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Sarahjane Barnes - One of the best experts on this subject based on the ideXlab platform.

  • the lower banded series of the stillwater complex montana whole rock lithophile chalcophile and Platinum Group Element distributions
    Mineralium Deposita, 2020
    Co-Authors: Sarahjane Barnes, Philippe Page, Michael L Zientek
    Abstract:

    The principal rock types of the Lower Banded series of the Stillwater Complex are gabbronorite and norite with minor troctolite and anorthosite. The whole-rock composition is largely controlled by the cumulate minerals plagioclase and pyroxene (±olivine). The rocks are very poor in incompatible Elements, at the 0.1 to 2 times mantle levels, indicating < 10% liquid fraction. The Pd and Pt are enriched in a layer known as the J-M Reef which occurs in a zone containing olivine-bearing rocks (OB I). This zone contains the same rock types as the rest of the Lower Banded series, but troctolite, olivine gabbronorite, and anorthosite are more abundant in OB I. The concentrations of lithophile Elements in OB I are similar to the rocks above and below OB I. In particular, the reef rocks show no additional signs of continental crust contamination such as additional Th or LREE enrichment, and the reef rocks are not enriched in incompatible Elements. The strongly chalcophile Elements Cu, Ni, Se, Bi, and Au all correlate with S, indicating that these Elements are controlled by sulfides. The PGE show two trends. The rocks below the J-M Reef and the reef rocks have high PGE+Au to S ratios and fall on a single trend, whereas those above the reef have low metal to S ratios. These low ratios for the rocks above the reef could arise because the magma was depleted in PGE+Au as it had already segregated some PGE+Au-rich sulfides. The relatively high PGE, Au, Cu, and Se concentrations of the rocks below the reef imply that the rocks contain ~ 0.1 wt% cumulate sulfides. However, they have very low S contents (< 300 ppm). The low S/Se ratios of these rocks (< 2000) and most of the rocks outside of the reef suggest that they have lost more than half of their S. The Pd/Pt and Pd/Ir ratios of the reef (~ 3.4 and 800, respectively) are much higher than those of the rocks below and above the reef. The high Pd/Pt and Pd/Ir ratios of the reef imply that the sulfides formed from a fractionated magma; however, there is no correlation between the Pd/Ir and Pd/Pt ratios and the host rock type. These ratios are dissimilar to the Bushveld reefs and the Main Sulfide Zone of the Great Dyke. They more closely resemble the reefs in more fractionated rocks such as the AP Reef of the Penikat Intrusion, the Roby Zone of the Lac des Iles Complex, or the disseminated sulfides of the Noril’sk I intrusion. The very high Pd/S and low Cu/Pd ratios of the J-M Reef require that the sulfides collected Pd from a very large volume of magma. None of the current models is entirely satisfactory; however, we favor a model where at depth the OB1 magma partially melted a komatiitic massive sulfide and then transported the sulfide droplets into the magma chamber at the level of the J-M reef.

  • Platinum Group Element concentrations in pyrite from the main sulfide zone of the great dyke of zimbabwe
    Mineralium Deposita, 2016
    Co-Authors: Rubén Piña, Sarahjane Barnes, Fernando Gervilla, Rosario Lunar, Thomas Oberthur
    Abstract:

    The Main Sulfide Zone (MSZ) of the Great Dyke of Zimbabwe hosts the world’s second largest resource of Platinum-Group Elements (PGE) after the Bushveld Complex in South Africa. The sulfide assemblage of the MSZ comprises pyrrhotite, pentlandite, chalcopyrite, and minor pyrite. Recently, several studies have observed in a number of Ni-Cu-PGE ore deposits that pyrite may host significant amounts of PGE, particularly Pt and Rh. In this study, we have determined PGE and other trace Element contents in pyrite from the Hartley, Ngezi, Unki, and Mimosa mines of the Great Dyke by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Based on the textures and PGE contents, two types of pyrite can be differentiated. Py1 occurs as individual euhedral or subhedral grains or clusters of crystals mostly within chalcopyrite and pentlandite, in some cases in the form of symplectitic intergrowths, and is PGE rich (up to 99 ppm Pt and 61 ppm Rh; 1.7 to 47.1 ppm Ru, 0.1 to 7.8 ppm Os, and 1.2 to 20.2 ppm Ir). Py2 occurs as small individual euhedral or subhedral crystals within pyrrhotite, pentlandite, and less frequently within chalcopyrite and silicates and has low PGE contents (<0.11 ppm Pt, <0.34 ppm Rh, <2.5 ppm Ru, <0.37 ppm Ir, and <0.40 ppm Os). Py1 contains higher Os, Ir, Ru, Rh, and Pt contents than the associated pyrrhotite, pentlandite, and chalcopyrite, whereas Py2 has similar PGE contents as coexisting pyrrhotite and pentlandite. Based on the textural relationships, two different origins are attributed for each pyrite type. Py1 intergrowth with pentlandite and chalcopyrite is inferred to have formed by late, low temperature (<300 °C) decomposition of residual Ni-rich monosulfide solid solution, whereas Py2 is suggested to have formed by replacement of pyrrhotite and pentlandite caused by late magmatic/hydrothermal fluids.

