Morphology of Witwatersrand gold grains from the Basal Reef; evidence for their detrital origin

Minter, W. E. L.; Goedhart, M.; Knight, J.; Frimmel, Hartwig E.

doi:10.2113/gsecongeo.88.2.237

Cited by 119 publications

(32 citation statements)

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“…The geomicrobiology of gold F Reith et al Minter et al, 1993), but similar younger deposits occur in California and New Zealand Youngson et al, 2006). Most QPC sequences contain detrital and authigenic sulphide minerals Falconer et al, 2006).…”

Section: Bacteria To Transform Goldmentioning

confidence: 92%

The geomicrobiology of gold

et al. 2007

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Microorganisms capable of actively solubilizing and precipitating gold appear to play a larger role in the biogeochemical cycling of gold than previously believed. Recent research suggests that bacteria and archaea are involved in every step of the biogeochemical cycle of gold, from the formation of primary mineralization in hydrothermal and deep subsurface systems to its solubilization, dispersion and re-concentration as secondary gold under surface conditions. Enzymatically catalysed precipitation of gold has been observed in thermophilic and hyperthermophilic bacteria and archaea (for example, Thermotoga maritime, Pyrobaculum islandicum), and their activity led to the formation of gold-and silver-bearing sinters in New Zealand's hot spring systems. Sulphatereducing bacteria (SRB), for example, Desulfovibrio sp., may be involved in the formation of goldbearing sulphide minerals in deep subsurface environments; over geological timescales this may contribute to the formation of economic deposits. Iron-and sulphur-oxidizing bacteria (for example, Acidothiobacillus ferrooxidans, A. thiooxidans) are known to breakdown gold-hosting sulphide minerals in zones of primary mineralization, and release associated gold in the process. These and other bacteria (for example, actinobacteria) produce thiosulphate, which is known to oxidize gold and form stable, transportable complexes. Other microbial processes, for example, excretion of amino acids and cyanide, may control gold solubilization in auriferous top-and rhizosphere soils. A number of bacteria and archaea are capable of actively catalysing the precipitation of toxic gold(I/ III) complexes. Reductive precipitation of these complexes may improve survival rates of bacterial populations that are capable of (1) detoxifying the immediate cell environment by detecting, excreting and reducing gold complexes, possibly using P-type ATPase efflux pumps as well as membrane vesicles (for example, Salmonella enterica, Cupriavidus (Ralstonia) metallidurans, Plectonema boryanum); (2) gaining metabolic energy by utilizing gold-complexing ligands (for example, thiosulphate by A. ferrooxidans) or (3) using gold as metal centre in enzymes (Micrococcus luteus). C. metallidurans containing biofilms were detected on gold grains from two Australian sites, indicating that gold bioaccumulation may lead to gold biomineralization by forming secondary 'bacterioform' gold. Formation of secondary octahedral gold crystals from gold(III) chloride solution, was promoted by a cyanobacterium (P. boryanum) via an amorphous gold(I) sulphide intermediate. 'Bacterioform' gold and secondary gold crystals are common in quartz pebble conglomerates (QPC), where they are often associated with bituminous organic matter possibly derived from cyanobacteria. This may suggest that cyanobacteria have played a role in the formation of the Witwatersrand QPC, the world's largest gold deposit.

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Section: Bacteria To Transform Goldmentioning

confidence: 92%

The geomicrobiology of gold

et al. 2007

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“…Octahedral gold grains have been identified as an important characteristic of secondary gold and observed in Mother Lode, California (Leicht, 1982), weathered Archean metamorphic rocks in Western Australia (Wilson, 1984), and in the Witwatersrand Au deposit, South Africa Minter et al, 1993). Although high temperature and high pressure conditions can result in the formation of octahedral gold , the ability of SRB to form octahedral gold from AuðS 2 O 3 Þ 2 3À is significant.…”

Section: Implications For the Formation Of Supergene Goldmentioning

confidence: 99%

Bioaccumulation of gold by sulfate-reducing bacteria cultured in the presence of gold(I)-thiosulfate complex

Lengke

Southam

2006

Geochimica et Cosmochimica Acta

182

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“…The morphologies of bio-precipitated gold so closely resemble the gold found in contemporary (Australia) and paleoplacers, e.g., South Africa's Witwatersrand basin, that a biogenic origin for these auriferous deposits [8,9,18,19] is now accepted.…”

Section: Introductionmentioning

confidence: 69%

Immobilisation of Platinum by Cupriavidus metallidurans

et al. 2018

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Abstract:The metal resistant bacterium Cupriavidus metallidurans CH34, challenged with aqueous platinous and platinic chloride, rapidly immobilized platinum. XANES/EXAFS analysis of these reaction systems demonstrated that platinum binding shifted from chloride to carboxyl functional groups within the bacteria. Pt(IV) was more toxic than Pt(II), presumably due to the oxidative stress imparted by the platinic form. Platinum immobilisation increased with time and with increasing concentrations of platinum. From a bacterial perspective, intracellular platinum concentrations were two to three orders of magnitude greater than the fluid phase, and became saturated at almost molar concentrations in both reaction systems. TEM revealed that C. metallidurans was also able to precipitate nm-scale colloidal platinum, primarily along the cell envelope where energy generation/electron transport occurs. Cells enriched in platinum shed outer membrane vesicles that were enriched in metallic, colloidal platinum, likely representing an important detoxification strategy. The formation of organo-platinum compounds and membrane encapsulated nanophase platinum, supports a role for bacteria in the formation and transport of platinum in natural systems, forming dispersion halos important to metal exploration.

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Morphology of Witwatersrand gold grains from the Basal Reef; evidence for their detrital origin

Cited by 119 publications

References 0 publications

The geomicrobiology of gold

The geomicrobiology of gold

Bioaccumulation of gold by sulfate-reducing bacteria cultured in the presence of gold(I)-thiosulfate complex

Immobilisation of Platinum by Cupriavidus metallidurans

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