Tons Of Gold Research Articles

The Repatriation of 100 Tons of Gold to India: Economic Implication and Strategic Significance

This paper studies the recent repatriation of 100 tons of gold to India, in May 2024, by the Reserve Bank of India (RBI). Exploring its economic, financial, and strategic implications. The analysis delves into the motives behind this significant move, its impact on India's economic stability, monetary policy, and global financial positioning, and offers recommendations for future gold reserve management.

The Gold of the Dacians

Abstract The Dacians hoarded about 200 tons of gold and 400 tons of silver, before the Roman conquest of 105/106 AD. The exploitation of gold and silver by the Dacians is attested by the multitude of artifacts discovered in the territory inhabited by them. The work presents the most important treasures of gold and silver of the Dacians, but also the evaluation of the spoils of war taken by the Romans after the defeat of the Dacians.

Assessing the Economic Value of Copper Mineral Resources in Ta Phoi Area, Lao Cai Province

Copper ore is one of the minerals that play an important role in the economic development of Lao Cai province. However, this is a non-renewable resource with high risk and great environmental impact in the mining process. Therefore, it is necessary to study and evaluate the economic value of mineral resources, creating a basis for planning the process of exploration, exploitation, rational use of resources, and environmental protection. This paper evaluates the economic value of mineral resources using resource assessment techniques. The total reserves and identified resources are 21,473 thousand tons of ore, corresponding to 160,278 tons of copper. In the case of using level 122 reserves, the identified resources is 16,412 thousand tons of ore, corresponding to 129,433 tons of copper. The forecasted resources are approximately 41,050 thousand tons of ore, which is equivalent to 198,235 tons of copper. The accompanying minerals, with a resource level 333, include 6.34 tons of gold (Au) and 24.39 tons of silver (Ag). The results show that copper content in the area is varied from 0.01% to 9.18% with an average of 1.50%, and the ore grade is changed from poor to medium. The distribution of copper ores is relatively uniform to very uneven, with the largest concentration found in the Ta Phoi area. The calculated potential recovery value (GTNth) and unit area value (URV) of copper minerals in the study area are substantial, with the highest URV is observed in the Ta Phoi area and the lowest one is obtained in the Coc San area. During the extraction process, the investor should consider recovering accompanying elements such as gold and silver to enhance the mine's economic value.

Metamorphism (greenschist facia down) of terrigenous rocks in the northern part of the Kularsky gold-bearing district, Yakutia: mineral ratios with cleavage

In the Kularsky gold-bearing area, where 170 tons of gold were extracted from placers, primary gold deposits have not been well studied; therefore, their development requires detailed geological analysis including the study of rock metamorphism. A large Ulakhan-Sis anticline composed of Permian carbonaceous-terrigenous rocks is found on the northwestern flank of the Kular-Nersky folded belt of the Verkhoyano-Kolyma orogenic region. In this article we describe the material composition of carbonaceous-terrigenous rocks prevalent in the northern part of the Kularsky district. The degree of their postdiagenetic transformations varies from metagenesis in Triassic rocks to muscovite-chlorite and biotite subfacies of the greenschist facia of metamorphism in Permian rocks of the Ulakhan-Sis anticline. As the transition from metagenesis to muscovite-chlorite and biotite subfacies of metamorphism the degree of recrystallization of rocks, the grain sizes of the recrystallization of clastic quartz and the width of newly formed muscovite flakes are increasing, monazite, ilmenite, biotite flakes appear in rocks. These changes occur before the completion of formation in the rocks of the S1 slate cleavage.After the formation of the latter, mainly before the appearance of a later crenulation cleavage S2, crystallization of pyrite occurs in the rocks. Porphyroblasts of biotite and magnesiosiderite appear during the formation of a crenulation cleavage S2. The appearance of biotite during the formation of the S1 and S2 cleavages may correspond to the theories about the two-stage metamorphism of the rocks of the area. Thus, further metamorphism studies in this region are required.

A picture of artisanal and small-scale gold mining (ASGM) in Brazil and its mercury emissions and releases.

