Evaluation of the contributions of gold derived from hypogene, supergene and surficial processes in the formation of placer gold deposits

2021 ◽  
pp. SP516-2020-260
Author(s):  
R. J. Chapman ◽  
D. Craw ◽  
N. R. Moles ◽  
D. A. Banks ◽  
M. R. Grimshaw
Keyword(s):  
Gold Particle ◽  
Visual Inspection ◽  
Alloy Composition ◽  
Gold Alloy ◽  
Gold Deposits ◽  
Placer Gold ◽  
Authigenic Minerals ◽  
Gold Particles ◽  
Gold Chemistry ◽  
Important Constituent

AbstractPlacer gold particles have traditionally been considered as either detrital products of weathering or authigenic minerals growing within placers. Recent advances in understanding of gold chemistry/bio-geochemistry demonstrate that gold growth in specific environments is plausible, but opinions differ on the importance of ‘new’ gold in the overall placer inventory. Here we draw upon visual inspection over 40,000 polished gold particle sections from locations worldwide to evaluate the implications of gold alloy composition and particle heterogeneity in determining the contributions of detrital and authigenic gold to fluvial placers. We conclude i. the detrital model of placer gold formation is widespread and demonstrable, ii. supergene gold may be a locally important constituent of fluvial placers, iii. gold-rich rims on placer gold particles comprise two distinct components: a surface micron-scale addition of pure Au and a tens- of- micron- scale inner rim formed by Ag depletion, iv. the importance to placer inventories of gold particle formation and modification by biogenic processes is considerably overstated.

scholarly journals Criteria for Determining the Genesis of Placers and Their Different Sources Based on the Morphological Features of Placer Gold

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 381
Author(s):  
Zinaida Nikiforova
Keyword(s):  
Native Gold ◽  
Morphological Characteristics ◽  
Gold Deposits ◽  
Primary Sources ◽  
Gold Content ◽  
Placer Gold ◽  
Gold Particles ◽  
Search Criterion ◽  
Different Sources ◽  
Gold Bearing

Based on the identified typomorphic features of placer gold, a set of determined morphogenetic criteria is proposed to identify the genesis of placer gold content and different sources in the platform areas, which allow more correctly selecting search methods and improving the efficiency of forecasting ore and placer gold deposits.Goldparticles larger than 0.25 mm with signs of wind-worn processing indicate the formation of autochthonous aeolian placers.Gold particles with signs of wind-worn processing with a size of 0.1–0.25 mm, forming an extensive halo of dispersion, indicate the formation of allochthonous placers in Quaternary deposits.Deflationary (autochthonous) placers of native gold can be found by the halo of its distribution of toroidal and sphericalhollow forms, which, of course, are the search morphogenetic criterion of aeolian placers.The presence of disc-shaped and lamellar gold particles with ridgelike edges in alluvial placers is typical for placers of heterogeneous origin, formed due to deflation of proluvialplacers.The discovery of pseudo-ore gold in alluvial placers indicates the arrival of gold from intermediate gold-bearing sources of different ages and not from primary sources, which is a morphogenetic criterion for determining different sources of the placer.In modern gold placers, the presence of gold of a pseudo-ore appearance can serve as a search criterion for the discovery of gold-bearing conglomerates with high gold content. The developed method for diagnosing the genotype of placer gold by its morphological characteristics (alluvial, aeolian, pseudo-ore) can be successfully used by industrial geological organizations to search and explore ore and placer gold deposits.

