scholarly journals Invisible Gold Paragenesis and Geochemistry in Pyrite from Orogenic and Sediment-Hosted Gold Deposits

Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 339 ◽  
Author(s):  
Ross R. Large ◽  
Valeriy V. Maslennikov
Keyword(s):  
Intermediate Stage ◽  
Gold Deposits ◽  
Arsenic Content ◽  
Invisible Gold ◽  
Chemical Association ◽  
Orogenic Events ◽  
Golden Mile ◽  
The Invisible ◽  
Gold Quarry

LA-ICPMS analysis of pyrite in ten gold deposits is used to determine the precise siting of invisible gold within pyrite, and thus the timing of gold introduction relative to the growth of pyrite and related orogenic events. A spectrum of invisible gold relationships in pyrite has been observed which suggests that, relative to orogenic pyrite growth, gold introduction in some deposits is early at the start of pyrite growth; in other deposits, it is late toward the end of pyrite growth and in a third case, it may be introduced at the intermediate stage of orogenic pyrite growth. In addition, we report a distinct chemical association of invisible gold in pyrite in the deposits studied. For example, in the Gold Quarry (Carlin type), Mt Olympus, Macraes and Konkera, the invisible gold is principally related to the arsenic content of pyrite. In contrast, in Kumtor and Geita Hill, the invisible gold is principally related to the tellurium content of pyrite. Other deposits (Golden Mile, Bendigo, Spanish Mountain, Witwatersrand Carbon Leader Reef (CLR)) exhibit both the Au-As and Au-Te association in pyrite. Some deposits of the Au-As association have late orogenic Au-As-rich rims on pyrite, which substantially increase the value of the ore. In contrast, deposits of the Au-Te association are not known to have Au-rich rims on pyrite but contain nano- to micro-inclusions of Au-Ag-(Pb-Bi) tellurides.

scholarly journals Genesis of Carbonate Breccia Containing Invisible Gold in Taebaeksan Basin, South Korea

Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1087
Author(s):  
Sang-Gun No ◽  
Maeng-Eon Park ◽  
Bong-Chul Yoo ◽  
Seung-Han Lee
Keyword(s):  
South Korea ◽  
Carbonate Rock ◽  
Gold Deposits ◽  
Invisible Gold ◽  
Gold Particles ◽  
X Ray ◽  
Taebaeksan Basin ◽  
The Matrix ◽  
Backscattered Electron

The Yemi breccia developed and is distributed within the Paleozoic carbonate rock (Maggol Formation) in the central part of the Taebaeksan Basin, South Korea. Explanation for the genesis of the Yemi breccia has been controversial. We investigated the petrological and mineralogical properties of the breccia and the matrix materials at 60 outcrops. The Yemi breccia is divided into crackle, mosaic, and chaotic breccias based on morphology. In addition, these are divided into blackish, reddish, grayish, and white to pinkish matrix breccias according to the materials of the matrix. Quartz, calcite, pyrite, hematite (after pyrite), and minor epidote, chlorite, and opaque materials mainly comprise the matrix materials. The pyrite grains from the Yemi breccia can be divided into two types based on the mineral texture: diagenetic and hydrothermal. We analyzed the chemistry of pyrite and hematite (after pyrite) from the Yemi breccia with an electron probe X-ray microanalyzer (EPMA). Invisible gold was detected within the pyrite grains by EPMA and disseminated micron-sized isolated gold particles were discovered by backscattered electron (BSE) images. The texture of Au-bearing pyrite and gold particles in the Yemi breccia is especially well matched with pyrite and gold from the Shuiyindong Carlin-type hydrothermal gold deposits, China. Therefore, we suggest an important role of hydrothermal fluid in karstification within the Paleozoic carbonate rock.

