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The article provides a review of the scientific research of Academician V.Yu. Kukushkin and his students on the reactivity of coordination compounds, metal complex catalysis, supramolecular chemistry, as well as in other areas. The recognition of the scientific contribution of Academician V.Yu. Kukushkin and his school in Russia and all over the world is highlighted. The article is dedicated to the 300th anniversary of the founding of St. Petersburg University. [ABSTRACT FROM AUTHOR]

Platinum group metals (PGMs), including palladium, play a pivotal role in various industries due to their unique properties. Palladium is frequently employed in technologies aimed at environmental preservation, such as catalytic converters that reduce harmful emissions from vehicles, and in the production of clean energy, notably in the hydrogen evolution process. Regrettably, the production of this vital metal for our environment is predominantly centered in two countries—Russia and South Africa. This centralization has led to palladium being classified as a critical raw material, emphasizing the importance of establishing a secure and sustainable supply chain, as well as employing the most efficient methods for processing materials containing palladium. This review explores techniques for palladium production from primary sources and innovative recycling methods, providing insights into current technologies and emerging approaches. Furthermore, it investigates the economic aspects of palladium production, including price fluctuations influenced by emission regulations and electric vehicle sales, and establishes connections between palladium prices, imports from major producers, as well as copper and nickel prices, considering their often co-occurrence in ores. [ABSTRACT FROM AUTHOR]

Ultrafine gold was found in more than 100 samples from a sedimentary cover of the Voronezh Anteclise during a geological survey. The Au content varies from hundreds to 3.8 g/m3, and the particle size is a few tens of micrometers with a thickness of 1–2 µm. The higher Au content is confined to sandy–clayey rocks from various stratigraphic levels. The chemical composition of native gold is characterized by a high amount of volatiles (Hg, As, S, Bi, etc.) with dominant Hg (up to 13%), as well as a constant presence of platinum group elements, Ag, Pb, Cu, and Zn. The maximum Au content is characteristic of areas with higher permeability in fault zones and geochemical barriers (clayey and ferruginous rocks, as well as phosphorites). The analysis of the genetic features of native gold of the Voronezh Anteclise allows us to ascribe it to an exhalative-sedimentary type known in other regions of Russia and the world. [ABSTRACT FROM AUTHOR]

The study of noble metal minerals of the Ural–Alaskan-type (UA-type) complexes has been traditionally focused on their platinum-bearing dunites and chromitites, while clinopyroxenites have been poorly considered. In this study, we report the first detailed data on the noble metal mineral assemblage in clinopyroxenites of the Kachkanar intrusion, which is a part of a UA-type complex and is renowned for its huge Ti-magnetite deposits. High concentrations of Pd, Au and Ag are closely linked to Cu-sulfide mineralization in amphibole clinopyroxenites, in which they form Pd-Ag-Au minerals: keithconnite Pd3−xTe, sopcheite Ag4Pd3Te4, stutzite Ag5−xTe3, hessite Ag2Te, merenskyite PdTe, kotulskite Pd(Te,Bi), temagamite Pd3HgTe, atheneite (Pd,Hg)3As, potarite PdHg, electrum AuAg and Hg-bearing native silver. Among those, six mineral phases are first reported for clinopyroxenites of the Ural platinum belt. Our evidence supports a petrological model, suggesting that during fractionation of high-Ca primitive magmas at high oxygen fugacity, Pt, Os, Ir, Ru and Rh accumulate in early olivine–chromite cumulates, while Pd, Au and Ag reside in the melt until sulfide saturation occurs and then concentrate in sulfide mineralization. Subsequently, this sulfide mineralization is likely affected by cumulate degassing, which results in a partial resorption of the sulfides and Pd, Au and Ag remobilization by fluid. Second-stage concentration of the sulfides and the chalcophile noble metals in the amphibole-rich rocks may occur when H2O from the fluid reacts with pyroxenes to form amphiboles, and the fluid becomes oversaturated with sulfides and chalcophile elements. [ABSTRACT FROM AUTHOR]

The Middle Paleoproterozoic (1.99 Ga) Tiksheozero ultramafic‒alkaline‒carbonatite complex in Northern Karelia is one of the Earth's oldest alkaline complexes. The major and trace-element compositions of minerals were used to decipher the genetic relations between ultramafic cumulates, alkaline rocks, and carbonatites. Based on detailed analysis of clinopyroxenes from ultramafic cumulates, it was assumed that they were derived from an alkaline melt. It was estimated that ultramafic cumulates and alkaline rocks were formed at close moderate pressure, which in combination with the above facts, is consistent with their cogenetic origin. The REE patterns of clinopyroxenes are characterized by the high LREE/HREE fractionation, with slightly convex-upward LREE patterns (La/Nd < 1), which are typical of deep-seated cumulates formed in an equilibrium with an alkaline basaltic melt. Two types of REE zoning were distinguished in apatite using cathodoluminescence imaging. The first type with an outward LREE decrease was found in apatite from silicate rocks of the complex and was likely produced by the closed-system overgrowth of apatite from a residual melt at the late magmatic stage. In contrast, apatite from carbonatite is characterized by a slight outward LREE increase, which is likely related to the re-equilibration of apatite with fresh batches of REE-enriched carbonatite magma. Precipitation of monazite along fractures and margins of apatite in complex with essential HREE and Y enrichment observed in syenite is indicative of the metasomatic interaction of this rock with fluid. Apatites from alkaline rocks and carbonatites define a common trend in the Y–Ho diagram, with a decrease in the Y/Ho ratio from foidolites to carbonatites. This fact together with the absence of signs of liquid immiscibility, and compositional variations in apatite in silicate rocks and carbonatites, are consistent with their origin through fractional crystallization rather than liquid immiscibility. [ABSTRACT FROM AUTHOR]

Zaykovite, ideally Rh3Se4, is a new mineral, the first natural rhodium selenide. It was discovered in the assemblages of platinum-group minerals from the Kazan gold placer, South Urals, Russia. The mineral occurs as crystals up to 40 μm in size within the grains of Pt3Fe alloy, in association with unnamed Pd–Sb–Te phase and Au–Pd alloy. In reflected light, zaykovite has a grey colour with bluish-greenish tint; it shows weak bireflectance and anisotropy. Reflectance values [ R max/ R min (%) for COM approved wavelengths (nm)] are: 30.1/29.3(470), 32.2/31.0(546), 33.4/32.0(589) and 35.1/33.7(650). The chemical composition corresponds to the empirical formula (Rh2.26Pt0.46Ir0.25Ru0.01Pd0.01Fe0.01)Σ3.00(Se2.77S1.21Te0.02)Σ4.00 Zaykovite is monoclinic, space group C 2/ m , a = 10.877(1), b = 11.192(1), c = 6.4796(6) Å, β = 108.887(2)°, V = 746.3(1) Å3, Z = 6 and D calc = 8.32 g cm–1. The crystal structure has been solved and refined to R 1 = 0.016 based on 858 unique observed reflections. The strongest lines of the powder X-ray diffraction pattern [ d (Å), (I), (hkl)] are: 5.43(37)($\bar{1}$ 11), 3.275(75)(310), 3.199(100)($\bar{1}$ 31), 3.061(87)(002), 2.568(62)(400), 2.545(41)(041), 3.413(34)($\bar{2}$ 41) and 1.697(34)(441). Zaykovite is a Se analogue of kingstonite, Rh3S4. A continuous series of solid solutions between kingstonite and zaykovite was encountered in the samples from the Kazan placer. The possible sources of this unique Rh–Se mineralisation in the South Urals could be serpentinised dunite–harzburgite or gabbro–clinopyroxenite–dunite complexes in the vicinity. [ABSTRACT FROM AUTHOR]

