Precious Metal Mineralization Research Articles

Empirical Approach for Estimating Reference Material Heterogeneity and Sample Minimum Test Portion Mass for "Nuggety" Precious Metals (Au, Pd, Ir, Pt, Ru).

Quantification of precious metal content is important for studies of ore deposits, basalt petrogenesis, and precious metal geology, mineralization, mining, and processing. However, accurate determination of metal concentrations can be compromised by microheterogeneity commonly referred to as the "nugget effect", i.e., spatially significant variations in the distribution of precious metal minerals at the scale of instrumental analytical beam footprints. There are few studies focused on the spatial distribution of such minerals and its detrimental effects on quantification of the existing suite of relevant reference materials (RM). In order to assess the nugget effect in RM, pressed powder pellets of MASS-1, MASS-3, WMS-1a, WMS-1, and KPT-1 (dominantly sulfides) as well as CHR-Pt+ and CHR-Bkg (chromite-bearing) were mapped with micro-XRF. The number of verified nuggets observed was used to recalculate an effective concentration of precious metals for the analytical aliquot, allowing for an empirical estimate of a minimum mass test portion. MASS-1, MASS-3, and WMS-1a did not contain any nuggets; therefore, a convenient small test portion could be used here (<0.1 g), while CHR-Pt+ would require 0.125 g and WMS-1 would need 23 g to be representative. For CHR-Bkg and KPT-1, the minimum test portion mass would have to be ∼80 and ∼342 g, respectively. Minimum test portions masses may have to be greater still in order to provide detectable analytical signals. Procedures for counteracting the detrimental manifestations of microheterogeneity are presented. It is imperative that both RM and pristine samples are treated in exactly the same way in the laboratory, lest powders having an unknown nugget status (in effect all field samples for analysis) can not be documented to be representing a safe minimum mass basis.

Merenskyite and Other Precious Metal Minerals In Sulfide Blebs From the Rudniy Ultramafic-Mafic Intrusion, Northwest Mongolia

Abstract The compositions of PGE and precious metal minerals located in sulfide blebs from the base of the melagabbro unit of the Rudniy ultramafic-mafic intrusion in northwest Mongolia were studied. Sulfide blebs occur in the elongated narrow zone (∼30 × 0.2 m), which extends along the contact with the leucogabbro. There are two layers in this zone, the upper (present throughout the zone) and the lower (present fragmentarily). The layers differ in bleb shape, size, and distribution. The layers also have different types of olivine crystals and PGE mineral abundances, but exhibit nearly identical whole-rock metal contents. Approximately 240 grains of PGE and precious metal minerals were studied, and at least eight different minerals were identified. Melonite group minerals (PtTe 2 –PdTe 2 –NiTe 2 ) dominate the majority of the single and composite grains in blebs from both layers. A correlation exists between the melonite group mineral compositions based on the host mineral and bleb layer. No other PGE minerals were identified in the lower layer. Three Ag phases, hessite (Ag 2 Te), sopcheite (Ag 4 Pd 3 Te 4 ), and telargpalite [(Pd,Ag) 3 Te], and three Sn phases, paolovite (Pd 2 Sn), taimyrite [(Pd,Cu,Pt) 3 Sn], and an unnamed Pt stannotelluride mineral (probably Pt 3 SnTe 4 ), were identified with hessite in the composite grains of the upper layer. A comparison of compositional data obtained from the melonite group and data from other occurrences indicates an uncommonly wide range of compositions, most likely indicating supercooling conditions during crystallization.

The capacity of aquatic macrophytes for phytoremediation and their disposal with specific reference to water hyacinth.

The actual amount of fresh water readily accessible for use is <1% of the total amount of water on earth, and is expected to shrink further due to the projected growth of the population by a third in 2050. Worse yet are the major issues of water pollution, including mining and industrial waste which account for the bulk of contamination sources. The use of aquatic macrophytes as a cost-effective and eco-friendly tool for phytoremediation is well documented. However, little is known about the fate of those plants after phytoremediation. This paper reviews the options for safe disposal of waste plant biomass after phytoremediation. Among the few mentioned in the literature are briquetting, incineration and biogasification. The economic viability of such processes and the safety of their economic products for domestic use are however, not yet established. Over half of the nations in the world are involved in mining of precious metals, and tailings dams are the widespread legacy of such activities. Thus, the disposal of polluted plant biomass onto mine storage facilities such as tailing dams could be an interim solution. There, the material can act as mulch for the establishment of stabilizing vegetation and suppress dust. Plant decomposition might liberate its contaminants, but in a site where containment is a priority.

