Platinum group elements PGE

The article is devoted to the publication of spiral ornaments of the Asian Bosporus with applied tips and cuffs of the 5th century BC, which are considered in the context of similar gold and silver ornaments found in the North Pontic region, Thrace and Macedonia, Asia Minor and Southern Italy. Solid cast silver and bronze spiral ornaments of the Northern Black Sea area are analyzed in detail, and the centers of production of the ornaments with applied endings and cuffs of the 6th–4th centuries BC are discussed, as well as the function of the ornaments. They were shown both on the black- and red-figure vases of ca. 520–470 BC as well as on coins of Lycia and Sicily of the second half of the 5th century BC as earrings, not as as temple pendants which is often argued. The assumption that the gold and bronze spiral ornaments covered with gold found in the Bosporus were most likely made in the Bosporus is confirmed. There is reason to believe that the spiral ornaments from Lycia could have served as prototypes of such ornaments. The earliest examples of gold spiral ornaments with cuffs with transverse ridges in Olbia and the Bosporus are generally dated to the first half of the 5th century BC. Ornaments with cuffs decorated with spiral decoration also appeared no later than the second quarter of the century. Obviously, they were extremely popular and were made not only in gold, but also in silver. As early as the 5th century BC, a simplified, single-piece version of such pendants appeared, cast in molds like the one found in Nymphaion. Such pendants were cast not only in silver and bronze, but also in gold, and were widely distributed both in the Bosporus and among the barbarian population of the Eastern Crimea, Sindika and the Kuban region, until the beginning of the 3rd century BC, when they went out of fashion.
The article is accompanied by a catalogue of silver spiral ornaments of the Asian Bosporus with applied tips and cuffs.

The Archean Legris Lake mafic–ultramafic complex (LLC) is spatially (~ 12 km east) and temporally (2690.59 ± 0.77 Ma) associated with the world-class Lac des Iles (LDI) palladium deposit. Modeling of whole-rock major-element compositions suggests that this complex, previously interpreted as gabbroic, is gabbronoritic in composition, adding to the likely association between LDI and the LLC. Mantle normalized trace-element profiles and modeled parental melt compositions from the cumulate lithologies indicate initial melt extraction from a metasomatized mantle source in an arc setting and subsequent crystallization of olivine, orthopyroxene, and plagioclase at depth following assimilation of SiO2 and S from tonalitic country rock. External S assimilation contributed to sulfide saturation at depth prior to or during emplacement, but sulfide melt entrainment in intruding magmas and its retention at the site of emplacement was variable. These interpretations are supported by (1) variation...

This paper focuses on the study of the famous royal purple dye. It aims to present a holistic approach by researching historical evidence, both for its use and its production, to highlight the importance of the dye within the Greek area. As a substantial part of information concerning the dyeing procedure of purple dye has been lost during the ages, it is crucial to establish points of documentation and identification. The latter can be achieved through chemical analysis, but as this dye is found on precious's cultural heritage items, which cannot always be sampled, a non-destructive approach should be considered as more appropriate. At first, the history of the dye purple is presented within the Greek area. Then, samples of purple dye are created based on traditional recipes from the Greek area, in order to compose a profile with the characteristics of purple using non-destructive and imaging techniques, thus emphasizing the importance of applying these techniques for the study of dyes on textiles. The results of the experiments show differences in behavior between the pure gland and the dyed samples, as well as the intensity of the color depending on the dyeing procedure.

Chondroitin sulfate (CS) is a sulfated glycosaminoglycan (GAG) and a key extracellular matrix (ECM) component of cartilage, ligaments, and connective tissues, essential for mechanical resilience, cartilage elasticity, and joint lubrication.

In osteoarthritis (OA) and rheumatoid arthritis (RA), CS plays a dual role as both a structural stabilizer and an anti-inflammatory modulator. Mechanistically, it promotes ECM synthesis by stimulating proteoglycans and type II collagen, suppresses cartilage-degrading enzymes (MMP-1, -3, -13), and reduces synovial inflammatory mediators such as IL-1β, IL-6, TNF-α, PGE₂, and nitric oxide.

Chondroitin sulfate (CS) also improves synovial viscosity, provides antioxidant protection, and protects subchondral bone integrity, making it a foundational nutrient for structural joint care.

Clinical evidence demonstrates that supplementation with 200-800 mg/day Chondroitin sulfate (CS) improves WOMAC scores, slows joint space narrowing, and alleviates morning stiffness with superior safety compared to NSAIDs.
Randomized trials confirm its structural benefits in OA, adjunctive value in RA, and supportive effects in cervical/lumbar degeneration, synovitis, and exercise-induced joint stress.

Within multi-nutrient formulations such as Keyora JointOra 5 in 1, Chondroitin sulfate (250 mg/day) synergizes with UC-II (immune tolerance), glucosamine sulfate (substrate supply), hyaluronic acid (synovial lubrication), and vitamin D₃ (immune regulation), forming a comprehensive repair network that integrates immune modulation, cartilage reinforcement, and synovial support.

Target populations include aging adults with OA, RA patients in remission, individuals with synovitis or morning stiffness, athletes under repetitive load, sedentary workers with spinal degeneration, and NSAID-intolerant populations.

Overall, CS represents a safe, multi-pathway structural and functional intervention with broad clinical applicability for long-term joint resilience.

Water is a scarce resource in the drylands of Africa and the Middle East and the identification of risks to aquifers is an important endeavor. There is a common and erroneous belief that only gold and coal deposits in Southern Africa are associated with acid-generating minerals. The study highlights the application the tools of geochemical analysis can reveal the classes of chemical reactions leading to the evolution of a shallow aquifer in an arid zone with active mining of sulfidic ore taking place. The prevailing hydro-geochemical processes were assessed at an open cast platinum mine. Major conclusions relate to the Acid Mine Drainage buffering within fractured aquifer system associated with the platinum deposit. The oxidation of pyrrhotite from in situ sources is the major contributing factor towards AMD formation. Neutralization of acid in the groundwater system has solved the pH problem but introduced a salinity problem.