The results of detailed study of the platinum-group minerals (PGM) from explosive breccias of the Poperechnoe Fe–Mn deposit (the Lesser Khingan Range, Russian Far East) are presented. Native PGMs are dominated by isoferroplatinum; rutheniridosmine, native iridium, platinum, and osmium are less common. Micron-sized segregations of laurite, bowieite, сuproiridsite, cuprorhodsite, hollingworthite, as well as new mineral phases of (Ir,Rh,Os)7(S,As)13, (Rh,Ir,Ru)7(S,As)13, and Pd3(Sb,As) were recognized as microinclusions in isoferroplatinum and on the surface of its grains. It is shown that the studied PGMs are derived from rocks of ultramafic formations: (1) vein pyroxenites, harzburgites, and dunites of metamorphic and cumulative complexes of the most depleted peridotite varieties of the suprasubduction wedge of island-arc ophiolites and (2) vein pyroxenites of cumulative high-pressure ultramafic complexes of the basement of the ensialic island arc and products of evolution of suprasubduction mantle melts. In terms of the contents of platinoids, the compositions of isoferroplatinum from explosive breccias are divided into four groups: group I: isoferroplatinum of fluid-metamorphogenic genesis from harzburgite, group II: isoferroplatinum of fluid-metamorphogenic genesis from dunites and magmatogenic-fluid-metasomatic genesis from vein pyroxenites; group III: isoferroplatinum of magmatogenic genesis from chromitites of dunites of the cumulative complex; and group IV: isoferroplatinum with an elevated Pd content, which is likely derived from the melt formed by explosive breccias. Three scenarios of PGM occurrence in the fluid-saturated andesite–dacite melt of explosive breccias at the Poperechnoe deposit are discussed: (1) directly from early ultramafic complexes in suprasubduction settings; (2) from the reservoir of ancient platinum placer deposits; and (3) from a mantle wedge above the Mesozoic subduction zone during the generation of initial island-arc melts. The first two petrogenetic models suggest "rejuvenation" of the 190Pt–4He age of isoferroplatinum grains as a result of the thermal effect of the andesite–dacite melt to the age of 125 ± 21 Ma. The third geodynamic scenario suggests that the Lower Cretaceous age of isoferroplatinum marks the processes of metamorphogenic-metasomatic transformation of the dunite–harzburgite mantle wedge and probably corresponds to the age of the subduction magmatism at the Poperechnoe Deposit in particular and within the Lesser Khingan terrane as a whole. PGM associations in andesite–dacite breccias of the Poperechnoe Deposit are a new type of potentially meaningful noble-metal mineralization in the Russian Far East, while explosive breccias themselves (fluidoliths) can serve as a criterion to search for lode and placer platinoid deposits of volcanogenic-explosive genesis in the territory of the Russian Federation. [ABSTRACT FROM AUTHOR]

To gain further insight into the origin of Ru–Os sulfides, the first in-situ sulfur isotopic data for Ru–Os sulfides from different polyphase platinum-group mineral (PGM) assemblages derived from the Quaternary deposits of the Guli massif located in the Maimecha-Kotui province are presented. A number of analytical techniques, including electron microprobe analysis and laser ablation attached to multiple-collector inductively coupled-plasma mass-spectrometry, were utilized. Polyphase platinum-group mineral (PGM) assemblages are represented by two types: (1) osmium and iridium alloys associated with Ru–Os sulfides of the laurite (Ru,Os)S2–erlichmanite (Os,Ru)S2 solid solution series, cuproiridsite (CuIr2S4), and unnamed Os–Ir sulfide (Os,Ir)S2; (2) ferroan platinum containing inclusions of laurite, Ru–Os–Ir alloys, and other PGMs. These detrital PGM assemblages were sourced from different bedrocks. It is concluded that PGM assemblages of types 1 and 2 were derived from dunite/chromitite and clinopyroxenite, respectively. The sulfur isotope signatures of Ru–Os sulfides of type 1 (δ34S = 0.9 ± 0.4‰, n = 8) imply that sulfur derived from a subchondritic source. The slightly lighter δ34S values in type 2 laurite (δ34S = –1.7 ± 0.2‰, n = 10) are likely due to the evolved composition of the ore-forming fluid. Despite these differences, the S-isotope data are consistent with the origin of sulfur from a common near-chondritic source. [ABSTRACT FROM AUTHOR]

Sluzhenikinite, Pd15(Sb7–xSnx) with 3 ≤ x ≤ 4, is a new mineral discovered in the pegmatoidal galena–chalcopyrite massive ore from the Oktyabrsk mine, Oktyabrsk deposit of the Noril'sk deposits, Russia. Sluzhenikinite forms euhedral elongate lamellar crystals (100–150 μm long and 10–50 μm wide) associated with Au–Ag alloy, insizwaite and myrmekitic intergrowths of Pt–Pd minerals (stibiopalladinite, maslovite and sobolevskite), in close association of sperrylite and base-metal sulfides (galena, chalcopyrite, cubanite and pentlandite). In plane-polarised light, sluzhenikinite is pale brown with weak bireflectance, imperceptible pleochroism, and weak anisotropy with straw yellow to deep blue rotation tints; it exhibits no internal reflections. Reflectance values for sluzhenikinite in air (R1,R2 in %) are: 46.2, 46.5 at 470nm; 52.1, 52.2 at 546nm; 54.7, 55.1 at 589nm; and 57.8, 59.0 at 650nm. Thirteen electron-microprobe analyses of sluzhenikinite gave an average composition: Pd 65.06, Sn 15.60 and Sb 19.58, total 100.24 wt.%, corresponding to the formula Pd14.88(Sb3.92Sn3.20)Σ7.12 based on 22 atoms; the average of twenty-one energy dispersive spectroscopy analyses on co-type material gave: Pd 63.36, Pt 1.15, Sn 16.28 and Sb 19.21, total 100.00 wt.%, corresponding to the formula (Pd14.62Pt0.14)Σ14.76(Sb3.87Sn3.37)Σ7.24. The density, calculated on the basis of the empirical formula, is 11.22 g/cm3. The mineral is monoclinic, space group P21/m, with a = 7.5558(1), b = 29.2967(3), c = 7.5713(1) Å, β = 119.931(2)°, V = 1452.44(4) Å3 and Z = 4. The crystal structure was determined using data from single-crystal X-ray diffraction and demonstrates conclusively that the correct stoichiometry is Pd15(Sb,Sn)7, rather than Pd2(Sb,Sn); R1 = 0.035, wR2 = 0.073, GoF = 1.118 for 209 refined parameters and 4738 unique reflections. The mineral is named after Sergey Fedorovich Sluzhenikin, an expert on platinum-group minerals, particularly from the area of the type locality. [ABSTRACT FROM AUTHOR]

