Silver and mercury in gold particles from the Proterozoic Witwatersrand placer deposits of South Africa; metallogenic and geochemical implications

Oberthuer, Thomas; Saager, R.

doi:10.2113/gsecongeo.81.1.20

Cited by 40 publications

(14 citation statements)

References 13 publications

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“…According to the results of thousands of precision analyses (Brauns, 1906;Vernadsky, 1914;Lindgreen, 1933;Smolin, 1970;Editorial Committee, 1970;Petrovskaya, 1973;Berman et al, 1978;Nedra, 1984Nedra, -1990Oberthür and Saager, 1986;Shikazono and Shimizu, 1987;Amuzinsky et al, 1992;Nekrasov et al, 1994;Spiridonov, 1995;So et al, 1995;Frimmel and Gartz, 1997;Hytőnen, 1999;Knight and Leitch, 2001, etc. ) it was established that the series Au-Ag is uninterrupted in composition.…”

Section: Au -Ag System Mineralsmentioning

confidence: 99%

“…In ores formed under low f S 2 conditions, there are cubic α-amalgams: mercurian gold (Au, Hg) (Nazmova and Spiridonov, 1979;Oberthür and Saager, 1986;Shikazono and Shimizu, 1988;Amuzinsky et al, 1992); mercurian electrum (Au, Ag, Hg), mercurian kuestelite (Ag, Au, Hg), gold-containing mercurian silver (Spiridonov and Pletnev, 2002). Mercurian gold contains up to 18 wt% Hg, and mercurian silver up to 26% Hg.…”

Section: Au (Ag) -Hg System Mineralsmentioning

confidence: 99%

See 1 more Smart Citation

Modern mineralogy of gold: overview and new data

Spiridonov¹,

Yanakieva²

2009

archeosciences

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Section: Au -Ag System Mineralsmentioning

confidence: 99%

Section: Au (Ag) -Hg System Mineralsmentioning

confidence: 99%

Modern mineralogy of gold: overview and new data

Spiridonov¹,

Yanakieva²

2009

archeosciences

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“…They are also common in metamorphosed Archean quartz pebble conglomerates of the Witwatersrand basin, where the origin of the gold is controversial (e.g., von Gehlen 1983;Oberthür & Saager 1986;Frimmel et al 1993). With the exception of a recent discovery of Au-Ag-Hg alloy in the Golden Cross fossil hot spring deposit in the Coromandel District (J. Mauk pers.…”

Section: Introductionmentioning

confidence: 99%

Au‐Ag‐Hg and Au‐Ag alloys in Nokomai and Nevis valley placers, northern Southland and Central Otago, New Zealand, and their implications for placer‐source relationships

Youngson

Wopereis²,

Kerr

et al. 2002

New Zealand Journal of Geology and Geophysics

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Gold in Quaternary placers in the Nevis and Nokomai valleys is dominantly a-phase Au-Ag-Hg alloy (c.<10 wt% each of Ag and Hg) with subordinate Au-Ag alloy. The α-Au-Ag-Hg alloy is typically coarse grained (up to 2 cm), angular, and rarely flattened or folded. Crystalline texture, quartz intergrowths, and psuedo-hexagonal crystal pluck cavities are common. Fluvial transport distance estimates based on maximum flatness index of Au-Ag-Hg alloy particles are typically <10-20 km. Coarse (up to 2 cm) crystalline cinnabar is commonly associated with the AuAg-Hg alloy, and both were probably derived from hydrothermal sources in western tributaries of the upper Nevis River and eastern tributaries of the upper Nokomai River. These sources are possibly related to strands of the Nevis-Cardrona Fault System. Secondary Au-Ag-Hg alloy with up to 38 wt% Hg occurs locally in the lower Nokomai alluvial plain, where it coats or cements detrital α-phase AuAg-Hg and Au-Ag alloy particles. The secondary Au-AgHg alloy has formed by diffusion between detrital gold particles and liquid Hg that is either natural or derived from local breakdown of cinnabar.Au-Ag alloy dominates over Au-Ag-Hg alloy in the lower half of the lower Nokomai alluvial plain and in the gravel of a Pleistocene perched channel incised into pumpellyiteactinolite facies semischist basement adjacent to the plain. The Au-Ag alloy is rounded and commonly flattened and folded. Crystalline texture, quartz intergrowths, and pluck cavities are rare in the Au-Ag alloy, and a fluvial transport distance of 25-40 km is estimated from maximum flatness index. Au-Ag alloy, three types of garnet, magnetite, clinozoisite, and well-foliated schist boulders in the abandoned channel gravel are allochthonous. They were derived from greenschist facies schist and sedimentary sources many tens of kilometres north of the Nokomai catchment, and transported either in Wakatipu Glacier till or fluvioglacial outwash gravel that entered the Nokomai valley via Nokomai Saddle, the confluence with the Mataura River, or both. Mercury minerals in hydrothermal deposits within the Otago Schist appear to be restricted to the Caples Terrane. A gold-mercury association is proposed for the Caples Terrane.

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“…It also occurs in placer deposits together with Au particles, as in the Witwatersrand. It is suggested that the major source of the Hg in the Witwatersrand Au is the surrounding sediments from which the element was mobilised and subsequently amalgamated with Au as a result of metamorphism (Oberthuer and Saager, 1986).…”

Section: Mercury (Hg)mentioning

confidence: 99%