermoelectric applications due to its low-cost, low-toxicity characteristics, but the thermoelectric (TE) property is still not good. In this work, PbS was used for improving TE properties of polycrystalline Cu1.8S bulk. Cu1.8S+ x wt% PbS (x = 0, 0.5, 1, 2, 3) bulk samples were fabricated via mechanical alloying (MA) and spark plasma sintering (SPS) techniques. The effects of adding PbS on the TE performance of Cu1.8S were investigated in detail at the temperature between 323 K and 773 K. According to the results, introducing PbS is an efficient approach for optimizing the TE properties of Cu1.8S, which is mainly due to the maintained electrical transport properties by the regulated hole carrier concentration and the modified band structure, as well as the reduced the thermal conductivity by the generated point defect and additional interfaces. An optimum thermoelectric figure of merit (ZT) value of 1.1 was obtained at 773 K for the Cu1.8S sample with 2 wt% PbS, which is 2.2 times higher than that of the pristine Cu1.8S (0.49 at 773 K).

All phase equilibria and thermodynamic data available in the literature on the copper sulfides high- and low-temperature chalcocite, djurleite and anilite have been critically analyzed for optimization of the solid-state phase diagram of the Cu-S system at 1 bar total pressure. A two-sublattice approach derived from a recently developed Gibbs energy model for digenite enables the consideration of the solid solution nature of both modifications of chalcocite and for the first time of djurleite. Anilite is considered as stoichiometric compound. The sulfur solubility of metallic copper is described by a substitutional approach. The obtained Gibbs energy functions for high- and low-temperature chalcocite, djurleite, anilite and copper alloy phase allow computations and predictions of phase equilibria and thermodynamic properties in good accordance with experimental data of the Cu-S solid-state system.

Sulfide minerals host most of the world’s supplies of metals such as Cu, Ni, Co, Zn, Pb, or Mo, and understanding their crystallization, dissolution, and textural evolution is key to understanding the formation of mineral deposits, metal recovery via metallurgy, and their environmental impact. Despite the prominence of hydrothermally formed sulfide minerals, the interpretation of textures in sulfide petrology relies mainly on comparison with results from experiments conducted under dry conditions. Here, we show experimentally that the exsolution of chalcopyrite (CuFeS2) lamellae from a bornite (Cu5FeS4)-digenite (Cu9S5) solid solution (bdss) is a back-reaction, which occurred during low temperature annealing (150 °C) following initial replacement of parent chalcopyrite by bdss at 300 °C. The back-reaction is rapid (days), and its progress is catalyzed by small amounts of fluid present in the porosity within the bdss. This porosity initially results from the formation of bdss via the replacement of parent chalcopyrite by an interface-coupled dissolution-reprecipitation mechanism. During annealing, bdss first breaks down into bornite and digenite via solid-state exsolution. The bornite-digenite assemblage then exsolves chalcopyrite in local patches. We discovered strikingly similar textures in iron oxide copper gold (IOCG) deposits from South Australia; in these samples, the fluid-driven nature of the exsolution reaction is reflected by the fact that the chalcopyrite lamellae propagate around cracks and fractures within bornite. As in our experiments, most of this natural bornite formed via replacement of chalcopyrite. These reactions are controlled by kinetic factors (e.g., relative nucleation rates of Cu-Fe-sulfides; presence of porosity) rather than equilibrium thermodynamics, but result in final assemblages and textures that may not be distinguishable from those evolving from equilibrium processes under dry conditions.