High-precision analysis of sulfur isotope composition was carried out for sulfide fractions from ten samples of olivine gabbronorite that composes a thick (approximately 300 m) swell of a ore-bearing apophysis that is parallel to the basal part of the Yoko-Dovyren massif in northern Baikal area, Russia. The δ34S values were found out to widely vary from +11‰ to –1.9‰. The maximum enrichment in isotopically heavy sulfur was identified within the basal horizon, which is 10 m thick, whereas the minimum values of δ34S were observed near the upper contact of the intrusive body. Sulfide droplets in chilled picrodolerite from the lower contact zone (Pshenitsyn et al., 2020) show a narrow range of δ34S (+8.65 ± 0.34‰, n = 5). Lower values of δ34S ranging from +2.09 to +2.53‰ are characteristic of the sulfide-rich net-textured ores, the mineralized olivine gabbronorite, and a cutting leucogabbro dike. The sulfur isotope compositions of two samples of pyrite-bearing rocks from the host carbonate–terrigenous rocks display discrete values of δ34S = +2.20‰ and δ34S = +9.40 ± 0.14‰ at a whole-rock sulfur concentration up to 3.5 wt %. Simple scenarios of the additive mixing of isotope-contrasting reservoirs corresponding to a juvenile magmatic source (δ34S = 0 and +2‰) and a provisionally chosen contaminant (δ34S = +9.4‰) are demonstrated to require a high degree of assimilation of host rocks (as much as 60–80%) and complete isotope equilibration of the hybrid system. In the contact picrodolerite with rare globular sulfides, the mixing mechanism is inconsistent with the estimated sulfur solubility in its parental magma: approximately 0.08 wt % (Ariskin et al., 2016). The high δ34S values in rocks from the basal part of the apophysis may be explained, under the assumption that contact-metamorphic H2S-bearing fluid was introduced into the magmatic system, by the thermal decomposition of pyrite coupled with dehydration of the host rocks. The proposed mechanism does not require a volume assimilation of crustal materials and is consistent with petrological and geochemical characteristics of the Dovyren magmas and derivative cumulates. [ABSTRACT FROM AUTHOR]

The Sopcha massif, which is part of the Paleoproterozoic layered Monchegorsk Pluton (Monchepluton), contains an ore horizon with an average thickness of ca. 4 m within the homogeneous orthopyroxenite sequence. This horizon has a layered internal structure with variations in composition from dunite to orthopyroxenite and sulfide mineralization enriched in platinum group elements (PGE). All the rocks of the ore horizon include accessory chrome-spinels, which demonstrate a high variability of the composition and are divided into two groups based on their optical properties and chemical composition. Group I chrome-spinels belong to Al-chromites. They occur as homogeneous grains in fine-to-medium-grained orthopyroxenite at the top of the horizon and form cores of zoned chrome-spinels in the medium-to-coarse-grained orthopyroxenite and harzburgite. Group II chrome-spinels belong to Fe-chromites. They form homogeneous grains in dunite and harzburgite and rims of zoned grains in harzburgite. Chemical compositions of Group I chrome-spinels are characterized by high contents of Al2O3 and Cr2O3, an increased MgO but low contents of FeOtot and values of Cr#= Cr/(Cr + Al) and Fe3+# = Fe3+/Fetot. Group II chrome-spinels have low Al2O3 and MgO contents, and sharply increased values of Cr# and Fe3+#. This variability in the composition of chrome-spinels is caused by decreasing melt temperature in the process of its cooling during two stages of magmatic crystallization. At the first stage, cumulus crystallization of Group I chrome-spinels and subsolidus diffusion between spinel and olivine ("mineral-mineral" reaction) occurred at a temperature of about 1170 °C. At the second stage, reactions between Group I chrome-spinels and intercumulus melt ("mineral-melt" reactions) resulted in the formation of a rims of zoned chrome-spinels and homogeneous Group II chrome-spinels at a temperature of 1070–970 °C. [ABSTRACT FROM AUTHOR]

Panskyite, Pd9Ag2Pb2S4, is a new mineral (IMA2020–039) discovered in the platinum-group element mineralisation of the Southern Kievey ore occurrence of the Fedorova–Pana layered intrusion, Kola Peninsula, Russia. It forms tiny anhedral grains (of 0.5 to 10 μm in size) in the interstices of rock-forming silicates, often forming tiny inclusions in base-metal sulfides (millerite, chalcopyrite, bornite and chalcocite) and complex intergrowths with other platinum group minerals (zvyagintsevite, laflammeite, vysotskite, thalhammerite, unnamed phase Pd9Ag2(Tl,Pb)2S4 and others). In plane-polarised light, panskyite is creamy white with weak bireflectance, weak pleochroism and distinct anisotropy with brown to grey rotation tints; it exhibits no internal reflections. Reflectance values for panskyite in air (R1, R2 in %) are: 43.8, 44.1 at 470 nm; 44.4, 44.7 at 546 nm; 45.6, 45.8 at 589 nm; and 47.2, 47.2 at 650 nm. Twelve electron-microprobe analyses of panskyite gave an average composition: Pd 55.61, Ag 12.36, Pb 23.50, Fe 0.21, Ni 0.24 and S 7.17 total 99.09 wt.%, corresponding to the formula (Pd9.05Fe0.07Ni0.07)Σ9.19Ag1.98Pb1.96S3.87 based on 17 atoms; the average of nine analyses on the synthetic analogue is: Pd 57.02, Ag 14.17, Pb 21.81 and S 7.44, total 100.44 wt.%, corresponding to Pd9.07Ag2.22Pb1.78S3.93. The density, calculated on the basis of the empirical formula, is 9.81 g/cm3. The mineral is tetragonal, space group I4/mmm, with a = 7.973(3), c = 9.139(3) Å, V = 581.0(4) Å3 and Z = 2. The crystal structure was solved from the single-crystal and powder X-ray diffraction data of synthetic Pd9Ag2Pb2S4. Panskyite is isostructural with thalhammerite (Pd9Ag2Bi2S4). The mineral name is for the locality, the Pansky massif of the Fedorova–Pana layered intrusion in the Kola Peninsula, Russia. [ABSTRACT FROM AUTHOR]

The research site includes part of the East Asian region within areas of South‐East Russia and the boundary part of North‐East China. The region has abundant precious metal deposits: gold and platinum group elements. The spatial distribution of these deposits is controlled by details of crustal and mantle geodynamics including the presence of faults of different types and kinematics, active plume, as well as by the position of the region above a stagnant oceanic slab. Spatial analysis of position, geodynamics, and synchronous formation of the largest East Asian gold districts (e.g., Aldan, Baley, and Jiaodong) and platinum‐bearing massifs provide insights to their connection with mantle plumes and permeable zones at stagnant slabmargins. The occurrence of ore deposits and mineralization of precious metals inside the slab area is related to disjunctive structures of lower crust and upper mantle, such that their resources are considerably lower. This article considers numerical modeling of permeable tectonic structures exposed into mantle upwelling along active continental margins inside the slab area. Small‐scale structures of this type potentially hold two‐phase alkaline massifs, which control the positions of intra‐slab ore deposits, like the Lazurnoe Au–Mo–Cu porphyry deposit, situated in the southern part of the Sikhote–Alin belt. The small sizes of similar massifs impede their discovery, emphasizing the importance of the proposed prospective model for precious metal‐bearing porphyry deposits in Western Pacific mobile belts. [ABSTRACT FROM AUTHOR]