This study presents a picture of ASGM in Brazil and prospective numbers on mercury emissions and releases in 2016, when the country declared production of about 90 tonnes of gold, of which circa 25 tonnes came from ASGM. However, it is also necessary to consider the illegal production of ASGM which is estimated to vary between 10% and eight times more than the legal production. The proposed method included: organization of spatial data on legal ASGM output, stakeholder identification and meetings, mercury metallurgical balance, quantitative measurement of mercury in the atmosphere and qualitative social aspects such as the miners' economic dependence on the managers and scenarios of illegal ASGM annual production. The main results revealed that the initial mercury (Hg)-gold (Au) production ratio was higher for the primary whole ore than for the concentrate secondary ore, which is the most frequent type of Brazilian ASGM. The amalgam filtering technique followed by mercury recovery is routine, decreasing the Hg releases to tailings ponds or to soil and water bodies. The mercury emissions by thermal decomposition of amalgam are independent of the initial mercury mass, depending only on the mercury in the amalgam and the (adequate) use or not of emission control systems. Illegal activities reduce the availability and proper use of these systems, resulting in higher emissions. Mercury emissions from ASGM in Brazil may increase the global mercury emissions estimates, while their mercury releases may represent a marginal increase. As the mercury emitted may be trapped by the rainforests added to the mercury released, the environmental contamination may pose health risks to Amazonian population, which requires immediate action.

Gold mineralisation by pyrite recrystallisation and arsenopyrite sequestration in the Jiaochong Au deposit, Tongling ore district, eastern China: Implications for the formation of stratabound ore deposits

The Middle–Lower Yangtze River Valley metallogenetic belt (MLYRB) is a large and economically valuable porphyry–skarn Cu–Au ore belt in China with a total reserve of >600 tonnes of gold. Orebodies in the MLYRB are commonly stratabound and extend for several tens of metres in length and locally for more than 1000 m. However, the origin of the stratabound orebodies is uncertain, with proposals including a magmatic or sedimentary genesis, and the specific processes by which these gold deposits were formed are also unclear. Here we report a study of the representative stratabound Jiaochong Au deposit in the Tongling ore district, where stratified gold orebodies are hosted at the Triassic -Permian strata boundary. A detailed field survey, petrologic observations, in situ sulfur isotopic analysis, and major and trace element compositional analysis of gold and sulfide grains were carried out to determine how the gold was enriched. Field survey shows that precipitated sulphides exhibit obvious mineral and textural zonation from wall-rock to orebody centres as follows: Zone 1, colloform pyrite (Py1) ± sphalerite ± chalcopyrite → Zone 2, euhedral pyrite (Py2) ± pyrrhotite + arsenopyrite ± colloform pyrite (Py1) → Zone 3, pyrrhotite + arsenopyrite. From zone 1 to zone 3, the sulphides were progressively phase-transformed, with the earlier Py1 being gradually consumed and converted into Py2, which finally became pyrrhotite. The gold deposition occurs in Zones 2 and 3 and forms two generations of gold grains, one group being completely enclosed within euhedral Py2 with low As contents (<0.1 wt%) and another group infilling fractures between arsenopyrite and pyrrhotite or occurring as inclusions within arsenopyrite with high As contents (0.4 to 1.4 wt%). The comparable S-isotope compositions of the ore sulfides to those of Mesozoic intermediate-felsic intrusions and the veining characteristics of colloform pyrite in the Tongling ore district suggest that Mesozoic magmatic-hydrothermal fluids, rather than Carboniferous sedimentary rocks as usually thought, provided the principal ore-forming materials. The gold precipitation in this study followed two continuous processes: recrystallisation and arsenopyrite sequestration; in the first process, Au is remobilised from the pyrite structure at higher temperatures up to recrystallisation of fine-grained, colloform morphologies into euhedral crystals and formation of Au-bearing metallic particles (Au1); with the ongoing recrystallisation more As is released and accumulated into the equilibrated fluids, forming As-rich pyrite or arsenopyrite and a second period of gold deposition (Au2). The continuous sulphide zonation texture and phase transformation, similar to Jiaochong, have been observed in other gold deposits in the MLYRB, and our gold enrichment processes may also give an explanation for the formation of these stratabound gold deposits.

