Sulfidation of native gold

Palyanova, Galina; Карманов, Н. С.; Savva, N. E.

doi:10.2138/am.2014.4677

Cited by 23 publications

(13 citation statements)

References 36 publications

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“…Mixed silver-gold sulfides and selenides, including nanoparticulate ones, have attracted intense interest as minerals and natural sources of precious metals [1][2][3][4][5][6][7][8][9][10][11][12][13][14] and due to high ionic conductivity, tunable optical characteristics, thermoelectric and other properties promising for materials applications [15][16][17][18][19]. Gold chalcogenides, in particular gold selenide, are much less examined, despite aqueous Au chalcogenide-derived complexes play the crucial role as carriers of gold in hydrothermal fluids and brines (e.g., [20][21][22][23][24][25] and references therein), and AuSe, Au(Se,S) and Au(Te,Se,S) phases in intergrowths with native gold have been found in the high-sulfidation epithermal deposits formed from acidic fluids [14].…”

Section: Introductionmentioning

confidence: 99%

Colloidal and Deposited Products of the Interaction of Tetrachloroauric Acid with Hydrogen Selenide and Hydrogen Sulfide in Aqueous Solutions

et al. 2018

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The reactions of aqueous gold complexes with H 2 Se and H 2 S are important for transportation and deposition of gold in nature and for synthesis of AuSe-based nanomaterials but are scantily understood. Here, we explored species formed at different proportions of HAuCl 4 , H 2 Se and H 2 S at room temperature using in situ UV-vis spectroscopy, dynamic light scattering (DLS), zeta-potential measurement and ex situ Transmission electron microscopy (TEM), electron diffraction, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Metal gold colloids arose at the molar ratios H 2 Se(H 2 S)/HAuCl 4 less than 2. At higher ratios, pre-nucleation "dense liquid" species having the hydrodynamic diameter of 20-40 nm, zeta potential −40 mV to −50 mV, and the indirect band gap less than 1 eV derived from the UV-vis spectra grow into submicrometer droplets over several hours, followed by fractional nucleation in the interior and coagulation of disordered gold chalcogenide. XPS found only one Au + site (Au 4f 7/2 at 85.4 eV) in deposited AuSe, surface layers of which partially decomposed yielding Au 0 nanoparticles capped with elemental selenium. The liquid species became less dense, the gap approached 2 eV, and gold chalcogenide destabilized towards the decomposition with increasing H 2 S content. Therefore, the reactions proceed via the non-classical mechanism involving "dense droplets" of supersaturated solution and produce AuSe 1−x S x /Au nanocomposites.

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Section: Introductionmentioning

confidence: 99%

Colloidal and Deposited Products of the Interaction of Tetrachloroauric Acid with Hydrogen Selenide and Hydrogen Sulfide in Aqueous Solutions

et al. 2018

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“…Moreover, "difficult to extract" gold may be connected with the presence of micron-scale inclusions of AueAg sulfides in pyrite aggregates. In our opinion, both AueAg sulfides and native gold, which crystallize primarily from melts, may be the source of redeposited phases in hydrothermal and hypergene processes [60].…”

Section: Resultsmentioning

confidence: 86%

Experimental constraints on gold and silver solubility in iron sulfides

Palyanova

Mikhlin

Кох

et al. 2015

Journal of Alloys and Compounds

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“…Cocker et al [28] studied the origin of the minerals of the Ag-Au-S-Se system on the adularia-sericite epithermal Broken Hills deposit in New Zealand. The authors concluded that uytenbogaardtite and petrovskaite can be formed both in hypogene and supergene conditions, and their precursors are solid solutions (Ag,Au) 2 S with a primitive cubic unit cell, stable in the conditions of formation of the main-stage mineralization at 220-250 • C. Thus, the problem is not formation, but preservation of AuAg sulfides, especially under oxidizing environment, in associations with sulfates and hydroxides in supergene conditions [10,11,14].…”

Section: Discussionmentioning

confidence: 99%

“…The results mostly characterize near-surface parts of gold grains where, according to [10], gold and silver sulfides are likely to be present. The microphotography was performed under high vacuum mode with the acceleration voltage of 30 kV.…”

Section: Scanning Electron Microscopy With Energy Dispersive X-ray Spmentioning

confidence: 99%

“…They are fairly loose, zonal structures similar to reaction rims on Au, Ag grains with elevated sulfur content. The data in Table 6 shows that the process of "sulfidation" [10] of native gold covers the area of higher Ag/Au ratios, compared to uytenbogaardtite, up to almost pure Ag 2 S. This most likely presumes the existence of solid solutions of Ag 2−x Au x S [11,14]. Note: dash stands for the concentration below the limit of detection; data for the points with the composition close to uytenbogaardtite (Ag/Au = 3, (Ag + Au)/(S + Se) = 2) are highlighted in italics.…”

Section: Chemical Composition Of S-containing Native Gold Samplesmentioning

confidence: 99%

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Contrasting Surficial Composition of Native Gold from Two Different Types of Gold Ore Deposits

et al. 2017

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Native gold grains sampled at two different gold ore deposits in Eastern Russia have been studied by the techniques of electron spectroscopy (X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES)), electron microprobe analysis (EMPA), and scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDX). The high-fineness gold of the deposit hosted by relatively high temperature gold-quartz-sulfide mesothermal ore formation contains no oxidized Au constituents on grain surfaces, whereas the less fine gold of the epithermal Au-Ag deposit contains gold oxidized to the Au (I) state, or higher, in half of the cases. At this deposit the surface of native Au consists of a thin layer (~15 nm) with elevated Ag and S contents and an underlying SiO 2 -containing layer~30-60 nm thick. Such a composite coating can perform a protective function and prevent the gold-silver sulfides in surficial parts of AuAg grains from oxidation. The sulfur-enriched marginal parts of native gold particles do not always correlate with the stoichiometry of well-known binary AuAg-sulfides and have a variable composition. This may be due to the existence of solid solutions, Ag 2−x Au x S, if there is enough S or S adsorption-stabilized cluster agglomerates, Ag n Au m S, under sulfur deficit. The effect of the formation of nano-scale surficial zonality on the surface of native gold is quite common in nature and applicable to geological exploration and technology of gold-ore processing. It can facilitate establishing the geochemical environment and genetic type of Au mineralization.

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Sulfidation of native gold

Cited by 23 publications

References 36 publications

Colloidal and Deposited Products of the Interaction of Tetrachloroauric Acid with Hydrogen Selenide and Hydrogen Sulfide in Aqueous Solutions

Colloidal and Deposited Products of the Interaction of Tetrachloroauric Acid with Hydrogen Selenide and Hydrogen Sulfide in Aqueous Solutions

Experimental constraints on gold and silver solubility in iron sulfides

Contrasting Surficial Composition of Native Gold from Two Different Types of Gold Ore Deposits

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