A method for determining the periodicity of a troponin component in isolated insect flight muscle thin filaments by gold/Fab labelling

1992 ◽  
Vol 101 (3) ◽  
pp. 503-508
Author(s):  
R. Newman ◽  
G.W. Butcher ◽  
B. Bullard ◽  
K.R. Leonard
Keyword(s):  
Gold Particle ◽  
Colloidal Gold ◽  
Striated Muscle ◽  
Flight Muscle ◽  
Insect Flight ◽  
Insect Flight Muscle ◽  
Fab Fragment ◽  
Thin Filaments ◽  
Gold Particles ◽  
Almost All

Insect flight muscle has a large component (Tn-H) in the tropomyosin-troponin complex that is not present in vertebrate striated muscle thin filaments. Tn-H is shown by gold/Fab labelling to be present at regular intervals in insect flight muscle thin filaments. The Fab fragment of a monoclonal antibody to Tn-H was conjugated directly with colloidal gold and this probe used to label isolated thin filaments from the flight muscle of Lethocerus indicus (water bug). The distribution of gold particles seen in electron microscope images of negatively stained thin filaments was analysed to show that the probe bound to sites having a periodicity of approximately 40 nm, which is the expected value for the tropomyosin-troponin repeat. Conjugates of Fab with colloidal gold particles of 3 nm diameter labelled almost all sites. Conjugates with gold particles of 5 nm and 10 nm diameter labelled less efficiently (70% and 30%, respectively) but analysis of the distribution of inter-particle intervals among a number of filaments again gave the same fundamental spacing of 40 nm. The error in the measurements (standard deviation approximately +/− 4.2 for 5 nm gold/Fab) is less than earlier estimates for the size of the gold/Fab complex. Measurements on gold/Fab in negative stain suggest that the bound Fab contributes a shell about 2 nm in thickness around the gold particle. The radius of the probe (about 4.5 nm for 5 nm gold/Fab) would then be consistent with the value of error found. The size of the probe suggests that the gold particle binds to the side of the Fab molecule, rather close to the antibody combining site. The potential resolution of the technique may thus be better than originally expected.

scholarly journals Information and computational GIS for monitoring the natural and technical systems of placer gold deposits

2021 ◽  
Vol 895 (1) ◽  
pp. 012036
Author(s):  
V I Usikov ◽  
Y A Ozaryan
Keyword(s):  
Remote Sensing ◽  
Information Technologies ◽  
Precious Metals ◽  
Gold Deposits ◽  
Raw Material ◽  
Expert Assessment ◽  
Labor Costs ◽  
Resource Base ◽  
Placer Gold ◽  
Geological Information

Abstract It is known that nowadays one of the main problems of mining is the depletion of reserves. The researchers consider mining waste as a source of replenishment of the resource base. Disputes on the prospects for technogenic raw material processing are becoming especially relevant. The object of research chosen by the authors in this article is the technogenic neoplasms resulting from dredging and hydraulic processing of placer gold. The paper presents the results of assessing the prospects and application of the information technologies, in particular, the analysis of data from remote sensing of the Earth in the design and organization of work to involve technogenic placers in operation. It is shown that these technologies are able to increase the efficiency of work and reduce labor costs at the stage of preliminary study of potential development targets. Technogenic complexes of depleted fields are a significant reserve of the mineral resource base of gold and other precious metals. This paper presents the results of the creation of a method for expert assessment of spatial and volumetric indicators of technogenic complexes of alluvial fields and other landscape objects using remote sensing of the territory and analysis of geological information. The Kerbinsky gold-bearing region of the Khabarovsk Region was chosen as the object of research.

scholarly journals Biological and Geochemical Development of Placer Gold Deposits at Rich Hill, Arizona, USA

Minerals ◽  
2018 ◽  
Vol 8 (2) ◽  
pp. 56 ◽  
Author(s):  
Erik Melchiorre ◽  
Paul Orwin ◽  
Frank Reith ◽  
Maria Rea ◽  
Jeff Yahn ◽  
...  
Keyword(s):  
Gold Deposits ◽  
Placer Gold

scholarly journals Typomorphic Features of Placer Gold from the Billyakh Tectonic Melange Zone of the Anabar Shield and Its Potential Ore Sources (Northeastern Siberian Platform)

