scholarly journals Aluviální zlato v oblasti Dlouhá Ves - Řepová (zábřežské krystalinikum)

2020 ◽  
Vol 28 (1) ◽  
pp. 9-22
Author(s):  
Zdeněk Dolníček ◽  
Miroslav Nepejchal ◽  
Jana Ulmanová
Keyword(s):  
Trace Amount ◽  
Pure Gold ◽  
Crystalline Complex ◽  
Ore Deposit ◽  
Minor Elements ◽  
Metavolcanic Rocks ◽  
Free Gold ◽  
Alluvial Gold ◽  
Small Vein ◽  
Vein Type

A detailed panning prospection of the Řepovský potok, Míroveček and Ospitský potok creeks (northern part of the Zábřeh Upland) proved that trace amount of alluvial gold occurs in the whole studied area. The collected gold sheets are 0.2 to 3 mm in size and mostly have shapes only weakly modified by transport in the stream. Although the chemical composition varies widely between Au-rich silver and pure gold (28.1 - 99.8 at. % Au), individual sheets are typically (few exceptions exist) compositionally homogeneous. Less than half of them has the narrow high-fineness rim, which was formed by leaching of silver in supergene conditions. In lower reach of the Řepovský potok creek there were also found gold sheets containing elevated mercury (0.1 - 5.1 at. %), which most probably originated from neighbouring vein-type Ag-Zn-Pb deposit Řepová. In contrast, the source of Hg-free gold sheets was not unambiguously established. The first possibility includes small vein-type mineralizations similar to the Řepová ore deposit and containing trace amount of gold (an occurrence of this type was newly recognized in the vicinity of Dlouhá Ves village). Second, one cannot exclude the trace occurrence of gold sheets directly in underlying metasiltstones or acid metavolcanic rocks of the Zábřeh Crystalline Complex [with respect to repeatedly observed intergrowths of gold with polymineral aggregates of phyllosilicates (muscovite, chlorite, biotite, clay minerals), feldspars (K-feldspar, albite, K-Na feldspar) and minor quartz in the alluvial gold sheets]. The particles of metallic Cu-Zn-Sn alloys with admixture of Ni, Sb and In, panned from the Řepovský potok creek, could contain metals originated from smelting of polymetallic ores from the deposit Řepová, which comprise the same minor elements.

Metalliferous potential of the United Kingdom

1974 ◽  
Vol 339 (1618) ◽  
pp. 289-297 ◽  
Keyword(s):  
United Kingdom ◽  
Mechanical Equipment ◽  
Potential Production ◽  
Ore Deposit ◽  
The United Kingdom ◽  
Future Production ◽  
Ore Bodies ◽  
Vein Type ◽  
Opencast Mines ◽  
Vein Deposits

The total estimated value of past non-ferrous metalliferous production, as well as that of fluorspar, barytes and witherite, in the United Kingdom, as a whole, is £5.95 x 10 9 at assumed average 1973 metal and mineral prices. Southwest England produced roughly 70% of this value. The outlook for future production appears to be best in Wales and Scotland. At least one large unmined ore deposit of disseminated type is known, although vein-type ore bodies are more likely to be found. The effects of the development of high-tonnage mechanical equipment favour opencast mines and imply that vein deposits must be rich in order to compete economically. The estimated value of potential production from England and Wales is put in the range of £6.3 x 10 8 to £1.3 x 10 9 at assumed average 1973 prices. No quantified estimate is considered possible for Scotland.

scholarly journals Trace Element Geochemistry in Quartz in the Jinqingding Gold Deposit, Jiaodong Peninsula, China: Implications for the Gold Precipitation Mechanism

Minerals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 326 ◽  
Author(s):  
Binghan Chen ◽  
Jun Deng ◽  
Hantao Wei ◽  
Xingzhong Ji
Keyword(s):  
Trace Element ◽  
Gold Deposit ◽  
Quartz Vein ◽  
Trace Element Content ◽  
Element Content ◽  
Trace Element Geochemistry ◽  
Precipitation Mechanism ◽  
Al Content ◽  
Free Gold ◽  
Vein Type