Chromitites (Cr ores) of the Ojen lherzolite massif (Serrania de Ronda, Betic Cordillera, Southern Spain) were found to contain platinum-group minerals (PGM) as discrete inclusions in the chromite and in the associated silicates. The PGM mineralogy consists of sulfides [laurite, erlichmanite, malanite, unnamed (Ni-Fe-Cu)2 (Ir, Rh)$3, unidentified Pd-S], sulfarsenides (irarsite, hollingworthite, ruarsite, and osarsite), arsenides [sperrylite, unidentified (Pd, Ni)-As], one unidentified Pd-Bi compound, and native platinumgroup elements (PGE) consisting of Ru and Pt-Fe alloys. Textural considerations suggest that the PGE chalcogenides with S and As were formed in the high-temperature magmatic stages, as part of the chromite precipitation event (primary PGM), in contrast with the native PGE, which originated during the low-temperature serpentinization of the ultramafic host of the chromitites (secondary PGM). The primary PGM inclusions in the Ojen chromite are unusual compared with PGM inclusions in chromitites from tectonitic upper-mantle of ophiolites and other alpine-type complexes in that i) they display a great variety of mineral species sulfides, sulfarsenides and arsenides, and ii) comprise specific phases of all six PGE. The singularity of the primary PGM mineralization probably reflects high activities of both S and As during chromite precipitation at Serrania de Ronda to be related with particular physico-chemical conditions during uplifting of sub-continental, astenospheric mantle. The nature, composition, and paragenetic association of secondary PGM at Ojen confirm the relatively-high mobility of the PGE at low temperature, and indicate that remobilization can be selective under appropriate redox conditions causing separation and redistribution of the PGE in the rocks as a result of the alteration process. In den Chromititen (Cr-Erzen) aus dem Ojen-Lherzolithmassiv (Serrania de Ronda, Betische Kordillere, Siid-Spanien) wurden Platingruppen-Minerale (PGM) als einzelne Einschliisse im Chromit und in den begleitenden Silikaten gefunden. Die Mineralogie der PGM setzt sich aus Sulfiden [Laurit, Erlichmanit, Malanit, einem unbenannten (Ni-Fe-Cu)2 (Ir, Rh)S 3 und einern nicht identifizierten Pd-S], Sulfarseniden (irarsit, Hollingworthit, Ruarsit und Osarsit), Arseniden [Sperrylit, einem nicht identifizierten (Pd, Ni)-As], einer nicht identifizierten Pd-Bi-Verbindung sowie gediegenen Platingruppen-Elementen (PGE) bestehend aus Ru und Pt-Fe-Legierungen, zusammen. Texturelle Untersuchungen haben ergeben, da6 die PGE-Chalkogenide mit S und As im Zuge der Chromitfiillung (prim/ire PGM) in den hochtemperierten, magrnatischen Stadien gebildet wurden, w~ihrend die gediegenen PGE w~ihrend der niedriggradigen Serpentinisierung des ultramafischen Nebengesteins der Chromitite (sekund~ire PGM) gebildet wurden. Die prim/iren PGM-Einschliisse in den Ojen-Chromiten sind im Vergleich zu PGM-Einschliissen in Chromititen aus dem tektonisierten oberen Mantel in Ophiolithen und anderen alpinotypen Komplexen ungew6hnlich: i) Einerseits zeigen sie eine grol3e Vielfalt an Mineralarten aus der Gruppe der Sulfide, Sulfarsenide und Arsenide. ii) Andererseits enthalten sie spezifische Phasen aller sechs PGE. Die Einzigartigkeit der prim/iren PGM-Mineralisation k6nnte hohe Aktivitiiten von S und As wiihrend der Chromit-F~illung in Serrania de Ronda widerspiegeln, die mit besonderen physiko-chemischen Bedingungen w/ihrend der Hebung des subkontinentalen, asthenosphiirischen Mantels zusammenhiingen. Die Art, die Zusammensetzung und die paragenetische Vergesellschaftung yon sekund~iren PGM in Ojen best/itigen die relativ hohe Mobilitfit der PGE bei niedriger Temperatur und zeigen, dal~ die Remobilisierung unter geeigneten Redox-Bedingungen selektiv wirken kann, wodurch eine Trennung und Neuverteilung der PGE in den Gesteinen als Ergebnis des Alterationsprozesses bewirkt wird.

Platinum metals exploration in Malawi has been associated with mafic to ultramafic rocks, sometimes associated with arnothosites. These rocks have been metamorphosed and it is possible that later oregenic events triggered magmatisation of buried intrusive bodies. These are associated with irumide orogeny. This paper tries to documents target areas for exploration of platinum minerals including nickel, copper and chrome.

Carbon monoxide (CO) oxidation is considered an important reaction in heterogeneous industrial catalysis and has been extensively studied. Pd supported on SiO 2 aerogel catalysts exhibit good catalytic activity toward this reaction owing to their CO bond activation capability and thermal stability. Pd/SiO 2 catalysts were investigated using carbon monoxide (CO) oxidation as a model reaction. The catalyst becomes active, and the conversion increases after the temperature reaches the ignition temperature (T ig ). A normal hysteresis in carbon monoxide (CO) oxidation has been observed, where the catalysts continue to exhibit high catalytic activity (CO conversion remains at 100%) during the extinction even at temperatures lower than T ig . The catalyst was characterized using BET, TEM, XPS, TGA-DSC, and FTIR. In this work, the influence of pretreatment conditions and stability of the active sites on the catalytic activity and hysteresis is presented. The CO oxidation on the Pd/SiO 2 catalyst has been attributed to the dissociative adsorption of molecular oxygen and the activation of the C-O bond, followed by diffusion of adsorbates at T ig to form CO 2 . Whereas, the hysteresis has been explained by the enhanced stability of the active site caused by thermal effects, pretreatment conditions, Pd-SiO 2 support interaction, and PdO formation and decomposition.

Since 50 years copper-silver ores have been extracted from the Lubin-Sieroszowice deposit located on the border between the Lower and Upper Permian sediments. It is a world class stratoidal type deposit. In the whole world the Kupferschiefer unit is recognized as a black, clayey organic-rich shale. The Cu-Ag deposit is a part of the Fore-Sudetic Monocline, and is located on the border of the Lower and Upper Permian strata The monocline includes three rock complexes. The first is the basement, which comprises Proterozoic crystalline rocks and Carboniferous sediments. It is overlain by monoclinally dipping Permian and Triassic sedimentary rocks. In this work, study on ore mineralisation of the red variety of the Kupferschiefer are presented. Oxidation of the Kupferschiefer as an epigenetic phenomena.The oxidized zones reveal low concentrations of simple copper sulphides with the dominating chalcopyrite accompanied by bornite, pyrite, covellite, galena, clausthalite, chalcocite, digeni...

The article focuses on the history of the finding and previous use of a necklace with coins on it; the necklace was retrieved from a female burial discovered in the early twentieth century in the Gdov District, Pskov Region. The metal used for the coins was studied during the necklace restoration; signs of welding and traces of bails were discovered. It was established that the bails had been attached to the coins using a combination of riveting and welding.

Данная работа посвящена группе перстней IV–III вв. до н.э., обнаруженных в ходе работ на могильнике Елизаветовского городища. Четыре бронзовых литых перстня входили в состав погребального инвентаря погребения № 52. Помимо указанных изделий, в статье рассматривается бронзовый фрагментированный перстень, найденный в результате визуального осмотра разрушающегося участка дороги в западной части Елизаветовского городища. В работе проведен анализ изображений, некоторые из которых находят аналогии в нумизматике эллинистического периода.

This work is devoted to a group of rings of the IV–III centuries BC, discovered during the work on the burial ground of the Elizavetovskoe settlement. Four cast bronze rings were part of the burial equipment of burial No. 52. In addition to these items, the article examines a fragmented bronze ring found as a result of a visual inspection of a crumbling section of road in the western part of the Elizavetovskoe settlement. The paper analyzes images, some of which find analogies in the numismatics of the Hellenistic period.