ПЕРСПЕКТИВЫ СОЛОВЬЕВСКОГО ЗОЛОТОРОССЫПНОГО ЦЕНТРА ПРИАМУРСКОЙ ПРОВИНЦИИ

The authors have carried out the analysis of geological and structural features and gold content of the Solovyov gold-bearing center, located on the western flank of the Amur gold-bearing province and confined to the junction of the Aldano-Stanovoi, Mongol-Okhotsk and Amur geoblocks. The center consists of nine ore-placer nodes (Berezitovy, Solovyovsky, Urkiminsky, Dzheltulaksky, Talginsky, Uspenovsky, Ilikano-Unakhinsky, Zolotogorsky and Mogotsky). In geological and structural terms, ore-placer nodes correspond to intrusive dome uplifts (Berezite, Solovyovsky and Urkiminsky nodes) or tectonic blocks of the Aldano-Stanovoy geoblock base metamorphic rocks, saturated with intrusive Archean to late Mesozoic formations (Jeltulak, Talginsky, Uspensky, Ilikano-Unakhinsky, Zolotogorsky and Mogotsky nodes). In the center there are 383 placers of gold and 9 deposits of ore gold – Berezitovoye, Mosin Mine, Kirovskoye, Solovyevskoye, Malourkanskoye, Odolgo, Uspenovskoye, Golden Mountain, Uganskoe, as well as dozens of gold manifestations. Since 1867, about 500 tons of gold have been extracted from the placers of the center, on average about 3.3 tons per year. Gold deposits yielded about 53 tons of ore gold. The ratio of the amount of placer and ore gold extracted from the subsoil is 9.4:1. This indicates the center high prospects for finding new gold deposits. The prospects for further exploitation of placers have been identified, consisting in the introduction of new technologies that ensure the extraction of small and fine fractions of gold and thereby involve poor and man-made placers in the exploitation. It is shown that the Solovyovsky placer gold center future depends on the identification and exploitation of new deposits of gold-polymetallic, gold-sulfide-quartz, gold-quartz, gold-antimony and gold-mercury formations.

Gold Is Old: Noble Metal in the Indian Economy Through Ages

Indians have had a fascination for possessing gold since ancient times. I document the sacredness of gold, ancient references to jewellery, gold extraction and minting technology, its function as money and store of value, and specie inflow due to trade surplus with the Occident up until the medieval era. India’s gargantuan stock of about 28,000 tonnes of gold is hoarding and not savings. Today, gold demand is causing leakage from the circular flow of gross domestic product and trade deficit. Policy suggestions are made that will re-channel idle excess stock of gold into financial markets, reduce the trade deficit and contribute to gross domestic product growth.

Mineral Associations of Concentrates from Gold-Bearing Placers of the Miass Placer Zone (South Urals) and Possible Primary Sources of Gold

Abstract —The placer deposits of the Miass valley in the Southern Urals have been known since the beginning of the 19th century. Over two centuries of mining more than 120 tons of gold have been extracted from alluvial and alluvial–deluvial placers. Despite the industrial significance of this territory, native gold of alluvial deposits is practically unstudied and there is no data on the mineral composition of concentrates. Native gold and heavy fraction minerals from seven placers of the Miass placer zone of deluvial–alluvial and alluvial types were researched. The study of the typomorphic features of native gold and distribution of heavy fraction minerals in loose deposits makes it possible to determine the genetic types of primary sources of placer formation. Chrome-spinel and ilmenite prevail in the concentrates, magnetite, epidote, rutile, titanite, clinopyroxene, hematite, zircon, garnets, and monazite are less common. Chromespinelides of various placers are represented by chromite and subferrichromite, they are characterized by a high average content of Cr2O3 (50.9 wt.%). Chromespinelide chemical composition features show evidence of its penetration into placer sediments from rocks of the ophiolitic association. The composition and morphological features of phosphates of rare earth elements (monazite and xenotime) indicate their metamorphogenic nature and penetration into placers from the Riphean strata. Native gold is characterized by a low degree of roundness. Mineral inclusions in native gold are represented by sulfides, arsenides, bismuthides, cuprous gold, platinoids. Composition of native gold from the Miass River valley placers varies over a wide range. The main admixtures are silver (4.5–23.4 wt.%) and mercury (up to 5.14 wt.%), copper (up to 2.03 wt.%) was noted in several grains. The EBSD study of native gold internal structure showed predominance of primary crystallization structures, a low degree of deformation and growth of gold-rich rims with a fine-grained mosaic structure. Formation of gold-rich rims in gold grains in placers is explained by recrystallization of the most deformed parts of gold during transportation. Placers occurred due to the destruction of primary sources located in the upper reaches of streams or near them, which is confirmed by a low degree of grains’ roundness. The composition of native gold in combination with a set of micro-inclusions indicate the gold–sulfide-quartz type of mineralization of most primary sources.