Lots of studies on gold precipitation mechanisms have focused on fluid inclusions within quartz. However, the trace elements in quartz reflect the properties of the ore fluid, and a comparison of the trace element content in different types of quartz can reveal the precipitation mechanism. The Jinqingding gold deposit is the largest gold deposit in the Muping–Rushan gold belt and contains the largest single sulfide–quartz vein type orebody in the gold belt. This study distinguished four types of quartz in this orebody through field work and investigations of the mineralogy and cathodoluminescence (CL) of the quartz and crosscutting relationships as seen under a microscope. In situ studies via electron probe micro-analyzer (EPMA) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) were used to determine the trace element content of the different quartz types. Type Qa displayed a comb structure in the field and zoning under the microscope and in CL. Milky white and smoke grey Qb was the most common quartz type and hosted the most sulfide and gold. Qc was Qa and Qb quartz that recrystallized around pyrite or overgrew and appeared different from Qa and Qb in CL images. Qd occurred within fractures in pyrite. Qa formed prior to the mineralization of gold, and Qd formed post-mineralization. Qb and Qc provided information regarding the ore fluid during mineralization. Sericites occurred with pyrite in fractures in the quartz, and some, along with free gold, filled in fractures in pyrite. Free gold occurred within Qa, Qb, Qc, and in brittle fractures in pyrite. Qc had the lowest Al content of all of the quartz types. As Al content is related to the acidity of the ore fluid in previous study, this indicated an acidity decrease during mineralization, which could be attributed to the sericitization. Sericitization could indicate a potential gold occurrence. The Ti content decreased from Qb to Qc, indicating a decrease in temperature during quartz overgrowth formation. Change in acidity and cooling can therefore be identified as possible causes of gold precipitation in the sulfide–quartz vein type in the Jinqingding gold deposit.

Quantitative texture analysis of alluvial gold: primary and secondary signatures

2021 ◽  
Author(s):  
Juan Gómez-Barreiro ◽  
Santos Barrios-Sánchez ◽  
José Manuel Compaña Prieto ◽  
Juan Morales Sánchez-Migallón ◽  
Kelvin dos Santos Alves ◽  
...  
Keyword(s):  
Rietveld Method ◽  
Secondary Growth ◽  
Primary Source ◽  
Close Correlation ◽  
Gold Deposits ◽  
Pure Gold ◽  
Transport Length ◽  
Alluvial Gold ◽  
Placer Deposits ◽  
Non Destructive

<p>The origin of gold nuggets (Au‐Ag alloys) is not completely understood. They crop out in placer deposits, potentially derived from a primary source (hydrothermal/magmatic). Meteorization, erosion and transport of primary gold deposits result in the liberation of a variety of particle size. Recent investigations suggest that both primary and secondary microstructural features may be preserved and could be related to deformation during transport, recrystallization and primary formation. Besides, the contribution of biological mechanisms (biomineralization) may have played an important role during secondary growth in some nuggets. In many cases, there is no clear evidence to distinguish between supergenic and hypogenic gold, so texture information could be excellent information to constrain the origin. Besides, it has been demonstrated that crystallography controls the de‐alloying processes in gold nuggets. This mechanism, that transforms the primary Au–Ag alloys into pure gold by preferential dissolution of Ag along crystal boundaries, could be determined by variations on texture, a factor never explored before, which may explain the dispersion in de‐alloying values in the same deposit.</p><p> </p><p>In this case we have explored a selection of gold nuggets collected in the W sector of the Iberian Massif (Spain), representing the principal morphological types. As a non-destructive technique neutron diffraction appears as the technique of choice in this case. Beside, neutrons absorption is very low so that large samples could be investigated. Samples were analyzed in transmission at ILL (Grenoble) for texture. Quantitative texture and gold crystallinity was calculated using Rietveld method as implemented in Maud software (EWIMV). Mono- and polycrystalline nuggets and alloy composition were clearly identified in each particle with this technique. Our results show a close correlation between the morphology (i.e. transport length) of the particle and the crystallographic results, particularly for fibrous and discoid shapes (i.e. Zingg, Corey shape factor), what could be used to develop better transport models (distance-to-bedrock sources) and understand multisource gold placer assemblages. </p>

scholarly journals X-Ray Fluorescence Analysis of XII–XIV Century Italian Gold Coins

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Monica Baldassarri ◽  
Gildo de Holanda Cavalcanti ◽  
Marco Ferretti ◽  
Astrik Gorghinian ◽  
Emanuela Grifoni ◽  
...  
Keyword(s):  
Fluorescence Analysis ◽  
Pure Gold ◽  
Gold Content ◽  
North African ◽  
Nondestructive Technique ◽  
Large Variability ◽  
X Ray ◽  
Minor Elements ◽  
High Concentrations ◽  
Gold Coins