  • chalcophile and Platinum Group Element distribution in pyrites from the sulfide rich pods of the lac des iles pd deposits western ontario canada implications for post cumulus re equilibration of the ore and the use of pyrite compositions in explorati
    Journal of Geochemical Exploration, 2015
    Co-Authors: Charley J Duran, Sarahjane Barnes, John T Corkery
    Abstract:

    The Lac des Iles Pd-deposits are atypical within the scope of Platinum-Group Element (PGE) deposits. This is because the deposits do not resemble a classical PGE deposit in a number of ways: the intrusion is small and concentrically zoned; most of the host rocks to the deposits no longer have a primary mineralogy and equilibrated under greenschist conditions; the textures of the rocks from the ore zones are extremely variable; and the ores have very high Pd/Ir and Pd/Pt ratios. In addition to the disseminated sulfides, there are sulfide-rich pods present throughout the stratigraphy. The sulfide mineral textures and proportions within the pods vary from those which are essentially magmatic to those which consist predominantly of pyrite. The pyrite could have been deposited from hydrothermal fluids or it could have formed by alteration of magmatic sulfides. In order to distinguish between these two origins, the PGE and chalcophile Element contents of the pyrite were investigated. It was found that the pyrite contains Os, Ir, Ru and Rh. These Elements also concentrate in the magmatic sulfides pyrrhotite and pentlandite. Their presence in the pyrite could be explained by redistribution of Fe from pyrrhotite to silicate minerals that are present within and around the sulfide pods, possibly during cooling. Maps of the distribution of the Elements show that there is zoning of the Elements. The IPGE–Rh are present towards the cores of pyrite along with As whereas Co and Se are present towards the rims. Mobile Elements such as Pb, Bi and Ag are present in thin overgrowths at the edges of pyrite and in a few cases, Pt, Te and Sn are also present in the overgrowths. Comparison of the composition and Element distribution with pyrites from other igneous settings (Sudbury and Aguablanca) shows similarities, suggesting a common ore-modifying process. In contrast, pyrites from low-temperature hydrothermal deposits have different compositions. A plot of Co/Se vs Sb/As appears to be effective at separating the igneous pyrites from pyrites found in other settings and could possibly be used in exploration.

  • a review of sulfur to selenium ratios in magmatic nickel copper and Platinum Group Element deposits
    Ore Geology Reviews, 2015
    Co-Authors: Matthias Queffurus, Sarahjane Barnes
    Abstract:

    Deviations in the sulfur to selenium ratios (S/Se) from mantle values in magmatic Ni–Cu–Platinum Group Elements (PGE) sulfide deposits have been widely used to constrain the ore forming processes. Basically, S/Se ratios greater than mantle values are interpreted to be the result of contamination of the mantle derived magma by S-rich sedimentary rocks, whereas S/Se ratios lower than mantle values are thought to be the result of S loss during post-crystallization. However, there are many other processes involved in producing a deposit and it is possible that these may be also important in controlling S/Se ratios. In order to investigate the relative importance of these processes, we have compiled a data base of S, Se, δ34S and metal values from Ni–Cu–PGE sulfide deposits. This compilation shows that processes affecting S/Se ratios can be divided into two main classes: the magmatic processes and the late- to post-magmatic processes. 1) Magmatic processes include the well-known addition of S from sedimentary rocks, variations in the sulfide to silicate liquid ratio (R-factor), depletion of the silicate magma in Se by early segregation of the sulfide liquid, and the moderate incompatibility of Se into the first sulfide minerals to crystallize from a sulfide liquid, the monosulfide-solid-solution (MSS). This incompatibility results in a change in S/Se ratio between the Fe-rich and Cu-rich zones of magmatic sulfide ores. The fractionation of Se during crystallization of sulfide liquids has not previously been appreciated. 2) Late- to post-magmatic processes include: hydrothermal alteration, high-grade metamorphism, serpentinization and supergene weathering. Some metamorphosed Cu-deposits have low S/Se ratios suggesting S-loss by breakdown of sulfide minerals during a high-grade metamorphic event. However, the effectiveness of this process remains unclear and alternative models exist. The preferential remobilization of S relative to Se during hydrothermal alteration, serpentinization and supergene weathering leads to a moderate decrease of S/Se ratios values and can mask the initial S/Se ratio.