Состояние основных производственных фондов и обеспечение промышленной безопасности

The level of accident rate at hazardous production facilities is largely determined by the degree of moral and physical depreciation of the fixed assets in the fuel and energy industry. Depreciation factor of the fixed assets is almost always present among the causes of accidents at hazardous production facilities in the modern-day Russia. Fixed assets are large blocks of the industrial safety foundation. Accident rate and injury rate, as inevitable and tragic costs of industrial production, originated in the industrial era, do not disappear in the post-industrialism, and become problematic in the crisis of industrialism. To assess the state of safety at hazardous production facilities, an up-to-date risk-oriented map is required related to the creation, availability, use and maintenance of the fixed assets of industrial production. The information is considered in the article concerning the fixed assets of the Russian industry from the middle of the 20th century to the present, which was obtained according to the statistical data from the official sources of the Central Statistical Office of the USSR and the RSFSR, the State Statistics Committee of Russia, Rosstat, and Rostechnadzor. Despite the stabilization of the asset renewal, in the last 15 years there is a tendency to accelerate the depreciation of fixed assets at hazardous production facilities. With an average renewal rate of 6% per year achieved over the past decade, the fixed assets of industry, including buildings, machinery, and equipment, should work for almost 17 years until they are replaced. In general, over the thirty years of post-Soviet reforms, underinvestment in the fixed capital of the Russian industry amounted to more than 98 trillion rubles, or 24.7 thousand tons of gold, which is more than 10 times the country gold reserve in 2023. Almost half of the «residual resource» was exhausted from the industrial material and technical funds. The current volume of the market for industrial safety expertise of technical devices is sharply incomparable with the scale of the task effectively solved by the economic management on underinvestment in fixed assets in industry of more than 1.5 trillion US dollars for the period from 1991 to 2022. Imported economic management was unable to ensure long-term conservation of the material and technical base of the Russian industry. On average, up to 70% of the equipment used at hazardous production facilities worked out the standard service life. Degree of the depreciation of fixed assets of the fuel industry in Russia in the early twenties exceeded the average industrial level by almost 7 percentage points, while in 2015–2021 the share of completely worn-out facilities in the extractive industry increased by 7.3 percentage points. The functions of supervision over the safe reproduction of industrial fixed assets must be responsibly transferred to the sovereign structures of risk-oriented ensuring of industrial safety in Russia.

Typomorphic Features and Source of Native Gold from the Sykhoi Log Area Placer Deposits, Bodaibo Gold-Bearing District, Siberia, Russia

The Bodaibo gold-bearing district in the Lena gold province of Siberia is one of the largest and oldest placer gold-bearing provinces in the world. Approximately 1650 tons of gold has been extracted from the region. Precise studies on the source of these unique placer deposits are lacking and still controversial. Native gold from four different locations was gathered to investigate its morphology, chemical signatures, structure and inclusions. Some data on primary bedrock mineralization were obtained from the published literature. The linear weathering crusts developed along the zones of disjunctive dislocations near the Sukhoi Log gold deposit were researched. If they coincided with zones of low-grade veinlet-disseminated gold–quartz–sulphide mineralization with small gold grain sizes, a supergene replacement of primary mineralization was known to have occurred, accompanied by the formation of gold-rich rims and an increase in the size, content and purity of gold. Such mineralization associated with linear weathering crusts can be a source of local eluvial–proluvial placers, while placers of large valleys are formed due to low-sulphide gold–quartz lodes.

Origin and evolution of the ore-forming fluids of the Bajiazi gold deposit in the Jiapigou gold ore belt, NE China: Constraints from fluid inclusions, H-O-S isotopes, and pyrite trace element concentrations