Canadian mining in Latin America (1990 to present): a provisional history

Since the early 1990s Canadian mining companies extended their presence in Latin America in unprecedented numbers and ways. This article presents a historical synthesis of this phenomenon. It shows Canadian overseas mining as predominantly focused on exploration and precious metal mining; traces its origins in the nexus between new techniques and hubs of speculative capital; and shows the political innovations produced by this commodity frontier, both in the deployment of new forms of corporate governmentality and in the emergence of locally-based movements for resource sovereignty and socio-ecological justice.

The paragenesis of silver minerals in the Pb-Zn Stan Terg deposit, Kosovo - an example of precious metal epithermal mineralization.

This study reports silver mineral association found recently in the Stan Terg lead and zinc mine, located in the Vardar Zone (in the northern Kosovo). The described mineralization comprises pyrargyrite, freieslebenite, high-Ag bearing tetrahedrite, freibergite and native compounds (electrum, native silver, native antimony). Ag-minerals occur in vuggs and cracks in massive galena ore, and have signs of the latest precipitated minerals in the deposit. The chemical composition of those minerals was confirmed by the electron microprobe. Freibergite from the Stan Terg deposit reveals zonality and contains between 13.91-20.28 at. % of Ag. High Ag solutions are indicated also by relatively high silver content in electrum, which is between 47.02 and 73.19 at. % of Ag. The Ag association is supposed to be an epithermal equivalent of precious metal mineralization which could be located in the external part of the Stan Terg hydrothermal system. This association occurs in low temperatures, below 200˚C. The Ag-minerals can be part of epithermal veins from the external part of the Stan Terg hydrothermal system. Similarly to the other know Pb-Zn-Ag hydrothermal system, silver association is related to formation of the rhodochrosite banded ore and Ag-Au-Sb±Hg dominated mineralization.

Вопросы налогового регулирования и стимулирования производства на примере добычи, производства и обращения драгоценных металлов и драгоценных камней

Вопросы налогового регулирования и стимулирования производства на примере добычи, производства и обращения драгоценных металлов и драгоценных камней

Concentration of precious metals during their recovery from electronic waste

The rapid growth of electronic devices, their subsequent obsolescence and disposal has resulted in electronic waste (e-waste) being one of the fastest increasing waste streams worldwide. The main component of e-waste is printed circuit boards (PCBs), which contain substantial quantities of precious metals in concentrations significantly higher than those typically found in corresponding ores. The high value and limited reserves of minerals containing these metals makes urban mining of precious metals very attractive. This article is focused on the concentration and recovery of precious metals during pyro-metallurgical recycling of waste PCBs. High temperature pyrolysis was carried out for ten minutes in a horizontal tube furnace in the temperature range 800–1350°C under Argon gas flowing at 1L/min. These temperatures were chosen to lie below and above the melting point (1084.87°C) of copper, the main metal in PCBs, to study the influence of its physical state on the recovery of precious metals. The heat treatment of waste PCBs resulted in two different types of solid products, namely a carbonaceous non-metallic fraction (NMFs) and metallic products, composed of copper rich foils and/or droplets and tin–lead rich droplets and some wires. Significant proportions of Ag, Au, Pd and Pt were found concentrated within two types of metallic phases, with very limited quantities retained by the NMFs. This process was successful in concentrating several precious metals such as Ag, Au, Pd and Pt in a small volume fraction, and reduced volumes for further processing/refinement by up to 75%. The amounts of secondary wastes produced were also minimised to a great extent. The generation of precious metals rich metallic phases demonstrates high temperature pyrolysis as a viable approach towards the recovery of precious metals from e-waste.