  • chalcophile and Platinum Group Element pge concentrations in the sulfide minerals from the mccreedy east deposit sudbury canada and the origin of pge in pyrite
    Mineralium Deposita, 2011
    Co-Authors: Sarah A. S. Dare, Hazel Margaret Prichard, Sarahjane Barnes, Peter Charles Fisher
    Abstract:

    Magmatic sulfide deposits consist of pyrrhotite, pentlandite, chalcopyrite (± pyrite), and Platinum-Group minerals (PGM). Understanding the distribution of the chalcophile and Platinum-Group Element (PGE) concentrations among the base metal sulfide phases and PGM is important both for the petrogenetic models of the ores and for the efficient extraction of the PGE. Typically, pyrrhotite and pentlandite host much of the PGE, except Pt which forms Pt minerals. Chalcopyrite does not host PGE and the role of pyrite has not been closely investigated. The Ni–Cu–PGE ores from the South Range of Sudbury are unusual in that sulfarsenide PGM, rather than pyrrhotite and pentlandite, are the main carrier of PGE, probably as the result of arsenic contribution to the sulfide liquid by the As-bearing metasedimentary footwall rocks. In comparison, the North Range deposits of Sudbury, such as the McCreedy East deposit, have As-poor granites in the footwall, and the ores commonly contain pyrite. Our results show that in the pyrrhotite-rich ores of the McCreedy East deposit Os, Ir, Ru, Rh (IPGE), and Re are concentrated in pyrrhotite, pentlandite, and surprisingly in pyrite. This indicates that sulfarsenides, which are not present in the ores, were not important in concentrating PGE in the North Range of Sudbury. Palladium is present in pentlandite and, together with Pt, form PGM such as (PtPd)(TeBi)2. Platinum is also found in pyrite. Two generations of pyrite are present. One pyrite is primary and locally exsolved from monosulfide solid solution (MSS) in small amounts (<2 wt.%) together with pyrrhotite and pentlandite. This pyrite is unexpectedly enriched in IPGE, As (± Pt) and the concentrations of these Elements are oscillatory zoned. The other pyrite is secondary and formed by alteration of the MSS cumulates by late magmatic/hydrothermal fluids. This pyrite is unzoned and has inherited the low concentrations of IPGE and Re from the pyrrhotite and pentlandite that it has replaced.

Hazel Margaret Prichard - One of the best experts on this subject based on the ideXlab platform.

  • Platinum Group Element geochemistry of boninite derived mesoarchean chromitites and ultramafic mafic cumulate rocks from the sukinda massif orissa india
    Ore Geology Reviews, 2019
    Co-Authors: Sisir K Mondal, Hazel Margaret Prichard, Sarifa Khatun, M Satyanarayanan, G Ravindra R Kumar
    Abstract:

    Abstract The Mesoarchean Sukinda Massif in the Singhbhum craton is the largest chromite ore deposit in India that contains ≈95% of Indian Cr resources. The Sukinda Massif consists of an elongated layered ultramafic unit (≈25 km × 400 m) that occurs within the 3.5 Ga supracrustal sequences of the Tomka-Daitari-Mahagiri greenstone belt in eastern India. The ultramafic unit comprises serpentinized dunite, orthopyroxenite and chromitite. There are six chromitite seams which are present within the serpentinized dunite. All ultramafic rocks are extensively weathered and capped by laterites (≈30 m thick). In the southwestern part of the Sukinda Massif, in the Katpal area, chromitite seams and the host ultramafic rocks are fragmented, forming breccias cemented by the gabbroic to granodioritic rocks. Whole-rock major, trace and Platinum-Group Elements (PGE) geochemistry indicates that the ultramafic unit and the gabbro, including the cementing matrix materials of the breccias, are cogenetic. The ultramafic rocks formed by fractional crystallization of a parental boninitic or high-Mg siliceous magma. The cementing gabbroic rocks formed from an evolved boninitic magma generated from fractionated boninite or high-Mg siliceous basalt. The positive correlation between MgO and Ni, and MgO and Cr is due to fractionation of early cumulus like olivine and chromite from the high-Mg parental magma. The correlation between Zr and Cu suggests that the parental boninitic magma was S-undersaturated. However, the matrix gabbro shows a flatter trend with increasing Zr and Cu, indicating sulfide saturation occurred later in the evolved boninitic magma. In Sukinda, the concentrations of PGE in the massive chromitites (≈176–875 ppb) from the main ultramafic unit and in chromitite fragments (≈61–279 ppb) from the breccias are higher than in serpentinite (≈19–71 ppb), orthopyroxenite (≈14–19 ppb) and gabbro (≈3–11 ppb). Three samples of the massive chromitites from the main ultramafic unit have significant PGE concentrations (PGEtotal ≈ 651–875 ppb) with IPGE (Ir, Os, Ru) ≈ 528–634 ppb, much higher than PPGE (Pd, Pt, Rh) ≈ 93–332 ppb. Detailed PGE mineralogical studies of these samples revealed presence of IPGE-bearing Platinum-Group minerals (PGM) dominated by Os-Ir-Ru alloys (containing minor Pt) enclosed in chromite grains. Other PGMs are laurite present as composite grain within chromite plus irarsite which are associated with cracks in chromite grains and a small sperrylite grain attached to an Os-Ir-Ru alloy. All the As-bearing PGM are associated with cracks in the chromite suggesting introduction of As during alteration of primary PGM to PGM-arsenides. The positive correlation between IPGE (Os, Ir, Ru) and MgO or Cr indicates they are fractionated during the early stage of magmatic differentiation from a S-undersaturated boninitic magma. The low Ir of the silicate rocks indicate prior removal of Ir-bearing alloys from the parental boninitic magma which would account for the occurrence of Os-Ir-Ru alloys in massive chromitites. The results suggest that Os-Ir-Ru alloys from the Sukinda chromitites crystallized at relatively high temperature and low fS2 condition within a S-undersaturated boninitic magma ascending from the upper mantle where they entrapped by the growing chromite crystals. Overall, the initial PGE analysis from the Sukinda breccias, presented herein, indicate similarities with the Nuasahi breccias in the Singhbhum craton, and highlight the potential for mineralization in this area.

