A multidisciplinary study of invisible gold in arsenopyrite from four mesothermal gold deposits in Siberia, Russian Federation

Genkin, A. D.; Бортников, Н. С.; Cabri, Louis J.; Wagner, Fritz; Stanley, Chris J.; Safonov, Yurii G.; McMahon, Greg; Friedl, J.; Kerzin, A. L.; Gamyanin, G. N.

doi:10.2113/gsecongeo.93.4.463

Cited by 128 publications

(100 citation statements)

References 6 publications

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“…The first range included elements with EF >2, which were Au (78 500), Cd (18 800), As (64), U (8), Cr (2), and Pb (2) Cd, Au, and As had the highest enrichment factors, falling in the class of extremely high enrichment (EF >40). Similar results on Au enrichment factors (20-400) in the sediments have been documented by Roychoudhury and Starke (2006), and the presence of arsernopyrite has been previously demonstrated (Genkin et al, 1998). The enrichment of metals (e.g.…”

supporting

confidence: 85%

Health risk posed by enriched heavy metals (As, Cd, and Cr) in airborne particles from Witwatersrand gold tailings

Maseki

Annegarn

Spiers

2017

J. South. Afr. Inst. Min. Metall.

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Severe episodes of windblown dust from mine tailings storage facilities (TSFs) are a common phenomenon on the Witwatersrand, especially during the spring windy season. For communities around TSFs, such events pose health and environmental challenges. This paper reports on health risk assessment using US Environmental Protection Agency (US EPA) risk assessment methods for heavy metal elements in windblown dust from TSFs on the central and east Witwatersrand. Samples of surface material from these TSFs were analysed for heavy metal content using inductively coupled plasma-mass spectrometry (ICP-MS). From a range of 30 heavy metals analysed, only As, Cd, Cr, Pb, and U were enriched by a factor of two or more above the average crustal composition and at concentrations that could be of possible health concern-elements present in the range of a few parts per billion (ppb) or lower were ignored. As, Cd, Cr, Pb and U were selected for a comprehensive risk assessment from exposure through airborne routes, mainly considering inhalation and ingestion. Ambient exposures were based on a worst-case measured episode of 540 μg m -3 (24-hour average), which was projected over each day of an annual exposure for the hours for which the wind speed was above the threshold for dust generation. US EPA risk assessment methods were used to determine the inhalation and ingestion hazard quotients and hazard indices for adults and children. The sum of the hazard indices was assessed to be below the non-cancer benchmark (hazard indices 1.0) considered to be acceptable for a lifetime exposure. The total risk for both exposures (inhalation and the ingestion) was within the range of 1 per 1 000 000 to 100 per 1 000 000-taken as 'acceptable risk' by the US EPA for adults and children. These results represent the first quantitative health risk assessment of the hazard posed by heavy metals in windblown mine tailings dust on the Witwatersrand goldfield. mine tailings, dust, airborne particles, health risk, inhalation, ingestion heavy metals, arsenic, cadmium, chromium.

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supporting

confidence: 85%

Health risk posed by enriched heavy metals (As, Cd, and Cr) in airborne particles from Witwatersrand gold tailings

Maseki

Annegarn

Spiers

2017

J. South. Afr. Inst. Min. Metall.

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“…They suggested that the gold-bearing arsenopyrite in the Olympiada deposit formed contemporaneously with halos of retrograde alteration controlled by shear zones, with deposition from a fluid through fluidrock interactions; the native gold was considered to have deposited later. Genkin et al (1998) stated that Au occurs chemically bound in arsenopyrite as well as in the form of submicroscopic Au 0 in the four deposits considered, with chemically bound Au dominant in three of the four deposits. It is difficult to deduce the manner in which gold is bonded to its neighbors (or to even know what these neighbors are) on the basis of 197 Au Mössbauer spectra.…”

Section: Review Of Recent Workmentioning

confidence: 97%

“…They concluded that the Au is likely structurally bound in arsenopyrite in their samples. Genkin et al (1998) studied arsenopyrite from four Siberian gold deposits using a variety of techniques (ore microscopy, instrumental neutron-activation analysis (INAA), SIMS, EPMA and 197 Au Mössbauer spectroscopy). They suggested that the gold-bearing arsenopyrite in the Olympiada deposit formed contemporaneously with halos of retrograde alteration controlled by shear zones, with deposition from a fluid through fluidrock interactions; the native gold was considered to have deposited later.…”

Section: Review Of Recent Workmentioning

confidence: 99%

“…It is difficult to deduce the manner in which gold is bonded to its neighbors (or to even know what these neighbors are) on the basis of 197 Au Mössbauer spectra. However, Genkin et al (1998) stated that the "…. invisible gold cannot be bonded in either the linear two-fold coordination typical for the monovalent, or the planar fourfold coordination typical for the trivalent valence state (Bartunik et al 1970, Parish 1982.…”