An extensive analytical study has been performed on a large number of gold coins (Norman-Swabian Augustale and Tarì, Grosso of Lucca, Florin of Florence) minted in Italy from the end of XII century to XIV century. The X-ray fluorescence (XRF) technique was used for verifying the composition of the coins. XRF is a nondestructive technique particularly suited for in situ quantitative analysis of gold and minor elements in the precious alloy. The Florins turned out to have a gold content very close to 24 carats (pure gold) although in a couple of cases we observed relatively high concentrations of iron (around 2%) or lead (around 1%). The Grosso of Lucca has a similar composition, with a measured gold content around 97% due to a higher silver percentage (about 2%), with respect to the average Florin. The Augustali analyzed showed, on average, a gold content around 89%. The average gold content of the Tarì analysed is around 72%, with a relatively large variability. The analysis revealed the use of native gold for the coinage of the Florins, excluding the possibility of recycling gold coming from other sources. On the other hand, the variability observed in the compositions of the Tarì and Augustali could suggest the reuse of Islamic and North African gold. The study could shed some light on the sudden diffusion of gold coins in Italy around the first half of XIII century, allowing hypotheses on the provenience of the gold used for a coinage that dominated the economic trades from then on.

Minor Elements in Layered Sphalerite as a Record of Fluid Origin, Mixing, and Crystallization in the Navan Zn-Pb Ore Deposit, Ireland

2014 ◽  
Vol 109 (6) ◽  
pp. 1513-1528 ◽  
Author(s):  
D. Gagnevin ◽  
J. F. Menuge ◽  
A. Kronz ◽  
C. Barrie ◽  
A. J. Boyce
Keyword(s):  
Ore Deposit ◽  
Minor Elements

An investigation into heterogeneity in a single vein-type uranium ore deposit: Implications for nuclear forensics

2015 ◽  
Vol 150 ◽  
pp. 75-85 ◽  
Author(s):  
A.C. Keatley ◽  
T.B. Scott ◽  
S. Davis ◽  
C.P. Jones ◽  
P. Turner
Keyword(s):  
Nuclear Forensics ◽  
Ore Deposit ◽  
Uranium Ore ◽  
Vein Type

Diagnostics of Gold Laser Plasmas

1988 ◽  
Vol 102 ◽  
pp. 357-360
Author(s):  
J.C. Gauthier ◽  
J.P. Geindre ◽  
P. Monier ◽  
C. Chenais-Popovics ◽  
N. Tragin ◽  
...  
Keyword(s):  
Experimental Results ◽  
Pure Gold ◽  
Electronic Temperature ◽  
X Ray ◽  
Laser Plasmas ◽  
Collisional Radiative Model ◽  
Radiative Model

AbstractIn order to achieve a nickel-like X ray laser scheme we need a tool to determine the parameters which characterise the high-Z plasma. The aim of this work is to study gold laser plasmas and to compare experimental results to a collisional-radiative model which describes nickel-like ions. The electronic temperature and density are measured by the emission of an aluminium tracer. They are compared to the predictions of the nickel-like model for pure gold. The results show that the density and temperature can be estimated in a pure gold plasma.

High Resolution Observations of Ion-Milling Induced Transformation in Synthetic Hollandses

1981 ◽  
Vol 39 ◽  
pp. 114-115 ◽  
Author(s):  
T. J. Headley
Keyword(s):  
High Resolution ◽  
Radioactive Waste Disposal ◽  
Ion Milling ◽  
Minor Elements ◽  
Waste Forms ◽  
Carbon Substrates ◽  
Structural Differences ◽  
Oxide Phases ◽  
Argon Ions ◽  
High Resolution Microscopy

Oxide phases having the hollandite structure have been identified in multiphase ceramic waste forms being developed for radioactive waste disposal. High resolution studies of phases in the waste forms described in Ref. [2] were initiated to examine them for fine scale structural differences compared to natural mineral analogs. Two hollandites were studied: a (Ba,Cs,K)-titan-ate with minor elements in solution that is produced in the waste forms, and a synthesized BaAl2Ti6O16 phase containing ∼ 4.7 wt% Cs2O. Both materials were consolidated by hot pressing at temperatures above 1100°C. Samples for high resolution microscopy were prepared both by ion-milling (7kV argon ions) and by crushing and dispersing the fragments on holey carbon substrates. The high resolution studies were performed in a JEM 200CX/SEG operating at 200kV.

The Pure Gold of Psychoanalysis and New Alloys

1993 ◽  
Vol 38 (4) ◽  
pp. 423-423
Author(s):  
Donald Morgan
Keyword(s):  
Pure Gold
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