During the Bronze Age (2250–1300 BCE), the territory of the Surxondaryo region was inhabited by bearers of a material culture known as the Sapalli culture. To date, around 70 archaeological sites and pottery locations associated with this culture have been discovered, 17 of which have been excavated by various expeditions. Among the artifacts uncovered at Sapalli culture sites are various ornaments resembling those worn by people even today. These include: head and hair ornaments (pins, hairpins, diadems, earrings), neck jewelry (beads, necklaces, pendants, amulets), yfyd jewelery (bracelets, rings). These items vary in craftsmanship techniques and materials used. Particularly notable are zoomorphic and anthropomorphic pins, rosette-shaped pins, amulets featuring animal motifs and swastika symbols, as well as earrings with eye-shaped patterns. This article presents a scientific analysis of 770 pieces of jewelry recovered from major Sapalli culture sites, including: 47 necklaces, 268 beads, 58 pendants, 1 chain, 96 bracelets, 143 pins, 47 amulets, 3 rings, 6 diadems, 101 earrings. This study examines their typology, functions, and historical-archaeological context.

В эпоху бронзы (2250–1300 гг. до н. э.) на территории Сурхандарьинской области расселились носители материальной культуры, известной как Сапаллинская культура. На сегодняшний день здесь обнаружено около 70 памятников и местонахождений керамики этой культуры, в 17 из которых проводились археологические раскопки различными экспедициями. Среди находок памятников Сапаллинской культуры представлены различные украшения, схожие с теми, что носят люди и в наше время. К ним относятся: украшения для головы (булавки-шпильки, диадемы, серьги); украшения для шеи (бусы, ожерелья, подвески, амулеты); украшения для рук (браслеты, кольца). Эти изделия различаются по технике изготовления и используемому сырью. Особенно выделяются булавки с зооморфными и антропоморфными фигурками, розетковидные булавки, амулеты с изображениями животных и свастических символов, а также серьги с глазчатым орнаментом. В данной статье проведен научный анализ 770 ювелирных изделий, выявленных на основных памятниках Сапаллинской культуры. Среди них: 47 ожерелий, 268 бус, 58 подвесок, 1 цепочка, 96 браслетов, 143 булавки, 47 амулетов, 3 кольца, 6 диадем и 101 серьга. Рассмотрены их типология, функции и историко-археологический контекст.

Статья посвящена публикации уникальных золотых украшений со вставками из агата, сердолика и бирюзы из коллекции вещей, приобретенных Н. И. Веселовским в 1895 г. в станице Крымской. Предметы происходили из нелегальных раскопок сотника Нестерова. Сложность  и совершенство техники  доказывает, что украшеия были выполнены в одной из первоклассных мастерских Древнего Востока в конце VIII в. до н. э.

The accuracy of the experimental (Canil, 1994; T -Canil) and the empirical (Ryan et al., 1996; T-Ryan) calibrations of the Ni geothermometer has been evaluated on two suites of geochemically and geothermobarometrically well characterised mantle xenoliths from Matsoku and lagersfontein by comparison to the more commonly used conventional geothermometers. The two published calibrations of the Ni geothermometer are in agreement to within ±500C in the temperature range of -900°C to 1200°C. Outside this temperature range, the two calibrations differ by between 75 and 150°C. The importance of the Ni geothermometer in diamond exploration and the studies of the mantle makes the resolution of this discrepancy very important. In addition to issues of calibration, errors in the determination of trace levels of Ni abundances in garnets may affect the accuracy of the Ni geothermometer. A 'reliable' Ni in garnet dataset was, therefore, required to minimise errors associated with Ni compositions used in temperature determination by Ni geothermometry. Thus, Ni compositions of garnets determined by PIXE, LA-ICP-MS and SIMS were compared to select the most 'reliable' dataset. Four matrix-matched secondary garnet standards were developed for the cross-checking and testing of the accuracy of data. The standards were developed by multi-method analyses, which included PIXE (using both the GeoPIXE and GUPIX software programmes for data reduction), LA-ICP-MS and solution ICP-MS. PIXE and LA-ICP-MS data were found to agree to within their 20' errors of, respectively, 2 to 10% and 4 to 12% for a concentration range of -15 to 112 ppm Ni. However, PIXE analyses were found to be superior in terms of smaller beam width, allowing several repeat analyses, and analysis of small and altered garnets thereby producing a relatively larger dataset. Available conventional geothermobarometers cannot all be accurate, since application of different geothermobarometers on the same rock can give significantly different results (Finnerty and Boyd, 1984). Therefore, prior to comparison with Ni geotherrnometry, conventional geotherrnometers were assessed by literature review

The Lake Ellen kimberlite located in the Upper Penin sula of Michigan represents a possible bedrock source for the diamonds found in the glacial deposits around the Great Lakes. The purpose of this research was to undertake a geochemical analysis in order to better understand the evolution of the kimberlite body and to elucidate on the garnet xenolith paragenesis. and scanning electron microscope analysis (SEM) were utilized in this research. The INAA revealed that with respect to other types of upper mantle rocks, the Lake Ellen kimberlite is enriched in both the light rare earth (LREE) and the heavy rare earth (HREE) with a negative europium anomaly. The SEM analysis revealed that the gar nets followed a Cr-poor, Ca-rich type of paragenesis which indicated that the Lake Ellen kimberlite is most likely nondiamondiferous. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

The Lake Ellen kimberlite located in the Upper Penin sula of Michigan represents a possible bedrock source for the diamonds found in the glacial deposits around the Great Lakes. The purpose of this research was to undertake a geochemical analysis in order to better understand the evolution of the kimberlite body and to elucidate on the garnet xenolith paragenesis. and scanning electron microscope analysis (SEM) were utilized in this research. The INAA revealed that with respect to other types of upper mantle rocks, the Lake Ellen kimberlite is enriched in both the light rare earth (LREE) and the heavy rare earth (HREE) with a negative europium anomaly. The SEM analysis revealed that the gar nets followed a Cr-poor, Ca-rich type of paragenesis which indicated that the Lake Ellen kimberlite is most likely nondiamondiferous. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

Ocean Drilling Program Site 1188 is located in an area of active low-temperature fluid venting within the PACMANUS hydrothermal field, which also includes nearby high-temperature sulfide chimneys. The hydrothermal system is hosted by the dacitic rocks of Pual Ridge in the Manus Basin (Binns et al., 2002). This 20 x 1.5 x 0.5-km ridge is part of a back-arc spreading system that is genetically related to active subduction beneath New Britain, Papua New Guinea. Pual Ridge is situated near the eastern end of the spreading system, where extension is propagating into older crust of the inactive New Ireland arc. All of the cored rocks underlying the fresh surficial dacitic volcanic rocks are intensively hydrothermally altered. Primary fluid inclusions in widespread but sparse anhydrite ± pyrite veins provide unique fluid samples that give direct evidence for the chemical and physical properties of hydrothermal fluids present beneath the seafloor, within the ridge edifice.