The sulfide PGE-Cu-Ni deposit "Ore horizon 330" (OH330) of the reef type is located within the orthopyroxenite of the Sopcha intrusion, which is part of the Paleoproterozoic layered Monchegorsk pluton (Monchepluton) in the Kola Region. OH330 is a sill-like body with a thickness of 4–6 m, traced along the entire perimeter of the Sopcha intrusion at a distance of 3.3 km and a width of 1.2 km. The OH330 deposit was studied in two well-exposed sections of its western flank. Here, OH330 is a thinly layered horison that lies among the host olivine orthopyroxenite. It consists of interlayers of dunite, harzburgite, and orthopyroxenite containing fine sulfide dissemination with increased contents of Ni (1290–5220 ppm), Cu (up to 2320 ppm), and platinum group elements (PGE) (0.43–1.40 ppm of the PGE tot). It is assumed that the OH330 parental magma was significantly contaminated with crustal material, saturated with sulfur and chalcophile elements. The separation of immiscible sulfide droplets during cooling led to the development of ore sulfide concentrations. The association of platinum group minerals (PGM) in harzburgite is represented by the predominant Pt Fe alloys and subordinate PGE bismuth-tellurides, arsenides, and tellurides. Compared to harzburgite, PGE bismuth-tellurides and tellurides are widely distributed in orthopyroxenite, whereas arsenides, Pt Fe alloys, and sulfides are minor. The PGE-Cu-Ni ore formed in a relatively wide temperature range from 1000 to 900 °C (base metal sulfides) to 900–600 °C (PGE sulfides and arsenides, and Pt Fe alloys) and ended at a temperature of 600–400 °C with a crystallization bismuth-tellurides and tellurides of Pt and Pd. • The OH330 sulfide PGE-Cu-Ni deposit is a sill-shaped, thin-layered body. • OH330 ore has mantle geochemical characteristics. • The ore formation was significantly influenced by contamination by crustal rocks. • PGMs are represented by Pt Fe alloys, bismuth-tellurides, tellurides and arsenides. • The platinum group minerals were formed over a wide range of temperatures. [ABSTRACT FROM AUTHOR]

The year 2019 commemorates the 175th anniversary of the discovery of the last of the platinum group metals, ruthenium. The discovery of this element is now attributed to the Russian chemist, Karl Karlovich Klaus (Carl Ernst Claus, 1796–1864). At that time, he was Professor of Chemistry at Kazan University, on the Volga River approximately 750 km (450 mi) east of Moscow. Klaus, whose laboratory practices violated practically every modern rule of laboratory safety, actually discovered the existence of the element in a crude extract of the spent platinum ores from the mint, by its odd taste and smell! Klaus and his discovery (including its defense against critics, who included Berzelius) are discussed here. [ABSTRACT FROM AUTHOR]

The ∼60 m thick Magilligan Sill is part of the British Palaeogene Igneous Province in the North Atlantic. The sill comprises layers of dolerite and olivine gabbro, and it intrudes a thick sequence of Mesozoic mudstones and marls, which are locally baked at the sill margins. Since 2014, the sill has been an exploration target for orthomagmatic Ni – Cu – platinum group element (PGE) sulfide mineralisation analogous to the Noril'sk-Talnakh intrusion in Russia. We present new petrological, geochemical, and S isotope data to assess the prospectivity of the sill and the underlying magmatic plumbing system. Most sulfides in the dolerite portions of the sill are <50 μm in size and comprise only pyrite with PGE abundances below the detection limit. In the olivine gabbros, >150 μm size pentlandite, chalcopyrite, and pyrrhotite grains contain <4 ppm total PGE, 1460 ppm Co, and 88 ppm Ag. Pyrite from the dolerites have δ34S ranging from −10.0‰ to +3.4‰ and olivine gabbro sulfides range from −2.5‰ to −1.1‰, suggesting widespread crustal contamination. The S/Se ratios of sulfides in the dolerites and olivine gabbros range from 3500 to 19 500 and from 1970 to 3710, respectively, indicating that the latter may have come from upstream in the magma plumbing system. The Magilligan Sill records multiple injections of mafic magma into an inflating sill package, each with distinct mechanisms towards S saturation. Whilst the sulfide minerals in the sill do not constitute significant mineralisation themselves, detailed in situ studies highlight a divergence in S saturation histories and suggest that a larger volume of olivine gabbro sulfides at depth may be prospective. [ABSTRACT FROM AUTHOR]

The fluid-explosive breccias of the Poperechny iron–manganese deposit, Lesser Khingan, Russia, contain high concentrations of platinum group elements (PGE), gold, and silver. Noble metals are represented by isoferroplatinum crystals, Os–Ir alloys, PGE sulfoarsenides, and gold grains with a size of tenths of a millimeter and micron-sized segregations of native silver. The mineral composition of the PGE of the Poperechny deposit is consistent with that of the ore and placer objects of the Ural–Alaskan type and corresponds to the isoferroplatinum–osmium magmatic assemblage. The euhedral morphology of the isoferroplatinum and PGE sulfoarsenides indicates that they were formed in a stable environment at the crust–mantle boundary owing to partial melting of slab rocks. The appearance of PGE minerals in the magmatic–hydrothermal system under subsurface conditions is related to a highly mobile gas-saturated fluid flux capable of transferring deep mineral phases. The high content of PGE (up to 11.3 g/t), gold (up to 2.58 g/t), and silver (up to 256 g/t) in the fluidolites of the Poperechny deposit makes it possible to revise the criteria for searching for the bedrocks and placer sources of noble metals in the Lesser Khingan. [ABSTRACT FROM AUTHOR]

Based on data on the concentration of noble metals (Au, Ag, Pt, Os, Ir, and Ru) in bulk samples of ferromanganese crusts, the presence of inclusions of micro- and nanosized grains of Ag, Au, Pd, and Pt, often with impurities of other elements, as well as their chaotic distribution, three sources of incorporation of these metals into ore crusts of Far Eastern seas are suggested: seawater, postvolcanic gas-hydrothermal fluids, and hydrothermal plumes. The presence of grains of platinoids and gold in ferromanganese crusts on only some mounts may result from peculiarities in the formation of volcanic rocks on the ancient continental basement. [ABSTRACT FROM AUTHOR]

Three styles of platinum-group element mineralization occur within the Ural-Alaskan type complexes of the Uralian Platinum belt: chromite-platinum, noble metal, and noble metal-copper ones. They are associated with dunite and chromitite (chromite-platinum), pyroxenite (noble metal) and gabbro (noble metal-copper). Three common platinum group element distribution patterns are observed for dunite and chromitite: (1) M-shaped (defined by positive Ir and Pt anomalies); (2) with positive Ir-Rh(Pt) anomalies; and (3) W-shaped with positive Os and Pt, or Os and Rh anomalies. In contrast, pyroxenite and gabbro are enriched in Pd and Au. The PGM assemblages correlate to the PGE + Au distribution patterns as exemplified by the predominance of Ir-rich Pt-Fe alloys within dunite and chromitite. The noble metal assemblages of pyroxenite and gabbro comprise tellurides, arsenides, and various Pd minerals, as well as native gold and Au-Ag alloy. An indicative Pd/Ir ratio in a succession dunite-chromitite-gabbro increases from 0.04 to 148 with a maximum value of ~5000 in massive sulfide ore of the Volkovsky that is attributable to the contrasting magma compositions defining chromite vs sulfide controls over PGE concentration. • Three PGE mineralization styles are linked to specific lithologies in the Ural-Alaskan type complexes. • Three types of PGE patterns (M-, W-shaped and Ir-Rh ± Pt) are typical of dunite and chromitite. • Pyroxenite and gabbro show sulfide-controlled patterns with enrichment in Au and Pd. • Platinum-group mineral assemblages correlate to the PGE + Au distribution patterns. [ABSTRACT FROM AUTHOR]