The Bajiazi gold deposit, located within the southeastern Jiapigou gold ore belt (JGB) along the northeastern corner of the North China Craton (NCC), contains > 6 tons of gold at an average grade of 24 g/t. More than 20 total auriferous quartz veins are hosted in the Neoarchean basement gneiss and amphibolite and are spatially and temporally associated with Mesozoic intermediate-acid dikes. The distribution of the gold orebodies is mainly controlled by NNE-trending brittle–ductile shear zones and faults. Three hydrothermal stages were identified, namely, quartz–pyrite (stage I), quartz–gold–polymetallic sulfide (stage II), and quartz–carbonate (stage III). Three types of fluid inclusions (FIs) were identified: H2O–NaCl (W-type), CO2–H2O (C-type), and pure CO2 (PC-type) FIs. From stage I to stage III, the FI suite changes from W-type and C-type in stage I to all three types in stage II and to only W-type in stage III. The FIs in the quartz of stages I to III mainly homogenized at temperatures (Th) of 283–395 °C, 183–287 °C and 116–186 °C, respectively, with salinities of 3.87 to 13.01 wt% NaCl equiv, 4.65 to 18.55 wt% NaCl equiv, and 3.83 to 9.68 wt% NaCl equiv, respectively. The ore-forming fluids of the Bajiazi gold deposit evolved from a H2O–NaCl–CO2 system in stages I and II to a H2O–NaCl system in stage III. Fluid immiscibility is an important mechanism leading to rapid precipitation of sulfides and gold. H–O–S isotope signatures indicate that the initial ore-forming fluids and materials were originally derived from magmatic sources. Electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) data on pyrite grains show that abundant gold mineralization occurred in the middle hydrothermal stage. The high Co/Ni ratios of pyrite are consistent with a magmatic–hydrothermal origin. The results, combined with previous regional studies, indicate that the Bajiazi gold deposit is a mesothermal magmatic–hydrothermal lode gold deposit.

Origin of Disseminated Gold-Sulfide Mineralization from Proximal Alteration in Orogenic Gold Deposits in the Central Sector of the Yana–Kolyma Metallogenic Belt, NE Russia

The Yana–Kolyma metallogenic belt, NE Russia, is a world-class gold belt with resources numbering ~8300 tons of gold. The belt is localized in the central part of the Verkhoyansk–Kolyma orogen, formed by a collage of diverse terranes. The Tithonian-to-Early-Cretaceous orogenic gold deposits are hosted in a sequence of Permian–Triassic and Jurassic clastic rocks and altered Late Jurassic andesite, dacite, granodiorite, trachyandesite, and trachybasalt dykes. High-fineness gold (800–900‰) in quartz veins and invisible gold in disseminated arsenian pyrite-3 (Py3) and arsenopyrite-1 (Apy1) are present in ores. Here, we present new data about microtextures; the chemical composition and stable sulfur isotopes of auriferous pyrite-3 and arsenopyrite-1 from proximal alterations in sediment-hosted (Malo–Taryn, Badran, Khangalas); and intrusion-hosted (V’yun, Shumniy) orogenic Au deposits in the central sector of the Yana–Kolyma metallogenic belt to better constrain the ore-forming process and tracking their evolution. Detailed petrography defined the following generations of pyrite: syn-sedimentary/diagenetic Py1, metamorphic Py2 and hydrothermal Py3, and Apy1. Hydrothermal Py3 and Apy1 are localized in the proximal pyrite–arsenopyrite–sericite–carbonate–quartz alteration in ore zones and make a major contribution to the economic value of the veinlet-disseminated mineralization with “invisible” gold in the orogenic deposits of the Yana–Kolyma metallogenic belt. Electron microprobe analysis (EMPA) of Py3 in both types of deposits shows concentrations of As (up to 3.16 wt%), Co, Ni, Cu, Sb, and Pb. Py3 in intrusion-hosted orogenic gold deposits reveals elevated concentrations of Co (up to 0.87 wt%), Ni (up to 3.52 wt%), and Cu (up to 2.31 wt%). The identified negative correlation between S and As indicates an isomorphic substitution of sulfur by As1−. Py3 from igneous rocks is characterized by a high degree of correlation for the pairs Fe2+→ Co2+ and Fe2+→ Ni2+. For hydrothermal Apy1, Co (up to 0.27 wt%), Ni (up to 0.30 wt%), Cu (up to 0.04 wt%), and Sb (up to 0.76 wt%) are typomorphic. According to atomic absorption spectrometry, the concentration of Au in Py3 reaches 159.5 ppm; in Apy1, it reaches 168.5 ppm. The determination of the precise site of the invisible gold within Py3 and Apy1 showed the predominance of solid-solution Au+ in the crystal lattice. The values of δ34S in Py3 and Apy1 (from −6.4 to +5.6‰, mean value of about +0.6‰), both from sediment-hosted and from intrusion-hosted deposits, display a relatively narrow range and are characteristic of the hydrothermal ore stage. Our analytical results showed no systematic differences between the chemical and stable sulfur isotope compositions of both auriferous pyrite-3 and arsenopyrite-1 from the proximal alteration in sediment-hosted (Malo–Taryn, Badran, Khangalas) and intrusion-hosted (V’yun, Shumniy) orogenic Au deposits, indicating that the primary source of sulfur, gold, and mineralizing fluids was likely from subcrustal and metamorphic systems in the Late-Jurassic-to-Early-Cretaceous Verkhoyansk–Kolyma orogen.

