Thermodynamic calculations of AuxAg1−x – Fluid equilibria and their applications for ore-forming conditions

Yi, Liang; Hoshino, Kazumasa

doi:10.1016/j.apgeochem.2014.11.019

Cited by 19 publications

(6 citation statements)

References 86 publications

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“…The mechanism of formation of native gold of varying chemical composition is very complicated and depends on many factors [22][23][24][25][26][27][28]. The content of elements in native gold is determined by their concentrations in hydrothermal solutions, which are governed by temperature, redox conditions, pH, presence of ligand elements Cl, S, and elements such as Se, Te, As, Sb.…”

Section: Discussionmentioning

confidence: 99%

Native Gold in the Chudnoe Au-Pd-REE Deposit (Subpolar Urals, Russia): Composition, Minerals in Intergrowth and Genesis

et al. 2021

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Composition of native gold and minerals in intergrowth of the Chudnoe Au-Pd-REE deposit (Subpolar Urals, Russia) was studied using optical microscopy, scanning electron microscopy, and electron microprobe analysis. Five varieties of native gold have been identified, based on the set of impurity elements and their quantities, and on intergrown minerals. Native gold in rhyolites from the Ludnaya ore zone is homogeneous and contains only Ag (fineness 720‰, type I). It is in intergrowth with fuchsite or allanite and mertieite-II. In rhyolites from the Slavnaya ore zone, native gold is heterogeneous, has a higher fineness, different sets and contents of elements: Ag, Cu, 840–860‰ (type II); Ag, Cu, Pd, 830–890‰ (III); Ag, Pd, Cu, Hg, 840–870‰ (IV). It occurs in intergrowth with fuchsite, albite, and mertieite-II (type II), or albite, quartz, and atheneite (III), or quartz, albite, K-feldspar, and mertieite-II (IV). High-fineness gold (930–1000‰, type V) with low contents of Ag, Cu, and Pd or their absence occurs in the form as microveins, fringes and microinclusions in native gold II–IV. Tetra-auricupride (AuCu) is presented as isometric inclusions in native gold II and platelets in the decay structures in native gold III and IV. The preliminary data of a fluid inclusions study showed that gold mineralization at the Chudnoe deposit could have been formed by chloride fluids of low and medium salinity at temperatures from 105 to 230 °C and pressures from 5 to 115 MPa. The formation of native gold I is probably related to fuchsitization and allanitization of rhyolites. The formation of native gold II-V is also associated with the same processes, but it is more complicated and occurred later with a significant role of Na-, Si-, and K-metasomatism. The presence of Pd and Cu in the ores and Cr in fuchsite indicates the important role of mafic-ultramafic magmatism.

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Section: Discussionmentioning

confidence: 99%

Native Gold in the Chudnoe Au-Pd-REE Deposit (Subpolar Urals, Russia): Composition, Minerals in Intergrowth and Genesis

et al. 2021

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“…Native gold occurs in a wide range of gold deposit types and settings [1,2,[5][6][7][8]. Impurity elements in native gold and minerals in association are indicators of geochemical and mineral types of deposits and regional geochemical conditions [13].…”

Section: Types Of Deposits With Palladian Goldmentioning

confidence: 99%

“…Depending on their concentrat ion, impurity-elements may be classified as major (>10 wt.%), minor (1-10 wt.%), and trace (<1 wt.%). Native gold with only silver impurity (argentian gold or Ag-bearing gold) is most widely spread at gold deposits [1][2][3][4][5][6][7][8]. Some review papers report data on the varieties of native gold with copper (cuprian gold), mercury (gold amalgam or mercury gold), and palladium (palladian gold) impurities [1,2,[9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Palladian Gold: Chemical Composition, Minerals in Association, and Physicochemical Conditions of Formation at Different Types of Gold Deposits