PECULIARITIES OF THE PYRITE CHEMICAL COMPOSITION IN THE SUPRA-ORE ZONE OF THE TASEEVSKOE GOLD-SILVER DEPOSIT (RUSSIA, TRANSBAIKALIA)

2021 ◽  
Vol 27 (5) ◽  
pp. 44-52
Author(s):  
G. Yurgenson ◽  
Keyword(s):  
Chemical Composition ◽  
Original Data ◽  
Gold Deposits ◽  
Arsenic Content ◽  
Gold Content ◽  
Silver Deposit ◽  
Objective Data ◽  
Gold Silver ◽  
Almost All

The relevance lies in the need to have objective data to assess the belonging of pyrite outcrops to the day surface to the supra-ore zones of gold deposits of a shallow gold-silver formation based on objective data on its chemical composition and forms of crystals and their aggregates. The purpose of the study is to determine the chemical composition of pyrite, the forms of its crystals and aggregates as typomorphic signs of their belonging to the supra-ore zone of the deposit of this formation. The object of the research is pyrite of the supra-ore zone of the Taseevskoye deposit, which is unique in terms of gold content and reserves. The subject of the research is the chemical composition and forms of pyrite separation. The method and methodology are presented by optical and electron microscopy with the determination of variations in the chemical composition of pyrite and morphological features of crystals and their aggregates. Results. The determination of the chemical composition of pyrite was carried out and it was found that almost all crystals are characterized by a sulfur deficiency, the formula coefficients of which are 1.801–1.939 with a change in content from 48.39 to 52.62 %. In 70 % of the measured pyrite crystals, arsenic is present from 0.72 to 4.78 % the formula coefficients of which are 0.007 - 0.076. In 2 % of pyrite crystals, along with As, antimony was found in an amount of 0.21 - 0.71 %, formula coefficients are 0.006 - 0.007. The forms of pyrite crystals are cubic, cubopentagondodecahedral, rarely cuboctahedral and subspherical aggregates, less often lenticular and veinlet, predominate. Conclusions. For the first time, original data on the chemical composition of pyrite in the supra-ore zone of the Taseevskoe gold-silver deposit were obtained. It is shown that its feature is high arsenic content (0.72 - 4.78 %), which can be an important typochemical sign for determining the belonging of chalcedony-like quartz containing it to the supra-ore zone of a shallow gold-silver formation

UNCLOAKING INVISIBLE GOLD: USE OF NANOSIMS TO EVALUATE GOLD, TRACE ELEMENTS, AND SULFUR ISOTOPES IN PYRITE FROM CARLIN-TYPE GOLD DEPOSITS

2009 ◽  
Vol 104 (7) ◽  
pp. 897-904 ◽  
Author(s):  
S. L.L. Barker ◽  
K. A. Hickey ◽  
J. S. Cline ◽  
G. M. Dipple ◽  
M. R. Kilburn ◽  
...  
Keyword(s):  
Trace Elements ◽  
Sulfur Isotopes ◽  
Gold Deposits ◽  
Invisible Gold ◽  
Carlin Type Gold Deposits

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

1998 ◽  
Vol 93 (4) ◽  
pp. 463-487 ◽  
Author(s):  
Alexander D. Genkin ◽  
Nikolai S. Bortnikov ◽  
Louis J. Cabri ◽  
F. E. Wagner ◽  
Chris J. Stanley ◽  
...  
Keyword(s):  
Russian Federation ◽  
Gold Deposits ◽  
Invisible Gold ◽  
Multidisciplinary Study

scholarly journals Invisible Gold in Pyrite from Epithermal, Banded-Iron-Formation-Hosted, and Sedimentary Gold Deposits: Evidence of Hydrothermal Influence

Minerals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 447 ◽  
Author(s):  
Yuichi Morishita ◽  
Napoleon Q. Hammond ◽  
Kazunori Momii ◽  
Rimi Konagaya ◽  
Yuji Sano ◽  
...  
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Gold Deposits ◽  
Iron Formation ◽  
Banded Iron Formation ◽  
Field Range ◽  
Invisible Gold ◽  
Epithermal Deposits ◽  
As Relationship ◽  
Low Sulfidation ◽  
The Relationship