The study of melt inclusions in minerals is the only direct approach to estimate the contents of volatile components in silicate melts, which are essential to constrain the processes of magma generation and evolution. In particular, the content of sulfur in silicate melts is closely connected with the P-T-fO 2 conditions of mantle melting and the formation of sulfide deposits. Inclusions in high-Mg olivine can provide access to the composition of the most primitive melts, but these are the most susceptible to post-entrapment modification such as 'Fe-loss'. The loss of Fe consequently decreases sulfur solubility and leads to silicate-sulfide immiscibility and formation of daughter sulfide globules, significantly affecting the initial proportions of S contained within the silicate part (glass) of melt inclusions. In this study, we investigated the budget of sulfur in heated and quenched melt inclusions hosted in primitive olivine (87–90 mol% Fo) by accounting for sulfur stored in silicate glass (melt), daughter sulfide globules and shrinkage bubbles. Melt inclusions from MORB-like olivine-phyric rocks (Kamchatsky Mys, Far East Russia) heated for 30 min at 1200 °C and 1300 °C were compared with similar experiments on olivine-hosted melt inclusions over a 5 min duration (at 1200 °C and 1350 °C). Sulfur contents were calculated in the following types of melt inclusions, containing: (i) both sulfide globules and shrinkage bubbles, (ii) only sulfide globules, (iii) only shrinkage bubbles, and (iv) completely homogenized. Our findings indicate that S content in shrinkage bubbles and its precipitates is negligible in reheated water-poor melt inclusions, whereas daughter sulfide globules are significant repositories of initial S. Therefore, when estimating initial S contents in parental melts, the amounts stored in both daughter sulfide and silicate glass should be considered. Our experiments with MORB-type melt inclusions in forsteritic olivine phenocrysts demonstrate that effective homogenization is best achieved by briefly overheating melt inclusions prior to rapid quenching. Although this technique does not allow for the Mg Fe equilibrium between melt inclusions and their host olivine to be fully achieved, it promotes the dissolution of daughter sulfide globules and shrinkage bubbles, and thus the release of initial sulfur back to the melt/glass. • Daughter sulfides in olivine-hosted melt inclusions (MI) contain up to 60% of total S • Shrinkage bubbles in water-poor MI glasses contain insignificant amounts of S • Experimental heating and quenching of MI successful in dissolving daughter sulfides • S contents in sulfide-saturated mafic melts can be accurately estimated using MI [ABSTRACT FROM AUTHOR]

Zoned clinopyroxenite-dunite Uralian-Alaskan-type complexes of the Uralian Platinum Belt are the source of economic platinum deposits. One of the striking features of Uralian-Alaskan-type complexes is a pronounced Pt anomaly, which clearly distinguishes them from cumulate series of ophiolite massifs elsewhere, but there is still uncertainty regarding the nature of the platinum enrichment and its geodynamic setting. We have studied the platinum-group element (PGE) and Os isotope systematics of platinum-group minerals, chromitites and ultramafic rocks from the Nizhny Tagil zoned clinopyroxenite-dunite massif in the Urals. The whole-rock 187Os/188Os ratios of the dunites vary from 0.1160 to 0.1332, averaging 0.1247, with more radiogenic values possibly affected by subduction-related fluids during Tagil island arc development (c. 410 Ma). Laurite and Os-Ir alloys have 187Os/188Os ratios of 0.12245 ° 0.00038, which are close to those of chromitites (187Os/188Os=0.1215 ± 0.0006) and correspond to an Os model age (TRD) of c. 800 Ma. This model age is c. 400 Myr older than a melt depletion event corresponding to Tagil island arc development, and can be ascribed to a Neoproterozoic mantle melting event under the influence of either a pre- Uralian subduction zone or a superplume, overprinted by younger processes. The Pt/Pd values in the ultramafic rocks show significant variations, increasing towards the chromite-PGE-bearing mineralization zone. The overall primitive mantle normalized PGE patterns are very similar to those reported for sub-arc mantle peridotites, which are characterized by a positive slope and high Pt/Pd ratios, and are distinct from those of typical peridotites and cumulates from Urals ophiolite massifs. Such a similarity may be explained by the melting of metasomatized depleted mantle that had undergone several melt extraction events in a subduction-zone setting. This is also evident from a high oxygen fugacity averaging 2.7 relative to fayalite-magnetite-quartz, which is distinctly more oxidized compared with mid-ocean ridge basalt and ocean island basalt settings. However, the striking similarities (P-T-fO2 and type of parental magma, high Pt/Pd ratio) to other zoned clinopyroxenite-dunite massifs such as Kondyor, situated within the stable Archean shield, allow us to conclude that this type of massif is not exclusive to subduction-zone settings, but may reflect the presence of a specific depleted, fluid-metasomatized type of relatively shallow mantle in the Paleozoic. The systematic Pt/Pd ratio increase in the Nizhny Tagil rocks towards the chromite mineralized zone suggests that Pt-Pd fractionation may be related to the preferential retention of Pt in chromitites as Pt-Fe alloys. [ABSTRACT FROM AUTHOR]

The article presents a study which aims to determine the conditions of formation of Os-bearing platinum group minerals (PGM) in oceanic and subcontinental mantle at the Middle Urals, Russia. Methods used to examine the intrinsic oxygen fugacity of Ru-Os-Ir alloys from the Verkh-Neivinsky Dunite and morphology and chemical composition of PGE mineralization are offered. Results reveal the similarity of redox conditions of the formation of Ru-Os-Ir alloys formed in oceanic and continental mantle.