Proximal and remote spectroscopic characterisation of regolith in the Albany–Fraser Orogen (Western Australia)

Vast parts of the Australian continent are prospective for precious and base metal mineralisation, but exploration is hindered by extensive cover of often deeply reaching regolith. New operational exploration methods are required that can help to characterise the cover and provide information about bedrock signatures. This paper shows how mineral mapping information from a combination of satellite multispectral Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) imagery and drill core hyperspectral profiling data (HyLogging™) can be used to unravel the regolith stratigraphy and to describe regional variations of regolith landforms, delivering important information for mineral exploration.The case study is located in the Neale tenements in the northeastern Albany–Fraser Orogen (Western Australia), which is prospective for Tropicana-style gold mineralisation. By interpretation of indicator minerals from hyperspectral drill hole logging data the regolith stratigraphy atop a metamorphic basement, comprising saprock, ferrugineous saprolite, kaolinitic saprolite, silcrete and transported cover, is recorded in cm-detail. Important mineralogical parameters extracted from the hyperspectral subsurface data and validated by XRD and FTIR, are 1) the abundance and type of iron oxides, 2) the abundance and crystallinity of kaolinite, 3) the abundance and composition of primary minerals, such as white mica, and 4) the abundance of quartz.The HyLogging™ data served as ground control points for mineral mapping information provided by CSIRO's ASTER Geoscience Products, which are a collection of mineral maps that highlight variations in the abundance, type or chemistry of selected mineral groups. Key ASTER Geoscience Products for regolith characterisation were the Ferric Oxide and AlOH abundance and composition images. The comparison of the surface with the subsurface data suggests three major different regolith landforms, including erosional, depositional and relict areas, which were used to generate a map showing transported versus relict and erosional areas. Erosional domains were mapped out in great detail, providing important information for exploration in saprolite dominated areas. Furthermore, source areas of transported material could be identified, which may help to understand the distribution of geochemical signatures collected during, for example, geochemical soil sampling projects.

Follow-up on Ujarassiorit mineral hunt finds and outreach activities, South-East Greenland

In connection with field work in South-East Greenland in 2014, we took the opportunity to examine the geology associated with potentially valuable mineral occurrences found by local rock collectors. The initial finds were made by local collectors as part of Ujarassiorit, which is an annual mineral hunt competition where anyone in Greenland can submit samples of rocks they have found in the countryside for closer examination by the Ministry of Mineral Resources (see www.ujarassiorit.gl). In the Tasiilaq region, Ujarassiorit resulted in finds of corundum, precious metal and base-metal mineral occurrences. Our intention was to locate the original sample sites with help from the local rock collectors, describe the geological context and assess the potential for mineral exploration. Further work will include laboratory analyses of rock samples and geological reporting.

Šlichová prospekce na lokalitách spojených s údajnou historickou těžbou drahých kovů v Moravskoslezských Beskydech

Šlichová prospekce na lokalitách spojených s údajnou historickou těžbou drahých kovů v Moravskoslezských Beskydech

Quartz-sericite and argillic alterations at the Peschanka Cu-Mo-Au deposit, Chukchi Peninsula, Russia

The porphyry Peschanka copper-molybdenum-gold deposit and the Nakhodka ore field located in the Baimka ore trend on the western Chukchi Peninsula are spatially related to monzonitic rocks of the Early Cretaceous Egdykgych Complex. Two types of quartz-sericite metasomatic rocks (QSR) have been identified at both the deposits and the ore field: (I) chlorite-quartz-muscovite rock with bornite and chalcopyrite (porphyry type) and (II) tourmaline-quartz-carbonate-muscovite ± phengite rock accompanied by veins with base-metal mineralization (subepithermal or transitional type), as well as carbonate-quartz-illite rock (argillic alteration) accompanied by veins with precious metal mineralization (epithermal type). The QSR I chlorite evolves from chamosite to clinochlore, which is caused by increasing H2S activity in mineralizing fluid and precipitation of sulfide minerals. The QSR I clinochlore is significantly depleted in silica as compared with that from the rocks affected by argillic alteration. The chemical composition of muscovite from both quartz-sericite alterations is similar. The QSR II carbonates evolve from calcite through dolomite to siderite, which results from the increasing activity of CO2 followed by the decreasing activity of H2S in mineralizing fluid. The Mn content in dolomite is similar to that in beresite (quartz-muscovite-carbonate-pyrite metasomatic rock) of the intrusion-related gold deposits. Illite from argillic alteration is depleted in Al as compared with that of postvolcanic epithermal Au-Ag deposits. However, carbonates from the discussed argillic alteration rhodochrosite and Mn-rich dolomite are similar to those from quartz-illite rock at postvolcanic epithermal Au-Ag deposits.