Gold endowment and unloading along pathway for giant gold mineralization: Insights from spatiotemporal variations of in-situ pyrite geochemistry and gold fineness from the Jiaodong gold deposits, north China Craton

Over 5000 tonnes of gold were accumulated in the Jiaodong Peninsula at the early Cretaceous, the sources and critical ore-forming processes of which are still controversial. Here, we conducted comprehensive in-situ textural, elemental and isotopic analyses on pyrite and gold grains from the different mineralization styles, hydrothermal stages and depths for three representative gold deposits (Linglong, Xiadian and Jiangjiayao) from the northwestern Jiaodong Peninsula, with the aim to exactly constrain the sources and ore-forming processes. Three groups of δ34Spyrite were identified in the studied deposits, of which the Group 1 shows stable and low δ34S (4.8–7.6‰) throughout the hydrothermal evolution while the Group 2 has elevated δ34S (6.0–12.8‰) coupled with increasing As and Au concentrations. The Group 3 shows moderate δ34S (5.2–9.8‰) accompanied by high Al and Si concentrations. The Group 1 suggests a low-δ34S primary auriferous fluid derived from a mantle-related source, whereas the Group 2 indicates the primary auriferous fluid leaching additional S, As and Au from the Precambrian metasedimentary rocks along pathway. The Group 3 is petrographically coupled with numerous silicate inclusions, indicating enhanced fluid-rock interaction between the auriferous fluids and the granitic wallrcoks. Gold fineness decreases from the early to the late hydrothermal stages, combined with increasing deposition of polymetallic sulfides, suggesting an increase of pH resulting in efficient Au deposition. Gold fineness and Bi concentrations in pyrite decrease with shallowing, suggesting that cooling affected Au deposition as well. Bismuth-Te-S minerals were identified in the deep depths, combined with the well correlated Bi and Ag, implying that Bi-Te complexes might play a role in transporting Au and Ag at high-temperature conditions. The above results corroborate that multiple sources and ore-forming processes were responsible for the giant gold mineralization, of which the gold endowment from Precambrian wallrocks needs to be further concerned.

A review of gold production, mercury consumption, and emission in artisanal and small-scale gold mining (ASGM)

Artisanal and small-scale gold mining (ASGM) is one of the largest sources of Hg emissions and is critical for addressing the Hg problem. Due to scarce and punctual statistics provided by governments and agencies, there is almost no accurate data on ASGM production, Hg use, and emissions. In this study, we surveyed different approaches to estimate ASGM production and collected data from different sources, including academic papers and technical reports. Globally, 380–870 tonnes of gold is produced by ASGM each year, with a median value of 520 tonnes. The Hg use in the ASGM sector was estimated to be 640–1000 tonnes each year, with a median value of 892 tonnes. Consequently, 248–838 tonnes of Hg are emitted from the ASGM sector each year, with a median value of 615 tonnes. However, significant discrepancies were found in the data calculated using different approaches, particularly in countries where the estimates were large, such as China. To obtain a more accurate picture of global ASGM activities, a general estimation approach combining specific studies of dominant countries is necessary. For better management of ASGM in the future, developing a solid baseline and comprehensive future projection scenarios and establishing international collaboration to construct guidance on ASGM are recommended.