the Trimethylstannyl Moiety: [(Me 3 Sn)(Me 3 E)NLi•(Et 2 O)] 2 (E = Si, Ge, Sn) 14 Results and Discussion 31 List of Symbols and Abbreviations vi Chapter 2 Conclusion References Chapter 3 Synthesis and Characterization of Luminescent Tetrameric Silver(I) Amides Possessing Group 14 Substituents: [(Me 3 Si) 2 NAg] 4 and [(Me 3 Sn)(Me 3 E)NAg] 4 (E = Si, Ge, Sn) x 6.2 Atomic concentration and molar composition of ZTT films calculated from high resolution XPS measurements. A.1 Atomic Coordinates (x 10 4 ) and Equivalent Isotropic Displacement Parameters (Å x 10 3 ) for C 20 H 52 N 2 O 2 Li 2 Sn 4 (1). A.2 Interatomic Distances (Å) and Angles (°) for C 20 H 52 N 2 O 2 Li 2 Sn 4 (1). A.3 Anisotropic displacement parameters (Å 2 x 10 3 ) for C 20 H 52 N 2 O 2 Li 2 Sn 4 (1). A.4 Hydrogen coordinates (x 10 4 ) and isotropic displacement parameters (Å 2 x 10 3 ) for C 20 H 52 N 2 O 2 Li 2 Sn 4 (1). A.5 Atomic Coordinates (x 10 4 ) and Equivalent Isotropic Displacement Parameters (Å x 10 3 ) for C 20 H 52 N 2 O 2 Li 2 Si 2 Sn 2 (2). A.6 Interatomic Distances (Å) and Angles (°) for C 20 H 52 N 2 O 2 Li 2 Si 2 Sn 2 (2). A.7 Anisotropic displacement parameters (Å 2 x 10 3 ) for C 20 H 52 N 2 O 2 Li 2 Si 2 Sn 2 (2). A.8 Hydrogen coordinates (x 10 4 ) and isotropic displacement parameters (Å 2 x 10 3 ) for C 20 H 52 N 2 O 2 Li 2 Si 2 Sn 2 (2). A.9 Atomic Coordinates (x 10 4 ) and Equivalent Isotropic Displacement Parameters (Å x 10 3 ) for C 20 H 56 N 2 O 2 Li 2 Ge 2 Sn 2 (3). A.10 Interatomic Distances (Å) and Angles (°) for C 20 H 52 N 2 O 2 Li 2 Ge 2 Sn 2 (3). A.11 Anisotropic displacement parameters (Å 2 x 10 3 ) for C 20 H 52 N 2 O 2 Li 2 Ge 2 Sn 2 (3). A.12 Hydrogen coordinates (x 10 4 ) and isotropic displacement parameters (Å 2 x 10 3 ) for C 20 H 52 N 2 O 2 Li 2 Ge 2 Sn 2 (3). xi A.13 Atomic Coordinates (x 10 4 ) and Equivalent Isotropic Displacement Parameters (Å x 10 3 ) for C 20 H 52 N 2 O 2 Cl 2 Be 2 Sn 4 (4). A.14 Interatomic Distances (Å) and Angles (°) for C 20 H 52 N 2 O 2 Cl 2 Be 2 Sn 4 (4). A.15 Anisotropic displacement parameters (Å 2 x 10 3 ) for C 20 H 52 N 2 O 2 Cl 2 Be 2 Sn 4 (4). A.16 Hydrogen coordinates (x 10 4 ) and isotropic displacement parameters (Å 2 x 10 3 ) for C 20 H 52 N 2 O 2 Cl 2 Be 2 Sn 4 (4). A.17 Atomic Coordinates (x 10 4 ) and Equivalent Isotropic Displacement Parameters (Å x 10 3 ) for C 14 H 36 Be 2 F 6 N 2 O 6 S 2 Sn 4 (5). A.18 Interatomic Distances (Å) and Angles (°) for C 14 H 36 Be 2 F 6 N 2 O 6 S 2 Sn 4 (5). A.19 Anisotropic displacement parameters (Å 2 x 10 3 ) for C 14 H 36 Be 2 F 6 N 2 O 6 S 2 Sn 4 (5). A.20 Hydrogen coordinates (x 10 4 ) and isotropic displacement parameters (Å 2 x 10 3 ) for C 14 H 36 Be 2 F 6 N 2 O 6 S 2 Sn 4 (5). A.21 Atomic Coordinates (x 10 4 ) and Equivalent Isotropic Displacement Parameters (Å x 10 3 ) for C 14 H 36 N 2 O 2 Cl 2 Be 2 Si 2 (6). A.22 Interatomic Distances (Å) and Angles (°) for C 14 H 36 N 2 O 2 Cl 2 Be 2 Si 2 (6). A.23 Anisotropic displacement parameters (Å 2 x 10 3 ) for C 14 H 36 N 2 O 2 Cl 2 Be 2 Si 2 (6). A.24 Hydrogen coordinates (x 10 4 ) and isotropic displacement parameters (Å 2 x 10 3 ) for C 14 H 36 N 2 O 2 Cl 2 Be 2 Si 2 (6). A.25 Atomic Coordinates (x 10 4 ) and Equivalent Isotropic Displacement Parameters (Å x 10 3 ) for C 24 H 72 N 4 Sn 8 Ag 4 (7). xii A.26 Interatomic Distances (Å) and Angles (°) for C 24 H 72 N 4 Sn 8 Ag 4 (7). A.27 Anisotropic displacement parameters (Å 2 x 10 3 ) for C 24 H 72 N 4 Sn 8 Ag 4 (7). A.28 Hydrogen coordinates (x 10 4 ) and isotropic displacement parameters (Å 2 x 10 3 ) for C 24 H 72 N 4 Sn 8 Ag 4 (7). A.29 Atomic Coordinates (x 10 4 ) and Equivalent Isotropic Displacement Parameters (Å x 10 3 ) for C 24 H 72 N 4 Si 4 Sn 4 Ag 4 (8). A.30 Interatomic Distances (Å) and Angles (°) for C 24 H 72 N 4 Si 4 Sn 4 Ag 4 (8). A.31 Anisotropic displacement parameters (Å 2 x 10 3 ) for C 24 H 72 N 4 Si 4 Sn 4 Ag 4 (8). A.32 Atomic Coordinates (x 10 4 ) and Equivalent Isotropic Displacement Parameters (Å x 10 3 ) for C 24 H 72 N 4 Ge 4 Sn 4 Ag 4 (9). A.33 Interatomic Distances (Å) and Angles (°) for C 24 H 72 N 4 Ge 4 Sn 4 Ag 4 (9). A.34 Anisotropic displacement parameters (Å 2 x 10 3 ) for C 24 H 72 N 4 Ge 4 Sn 4 Ag 4 (9). A.35 Atomic Coordinates (x 10 4 ) and Equivalent Isotropic Displacement Parameters (Å x 10 3 ) for C 24 H 72 N 4 Si 4 Ag 4 (10). A.36 Interatomic Distances (Å) and Angles (°) for C 24 H 72 N 4 Si 4 Ag 4 (10). A.37 Anisotropic displacement parameters (Å 2 x 10 3 ) for C 24 H 72 N 4 Si 4 Ag 4 (10). A.38 Hydrogen coordinates (x 10 4 ) and isotropic displacement parameters (Å 2 x 10 3 ) for C 24 H 72 N 4 Si 8 Ag 4 (10). xiii A.39 Atomic Coordinates (x 10 4 ) and Equivalent Isotropic Displacement Parameters (Å x 10 3 ) for C 28 H 76 N 2 O 4 Cl 4 Sn 4 Zn 2 (11). A.40 Interatomic Distances (Å) and Angles (°) for C 28 H 76 N 2 O 4 Cl 4 Sn 4 Zn 2 (11). A.41 Anisotropic displacement parameters (Å 2 x 10 3 ) for C 28 H 76 N 2 O 4 Cl 4 Sn 4 Zn 2 (11). A.42 Hydrogen coordinates (x 10 4 ) and isotropic displacement parameters (Å 2 x 10 3 ) for C 28 H 76 N 2 O 4 Cl 4 Sn 4 Zn 2 (11). A.43 Atomic Coordinates (x 10 4 ) and Equivalent Isotropic Displacement Parameters (Å x 10 3 ) for C 26 H 38 N 2 Sn 2 Zr 2 (12). A.44 Interatomic Distances (Å) and Angles (°) for C 26 H 38 N 2 Sn 2 Zr 2 (12). A.45 Anisotropic displacement parameters (Å 2 x 10 3 ) for C 26 H 38 N 2 Sn 2 Zr 2 (12). A.46 Hydrogen coordinates (x 10 4 ) and isotropic displacement parameters (Å 2 x 10 3 ) for C 26 H 38 N 2 Sn 2 Zr 2 (12). A.47 Atomic Coordinates (x 10 4 ) and Equivalent Isotropic Displacement Parameters (Å x 10 3 ) for C 12 H 36 N 4 Si 4 Sn 4 (13). A.48 Interatomic Distances (Å) and Angles (°) for C 12 H 36 N 4 Si 4 Sn 4 (13). A.49 Anisotropic displacement parameters (Å 2 x 10 3 ) for C 12 H 36 N 4 Si 4 Sn 4 (13). A.50 Hydrogen coordinates (x 10 4 ) and isotropic displacement parameters (Å 2 x 10 3 ) for C 12 H 36 N 4 Si 4 Sn 4 (13). xiv A.51 Atomic Coordinates (x 10 4 ) and Equivalent Isotropic Displacement Parameters (Å x 10 3 ) for C 12 H 36 N 4 Ge 4 Si 4 (14). A.52 Interatomic Distances (Å) and Angles (°) for C 12 H 36 N 4 Ge 4 Si 4 (14). A.53 Anisotropic displacement parameters (Å 2 x 10 3 ) for C 12 H 36 N 4 Ge 4 Si 4 (14). A.54 Hydrogen coordinates (x 10 4 ) and isotropic displacement parameters (Å 2 x 10 3 ) for C 12 H 36 N 4 Ge 4 Si 4 (14). A.55 Atomic Coordinates (x 10 4 ) and Equivalent Isotropic Displacement Parameters (Å x 10 3 ) for C 12 H 36 N 4 Pb 4 Si 4 (15). A.56 Interatomic Distances (Å) and Angles (°) for C 12 H 36 N 4 Pb 4 Si 4 (15). A.57 Anisotropic displacement parameters (Å 2 x 10 3 ) for C 12 H 36 N 4 Pb 4 Si 4 (15). CHAPTER 2 SYNTHESIS AND CHARACTERIZATION OF GROUP I AND II STANNYLAMIDES SECTION A: SYNTHESIS AND CHARACTERIZATION OF HOMOLEPTIC AND HETEROLEPTIC LITHIUM AMIDES POSSESSING THE TRIMETHYLSTANNYL MOIETY: [(Me 3 Sn)(Me 3 E)NLi•(Et 2 O)] 2 (E = Si, Ge, Sn) by direct methods (SHELXS-97) and refined by full-matrix least-squares procedures (SHELXL-97), Lorentz polarization corrections and absorption correction (SADABS) were applied, µ = 5.303 mm -1 , min./max. transmission 0.5325/0.1869. Synthesis of [(Me 3 Sn)(Me 3 Si)NAg] 4 (8): Compound 8 was prepared in an analogous fashion to compound 7 using [(Me 3 Sn)(Me 3 Si)NLi•(Et 2 O)] 2 (0.50 g, 0.75 mmol) and AgBr (0.28 g, 1.50 mmol). Colorless crystals were grown from hexane overnight. Yield:

The South Manasan ultramafic intrusion (ca. 1880 Ma) located in the Early Proterozoic Thompson Nickel Belt (TNB) contains Ni and platinum group element (PGE) mineralization hosted by disseminated sulfide. Whole-rock Ni values range from 0.3 to 1.7 wt. % and total precious metals (TPMs) range from 0 to 1.3 ppm Pt + Pd + Au and equate to tenor values (i.e., metal in 100% sulfide) of 11-39 wt. % Ni and 8-27 ppm TPMs. The South Manasan intrusion is a steeply dipping sill-like body with a boudinaged outline having a strike length of approximately 1200 m, average width of 125 m and a minimum depth extent of 1000 m. The intrusion is composed of approximately 25% fresh dunite, 50% serpentine altered dunite and 25% tectonized and carbonate altered dunite. The most intense alteration is found near the intrusion's margin where it is in contact with metasedimentary rocks of the Pipe Formation, part of the surrounding Ospwagan Group. In fresh dunite the sulfide assemblage characterized by an intercumulate texture is dominated by pentlandite with accessory pyrite; the latter having a symplectic-like texture. The pentlandite-pyrite assemblage in the serpentinized dunite, although still characterized overall by an intercumlate-texture, has well developed platy intergrowths with chlorite and serpentine. In the most intensely modified unit (the carbonate altered dunite) the sulfide assemblage consists primarily of pyrrhotite and pentlandite. Whole-rock geochemical data (n= 360), modal mineralogy and mineral chemistry obtained on representative drill core throughout the South Manasan intrusion have been used to establish a type section in order to evaluate the relative roles of primary magmatic versus secondary (i.e., serpentinization, carbonate alteration and deformation) processes. These data indicate that the primary silicate-sulfide assemblage was systematically modified during iv serpentinization, carbonate alteration and deformation of the South Manasan intrusion such that a sequence of primary versus secondary events can be established. Intrusion of the original komatiitic magma and formation of the South Manasan intrusion took place at a shallow level into consolidated Ospwagan Group sediments with subsequent contamination of this melt with crustal S. This triggered sulfide saturation and generation of an immiscible sulfide melt. Calculated Ni and TPM tenor values constrain the R factor to between 500 and 2500. The early crystallization of olivine inhibited the sulfide melt from settling to the bottom of the magma column and as a consequence, the sulfides now have a primary interstitial magmatic texture. The current sulfide association dominated by pentlandite>>pyrite>chalcopyrite has a mineral paragenesis that is consistent with subsolidus re-equilibration of a primary pentlanditepyrrhotite-chalcopyrite assemblage. The subsequent processes of serpentinization, deformation and carbonate alteration resulted in modifying the primary sulfide assemblages and their textures (i.e., to platy habits), but did not greatly alter the bulk composition, in particular metal contents, except for addition of volatiles (H 2 O, CO 2 ). It is concluded therefore that the enrichment of the sulfide assemblage at South Manasan in Ni and PGEs is a consequence of a primary magmatic process involving high R factor and that the effects of later overprinting processes (alteration, deformation) are not responsible for the presently observed high-tenor sulfide association.