The southeastern part of the North Asia craton was found to contain several circular basite-hyperbasite plutons with associated commercial platinoid placers. An analysis of geodynamic models for the formation of the region and materials of seismic tomography showed that the subduction processes that were active in the Asia-Pacific convergence zone during Mesozoic time generated a stagnant oceanic slab in the transitional mantle zone. The NE and SW boundaries of the slab appear to be coincident with transform faults. The projection of the transform fault that bounds the slab on the north-northeast coincides with the Konder-Feklistov metallogenic belt that was identified previously and its Aldan (Inagli) segment. The high platinoid potential of the circular massifs in the belt is explained by the effects of lower-mantle derivates on ascending upper-mantle plumes. [ABSTRACT FROM AUTHOR]

Abstract: The ultramafic–mafic Noril''sk-1 intrusion in Polar Siberia (Russia) hosts one of the world''s major platinum-group-element (PGE)-Cude deposits. In situ Hf-isotope analyses of zircon and baddeleyite, combined with whole-rock Nd-isotope results, identify three distinct clusters of Hfe values restricted to different lithological units (e.g., gabbro-diorite, unmineralised layered sequence gabbros, and mineralised portions, represented by ultramafic and taxitic-textured rocks). Hf-isotope signatures of zircon and baddeleyite from unmineralized mafic rocks (εHf from 7.3±1.1 to 11.4±0.3) reflect the dominant role of mantle-derived magmas and suggest that a juvenile mantle was one of the main sources for the ultramafic–mafic Noril''sk-1 intrusion. The less radiogenic Hf-isotope values for zircons from mineralised rocks (εHf from 4.9±1.4 to 6.4±1.2) and gabbro-diorite (εHf −1.2±1.9) are indicative of involvement of distinct source components, possibly equivalent to a subcontinental lithospheric mantle and a continental crust, respectively. The significant range in the initial 176Hf/177Hf values of unmineralised rocks and mineralised lithologies indicates interaction of distinct magma sources during formation of the Noril''sk-1 intrusion. Our new findings, in conjunction with whole-rock Nd-isotope results, imply that economic intrusions hosting PGE–Cuts of the Noril''sk area have a far more complex magmatic history than is commonly assumed. [Copyright &y& Elsevier]

The article offers information on volcanic glasses from the Elgygytgyn crater and their origin. It informs that minerals in glasses with planar textures and high-pressure silica phases show their origin from an impact event such as meteorite fall. It was found in the study that there is no linear correlation of platinum group elements with nickel, cobalt and chromium which show that there contamination of rocks constituting the Elgygytgyn crater by extraterrestrial matter which can be linear correlations in pairs of elements even in the case of their relatively low concentrations in rocks.

Platinum group minerals (PGM) are rather widespread as admixture in gold placer deposits in Tuva. The present paper reports new data on PGM in the Kundus gold placer confined to the Kaakhem ophiolite belt. The minerals are mainly represented by solid solutions of the Os-Ir-Ru system. They make up rims of sulfoarsenides, sulfides, and arsenides of the platinum group elements (PGE) developed after primary minerals. PGMs of this placer always contain traces of Pd (0.33-1.58 wt %), Cu (0.29-0.50 wt %), and As (0.03-2.17 wt %), as well as Ni and Sb (within the detection limit). Typomorphic features of minerals along with the set of main elements and isomorphic trace-elements in the major and secondary mineral species, suggest that sources for the studied placer was represented by the Alpine-type ultramafics and associated chromitites. We cannot also rule out that PGM mineralization was influenced later intrusions that promoted the formation of rims of sulfoarsenides, sulfides, and arsenides of PGE. The PGM rims are marked by the S and As isomorphism, which characterizes the composition of mixtures rather than independent mineral types (end members of isomorphic series). In one case, minerals are represented by the isomorphous mixture of sulfoarsenides with a limited role of sulfides; in another case, by arsenides with a limited role of sulfoarsenides. [ABSTRACT FROM AUTHOR]

The article focuses on the identification of several new high grade gold and platinum group minerals including nevyanskite, sysertskite and ruthenplatosmiride. It states that these minerals are found in a gravity concentrate of a mineralogical technological sample in the jaspilite weathering crust in the Mikhailovka deposit of the Kursk Magnetic Anomaly (KMA), Russia. According to V. I. Smirnov, residual and sedimentary infiltration weathering crusts of different formation types are essential for the study of numerous genetic groups of iron deposits.

The Nizhny Tagil and Guli clinopyroxenite-dunite massifs, located in the Middle Urals and Maimecha-Kotui Province, respectively, are associated with world-class platinum-group elements (PGE) placer deposits. Both massifs contain small bodies of schlieren to massive chromitite associated with dunite. The predominance of Pt-Fe alloys at Nizhny Tagil is consistnt with the whole-rock 'M'-shaped mantle-normalized PGE pattern of the chromitite. In contrast, the preponderance of laurite and Os-Ir alloys at Guli is consistent with a negatively sloped PGE pattern, the latter being characteristic of ophiolite-type podiform chromitites. The 'unradiogenic' Os/Os values obtained for both platinum-group minerals (PGM) and chromitite are indicative of a common near-to-chondritic source for the PGE and implies that the osmium isotope budget of chromitite is largely controlled by laurite and Os-rich alloy. Average model Os/Os ages calculated for the Nizhny Tagil and Guli massifs correspond to the late Riphean (e.g., 862 ± 48 Ma and 616 ± 8 Ma, respectively). The compositional and isotope-geochemical results provide new constraints on the temporal evolution of ultramafic rocks of the Uralian Platinum Belt and northern segment of the Siberian Platform. [ABSTRACT FROM AUTHOR]

This study firstly presents chemical and initial Os-isotopic compositions of Os-Ir-Ru minerals of two ultramafic formations of Polar Siberia, which are exemplified by Guli clinopyroxene-dunite massif of the Maimecha-Kotui Province and the Kunar dunite-harzburgite massif from the Chelyuskin ultramafic belt of the Taimyr Peninsula. The study employed a range of methods, including electron microprobe analysis, negative thermal ionization mass spectrometry (N-TIMS) and laser ablation attached to an inductively coupled plasma mass spectrometry (LA MC-ICP-MS). The majority of platinum-group minerals (PGM) from the Guli massif are Os-(Ir-Ru) solid solutions or Os-rich minerals. At Kunar, minerals of Ru-Os-Ir system (i.e., osmium, ruthenium, iridium and rutheniridosmine) dominate the PGM assemblage. The ruthenium trend in the mineral compositions is due to the formation of these minerals under high pressures and temperatures at considerable depths. The Os/Os values of Os-rich minerals from the Guli massif range from 0.12309 ± 0.00002 to 0.12606 ± 0.00003 ( n = 168). The initial Os-isotopic composition of PGM from the central block of the Guli massif is characterized by the Os/Os values, varying in the range 0.12404-0.12606. Osmiumrich minerals from the southwestern block of the Guli massif are characterized by the least 'radiogenic' Os/Os values (i.e., 0.12309-0.12341). Low relative to the chondritic universal reservoir (CHUR) Os/Os values are indicative of a near-to-chondritic source of platinum-group elements (PGE). The most 'productive' stage of PGM formation at Guli ( n = 121) is recorded in the time interval of 545-615 Ma. The older model Os/Os ages of osmium minerals are characteristic of the southwestern block of the Guli massif (e.g., 745-760 Ma). The results of the initial Os-isotopic composition for Os-rich alloys are consistent with a model, in which PGM were formed during multi-stage melt depletion events in the mantle. This agrees well with the suggestion that the Guli massif consists of heterogeneous blocks of ultramafic rocks. The Os/Os ratio in the investigated PGM from the Kunar massif varies in a wider range (0.1094-0.1241, n = 28). For the dominant set of PGM samples ( n = 25), regardless of their chemical composition, four groups of the initial osmium isotopic compositions can be estimated, with average Os/Os values of 0.1217 ± 0.0002 ( n = 7), 0.1223 ± 0.0002 ( n = 7), 0.1230 ± 0.0002 ( n = 6) and 0.1238 ± 0.0003 ( n = 6), respectively. The average model Re-Os ages for the defined groups of the Kunar massif are consistent with Late Riphean age interval (e.g., 975 ± 42 Ma, 892 ± 42 Ma, 791 ± 28 Ma and 681 ± 42 Ma, respectively). Significant variations in the Os/Os values and model ages for Ru-Os-Ir alloys at Kunar are close to those from other duniteharzburgite massifs of the Earth, pointing out for their prolonged multi-stage evolution within the upper mantle. [ABSTRACT FROM AUTHOR]

The results of investigation of heavy fraction minerals from the Degdekan deposit hosted by the lower portion of stratified Mid Permian sediments are presented; the investigation was conducted via electron microscopy using a QEMSCAN hardware and software instrument equipped with a QUANTAX quantitative analysis system. The following mineral phases of platinoids have been detected for the first time: native osmium, rutheniridosmine, osmiridium, ruthenosmiridium, laurite, iridarsenite, and Ru, Os, and Ir arsenide. [ABSTRACT FROM AUTHOR]

The article focuses on a study which examined the redox conditions of osmium-rich minerals formation from the Guli Massif, Russia. It notes on the intrinsic oxygen fugacity of native osmium and iridium osmium from dunite and chromatite. The factors that influenced the regular difference in a chemical composition of platinum group element (PGE) are noted.