A modified partitioning algorithm for classification of e-waste

Electronic and electrical industry is the largest and fastest growing manufacturing industry because of tremendous growth in both software applications and upgraded hardware. The past two decades have seen an exceptionally strong growth in the electronic equipment market. Electronic and electrical products become electronic waste (e-waste) when the products or items used lifecycle being ended. Electronic products are made up of many materials like plastics, heavy metals (lead, mercury, gold, platinum, silver, copper, zinc, selenium, cadmium, chromium and many more), dioxin, furans and others which require special end-of-life handling. The estimation of Global e-Sustainability Initiative is that about 320 tons of gold (8% of the total gold supply in the world) and throughout the world, 7,500 tons of silver are being used in the electronics manufacturing industry. Around 30-50 million tons of e-waste is produced every year and the production trend is overwhelming. By the end of the decade, the e-waste recycling market is going to touch $44.3 billion, which is more than four (04) times from its existing size. There are three concerns that arise for the crisis of e-waste. The first is the total volume of units of obsolescent electronic items. The second fact is the global problem as the generation of e-waste in vulnerable amount since everywhere there are people. And the third fact is that, the rate of obsolescence of electronic items i.e. 5 -10% yearly. The developing world has forecasted that by the year 2030 the developed country should discard the use of twice numbers of Personal Computers (PC) than developing countries. Moreover, in developing countries the e-waste is processed either by informal sector or being resold or refurbished and resold recycled in an unsafe manner using unskilled labours. Environmental pollution and occupational health hazards are frequently observed due to informal recycling of e-waste. In developed countries, e-waste is collected to recover some precious metals and safely rid of the toxic metals as they have contained but in developing countries, e-waste is collected mainly to recover a few metals of value and the rest are dumped in nearby areas. In developing countries, the laws for restricting hazardous waste are flexible by which the developed countries export their e-waste to developing countries because of low labour wages and the availability of second-hand market.

Characteristics and Potential of Placer Gold Deposit in Lakan Bilem Block, West Kutai District, East Kalimantan, Indonesia

Kalimantan is recognized as one of Indonesian islands with huge prospect of minerals particularly gold both primary and secondary deposit styles. However, the publication of the gold resources is still restricted to be described in regional/district scale maps or exploration company internal reports, hence, a detailed study on deposit scale remains limited. This study is aimed to document the characteristics and the estimation of potential or resources of the secondary (placer) gold deposit in Lakan Bilem block, West Kutai district, East Kalimantan province, Indonesia. The study was done by field observation followed by microscopic analysis and simple resources estimation of the gold. Gold in the study area occur in the semi-consolidated paleo alluvial deposit as trace mineral. The gold morphologies show platy to angular form with coarse surface which indicates the process of gold deposition is predominantly controlled by hydrodynamic transportation at a relatively moderate regime. Estimation of the indicated resources of gold results a total of 4.96 tonnes of gold potentially occurred in the study area. Exploration drilling with 100 spacing grid is suggested to delineate lateral and vertical distribution of the gold deposit. The drilling also will upgrade confidence level of the resources from indicated to measured resources.

Fluid inclusion and stable isotope (H–O–S–Pb) constraints on the genesis of the Haxi gold deposit, west Junggar, China

The Haxi gold deposit located in the Hatu–Saertuohai metallogenic belt of the west Junggar region, China, is a newly discovered gold deposit with proven reserves of ∼10 tons of gold and an average grade of 6.70 g/t. Primarily, the deposit is hosted in the early Carboniferous Tailegula Formation, controlled by the NEE-trending Anqi fault. The gold ore bodies contain gold-bearing quartz veins and altered basalt. The ore mineral is dominated by abundant sulfides, such as pyrite, arsenopyrite, chalcopyrite, and a little gersdorffite. To date, three types of fluid inclusion in quartz veins have been identified: liquid–gas (V-type), CO2–H2O (C-type), and liquid–rich (L-type). The ore-forming fluids exhibit medium homogenization temperatures (Th) of 226 °C–325 °C with low salinities of 2.24–9.34 wt% NaCl equivalent and low densities from 0.72 to 0.88 g/cm3. The δD values range from −115.3‰ to −100.7‰, with an average value of −109.1‰; the δ18O values range from 11.3‰ to 12.2‰, with an average value of 11.8‰; and the δ34S values in sulfide range from 0.3‰ to 1.8‰, with an average of 1.2‰. The average values of 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb in sulfide are 18.059, 15.547, and 37.996, respectively. To summarize, the metallogenic fluids were derived not from a single source but from late magmatic–hydrothermal fluid mixed with paleo-atmospheric water; furthermore, the ore-forming materials principally originated from a crust–mantle mixed source. The Pb model age calculated using Hautman’s formula is 347–365 Ma, leading to the speculation that the metallogenic period may be Devonian–Carboniferous.