The early inhabitants of South America had recognised platinum and had used it for making ornaments well before the Spanish Conquest. Their techniques and ability in metal working are reviewed, based upon archaeological evidence and modern metallographic examination.

Chromitite lenses rich in the platinum-group elements (PGE) have recently been discovered in the deeper part of the mantle section of the northern part of the Oman ophiolite. In terms of stratigraphic level, there are two types of chromitite: Moho transition zone (MTZ) and mantle types. The mantle type can be further classified into two subtypes: PGE-poor and PGE-rich. Platinum-group minerals (PGM) have been mainly observed in the PGE-rich mantle chromitite and, to a lesser extent, in the PGEpoor mantle chromitite, although a few PGM grains have been detected from the MTZ chromitites. The PGM comprise four main categories in the following order of abundance: (1) sulfides [Os-rich laurite, erlichmanite and unnamed (Ir,Rh)(Ni,Cu,Fe) 2 S 3 ], (2) sulfarsenide and arsenide (irarsite-hollingworthite series, palladoarsenide), (3) alloys and native metals [Os-Ir alloy, (Cu-Pt-Fe-Ir-Rh) alloy, Pt-Fe alloy, (Ni-Ru-Os-Ir) alloy, Ir-Pt alloy, Ir-Rh alloy and native Pd metal], and (4) PGE oxide (Ru-Os-Ir oxide). Base-metal sulfides (BMS) and base-metal alloys (BMA) also are found, as inclusions in chromian spinel and interstitial matrix, mainly in the MTZ and PGE-poor mantle chromitites. The common abundance of PGE sulfides, i.e., Os-rich laurite, in the Oman chromitites is ascribed to the sulfide-undersaturated nature of the magma involved in chromitite formation. However, the sulfur fugacity was sufficiently high to produce the Os-rich laurite and, to a lesser extent, erlichmanite and Ru-poor Os-Ir alloy. The sulfur fugacity was higher in the formation of the PGE-poor mantle chromitite relative to the PGE-rich chromitite, as indicated by the presence of the unnamed Ir-rich sulfides and, to a lesser extent, BMS. The presence of PGE oxide commonly associated with fractured chromian spinel indicates that the PGE distribution in rocks can easily be modified at an early stage of serpentinization.

List of Data repositories Data repository 1: Table of precision and analytical ranges for the lithogeochemical methods used to obtain data from the whole-rock samples of the South Manasan intrusion. Digital file in Excel 2010 format. Data repository 2: Table of lithogeochemical results from the whole-rock analysis of the South Manasan intrusion. Digital file in Excel 2010 format. Data repository 3: Table of mineral chemistry results from the SEM-EDS analysis of mineral grains in carbon-coated polished thin sections from the South Manasan intrusion. Digital file in Excel 2010 format. Data repository 4: Table of mineral chemistry results from the Microprobe analysis of mineral grains in carbon-coated polished thin sections from the South Manasan intrusion. Digital file in Excel 2010 format.

The hydrometalation of alkynes with group 14 elements such as tin- or silyl hydrides is a classical transformation in organic synthesis. Strangely, among the group 14 elements, the use of germanium hydrides is rarely seen. Two efficient, stereodivergent, and broadly applicable routes to (Z)- and (E)-α-CF3-vinylgermanes by regio- and stereoselective hydrogermylation of α-trifluoromethylated alkynes under radical or transition-metal-catalyzed conditions are reported. Furthermore, we demonstrate that the resulting stereodefined fluorinated building blocks are remarkable cross-coupling partners, provided that the vinylgermane is appropriately tuned electronically, as demonstrated by the synthesis of trisubstituted (Z)- and (E)-α-trifluoromethylated alkenes.

One of the strengths of the electrical resistance tomography (ERT) technique is its flexibility in terms of survey geometries. In this paper an unconventional and novel ERT application that is geometrically analogous to in-seam seismic tomography is introduced. The novelty of the application is its in-mine tunnel-to-tunnel use to target a thin, near-horizontal, tabular orebody. The objective of this ERT application is to delineate geological features that disrupt the lateral continuity of the economic horizon. Results from in-mine trial surveys are presented to support the concept.

Pt-Pd phases of Bi-Te-As alloys, occur in virtually all known PGE deposits in the world, also evidenced by their naming, which refers to particular deposits, let us use, for example, merenskite, stilwaterite, moncheite. These minerals are an important source both for platinum and palladium as well as for tellurium. These phases are accompanied by sulphides among which they are usually located. Most often they are pyrite, pyrrhotite, chalcopyrite, pentlandite and many others. They form massive sulphide ore or are admixtures in ultramafic and mafic rocks in novae complexes of rocks containing PGE deposits in the world. It was made about 20. thousands of microanalysis in samples from selected PGE deposits (e.g. Sudbury, Monchepluton, Imandra, Fedoro-Panski, Imandrovski etc.). Analyzing the discussed alloys one can notice some regularities indicating that they can be part of a solid solution, which, depending on the conditions of crystallization, breaks down into individual phases. Care...

The Sm‐Nd, Rb‐Sr, and 18O/16O isotopic systems have been used to distinguish between the effects of seafloor hydrothermal alteration and primary magmatic isotopic variations. The Sm‐Nd isotopic system is essentially unaffected by seawater alteration, while the Rb‐Sr and 18O/16O systems are sensitive to hydrothermal interactions with seawater. Sm‐Nd mineral isochrons from the cumulate gabbros of the Samail ophiolite have an initial 143Nd/144Nd ratio of εNd = 7.8 ± 0.3, which clearly substantiates the oceanic affinity of this complex. The initial 143Nd/144Nd ratios for the harzburgite, plagiogranite, sheeted diabase dikes, and basalt units have a limited range in εNd of from 7.5 to 8.6, indicating that all the lithologies have distinctive oceanic affinities, although there is also some evidence for small isotopic heterogeneities in the magma reservoirs. The Sm‐Nd mineral isochrons give crystallization ages of 128 ± 20 m.y. and 150 ± 40 m.y. from Ibra and 100 ± 20 m.y. from Wadi Fizh, ...