  • Platinum Group Element pge geochemistry of mesoarchean ultramafic mafic cumulate rocks and chromitites from the nuasahi massif singhbhum craton india
    Lithos, 2014
    Co-Authors: Sarifa Khatun, Sisir K Mondal, Meifu Zhou, V Balaram, Hazel Margaret Prichard
    Abstract:

    Abstract The Mesoarchean Nuasahi Massif in eastern India comprises a lower ultramafic and an upper gabbro unit. The lower unit consists of orthopyroxenite, harzburgite, dunite and three chromitite bands. All of these rocks are characterized by adcumulate textures. The upper unit consists of gabbro with magnetite layers. At the contact between the eastern orthopyroxenite and the lower part of the upper gabbro, a sulfide-rich breccia zone with Platinum-Group-Element (PGE) mineralization is present. Detailed studies of major-, trace- and PGE abundances suggest that the ultramafic–mafic cumulate rocks, chromitites and breccias are genetically linked. The chondrite-normalized U-shaped rare earth Element (REE) patterns of the harzburgite resemble those of Phanerozoic boninite. The overall U-shaped REE patterns of the ultramafic rocks indicate derivation of the parental magma from a metasomatized depleted mantle source. The upper gabbros have higher relative abundances of trace Elements than the lower ultramafic rocks, due to crystallization from a fractionated magma. Whole-rock geochemistry suggests that the lower ultramafic cumulate rocks with chromitites crystallized from a boninitic parental magma, whereas the upper gabbros with magnetite bands may be formed from residual boninitic magma that was contaminated by more tholeiitic-like magmas. The boninitic parental magma that crystallized to form the lower ultramafic unit was most likely generated by second-stage melting of a depleted metasomatized mantle source in a supra-subduction zone (SSZ) setting and emplaced into crustal sequences. The PGE abundances in the Nuasahi rocks provide additional constraints on their geochemical evolution during the Mesoarchean. Primitive-mantle-normalized PGE diagrams show (1) Ru enrichment in chromitites (Pd/Ru = 0.17–0.64), (2) Pd/Pt fractionation in both chromitites (Pd/Pt = 3.1) and ultramafic rocks (Pd/Pt = 0.62), (3) marked Ir depletion in ultramafic rocks (Pd/Ir = 6.3) and (4) overall PGE enrichment in chromitites (PGEtotal = 142–502 ppb). The large Ir depletion in the ultramafic rocks, and the overall Ir-depleted character of other rocks from the Nuasahi Massif, may be related to multiple episodes of melt extraction from the mantle source, giving it a subchondritic character.

  • chalcophile and Platinum Group Element pge concentrations in the sulfide minerals from the mccreedy east deposit sudbury canada and the origin of pge in pyrite
    Mineralium Deposita, 2011
    Co-Authors: Sarah A. S. Dare, Hazel Margaret Prichard, Sarahjane Barnes, Peter Charles Fisher
    Abstract:

    Magmatic sulfide deposits consist of pyrrhotite, pentlandite, chalcopyrite (± pyrite), and Platinum-Group minerals (PGM). Understanding the distribution of the chalcophile and Platinum-Group Element (PGE) concentrations among the base metal sulfide phases and PGM is important both for the petrogenetic models of the ores and for the efficient extraction of the PGE. Typically, pyrrhotite and pentlandite host much of the PGE, except Pt which forms Pt minerals. Chalcopyrite does not host PGE and the role of pyrite has not been closely investigated. The Ni–Cu–PGE ores from the South Range of Sudbury are unusual in that sulfarsenide PGM, rather than pyrrhotite and pentlandite, are the main carrier of PGE, probably as the result of arsenic contribution to the sulfide liquid by the As-bearing metasedimentary footwall rocks. In comparison, the North Range deposits of Sudbury, such as the McCreedy East deposit, have As-poor granites in the footwall, and the ores commonly contain pyrite. Our results show that in the pyrrhotite-rich ores of the McCreedy East deposit Os, Ir, Ru, Rh (IPGE), and Re are concentrated in pyrrhotite, pentlandite, and surprisingly in pyrite. This indicates that sulfarsenides, which are not present in the ores, were not important in concentrating PGE in the North Range of Sudbury. Palladium is present in pentlandite and, together with Pt, form PGM such as (PtPd)(TeBi)2. Platinum is also found in pyrite. Two generations of pyrite are present. One pyrite is primary and locally exsolved from monosulfide solid solution (MSS) in small amounts (<2 wt.%) together with pyrrhotite and pentlandite. This pyrite is unexpectedly enriched in IPGE, As (± Pt) and the concentrations of these Elements are oscillatory zoned. The other pyrite is secondary and formed by alteration of the MSS cumulates by late magmatic/hydrothermal fluids. This pyrite is unzoned and has inherited the low concentrations of IPGE and Re from the pyrrhotite and pentlandite that it has replaced.

  • the location of the chalcophile and siderophile Elements in Platinum Group Element ore deposits a textural microbeam and whole rock geochemical study implications for the formation of the deposits
    Chemical Geology, 2008
    Co-Authors: Sarahjane Barnes, Hazel Margaret Prichard, Peter Charles Fisher, Richard A. Cox, Bélinda Godel
    Abstract:

    Recent analytical developments now make it possible to determine chalcophile and siderophile Elements in situ in base metal sulfide minerals (BMS). Three points can be considered using these analyses: a) are the different Elements preferentially concentrated in any particular BMS; b) what percentages of the siderophile and chalcophile Elements are present in the BMS; c) what processes affect the distribution of the siderophile and chalcophile Elements among the BMS. We have compared siderophile and chalcophile Element distributions in pentlandite, chalcopyrite and pyrrhotite from Platinum-rich ore deposits that have undergone different cooling rates and degrees of metamorphism to address these questions. We found that Re, Os, Ir, Ru and Rh are concentrated in both pentlandite and pyrrhotite. In addition to these Elements pentlandite concentrates Ni, Co and Pd. Copper, Zn, Cd and Ag are concentrated in chalcopyrite or cubanite. Gold and Pt do not preferentially concentrate in any particular BMS, with very little of these Elements located in BMS. The BMS from sulfide droplets of the Noril'sk (Russia) host almost all of the siderophile Elements (except Pt and Au) and much of the Co and Ag. Platinum occurs as Pt-bearing mineral inclusions within the BMS. The droplets occur in unmetamorphosed subvolcanic sills, which would have cooled relatively quickly. The high percentage of PGE in the BMS and the close association of the Pt-minerals with the BMS suggest that the model whereby a base metal sulfide liquid collected the siderophile and chalcophile Elements to form the deposit is correct. We suggest that the Pt partitioned into the sulfide liquid and could have partitioned into the BMS at high temperatures, but that a lower temperatures the BMS structure would not accommodate the Pt and Pt-minerals exsolved during cooling. Alternatively, if Pt could not partition into the BMS then Pt would have concentrated in the fractionated sulfide liquid and crystallized as Pt-minerals from the final liquid. In the Platinum-Group Element (PGE) reefs of unmetamorphosed layered intrusions (Busveld Complex, South Africa and Great Dyke, Zimbabwe) 30 to 60% of the siderophile Elements (except Pt and Au) are present in pentlandite, pyrrhotite and chalcopyrite. The balance is found in Platinum-Group minerals (PGM), which occur associated with the BMS. We suggest that the reason that a larger percentage of PGE are in the form of PGM is the result of the slower cooling of the BMS in the layered intrusion, which would allow more time for exsolution of the PGE than in the case of the BMS from subvolcanic sills. In the PGE-reefs from the metamorphosed layered intrusion (Penikat, Finland) the percentage of siderophile Elements present in BMS covers a larger range, of 8 to 70%. There are many more PGM present and there has been extensive recrystallization of the BMS. Most of the PGM are associated with BMS, but in many cases the Pd-bismuthotellurides and in a few cases the Pt-sulfarsenides and -arsenides are not found associated with BMS. Three processes could possibly have led to this. The BMS, which originally contained the PGM as exsolutions, dissolved during metamorphism, leaving behind insoluble PGM. Alternatively the bismuthotellurides, arsenides and sulfarsenides could have been locally remobilized from the BMS into the surrounding silicates during metamorphism. The third possibility is that Pd and to a lesser extent Pt could have been introduced to the PGE reef by fluids and precipitated as PGM from the fluid.