Minerals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 281
Author(s):  
Boris Gerasimov ◽  
Vasily Beryozkin ◽  
Alexander Kravchenko
Keyword(s):  
Native Gold ◽  
Gold Mineralization ◽  
Coarse Fraction ◽  
Gold Deposits ◽  
Primary Sources ◽  
The Arctic ◽  
Geochemical Data ◽  
Placer Gold ◽  
Anabar Shield ◽  
Tectonic Mélange

Precambrian shields and outcropped Precambrian rock complexes in the Arctic may serve as the most important sources of various types of mineral raw materials, including gold. The gold potential of the Anabar shield in the territory of Siberia has, thus far, been poorly studied. A number of primary and placer gold occurrences have been discovered there, but criteria for the prediction of and search for gold mineralization remain unclear. The main purpose of this paper was to study the typomorphic features of placer gold in the central part of the Billyakh tectonic mélange zone in the Anabar shield and to compare them to mineralization from primary sources. To achieve this, we utilized common methods for mineralogical, petrographic, and mineragraphic analyses. Additionally, geochemical data were used. As a result of this investigation, important prospecting guides were identified, and essential criteria for the prediction of and search for gold deposits were elucidated. The characteristics of the studied placer gold were specific for gold derived from a proximal provenance. These characteristics included the poor roundness of the native gold grains, a cloddy–angular and dendritic form, an uneven surface, and a high content of coarse-fraction native gold (0.5–2 mm), which was as high as 24% of the volume of analyzed native gold. In addition, we conducted a study on the mineralogical features of the gold-sulfide mineralization that was disseminated throughout a small exposure area of paleo-Proterozoic para- and orthogneisses in the Anabar shield basement. A comparison of mineral inclusions in the coarse-fraction native gold and mineral assemblages in the ore deposits showed that one of the possible primary sources for placer gold might be small bodies of metasomatically altered orthogneisses associated with large granitoid plutons.

How Recyclability can Reduce Induction Period of Gold Nanocatalysts

2019 ◽  
Vol 57 ◽  
pp. 1-6 ◽  
Author(s):  
Sedigheh Ghadamgahi
Keyword(s):  
Catalytic Activity ◽  
Reaction Time ◽  
Gold Particle ◽  
Particle Diameter ◽  
Gold Catalysts ◽  
Gold Particles ◽  
Transmission Electron ◽  
The Mean ◽  
Full Conversion ◽  
Catalytic Test

The effect of recyclability on the catalytic activity of supported Au101(PPh3)21Cl5 nanoparticles (1.0 wt% Au101/AC) was investigated for benzyl alcohol oxidation under mild conditions. The influence of recyclability on the catalytic activity of activated Au101/AC nanocatalysts was studied trough a comparison of gold particle diameter and also catalysts conversion between the fresh (as synthesized) and recycled gold catalysts. The monitoring of gold particle diameters by transmission electron microscopy (TEM) showed that the gold particles size gradually increased during the catalytic reaction. The mean diameter of the fresh gold catalysts increased from approximately 3 to 3.2, 5.1 and 5.3 nm after 1, 2 and 3 h reaction time, respectively. Whereas the average gold particle diameter of the recycled samples were slightly enlarged from approximately 5.3 (the sample recycled after 3 h of the first catalytic test) to 5.7, 5.9 and 6.2 nm with durations of 1, 2 and 3 h reaction time, respectively. Therefore, larger gold particles gradually formed for fresh and also recycled gold catalysts during reaction tests. Meanwhile, the catalytic activity of activated 1.0 wt% Au101/AC catalysts jumped to full conversion when the recycled gold catalysts were utilized due to removing ligand stabilizer from gold particles and so bigger particles had formed.

Indicative features of placer gold for the prediction of the formation types of gold deposits (east of the Siberian Platform)

2018 ◽  
Vol 59 (10) ◽  
pp. 1318-1329 ◽  
Author(s):  
Z.S. Nikiforova ◽  
B.B. Gerasimov ◽  
E.G. Glushkova ◽  
A.G. Kazhenkina
Keyword(s):  
Siberian Platform ◽  
Gold Deposits ◽  
Placer Gold
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