The petrogenesis of sulphide ores in the O'okiep district has remained controversial. Based mainly on the concentration of chalcophile metals (PGE, Cu, Ni), it is proposed that the sulphides segregated from a basaltic magma generated during melting of sub-continental lithospheric mantle. Sulphide saturation of the magma was delayed due to relatively high f O 2 until crustal contamination occurred during the advanced stages of differentiation. The immiscible sulphide melt was entrained and fractionated in dynamic magma conduits. Sulphides enriched in monosulphide solid solution (mss) component precipitated at depth in the Kliprand area of southern Namaqualand to form the Hondekloof deposits, whereas the O'okiep ores crystallised at shallower levels from highly fractionated residual sulphide liquids enriched in intermediate solid solution (iss). Sulphides of intermediate composition occur at Ezelsfontein. In the context of this model, the O'okiep intrusions could represent the proximal magmatic members of an IOCG suite of deposits, raising the prospect for additional IOCG deposits elsewhere in southern Africa. The model also predicts an enhanced potential at O'okiep for undiscovered Ni sulphide ores at depth.

Extensive faulting and fracturing have been documented by detailed field studies of a 48 km2 area in the upper Precambrian Duluth complex, northeastern Minnesota. FaultPand fractures dip steeply, trend principally N35%, N05"W, and N40°W, and were recognized by the displacement of plagioclase and plagioclase-olivine cumulate layers within the so-called South Kawishiwi intrusion. This work represents the first field documentation of extensive faulting in the Duluth complex and shows that fault offsets are an important complicating factor in understanding the geology of the complex. Further, faults of the type mapped are compatible with the structures predicted but not previously recognized by models that genetically link the Duluth complex to a major period of crustal rifting, and these faults have important economic implications, as offsets along them are certain to affect the continuity of important copper-nickel sulfides that occur along the basal part of the Duluth complex. On a document6 la distribution gCnCrale des failles et des fractures dans des Ctudes de terrain couvrant une region de 48 km2 dans le complexe prkcarnbrien de Duluth dans le nord-est du Minnesota. Les failles et fractures ont un pendage fort, elles s'orientent selon trois directions principales, N35OE, N05"O et N40°0, et on les reconnait par le dCplacement des couches de cumulats de plagioclase et de plagioclase-olivine dans ce qu'on dCsigne cornme I'intrusion de South Kawishiwi. Ce travail repdsente la prernikre documentation sur le terrain de failles extensives dans le complexe de Duluth et il montre que les rejets de faille sont un facteur de complication important dans la comprt5hension de la gCologie du complexe. De plus, les failles du type que nous avons cartographiCes sont compatibles avec les ;tructures prkdites mais non reconnues jusqu'h maintenant par les modkles qui rattachent gknktiquement le complexe de Duluth h une p6riode majeure de rifting de la croiite; ces failles ont d'importantes implications Cconorniques puisque les rejets le long des failles affectent certainement la continuit6 d'importants gisements de sulfures de cuivre-nickel qu'on retrouve h la base du complexe de Duluth.

Al Introduction Al Regional geology Al Previous work A3 Sulfide occurrence A3 Lithology A4 Pyroxene cumulates A4 Metagabbroic sequence A6 Mineral and rock analyses A8 Geothermometry and metamorphism A15 Summary and discussion A16 References cited A21 FIGURES Contents iii

Magmatic Ni-PGE deposits represent some of the most magnetically challenging styles of mineralization. In the past, exploration for magmatic Ni-PGE mineralization has largely been focused on layered mafic to ultramafic intrusions, e.g., the Bushveld Complex in South Africa However, recent advances have shown that Ni-PGE mineralization is typically associated with specific intrusion types, e.g., chonoliths, bladed-dykes and funnels, that acted as high-throughput magma conduits within much larger magmatic provinces. The rocks present within these systems are compositionally diverse, and commonly display strong, stable and often complex remanent magnetization, in association with magnetite, titanomagnetite and pyrrhotite. The objective of this paper is to provide an understanding of the complexities of magnetization in magmatic Ni-PGE systems which will hopefully assist with more effective targeting, particularly in poorly explored, under-cover terrains. Some of the many issues related...

To better understand the mechanism of Mg isotopic variation in magma systems, here we report high precision Mg isotopic data of 17 bulk rock samples including dunite, clinopyroxenite, hornblendite and gabbro and 10 pairs of dunite-hosted olivine and chromite separates from the well-characterized Alaskan-type Xiadong intrusion in NW China, which formed by continuous and high degree of lithological differentiation from mafic magmas. Chromite separates have highly variable d 26 Mg values from À0.10‰ to 0.40‰, and are consistently heavier than coexisting olivine separates (À0.39‰ to À0.15‰). Both mineral d 26 Mg values and the degrees of inter-mineral fractionation are well correlated with geochemical indicators of magma differentiation, indicating that these inter-sample and inter-mineral Mg isotope fractionations are caused by magma evolution. The d 26 Mg values range from À0.20‰ to À0.02‰ in the dunite, À0.43‰ in the clinopyroxenite, À0.43‰ to À0.28‰ in the hornblendite, 0.18‰ in the chromite-bearing hornblendite, and À0.56‰ to À0.16‰ in the gabbro. The Mg isotopic variations in different types of rocks are closely related to fractional crystallization and accumulation of different proportions of oxides vs. silicates. Chromite crystallization and accumulation is the most important factor in controlling Mg isotope fractionation during the formation of the Xiadong intrusion. Compared to basaltic and granitic magmas, differentiation of the Alaskan-type intrusions occurs at a relatively high oxygen fugacity, which favors chromite crystallization and consequently significant Mg isotope fractionations at both mineral and whole-rock scales. Therefore, Mg isotope systematics can be used to trace the degree of magma differentiation and related-mineralization.

ABSTRACTThe Waterberg platinum deposit is an extraordinary example of a vein-type hydrothermal quartz-hematite-PGE (platinum-group element) mineralization. This study concentrates on the geochemical character of the ores and the platinum-group mineral (PGM) assemblage by application of reflected-light and scanning electron microscopy followed by electron probe microanalysis.The PGM-bearing quartz veins show multiple banding indicating numerous pulses of fluid infiltration. Mineralization was introduced contemporaneously with the earliest generation of vein quartz and hematite. High oxygen and low sulfur fugacities of the mineralizing fluids are indicated by hematite as the predominant opaque mineral and the lack of sulfides.The ‘Waterberg type’ mineralization is characterized by unique metal proportions, namely Pt>Pd>Au, interpreted as a fingerprint to the cradle of the metals, namely rocks and ores of the Bushveld Complex, or reflecting metal fractionation during ascent of an...