Reid R. Keays - One of the best experts on this subject based on the ideXlab platform.

  • geochemical stratigraphy of the keweenawan midcontinent rift volcanic rocks with regional implications for the genesis of associated ni cu co and Platinum Group Element sulfide mineralization
    Economic Geology, 2015
    Co-Authors: Reid R. Keays, Peter C Lightfoot
    Abstract:

    The development of the North American Midcontinent rift can be understood in the context of a tectonic and magmatic event in which the far-field effects of continental drift influenced magmatism produced by a mantle plume. We report and interpret new data for samples collected from stratigraphically controlled sequences of basaltic rocks in the Osler Volcanic Group and the Mamainse Point Volcanic Group in Ontario, Canada. We confirm that the earliest phase of rift development involved primitive melts that produced basalts in the Lower Formation of the Osler Volcanic Group with Fo74–80 olivine (1,490–2,280 ppm Ni). The earliest basalts are primitive in both the Mamainse Point Volcanic Group and Osler Volcanic Group sections, with elevated MgO, Cr, and Ni; these rocks also have high TiO2 and high Gd/Yb, which are features that indicate low degrees of melting of a garnet-bearing lherzolite mantle. The Central Formation A and B basalts of the Osler Volcanic Group that overlie the Lower Formation lavas record an upward increase and then decrease in the degree of contamination of basaltic rocks with normal Ni and Platinum Group Element (PGE) abundance levels that require no sulfide saturation event to accompany contamination. The Upper Formation of the Osler Volcanic Group is characterized by a limited number of PGE-depleted flows; although these basalts are highly fractionated and typically develop textures with stellate to laminated plagioclase feldspar, they are usually not significantly contaminated. The Lower and Upper formations of the Mamainse Point Volcanic Group show a diversity in geochemistry consistent with contributions from different mantle sources, but contamination is restricted to a small number of flows with normal Ni and PGE abundance levels. There is no indication of a regional metal depletion signature on the scale of the Nadezhdinsky Formation at Noril’sk, but there is evidence that local S saturation events were triggered in the unexposed conduits feeding some of the upper sequence flows in response to fractionation of the magma. Massive to heavy disseminated Ni-Cu-PGE sulfide mineralization in the Midcontinent rift is hosted by small primitive intrusions that were formed early in the evolution of the rift and are typically associated with transtensional structures in the cratonic blocks adjacent to the main rift. Examples include the Eagle deposit in Michigan, the Tamarack mineralization in Minnesota, and the Current Lake Complex in Ontario. The American examples are associated with splays of the Great Lakes tectonic zone and the Canadian example is associated with the Quetico fault zone. The intrusions share the geochemical fingerprints of the more primitive lowermost volcanic rocks of the Midcontinent rift and they are broadly contemporaneous with the development of the lower stratigraphy of the Osler Volcanic Group and Mamainse Point Volcanic Group. Although the low-grade but large-tonnage Cu-Ni-PGE deposits of the Duluth were formed significantly later than the small primitive intrusions, their host rocks share the same lithophile trace Element signature as these early intrusions. The parental magmas that produced all of these intrusions were derived from deeper mantle depths, where garnet was a stable phase, than the magmas that produced the Central Formation basalts and some of the Upper Formation basalts investigated in this study.

  • geochemistry and mineralogy of Platinum Group Element mineralization in the river valley intrusion ontario canada a model for early stage sulfur saturation and multistage emplacement and the implications for contact type ni cu pge sulfide mineralization
    Economic Geology, 2014
    Co-Authors: David A Holwell, Reid R. Keays, Emily Firth, Jon Findlay
    Abstract:

    The River Valley intrusion within the ~2.48 Ga East Bull Lake intrusive suite in Ontario, Canada, is an example of a mafic igneous intrusion with “contact-type” Ni-Cu-PGE sulfide mineralization along its base. Whereas many contact-type deposits are thought to form from in situ contamination of the magma by the addition of crustal S during emplacement, there are some intrusions, including the River Valley intrusion, which appear to have a much more complex history where the timing of S saturation, and thus the critical ore genesis processes, may have occurred much earlier, prior to emplacement. The River Valley intrusion is made up of a basal ~100 m of unlayered, inclusion-bearing units, overlain by layered cumulates. The basal units contain autoliths of gabbroic rocks and inclusions of footwall gneiss and amphibolites, all within a gabbroic matrix. Platinum-Group Element-rich magmatic sulfide mineralization occurs throughout both the inclusions and the matrix as blebby and disseminated sulfides. The matrix and inclusions can be separated into two distinct textural types: hydrothermally altered greenschist assemblages and unaltered metamorphic amphibolite assemblages. The Platinum Group mineral (PGM) assemblages vary only between textural types, and not between inclusions and matrix, being dominated tellurides in all rock types. The hydrothermally altered rocks, however, have fewer tellurides and an increased amount of Sb- and As-bearing PGM, indicative of minor fluid interaction, although the PGM have not been mobilized significantly away from the base metal sulfides. Precious and base metal geochemistry shows all rock types to have an excellent correlation between all the Platinum Group Elements (PGE), indicating the presence of a single, well homogenized, PGE-rich sulfide liquid. However, Au and Cu appear to be decoupled from the PGE at low concentrations, although correlate well with each other, which is interpreted to be due to minor fluid redistribution and alteration of sulfide bleb margins. The overlying Layered units above the mineralized units are not PGE depleted. Trace Element data, including (Th/Yb)PM and (Nb/Th)PM ratios, demonstrate that all River Valley rocks were formed from crustally contaminated magmas following interaction with local country rocks in a deeper subchamber; although some samples have S/Se ratios indicative of crustal S, most have S/Se ratios lower than the mantle range, indicative of S loss. We propose a multistage model for the formation of the mineralization in the River Valley intrusion with a major contamination event at depth with the addition of S from local crustal rocks, inducing sulfide saturation. Sulfide droplets were then enriched in PGE within a conduit system with possible further upgrading of sulfide metal tenors (and reduction of S/Se ratios) via partial dissolution of sulfide. The PGE-enriched sulfide liquid then settled in a staging chamber and partially crystallized before a major pulse of magma entrained sulfide liquid, eroded blocks of precrystallized and mineralized gabbro and footwall rocks, and emplaced an inclusion-bearing package as the lower 100 m or so of the River Valley intrusion. Later emplacement of main River Valley magma was from an S-undersaturated, PGE-fertile magma. The River Valley intrusion is thus an example whereby contact-type mineralization is purely a function of the earliest magma intruded containing preformed sulfide mineralization, rather than contamination triggering sulfide saturation in situ. In such cases, processes at depth determine the generation and subsequent tenor of the mineralization. In particular, dissolution of the sulfide can upgrade metal tenor, but subsequently will reduce S/Se ratios, masking the signature of crustal contamination. In addition, a multistage emplacement such as this will not necessarily preserve the characteristic increase in Cu/Pd ratios in the overlying cumulates that is often used in exploration for PGE deposits in mafic intrusions. Thus, a full understanding of all the field, geochemical, and mineralogical factors is required to construct genetic models for such deposits and especially in the interpretation of S/Se and Cu/Pd ratios as an indicator of crustal contamination and the presence of PGE mineralization.

  • Platinum Group Element geochemistry of the continental flood basalts in the central emeisihan large igneous province sw china
    Chemical Geology, 2009
    Co-Authors: Xie-yan Song, Reid R. Keays, Long Xiao, Huowen Qi, Christian Ihlenfeld
    Abstract:

    In the central zone of the Emeishan Large Igneous Province (ELIP), southwestern China, the Permian Emeishan continental flood basalts (ECFB) can be divided into high- and low-Ti basalts and alkaline basalts. At the southern margins of the central ELIP, the low- and high-Ti basalts comprise the lower and upper parts of the ECFB sequences, respectively; the alkaline basalts occur in the lower part of the ECFB sequence in a few locations. The high-Ti basalts are high in Pd (4-16 ppb) and Pt (7–18 ppb), but have large variations in Ir (0.04–0.88 ppb). The alkaline basalts have low TiO2 contents (1.8–2.15 wt.%) and are depleted in PGE (  30,000) and very low Pt/Y ratios (230 to as low as 6) strongly suggest that the PGE-depletion in the low-Ti basalts and alkaline basalts is related to sulfide removal. The positive relationship between Pt and Pd depletion and increases in Zr/Nb and Th/Nb ratios indicate that crustal contamination played a role in driving the low-Ti basaltic magmas to S-saturation. In contrast, for the PGE-undepleted high- and low-Ti basalts, Pd decreases slightly with decreasing MgO and Ir, and Pd/Cr ratios increase with decreasing Pt/Y, indicating that fractionation occurred under S-undersaturated conditions. Some PGE-undepleted low-Ti basalts have very high Pd/Pt ratios (up to 6, much higher than that of the primitive mantle ~ 0.6) and extremely low Ir concentrations (< 0.03 ppb), suggesting that the magmas experienced fractionation of olivine, chromite, pyroxene and PGE minerals rich in Os, Ir, Ru, and Pt. The remaining high-Ti basalts have moderate Pd/Pt ratios (< 2.3) and very high Ir concentrations, up to 0.88 ppb, indicating that they possibly contain chromite and PGE minerals rich in Os, Ir, and Ru.