Section: Review Of Recent Workmentioning

confidence: 99%

“…In the present paper, we report on a multifaceted investigation into the chemistry and speciation of invisible gold in five samples of arsenopyrite from four mesothermal deposits: the Olympiada and Sentachan deposits in Siberia, Russia (Genkin et al 1998), the São Bento mine in Minas Gerais, Brazil (Steele et al 2000) and the Sheba mine in the Transvaal, South Africa (Schouwstra & De Villiers 1988, Cabri et al 1989). The present study involves a detailed characterization of the arsenopyrite grains by traditional methods such as EPMA, and by more recently applied methods such as SIMS and micro-XANES.…”

Section: Review Of Recent Workmentioning

confidence: 99%

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Chemical Speciation of Gold in Arsenopyrite

Cabri¹,

Newville

Gordon

et al. 2000

The Canadian Mineralogist

134

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The speciation of Au in gold-bearing arsenopyrite (FeAsS) from four gold deposits (Olympiada, Sentachan, São Bento and Sheba) was determined by micro-X-ray absorption near-edge structure (XANES) on grains well characterized microscopically and by electron-microprobe and secondary-ion mass spectrometry analyses and images. "Invisible" gold in arsenopyrite occurs in two apparently mutually exclusive chemical forms: chemically bound and elemental. Arsenopyrite from the Sentachan, São Bento and Sheba deposits contains chemically bound gold. With comparable constituent electronegativities and a white-line feature in the XANES indicating unoccupied Au 5d-states, but absorption-edge positions comparable to Au 1+ species, the bonding is interpreted as being covalent rather than ionic. The invisible gold in arsenopyrite from the Olympiada deposit, on the other hand, occurs as very small particles of Au 0 , probably less than a few nanometers in diameter. Micro-XANES data for the Olympiada and Sentachan arsenopyrite support earlier results obtained by 197 Au Mössbauer spectroscopy on arsenopyrite concentrates. In some arsenopyrite crystals, the gold concentration is closely related to growth zoning. This feature represents conditions during crystallization and does not correlate with the chemical form of the gold. Similarly, selenium, where present, correlates with gold in some deposits and not in others, irrespective of the gold speciation. The finding of two types of invisible gold in arsenopyrite from different deposits has beneficial implications for extractive metallurgy.

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Selective x‐ray Bragg spectrometry: optimizing fluorescence microprobe sensitivity for precious metals

et al. 2007

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INTRODUCTIONThe knowledge of the speciation of trace metals at micro-to nano-scale in soil and sediments is fundamental to understanding and predicting element mobility, bioavailability and biotoxicity. X-ray microprobes have seen much improvement in last decade due to the advent of third generation synchrotron sources and progress in focussing mirror and detector technology. Some of the advantages of this technique are:• Sub-micron resolution;• Low detection limits (ca. 1 ppm);• Non-destructiveanalysis (at least for inorganic samples);• Ability to study wet samples or samples under controlled environment;• Ability to combine concentration information (x-ray fluorescence) with speciation information (xray absorption near-edge spectroscopy).The next challenge is in rendering the instrument more user-friendly and in reducing detection limits. We present here the results from an instrument development project aimed at developing an X-ray spectrometer configuration for the X-ray fluorescence microprobe optimized for the detection of precious metals in geological and biological samples. The objective is to improve detection limits and reduce interference from major elements and beam scatter. The approach used Bragg diffraction from a surface shaped to form a segment of logarithmic spiral (log-spiral) to focus X-rays from precious metals onto a solid-state detector. The result is an enhancement of precious metal lines within the narrow band-pass of the Bragg crystal surface with suppression of detector artefacts such as tailing and escape peaks arising from interfering elements and scattered photons. BACKGROUNDGold in ore can be economic at concentrations of a few ppm, depending on ore mineralogy and the nature of gold residence in the ore. Consequently, interest in the distribution of gold between coexisting sulphide minerals in ore demands the imaging and analysis of gold at ppm to sub-ppm levels. Similarly, thermodynamic data suggest that the concentrations of gold in the fluids involved in ore formation in magmatic hydrothermal systems are seldom higher than a few ppm. Hence, the study of ore fluids trapped and preserved as fluid inclusions in minerals necessitates the detection of gold at ppm to sub-ppm levels during in situ analysis of fluid inclusions. Gold anomalies in soils and calcrete are often in the range of 10s to 100s of ppb; knowledge of gold speciation in these fine-grained samples is fundamental for understanding the origin of these anomalies and in ranking anomalies to select the most prospective exploration targets.

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A multidisciplinary study of invisible gold in arsenopyrite from four mesothermal gold deposits in Siberia, Russian Federation

Cited by 128 publications

References 6 publications

Health risk posed by enriched heavy metals (As, Cd, and Cr) in airborne particles from Witwatersrand gold tailings

Health risk posed by enriched heavy metals (As, Cd, and Cr) in airborne particles from Witwatersrand gold tailings

Chemical Speciation of Gold in Arsenopyrite

Selective x‐ray Bragg spectrometry: optimizing fluorescence microprobe sensitivity for precious metals

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