Abstract: This paper presents the results of the first comprehensive geological, petrographic, mineralogical, geochemical, and geochronological studies of ultramafic and mafic magmatism in the poorly explored southwestern Tuva (evidence from the Birdag and Khayalyg massifs). These massifs intrude ortho- and paraschists, which are presumably Middle Proterozoic. Amphibole gabbros in the Khayalyg massifs contain numerous relict host-rock xenoliths. The massifs are dominated by meso- and leucocratic amphibole gabbros with minor ultramafic (serpentinous plagioclase harzburgites and plagioclase lherzolites) and transitional (wehrlites, olivine clinopyroxenites, hornblendites, melanocratic olivine gabbronorites) rocks. The serpentinous plagioclase harzburgites and plagioclase lherzolites occur in the amphibole gabbros of the Birdag massif as small lenticular bodies. The latter are interpreted as xenoliths of ultramafic restites of earlier protrusion rather than mafic-melt differentiates. The wehrlites, olivine clinopyroxenites, hornblendites, and melanocratic olivine gabbronorites forming the outer zones of the xenogenic bodies of ultramafic restites are considered hybrid rocks. They resulted from the contact reactions of mafic melts and their fluids with the xenogenic bodies of ultramafic restites, which were feldspathized during this interaction. In the gabbros from both massifs, the chondrite-normalized content of MREE and HREE is lower and that of LREE is higher than those in N-MORB. The plagioclase peridotites, wehrlites, and olivine clinopyroxenites forming xenogenic bodies among the amphibole gabbros of the Birdag massif are richer in REE (especially LREE) than the ultramafic restites in ophiolite associations. This is because they were infiltrated by fluids enriched in these elements during their alteration under the influence of later mafic melts. The studies suggest that the Birdag and Khayalyg ultramafic–mafic massifs result from the spatial coexistence of (1) more ancient small protrusions of ultramafic restites, which occurred as allochthons among Middle Proterozoic(?) metamorphic rocks, (2) later gabbroic intrusions (from 494 ± 16 to 450–447.4 ± 5 Ma), and (3) hybrid transitional rocks (wehrlites, olivine clinopyroxenites, hornblendites, melanocratic olivine gabbros) making up contact-reaction zones along their boundaries. [Copyright &y& Elsevier]

The article presents a study which examines the zircons in the Niznii Tagil dunite massif (NTM) in Ural Platinum Belt. The study employs CPM-18 and EDX-900HS spectrometers in identifying the concentrations of the primary components of the zircons. It uses mass-spectrometry with inductively coupled plasma (ICP-MS) to determine the concentration of rare earth elements (REEs). It says that the habit of zircons differs from prismatic to round while zonation is characterized by varying frequency. It highlights various groups which were distinguished based on the composition and age of the zircons such as Group I comprised of relict grains changed by various degrees, Group II featuring clear idiomorphism, zonation, and rare inclusions, and Group III consisting of less radioactive crystals.

The article examines the North Asia Superplume (NAS) and the platinum mineralization of the southeast region of Russia. It notes the influence of NAS which corresponds to the Amur ore-magmatic system of ring shape in many aspects. The recognition of the ore-generating influence of NAS derivatives on platinoid-ore mineralization concentration helps develop criteria for mineralization and accomplish updated platinum-mineragenic zoning of the region. It points out that the occurrence of North Asian Superplume NAS is associated to Mesozoic magmatic massifs.

The concentration levels and distribution features of the platinum group elements (PGE) in black shales with high carbon content from the Bureya Massif, Far East Russia are discussed. This study compares PGE and gold (Au) values in black shale ores from the eastern Bureya Massif. Mineralogical studies using SEM-EDS on PGE-bearing inclusions in black shales reveal that they always contain O and C along with Pt, Pd, Ir and Os. It is believed that PGE are present in the form of organometallic compounds which are extremely resistant to any exposure, including acid dissolution and fire assay procedures. There is a lot of variation in the concentration values obtained using different analytical methods. Observations, problems and possible causes for the erratic and low recoveries of Au and PGE in the highly carbonaceous black shales are discussed. [ABSTRACT FROM AUTHOR]

The article offers information on the presence of osmium group minerals in ancient gold products. It investigates the characterization of osmium from inclusions in gold adornments which was found in burial mounds of the Urals and Serbia in Russia. It mentions that the particle cut from the gold particle is treated with alkalis and acids, then gold is stuck on electrically conductive tape and subsequently covered by carbon. It informs that study of metal involves microprobe analysis and optical methods. It also presents the tables reporting the composition of inclusions of osmium minerals in ancient gold products and from the burial mounds of the Urals and Serbia.

Abstract: The metallogeny of the Russian Arctic zone, with a high potential for U, platinum-group metals, Au, Sn, trace elements, etc., in its different sectors, has been controlled by the type of early continental structures and by the uniform Meso-Cenozoic evolution of the area. The suggested reasonable development strategy is to conserve and further develop the existing mining districts associated with known large fields and to discover new primary (U, Au, etc.) and placer deposits. It is important to provide scientific background and environmental monitoring in the area at the stages of mineral prediction, exploration, and development. [Copyright &y& Elsevier]

The platinum-group minerals (PGM) in placer deposits provide important information on the types of their primary source rocks and ores and formation and alteration conditions. The article shows for the first time the results of a study of placer platinum mineralization found in the upper reaches of the Kitoy River (the southeastern part of the Eastern Sayan (SEPES)). Using modern methods of analysis (scanning electron microscopy), the authors studied the microtextural features of platinum-group minerals (PGM), their composition, texture, morphology and composition of microinclusions, rims, and other types of changes. The PGM are Os-Ir-Ru alloys with a pronounced ruthenium trend. Many of the Os-Ir-Ru grains have porous, fractured, or altered rims that contain secondary PGE sulfides, arsenides, sulfarsenides, Ir-Ni-Fe alloys, and rarer selenides, arsenoselenides, and tellurides of the PGE. The data obtained made it possible to identify the root sources of PGM in the placer and to make assumptions about the stages of transformation of primary igneous Os-Ir-Ru alloys from bedrock to placer. We assume that there are several stages of alteration of high-temperature Os-Ir-Ru alloys. The late magmatic stage is associated with the effect of fluid-saturated residual melt enriched with S, As. The post-magmatic hydrothermal stage (under conditions of changing reducing conditions to oxidative ones) is associated with the formation of telluro-selenides and oxide phases of PGE. The preservation of poorly rounded and unrounded PGM grains in the placer suggests a short transport from their primary source. The source of the platinum-group minerals from the Kitoy River placer is the rocks of the Southern ophiolite branch of SEPES and, in particular, the southern plate of the Ospa-Kitoy ophiolite complex, and primarily chromitites. [ABSTRACT FROM AUTHOR]