Time variation in systematic risk, returns and trading volume: Evidence from precious metals mining stocks

We investigate whether trading volume has explanatory power for time variation in CAPM betas as well as returns, for the precious metals mining sector. We show that significant dependencies exist between these variables; however, empirical linkages are only revealed when quantile regression method is employed. The observed dynamics are particularly strong between trading volume and returns. We find that returns from lower (higher) quantiles have a negative (positive) relation with volume. We discuss the consistency of this asymmetric relation with equilibrium volume–return autocorrelation models suggested in prior work.

Judicial privilgies of Saxons in mixed disputes in Medieval Serbia

Based on the contemporary testimonies, wealth of the Serbian medieval kings was significantly increased by exploitation of number of precious metal mines that existed in their realm. Beginnings of the mine exploitation in medieval Serbia are related to the settlements of Saxon miners. Saxons were mining experts in medieval Europe who worked in distant mines far away from their homeland Saxony. They worked in this profitable mining business not only in Serbia, but also in Bohemia, Hungary (Transylvania and modern Slovakia) and Bosnia. The settlement of Saxons in Serbia occurred in time of the reign of King Stefan Uros I (1234-1276). Although without preserved sources which could directly support this thesis, Serbian historiography advocates that certain privileges were granted to the Roman Catholic Saxons at the time of their migration in orthodox Serbia. It appears that these privileges included self-government, freedom of religion, and mining concessions. Also judicial privileges are often mentioned in historiography especially the right of Saxons to one half of the members of their ethnicity in judicial collegium and jury in the case of a dispute with member of another ethic group. This paper attempts to test the thesis related to composition of mixed courts and juries by applying historical method, and linguistic, systemic and historical interpretation of the sources such as King's Charters issued to Dubrovnik, Dusan's Code and Despot Stefan's Mining Code.

Metallogeny of the Triassic‐Jurassic Rift‐Related Mineralizations in Argentina

The Triassic-Jurassic NNW-SSE extensional phase affected the western margin of Gondwana and marked the beginning of the fragmentation of this supercontinent. Extensional faulting began in the Late Permian in the northern areas, becoming younger to the south, i.e. Jurassic in Patagonia. During this stage extensive rhyolitic ignimbrite magmatism developed. The rift system, was filled with continental sediments that locally have intercalated bimodal, predominantly mafic, volcanic rocks. The region affected by the Triassic-Jurassic rifting in the Argentine territory hosts a number of deposits that have no direct link with magmatic activity and whose age has previously been attributed, in general, to the Mesozoic (Zappettini, 1999), or are herein ascribed to this event. These include the Se-rich polymetallic deposits, five elements deposits, Pb-Zn-Ag simple veins, epithermal Mn, fluorite and barite veins. The various types of deposits analyzed have a wide regional distribution reflecting the extent of the processes of rifting that started during the Triassic and reached the Cenozoic, generating thermal and fluid flow anomalies leading to hydrothermal mineralizing processes. Where there was a favorable source, fluids collected selected elements resulting in a mineralogical specialization and inhomogeneities in the distribution of the mineralization types along the belt affected by rifting. Characteristically, where the rifting affected Paleozoic or older sedimentary sequences, polymetallic and barite type deposits were generated. Where rifting affected acidic Triassic-Jurassic volcanic and volcaniclastic sequences the fluids originated fluorite mineralization. In the cases where there was an associated restricted basic magmatism or by leaching or volcanic sequences Mn ore bodies were formed. In all cases, this rift environment has been favorable for the emplacement of alkaline to subalkaline acid magmatic rocks. In these cases, besides the presence of fluorine and fluorine-rich fluids, evidenced by the presence of fluorite and / or topaz, there are associated REE mineralizations (Rodeo de los Molles, Sierras Pampeanas of San Luis and Rangel district, Puna of Salta), Mo-rich stockworks (Elsiren and German) and epithermal gold deposits (Pantanito, and, in general, the Au-Ag epithermal deposits of the Deseado Province). In this context the Pb-Ag polymetallic mineralization of the Navidad deposit formed in relation to a rift-related magmatism represented by volcanic and pyroclastic deposits associated with biochemical and epiclastic sediments deposited within the Canadon Asfalto hemigraben (e.g. Fernandez et al., 2008). From a global point of view, the fluorine, manganese and polymetallic deposits related to extensional environments may be associated with precious metal mineralization (Au-Ag) and Mo-rich porphyries, so that their presence can be used regionally as an exploration guide (e.g. Wallace, 2010).