Palyanova,

Zhegunov,

Beliaeva

et al. 2023

Minerals

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This paper reviews and summarizes the available information on the composition of palladian gold with various contents and sets of isomorphic impurities (Ag, Cu, Hg) at 50 deposits and ore occurrences with Au-Pd mineralization. It is revealed that Palladian gold is represented by the systems Au–Pd, Au–Pd–Hg, Au–Pd–Cu, and Au–Pd–Ag–Hg, but more frequently corresponds to Au–Pd–Ag, Au–Pd–Ag–Cu, and Au–Pd–Ag–Cu–Hg. Objects with palladian gold belong to different types of gold deposits and to the deposits at which the main components of ores are PGE, Cr, Cu, Ni, V, and Ti. We propose a classification of the types of deposits with palladian gold: (1) PGE ore deposits related to mafic–ultramafic magmatic complexes (two subtypes—(a) low-sulfide-grade (less than 2%–5% sulfides) Alaskan, and (b) high-sulfide-grade (more than 5% sulfides) Norilsk); (2) orogenic gold deposits (OG); (3) epithermal (porphyry) gold–copper deposits (EPGC); (4) iron oxide copper gold deposits (IOCG); (5) ferruginous quartzite deposits; (6) volcanic exhalation; and (7) gold-PGE placers of five subtypes corresponding to the types of 1–5 primary sources. Palladian gold is mainly high-fineness (910‰–990‰), is less frequently medium-fineness, and contains Ag and Cu, but does not contain Hg at the deposits of types 1, 3, and 4. The only exception is the Au-Pd-Hg Itchayvayam ore occurrence (Kamchatka, Russia), for which two varieties of Pd,Hg-bearing native gold (fineness 816‰–960‰ and 580‰–660‰) are determined. Low-fineness palladian gold with the major content of Ag is typical of OGD deposits. Medium-fineness palladian gold occurs at ferruginous quartzite deposits and in volcanic exhalations. Hg, Ag, Cu-bearing high-fineness palladian gold is present mainly in placer deposits (type 7). The most common minerals in association with palladian gold are arsenides, stibioarsenides, sulfides, stannides, bismuthides, tellurides, and selenides of Pd and Pt. These are typical of deposit types 1 and 7. The minerals of Au, Ag, and Cu (tetra-auricupride, aurostibite, chalcopyrite, bornite, chalcocite, eucairite, etc.) are in association with palladian gold at OG, EPGC, and IOCG deposits. Hg minerals (cinnabar, tiemannite, coloradoite, potarite) are at some deposits (types 1, 2, 7-1, 7-4). Cu, Fe, and Pd oxides (tenorite, hematite, magnetite, PdO, (Pd,Cu)O) and Fe and Pd hydroxides (goethite, (Fe,Pd)OOH) occur at the deposits of the 3, 4, and 7 groups and indicate the highly oxidizing conditions of ore formation. The most common minerals among host minerals are quartz and muscovite, including fuchsite (Cr-Ms), chlorite, albite, K-feldspar, hornblende, and carbonates (calcite, siderite, etc.). The fineness, content, and set of impurities in palladian gold and minerals in association with it reflect the mineralogy of Au-Pd ores and allow them to be used as indicators for the deposit types.

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“…Numerous studies have established the important role of halogens (Cl, F) for the transport of metals in ore deposits related to igneous rocks (Holland 1972;Kilinc and Burnham 1972;Gunow et al 1980;Boudreau et al 1986;Carten 1987;Holloway 1988, 1990;Richards 1990a;Richards et al 1991;Webster 1992;Stanton 1994;Candela 1997;Heinrich 2005;Yang and Lentz 2005;Ulrich and Mavrogenes 2008;Richards 2009;Zajacz et al 2010;Lesne et al 2011;Vigneresse et al 2014;Webster et al 2014;Liang and Hoshino 2015;Zellmer et al 2015). A recent review of fluid saturation and volatile partitioning between melts and hydrous fluids in crustal magmatic systems (Baker and Alletti 2012) indicates that, whenever a fluid phase first forms, it will strip not only Cl and S from the melt, but also metals associated with chlorine (e.g.…”

Section: Introductionmentioning

confidence: 98%

Halogen Contents of Mineralized Versus Unmineralized Potassic Igneous Rocks

Müller

Groves

2015

Potassic Igneous Rocks and Associated Gold-Copper Mineralization

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Thermodynamic calculations of AuxAg1−x – Fluid equilibria and their applications for ore-forming conditions

Cited by 19 publications

References 86 publications

Native Gold in the Chudnoe Au-Pd-REE Deposit (Subpolar Urals, Russia): Composition, Minerals in Intergrowth and Genesis

Native Gold in the Chudnoe Au-Pd-REE Deposit (Subpolar Urals, Russia): Composition, Minerals in Intergrowth and Genesis

Palladian Gold: Chemical Composition, Minerals in Association, and Physicochemical Conditions of Formation at Different Types of Gold Deposits

Halogen Contents of Mineralized Versus Unmineralized Potassic Igneous Rocks

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