Pyrrhotite (or Cu-poor) massive ores of the Skalisty mine located in Siberia, Russia, are unique in terms of their geochemical features. These ores are Ni-rich with Ni/Cu ratios in the range 1.3–1.9 and contain up to 12.25 ppm Ir + Rh + Ru in bulk composition, one of the highest IPGE contents for the Norilsk–Talnakh ore camp. The reasons behind such significant IPGE Contents cannot simply be explained by the influence of discrete platinum-group minerals on the final bulk composition of IPGE because only inclusions of Pd minerals such as menshikovite, majakite, and mertieite II in Pd-maucherite were observed. According to LA-ICP-MS data obtained, base metal sulfides such as pyrrhotite, pentlandite, and pyrite contain IPGE as the trace elements. The most significant IPGE concentrator being Py, which occurs only in the least fractionated ores, and contains Os up to 4.8 ppm, Ir about 6.9 ppm, Ru about 38.3 ppm, Rh about 36 ppm, and Pt about 62.6 ppm. High IPGE contents in the sulfide melt may be due to high degrees of partial melting of the mantle, interaction with several low-grade IPGE impulses of magma, and (or) fractionation of the sulfide melt in the magma chamber. [ABSTRACT FROM AUTHOR]

Ferrotorryweiserite, Rh5Fe10S16, occurs as small grains (≤20 µm) among droplet-like inclusions (up to 50 μm in diameter) of platinum-group minerals (PGM), in association with oberthürite or Rh-bearing pentlandite, laurite, and a Pt-Pd-Fe alloy (likely isoferroplatinum and Fe-Pd-enriched platinum), hosted by placer grains of Os-Ir alloy (≤0.5 mm) in the River Ko deposit. The latter is a part of the Sisim placer zone, which is likely derived from ultramafic units of the Lysanskiy layered complex, southern Krasnoyarskiy kray, Russia. The mineral is opaque, gray to brownish gray in reflected light, very weakly bireflectant, not pleochroic to weakly pleochroic (grayish to light brown tints), and weakly anisotropic. The calculated density is 5.93 g·cm–3. Mean results (and ranges) of four WDS analyses are: Ir 18.68 (15.55–21.96), Rh 18.34 (16.32–20.32), Pt 0.64 (0.19–1.14), Ru 0.03 (0.00–0.13), Os 0.07 (0.02–0.17), Fe 14.14 (13.63–14.64), Ni 13.63 (12.58–14.66), Cu 4.97 (3.42–6.41), Co 0.09 (0.07–0.11), S 29.06 (28.48–29.44), and total 99.66 wt.%. They correspond to the following formula calculated for a total of 31 atoms per formula unit: (Rh3.16Ir1.72Pt0.06Ru0.01Os0.01)Σ4.95(Fe4.48Ni4.11Cu1.38Co0.03)Σ10.00S16.05. The results of synchrotron micro-Laue diffraction studies indicate that ferrotorryweiserite is trigonal; its probable space group is R 3 ¯ m (#166) based on its Ni-analog, torryweiserite. The unit-cell parameters refined from 177 reflections are a = 7.069 (2) Å, c = 34.286 (11) Å, V = 1484 (1) Å3, and Z = 3. The c:a ratio is 4.8502. The strongest eight peaks in the X-ray diffraction pattern derived from results of micro-Laue diffraction study [d in Å(hkil)(I)] are 2.7950 (20 2 ¯ 5) (100); 5.7143 (0006) (60); 1.7671 (22 4 ¯ 0) (44.4); 3.0486 (20 2 ¯ 1) (39.4); 5.7650 (10 1 ¯ 2) (38.6); 2.5956 (20 2 ¯ 7) (37.8); 3.0058 (11 2 ¯ 6) (36.5); and 1.5029 (4 2 ¯   2 ¯ 12) (35.3). Ferrotorryweiserite and the associated PGM crystallized from microvolumes of residual melt at late stages of crystallization of grains of Os- and Ir-dominant alloys occurred in lode zones of chromitites of the Lysanskiy layered complex. In a particular case, the residual melt is disposed peripherally around a core containing a disequilibrium association of magnesian olivine (Fo72.9–75.6) and albite (Ab81.6–86.4), with the development of skeletal crystals of titaniferous augite: Wo40.8–43.2En26.5–29.3Fs20.3–22.6Aeg6.9–9.5 (2.82–3.12 wt.% TiO2). Ferrotorryweiserite represents the Fe-dominant analog of torryweiserite. We also report occurrences of ferrotorryweiserite in the Marathon deposit, Coldwell Complex, Ontario, Canada, and infer the existence of the torryweiserite–ferrotorryweiserite solid solution in other deposits and complexes. [ABSTRACT FROM AUTHOR]

We have undertaken a detailed study of platinum group element (PGE) mineralogy and geochemistry of disseminated sulfides associated with the marginal zone of the Chineisky layered mafic intrusion. Towards an intrusive contact the marginal zone reveals a gradual progression from gabbro-gabbronorites towards monzodiorite. Sulfides occur in all the rocks of the marginal zone including exocontact sandstone. They occur mainly as pyrrhotite, chalcopyrite, and pentlandite and show progressive enrichment in Cu towards the intrusive contact. In the same direction, PGE mineralogy reveals the following systematic changes: (1) size of PGE mineral grains decreases from 50 µm up to 1 µm; (2) the association of Pd minerals with Ni and Co arsenide and sulfarsenides becomes stronger; and (3) the composition of PGE minerals changes for palladium: Pd-Sn → Pd-As → Pd-Sb → Pd-Te → Pd-Bi; for platinum: Pt-Fe + PtAs2 → PtS + PtAs2 → PtAs2. This zoning pattern is interpreted as the result of fractional crystallization of an immiscible sulfide melt, with the residual liquid, enriched in Cu, PGE, and volatile elements, being expelled towards the periphery of the intrusive body. PGE minerals also decompose in an oxidation zone. The most stable of them are paolovite and sperrylite, which both accumulated in placers derived from the massif. Pd is removed from the decomposed minerals, and then absorbed by brown iron and goethite in the oxidation zone. [ABSTRACT FROM AUTHOR]

Gottfried Wilhelm Osann (1797, Weimar - 1866, Würzburg) was chemistry professor at Tartu University (Universitas Dorpatensis) in 1823-1828. In that period he analysed the crude platinum received from the Ural Mountains and discovered a new platinum metal. He named this metal ruthenium after the medieval name of Russia in Latin. As the quantity of the new element he had was small he could not isolate the metal. This was done several years later and published in 1844 by Carl Claus in Kazan, Russia. Claus is often mentioned as the discoverer of ruthenium and G. W. Osann is forgotten. [ABSTRACT FROM AUTHOR]