New insights into precious metal enrichment on the Isle of Rum, Scotland

The Rum Layered Suite (NW Scotland) is generally regarded as one of a handful of classic examples of open‐system layered mafic‐ultramafic intrusions, or ‘fossilized’ basaltic magma chambers, world‐wide. The eastern portion of the Rum intrusion is constructed of sixteen repeated, coupled, peridotite–troctolite units. Each major cyclic unit has been linked to a major magma replenishment event, with repeated settling out of ‘crops’ of olivine and plagioclase crystals to form the cumulate rocks. However, there are variations in the lithological succession that complicate this oversimplified model, including the presence of chromitite (&gt;60 vol. percent Cr‐spinel) seams. The ∼2 mm thick chromitite seams host significant platinum‐group element (PGE) enrichment (e.g. ∼2 ppm Pt) and likely formed in situ, i.e. at the crystal mush–magma interface. Given that the bulk of the world's exploited PGE come from a layered intrusion that bears remarkable structural and lithological similarities to Rum, the Bushveld Complex (South Africa), comparisons between these intrusions raise intriguing implications for precious metal mineralization in layered intrusions.

A large and complete Jurassic geothermal field at Claudia, Deseado Massif, Santa Cruz, Argentina

Late Jurassic geothermal deposits at Claudia, Argentinean Patagonia, are among the largest (40km2) and most varied in the Deseado Massif, a 60,000km2 volcanic province hosting precious metals (Au, Ag) mineralization generated during diffuse back arc spreading and opening of the South Atlantic Ocean. Both siliceous sinter and travertine occur in the same stratigraphic sequence. Deposits range from those interpreted as fluvially reworked hydrothermal silica gels, to extensive apron terraces, to a clustering of high-temperature subaerial vent mounds. Paleoenvironmentally diagnostic textures of sinters include wavy laminated, bubble mat and nodular fabrics, and for travertines comprise fossil terracette rims, wavy laminated, bubble mat, spherulitic, oncoidal, and peloidal fabrics. Of special note is the presence of relatively large (to 25cm high), inferred subaqueous “Conophyton” structures in travertines, which serve as analogs for some Precambrian stromatolites and imply the presence of relatively deep pools maintained by voluminous spring discharges. The Claudia geothermal field is geographically and geologically linked to the Cerro Vanguardia epithermal project (total resource of ~7.8millionounces Au equivalent) via proximity, similar veins, and structural linkages, making it an especially large and relevant prospect for the region. The combined Claudia–Cerro Vanguardia hydrothermal system likely represents a fortuitous alignment of focused fluid flow and structure conducive to forming a giant epithermal ore deposit, with respect to size, ore concentration and potentially duration, in the Late Jurassic of Patagonia.

Petrochemistry and hydrothermal alteration within the Tyrone Igneous Complex, Northern Ireland: implications for VMS mineralization in the British and Irish Caledonides

Although volcanogenic massive sulfide (VMS) deposits can form within a wide variety of rift-related tectonic environments, most are preserved within suprasubduction affinity crust related to ocean closure. In stark contrast to the VMS-rich Appalachian sector of the Grampian-Taconic orogeny, VMS mineralization is rare in the peri-Laurentian British and Irish Caledonides. Economic peri-Gondwanan affinity deposits are limited to Avoca and Parys Mountain. The Tyrone Igneous Complex of Northern Ireland represents a ca. 484–464 Ma peri-Laurentian affinity arc–ophiolite complex and a possible broad correlative of the Buchans-Robert’s Arm belt of Newfoundland, host to some of the most metal-rich VMS deposits globally. Stratigraphic horizons prospective for VMS mineralization in the Tyrone Igneous Complex are associated with rift-related magmatism, hydrothermal alteration, synvolcanic faults, and high-level subvolcanic intrusions (gabbro, diorite, and/or tonalite). Locally intense hydrothermal alteration is characterized by Na-depletion, elevated SiO2, MgO, Ba/Sr, Bi, Sb, chlorite–carbonate–pyrite alteration index (CCPI) and Hashimoto alteration index (AI) values. Rift-related mafic lavas typically occur in the hanging wall sequences to base and precious metal mineralization, closely associated with ironstones and/or argillaceous sedimentary rocks representing low temperature hydrothermal venting and volcanic quiescence. In the ca. 475 Ma pre-collisional, calc-alkaline lower Tyrone Volcanic Group rift-related magmatism is characterized by abundant non-arc type Fe-Ti-rich eMORB, island-arc tholeiite, and low-Zr tholeiitic rhyolite breccias. These petrochemical characteristics are typical of units associated with VMS mineralization in bimodal mafic, primitive post-Archean arc terranes. Following arc-accretion at ca. 470 Ma, late rifting in the ensialic upper Tyrone Volcanic Group is dominated by OIB-like, subalkaline to alkali basalt and A-type, high-Zr rhyolites. These units are petrochemically favorable for Kuroko-type VMS mineralization in bimodal-felsic evolved arc terranes. The scarcity of discovered peri-Laurentian VMS mineralization in the British and Irish Caledonides is due to a combination of minimal exploration, poor-preservation of upper ophiolite sequences, and limited rifting in the Lough Nafooey arc of western Ireland. The geological and geochemical characteristics of the Tyrone Volcanic Group of Northern Ireland and peri-Gondwanan affinity arc/backarc sequences of Ireland and northwest Wales represent the most prospective sequences in the British and Irish Caledonides for VMS mineralization.