Age and compositions of garnet in a magnesian skarn Au-Cu deposit, Tibet, implications for ore-fluid evolution

Compared to calcareous skarn Au-Cu deposits, magnesian skarn (Mg-skarn) Au-Cu deposits are scarce; hence the early evolution of the ore-fluids to late mineralization for the kinds of deposits has been inadequately investigated. Located at the southern margin of the Bangong-Nujiang metallogenic belt, the Galale Au-Cu deposit contains 32.59 tonnes of gold (average grade 2.04 g/t) and 105,600 tonnes of copper (average grade 0.66 %). The orebodies are hosted in an Mg-skarn with associated minerals, including olivine, pyroxene, garnet, and serpentine, which developed in the contact zone between the granodiorite and dolomite of the Jiega Formation. However, the genetic relationship between the Mg-skarn, granodioritic magma, and Au-Cu mineralization remains unclear. The contribution of early stage ore-forming fluids to late Au-Cu mineralization is still vague. In this study, we present the major and trace element compositions, and U–Pb isotope data for garnets obtained from the Galale deposit. We used the data to define the timing, nature, and evolution of early ore-forming fluid and described the genesis of the deposit. The color, at macro- and micro-scales, and chemical composition of the garnets can be used to divide them into two categories, namely early Al-rich Grt-I type garnets, and late stage Fe-rich Grt-II type garnets. In practice, Grt-I (And29.5∼56.1Gro41.3∼68.0Pra1.6∼2.8) and Grt-II (And96.7∼99.9Gro0∼2.7Pra0.1∼0.7) are grossular-andradite solid solution system garnets. Based on the chondrite-normalized REE patterns, Grt-I can be further divided into two sub-classes: Grt-I-1 domain in the core, enriched in HREEs and U, and Grt-I-2 material in the rim, relatively depleted in HREEs. Grt-II is enriched in LREEs and depleted in HREEs. Eu anomalies are slightly negative for the Grt-I-1 domain, weakly positive for the Grt-I-2 domain, and strongly negative for the Grt-II type garnets. The variations in texture and composition in garnets indicated that the formation of Grt-I garnets occurred during diffusive metasomatism in a relatively closed system, in a moderately oxidized ore-forming fluid setting. The formation of Grt-II occurred in a strongly oxidized setting during advective metasomatism in an open system. The enrichment of REE and U in Grt-I garnets was mainly controlled by a “menzerite” type substitution mechanism, partially explaining the strong positive correlation between Mg and REE concentrations. In the Grt-II type garnets, enrichment may also have been co-controlled by coupling substitution and adsorption. In situ U–Pb dating of garnet shows that Grt-I-1 and Grt-I-2 material has isotopic ages of 92 ± 2 Ma (2σ, MSWD = 0.85) and 91 ± 2 Ma (2σ, MSWD = 0.96), respectively. The results were consistent with the previous ages obtained from the granodiorite and Molybdenite using Re–Os isotopic dating within error. This indicates that magma, skarn alteration, and mineralization were spatially and temporally related. In addition, it indicates that the Galale deposit is a typical Mg-skarn Au-Cu deposit. In the earliest stages of deposit development, ore-forming fluids with a high oxygen fugacity (fO2) have inherited their characteristics from the magma. The crystallization of many magnetites during the oxide stage has decreased oxygen fugacity in the metallogenetic system. This has resulted in a relatively low fO2 fluid for Au-Cu precipitation. The study demonstrates that the ore-fluid fO2 plays a vital role in metal migration, hence Au-Cu mineralization in Mg-skarn deposits.

Gold Particles Recovery using Novel Reducing Agent with Regard to Continuous Approach

Background: Over 300 tonnes of gold utilised in electronics devices every year, end-of-life electronic equipment offers an crucial recycling potential for secondary gold supply. Electronic boards are among common and exploitable sources of gold that are widely used in various industry. The aims of this paper is to use gold element of electronic boards by adjusting its surface functionality and particle size to make this metal to be used in various applications Methods: to gain this purpose by using acidic solutions and up to bottom chemical synthesis method among physical, chemical, and biological methods and by transferring gold particle size from micrometer to nanometer, surface-area-to-volume ratio will be increase such that new structural properties emerge, change, or improve. Results: Tests such as Fourier-Transform Infrared spectroscopy, X-Ray Diffraction, and Field Emission Scanning Electron Microscopy have confirmed high-quality production and proper extraction of gold particles on a nanometer scale from electronic plates and confirmed crystalline structure of extracted gold in range of 70-110 nm. Conclusion: The main objective of this research is to derive and fabricate gold nanoparticles using chemical oxidative route using HCl and Aqua regia to produce gold nanoparticles in Nano dimension scale. Results has shown that gold nanoparticles are synthesized successfully via chemical process. Moreover, Acid concentration and reaction time has enormous effect on production procedure.