The research interest for many authors has been focused on the origin, recovery, and exploration of critical metals, including platinum-group elements (PGEs), with the aim of finding new potential sources. Many giant porphyry Cu deposits are well known around the Pacific Rim, in the Balkan–Carpathian system, Himalayas, China, and Malaysia. However, only certain porphyry Cu-Au deposits are characterized by the presence of significant Pd and Pt contents (up to 20 ppm). This contribution provides new analytical data on porphyry-Cu-Au±Pd±Pt deposits from the Chalkidiki Peninsula and an overview of the existing geochemical characteristics of selected porphyry-Cu deposits worldwide in order to define significant differences between PGE-fertile and PGE-poor porphyry-Cu intrusions. The larger Mg, Cr, Ni, Co, and Re contents and smaller LILE elements (Ba and Sr) in fertile porphyry-Cu-Au-(PGE) reflect the larger contribution from the mantle to the parent magmas. In contrast, the smaller Mg, ...

Les colorants naturels, utilisés depuis les temps préhistoriques, sont principalement extraits du monde végétal. Les applications des plantes tinctoriales ont concerné non seulement textiles et vannerie, mais aussi la peinture ou teinture de la peau et des cuirs, des cheveux et poils, etc. Des exemples de leur importance dans le patrimoine culturel des sociétés du Pacifique sont présentés, en développant celui de recherches interdisciplinaires récentes, d'ordre botanique, chimique et anthropologique, qui concernent plusieurs espèces de Ventilago (Rhamnaceae) de Nouvelle-Calédonie et du Vanuatu. Les colorants naturels suscitent actuellement un regain d'intérêt, dû à leurs applications potentielles dans divers secteurs industriels (industries agro-alimentaires et cosmétiques).

The effect of grinding environment on the flotation behaviour of sulphide-poor platinum group element (PGE) ores was studied with 3 different ores containing Ni, Cu and PGE. The sulphur content of the investigated ore samples varied from 0.3% to 0.6%. Grinding tests were performed with a Magotteaux Mill Ò which is instrumented for measurement and monitoring of pulp properties. Flotation tests were done with a 5L Magotteaux float cell. Pulp potential, pH and dissolved oxygen (DO) levels were measured continuously during grinding. Pulp oxidation-reduction potential (ORP) and DO were adjusted by the addition of CO 2 , N 2 and nitric acid. Iron or 30% chrome containing balls were used in grinding. In this study, a number of grinding and flotation tests were done with natural ore samples into which 1 g of synthetic sperrylite was added. This study presents some aspects of the effect of a reducing grinding environment on the flotation response of lowS content PGE containing ores. Highly reducing grinding environment created with CO 2 was found to have a positive effect on flotation behaviour of PGE minerals from lowS content ores.

The 2,430 Ma Burakovsky layered complex, located in Karelia, Russia, is one of the largest layered Fennoscandian intrusions. It consists, from the base to the top, of a thick ultramafic part dominated by dunite and peridotite overlain by a layered mafic part that consists of alternating layers of pyroxenite, wehrlite and gabbro (Transitional Banded Zone, TBZ), and a thick sequence of gabbroic rocks [Gabbronorite Zone (GNZ), Pigeonite Gabbronorite Zone (PGNZ), Magnetite Gabbronorite-Diorite zone (MGDZ), which predominates. The Main Chromite Horizon, located at the interface between the ultramafic part and the layered series, hosts laurite and Os-Ir alloy grains observed as tiny inclusions in chromite crystals. The Transitional Banded Zone and Gabbronorite Zone are characterized by disseminated sulfide blebs hosted by clinopyroxene and plagioclase. The blebs consist of a chalcopyrite-pyrrhotite-pentlandite assemblage locally associated with PGM found as discrete grains in sulfides, in clinopyroxene, but more commonly around the margin of sulfide grains. Platinum-group minerals consist of dominant Pd and Pt arsenides and sulfarsenides and Pt-(Pd-Bi) tellurides (sperrylite, platarsite, palladoarsenide, kotulskite, moncheite) with minor amounts of native Pt. The expression of the mineralization is consistent with the late crystallization of an immiscible semimetalrich liquid that forms discrete PGM grains around sulfide blebs and in veinlets injected in the adjacent silicates. The PGM were also observed in association with secondary phases, dominated by epidote replacing primary base-metal sulfides. This feature, commonly described in other layered intrusions, is here mainly observed around the platinum-group minerals-base-metal sulfides association hosted by plagioclase. The existence of compositional heterogeneities in primary plagioclase likely acts as a target for the development of alteration.

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Umm Rilan area is made up of talc-carbonate and talc serpentinite rocks of ophiolitic mélange, metavolcanics and granitoid rocks. The derivatives of ultramafic rocks as a result of metamorphism and the neighboring massive metavolcanic of the Late Proterozoic orogeny are related to a dismembered Pan-African ophiolitic mélange. In ultramafic rocks talc occurs as lenticular veins and along shear zone planes. Talc-carbonate rocks are whitish green, massive, slightly deformed, very fine-to fine-grained and composed of talc with carbonates as well as iron and manganese oxides as accessories. The talc carbonate rocks consist essentially of talc, malachite, dolomite, tremolite and magnesite. Geochemically, these rocks exhibit maficultramafic cumulate ophiolite rocks of metamorphic peridotite and dunite in composition. The different variation diagrams indicate that these rocks are originated from cumulative komatiite with tendency to be tholeiitic magma and revealed that these rocks are formed in low Tiophiolites of tholeiitic environment. The scanning electron microscopic analysis detected that, the presence of Ta, Zn and Fe minerals in association with Cu, Ca and Mg mineralization. The contents of Cu, Zn and Pb show high tendency to be concentrated in the hydrothermally altered products associated with the sulfide minerals. The studied talc-carbonate rocks suffered low grade metamorphism in greenschist facies and was formed under medium pressure and low temperature of low Al2O3/CaO ratio related to the ultramafic rocks. Umm Rilan talc-carbonates are of hydrothermal origin. Tectonic activity plays a major role in the formation of Umm Rilan talc deposits by allowing fluids to penetrate the ultramafic rocks, creating a micro-permeability that facilitates reactions with the host rock (ultramafic-mafic rocks).

Two new porphycenes functionalized with ferrocenyl pendants have been synthesized and characterized spectroscopically and structurally. The porphycene-based emission in porphycene-ferrocene dyads was switched on and off by the reversible control of the ferrocenyl pendant redox states. Transient absorption spectroscopy with a femtosecond laser-pulsed technique has successfully detected the picosecond charge-separated excited state of the dyad upon Q-band excitation of the porphycene ring.

The Ni-Cu-platinum-group element ores in the sublayer and footwall breccia of the Sudbury structure have distinctive geochemical halos. In the Fraser mine, F/Cl ratios of the sublayer rocks appear to decrease, Na 2 O/K 2 O ratios of the footwall breccia samples decrease, and Cl in both units increases with proximity to mineralization. These halos are interpreted to result from interaction of residual magmatic fluids with host rocks, which altered the host-rock mineralogy and precipitated Cl-bearing minerals. The results of this study, together with the results of previous studies, suggest that most ores at Sudbury, including sublayer-and footwall breccia-hosted contact ores and Sudbury breccia-hosted footwall ores, are surrounded by Cl and possibly alkali halos and that these geochemical signatures may be used to identify rocks that are proximal to mineralization.