The Formation of Low-Volume, High-Tenor Magmatic PGE-Au Sulfide Mineralization in Closed Systems: Evidence from Precious and Base Metal Geochemistry of the Platinova Reef, Skaergaard Intrusion, East Greenland

The majority of magmatic platinum-group element (PGE) deposits in layered mafic/ultramafic intrusions are characterized by visible Cu-Ni Sulfide mineralization, often located in the lower parts of a magmatic stratigraphy that show evidence of multiple magma injections and crustal contamination. The Platinova Reef, hosted by the 55 Ma Skaergaard intrusion, East Greenland, is an example of a rarer type of PGE deposit, typified by a Pd-Au-Cu-dominant, Ni-Pt-poor, Sulfide assemblage present in the upper parts of the host intrusion. Such deposits are generally considered to form through prolonged fractional crystallization of the magma, with magnetite crystallization playing a role in late-stage S saturation. In the case of the Skargaard intrusion, the crystallization of the cumulate rocks, and the generation of the mineralization hosted within them, occurred within a closed system, from a single, homogenized batch of magma. The Platinova Reef is characterized by offsets in the stratigraphic position of individual metal peaks; an anomalously low Sulfide content ( 1 ppm), the Intermediate zone (Pd 0.1–1 ppm), the Au zone (Au >1 ppm), and the upper Cu zone (Cu >200 ppm with precious metals 3 to 10 4 ppm, low Cu/Pd ratios, and a remarkable upward decrease in Pd/Au ratio from 40 to 1, whereas the sulfides in the Cu zone are lower tenor (10 3 ppm Pd), higher volume, and have high Cu/Pd ratios and Pd/Au To explain these features, we present a multistage model of preconcentration, dissolution upgrading, and further metal enrichment. This involves initial S saturation of the Skaergaard magma at a late stage in the crystallization history. The Sulfide liquid produced scavenged metals from the entire volume of the chamber as it sank but was then dissolved as it came into contact with hotter, Fe-rich and S-undersaturated magma at the bottom of the chamber, producing a highly metal rich magma layer at the bottom of the chamber. This layer then became S saturated as a result of continued magnetite crystallization, with the tiny sufide droplets that segregated into this precious metal-enriched magma layer becoming highly enriched in PGE themselves. These were then trapped in situ by the crystallizing cumulate pile forming the Subzone, Pd zone and Intermediate zone. sulfides formed in the rest of the chamber, which was PGE depleted at this stage would have been of low tenor. These Sulfide droplets grew and settled, concentrating any remaining Au when they encounter the floor to form the Au zone and formed the low tenor sulfides of the Cu zone above this. We propose that the Platinova Reef exhibits an unusual example of a style of magmatic precious metal mineralization formed through Sulfide dissolution upgrading in the latter stage of crystallization of a closed system. The offsets in individual metal peaks mineralization demonstrate the relative partitioning of Pd(+Pt) > Au > Cu into a Sulfide liquid from a silicate magma and demonstrates the importance of partitioning behavior in low-volume magmatic Sulfide melts. This feature can lead to the characteristic stratigraphic offsets in peak metal abundances. The role of magnetite crystallization appears to be an important control on S saturation in such systems, and thus may be an important indicator of the location of mineralized horizons. In addition, in such deposits, indicators of crustal contamination by external S and multiple injections of magma, common features of more Ni rich PGE reefs, are less likely to be present.