“Invisible gold” in pyrite is defined as an Au solid solution of the pyrite lattice, sub-microscopic Au nanoparticles (NPs) in the pyrite, or other chemisorption complexes of Au. Because the relationship between the Au and As concentrations in pyrite could indicate the genesis of the deposit, the purpose of this study is to assess the micro-analytical characteristics of the Au–As relationship in pyrite from epithermal and hydrothermally affected sedimentary Au deposits by secondary ion mass spectrometry. The Au and As concentrations in pyrite vary from 0.04 to 30 ppm and from 1 to 1000 ppm, respectively, in the high-sulfidation Nansatsu-type epithermal deposits; these concentrations are both lower than those of the low-sulfidation epithermal Hishikari deposit. The Au concentrations in pyrrhotite and pyrite reach 6 and 0.3 ppm, respectively, in the Kalahari Goldridge banded-iron-formation-hosted gold deposit, and Au in pyrrhotite may sometimes exist as NPs, whereas As concentrations in pyrrhotite and pyrite are both low and lie in a narrow range from 6 to 22 ppm. Whether Au is present as NPs is important in ore dressing. The Au and As concentrations in pyrite from the Witwatersrand gold field range from 0.02 to 1.1 ppm and from 8 to 4000 ppm, respectively. The shape of the pyrite grains might prove to be an indicator of the hydrothermal influence on deposits of sedimentary origin, which implies the genesis of the deposits.

scholarly journals Albite ± Actinolite-Altered Porphyry Dykes in Archean Gold Deposits of the Boulder Lefroy-Golden Mile Fault System, Yilgarn Craton, Western Australia: Petrography, Chronology, and Comparison to Canadian Albitites

Minerals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1288
Author(s):  
Andreas G. Mueller ◽  
Neal J. McNaughton ◽  
Janet R. Muhling
Keyword(s):  
Alkali Feldspar ◽  
Gold Deposits ◽  
Strike Slip ◽  
Fault System ◽  
Main Stage ◽  
Yilgarn Craton ◽  
Trapping Temperature ◽  
World Class ◽  
Ore Grade ◽  
Golden Mile

The Boulder Lefroy-Golden Mile fault system in the Archean Yigarn Craton is the most productive gold-mineralized structure in Australia (>2300 t Au). The New Celebration deposit (51 t Au) is part of a group of hematite- and anhydrite-bearing mesothermal deposits and Fe-Cu-Au skarns associated with monzodiorite-tonalite intrusions in the strike-slip fault system. Ore-grade biotite-carbonate and late sericite-carbonate-alkali feldspar replacement is bound to the contacts of a felsic (low Cr, Ni, V) quartz-plagioclase porphyry dyke dated at 2676 ± 7 Ma. The sodic-potassic alteration of the felsic boudinaged dyke contrasts with the albite-actinolite alteration in the adjacent mafic (high Cr, Ni, V) plagioclase porphyry dated at 2662 ± 4 Ma, although both share the same sulfide-oxide assemblage: pyrite ± chalcopyrite, magnetite ± hematite. The younger porphyry locally crosscuts foliation and is bordered by post-kinematic actinolite-pyrite selvages overprinting talc-chlorite-phlogopite-dolomite schist. It contains auriferous pyrite (70 ppb Au; 610 ppb Ag) where sampled for zircon U-Pb chronology at +224 m elevation. Above the sample site, the dyke was mined as gold ore (1–6 g/t Au) at +300–350 m. Temperature estimates based on actinolite-albite pairs (300–350 °C) agree with the fluid inclusion trapping temperature of main-stage auriferous veins (330 ± 20 °C). These relationships are interpreted to indicate syn-mineralization emplacement. Gold-related albite-altered porphyry dykes (albitites) also occur in the world-class Hollinger-McIntyre (986 t Au) and Kerr Addison-Chesterville deposits (336 t Au), Abitibi greenstone belt, Canada.

UNCLOAKING INVISIBLE GOLD: USE OF NANOSIMS TO EVALUATE GOLD, TRACE ELEMENTS, AND SULFUR ISOTOPES IN PYRITE FROM CARLIN-TYPE GOLD DEPOSITS

2009 ◽  
Vol 104 (7) ◽  
pp. 897-904 ◽  
Author(s):  
S. L. L. Barker ◽  
K. A. Hickey ◽  
J. S. Cline ◽  
G. M. Dipple ◽  
M. R. Kilburn ◽  
...  
Keyword(s):  
Trace Elements ◽  
Sulfur Isotopes ◽  
Gold Deposits ◽  
Invisible Gold ◽  
Carlin Type Gold Deposits
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