A Note on New Find of Thick Copper and Associated Precious Metal Mineralisation from Alwar Basin of North Delhi Fold Belt, Rajasthan

The state of Rajasthan is endowed with world class base metal deposits notably the Pb-Zn deposits of Zawar, RajpuraDariba and Rampura-Agucha and copper in Khetri- Nim ka Thana belt. The present note reports the geological attributes of a major new find of unusually thick copper mineralisation in Alwar basin of North Delhi Fold Belt (NDFB) that holds potential for a large copper deposit of economic significance. The mineralization is restricted to the Ajabgarh Group which comprises of argillaceous, arenaceous and calcareous components (Banerjee, 1980; Mukhopadhyay, 2009). The Kushalgarh, Seriska, Thanaghazi, Bharkol and Arauli Formations from bottom to top constitute the Ajabgarh Group. Kushalgarh Formation overlies the quartzite of the Pratapgarh Formation with a sharp contact and is represented by biotite-marble, banded calcareous semi-pelite and quartzite. The present work is restricted to the Thanagazhi Formation of the Ajabgarh Group (Boopathi, 2010). Thanaghazi Formation has a gradational contact with the overlying Bharkol Formation (Singh, 1988). The lower part is calcareous and is associated with quartzite. At several places spotted and pyritiferous phyllites overlie the carbon phyllite.The Alwar basin in the NDFB is known for several incidences of copper and two small copper deposits were reported by GSI at Bhagoni and Kho-Dariba. Copper dominated geochemical anomalies have been reported from the Alwar basin at a number of places, but thick mineralisation of economic significance remained elusive to the mappers and exploration geologists. Reconnaissance prospecting that was followed by detailed mineral exploration by the present authors has led to the first time discovery of an unusual very thick copper mineralisation in Mundiyawas-Khera area in Alwar basin. The explored block (Latitude 27o21'00" to 27o23' 00" N, Longitude 76o16' 30" to 76°17'35" E) is located 5 km SSW of Tehsil headquarter Thanaghazi, Alwar district, Rajasthan.

Fluid Inclusion and Stable Isotope Studies at Don Sixto, a Precious Metal Low Sulfidation Deposit in Mendoza Province, Argentina

AbstractThe Don Sixto mining area in Mendoza province, central‐western Argentina, contains an epithermal low sulfidation Au–Ag deposit. It is a small deposit (∼4 km2), with a gold resource of 36 t. In Don Sixto, ore minerals are disseminated in the hydrothermal quartz veins and hydrothermally altered volcanic‐pyroclastic rock units of Permian–Triassic age. On the basis of the texture, ore mineral paragenesis and cross cutting relationship of gangue minerals, seven stages of mineralization were recognized and described. The first six stages are characterized by quartz veins with minor amounts of base metal minerals and the last stage is represented by fluorite veins with minimal quantities of base metal minerals; the precious metal mineralization is mainly related to the fourth stage. The hydrothermal veins exhibit mainly massive, crustiform and comb infilling textures; the presence of bladed quartz replacement textures and quartz veins with adularia crystals are indicative of boiling processes in the system. Fluid inclusion and complementary stable isotope studies were performed in quartz, fluorite, and pyrite samples from the vein systems. The microthermometric data were obtained from primary, biphasic (liquid‐vapor) fluid inclusion assemblages in quartz and fluorite. The maximum values for salinity and homogenization temperature (Th) came from the stage IV where quartz with petrographic evidence of boiling has average values of 4.96 wt% NaClequiv. and 286.9°C respectively. The lower values are related to the last stage of mineralization, where the fluid inclusions in fluorite have average salinities of 1.05 wt% NaClequiv. and average homogenization temperatures of 173.1°C. The oxygen and sulfur isotopic fractionation was analyzed in quartz and pyrite. The calculated isotopic fractionation for oxygen in the hydrothermal fluid is in the range of δ18OH2O = −6.92 up to −3.08‰, which indicates dominance of a meteoric source for the water, while sulfur reaches δ34SH2S = 1.09‰, which could be reflecting a possible magmatic, or even a mixed source.