  • Formation of Ni–Cu–Platinum Group Element sulfide mineralization in the Sudbury Impact Melt Sheet
    Mineralogy and Petrology, 2004
    Co-Authors: Reid R. Keays, Peter C Lightfoot
    Abstract:

    The Ni–Cu–Platinum Group Element (PGE) sulfide deposits of the Sudbury Structure have provided a major portion of the world’s total nickel production and their host rocks have been the subject of numerous research studies, yet a number of perplexing problems remain to be solved. On the one hand, studies seeking to explain the formation of the Sudbury Structure have now converged on a genetic model which proposes that the Main Mass and Offset Dykes of the Sudbury Igneous Complex (SIC) were produced by crystallization of an impact-generated melt sheet. On the other hand, these models have yet to be fully reconciled with the production of the very large volume of magmatic Ni, Cu, Co, and PGE-rich sulfide mineralization and the associated mafic rock types. This paper explores this problem using new precious metal data from the Main Mass and Offset Dykes. These data are used to understand the relationships between these rocks, and to provide constraints on how the Ni–Cu–PGE sulfide ore deposits fit into the geological evolution of the Sudbury Structure.

Jungwoo Park - One of the best experts on this subject based on the ideXlab platform.

  • Platinum Group Element geochemistry of the volcanic rocks associated with the jaguar and bentley cu zn volcanogenic massive sulfide vms deposits western australia implications for the role of chalcophile Element fertility on vms mineralization
    Mineralium Deposita, 2021
    Co-Authors: Jungwoo Park, Ian H Campbell
    Abstract:

    We report whole-rock major, trace, and Platinum-Group Element (PGE) geochemistry of volcanic rocks from the Teutonic Bore complex that hosts the Jaguar and Bentley Cu–Zn volcanogenic massive sulfide (VMS) deposits. This study aims to understand their sulfide saturation history and chalcophile Element evolution during differentiation of the Jaguar and Bentley magmas, and investigate the role of chalcophile Element fertility on the formation of VMS deposits. The fractionated primitive mantle–normalized trace Element patterns, with negative Nb and Ti anomalies of basalts, andesites, dacites, and rhyolites from Jaguar and Bentley, are similar to each other. The trace Elements and PGE show continuous variations when plotted against fractionation indices such as Yb, which can be explained by a two-stage fractional crystallization model: stage 1 Rayleigh fractionation of plagioclase + clinopyroxene + Cr-spinel, and stage 2 the fractional of plagioclase + clinopyroxene + magnetite + 0.1 wt% sulfide liquid. Dolerites, which postdate the mineralization, differ from the other rock types and require a different magma source. Andesite and basalt are the most PGE-enriched lithologies in Jaguar and Bentley. The PGE behave incompatibly in the early stage of magma differentiation at  4 ppm Yb, indicating sulfide saturation at this point. When Pd/MgO and Pd/Pt are used as chalcophile Element fertility indicators, the andesite before sulfide saturation (< 4 ppm Yb) is as fertile as the magmas associated with porphyry Cu-only deposits. In contrast, the andesite after sulfide saturation and other lithologies are characterized by markedly depleted fertility similar to those of barren suites. This suggests that sulfide-undersaturated andesite, and probably basalt, may have been a significant source for Cu in the Jaguar and Bentley Cu–Zn VMS deposits. However, the Au fertility of the Jaguar and Bentley andesite must have been low and not enough to form Au-rich VMS deposits because their Pd/MgO and Pd/Pt values are 5–10 times lower than those of andesite and dacite from the modern Au-rich seafloor massive sulfide deposits. This can be explained if ore formation occurred shortly after sulfide saturation. If the amount of sulfide melt to precipitate was small, Au, with its high partition coefficient into immiscible sulfide melts, would have been largely stripped from the silicate melt, whereas Cu, with its lower partition coefficient, would be little affected. Our study shows that chalcophile Element fertility may play an important role in the formation of VMS deposits, especially in controlling the Au contents of the ore, if the magmatic-hydrothermal component is the dominant source for metals in VMS systems.

  • Chalcophile Element fertility and the formation of porphyry Cu ± Au deposits
    Mineralium Deposita, 2019
    Co-Authors: Jungwoo Park, Ian H Campbell, Sanjeewa P K Malaviarachchi, Helen A Cocker
    Abstract:

    Chalcophile Element fertility, the chalcophile metal abundance in the source magma, is likely to be a critical factor for the formation of porphyry Cu ± Au deposits. In this study, we provide evidence to support this hypothesis by comparing the Platinum Group Element (PGE) geochemistry of barren and ore-bearing Cu ± Au granitic suites. We report the PGE contents of three barren volcanic and subvolcanic suites from Argentina and Japan and two Cu ± Au bearing suites from Indonesia and Chile. These results are compared with those from previous studies of a porphyry Cu-only subvolcanic suite from Chile and three porphyry Cu-Au-bearing suites from Australia and the USA. The barren suites are depleted in PGE abundances by the time of fluid exsolution (

  • Platinum Group Element abundances in the upper continental crust revisited new constraints from analyses of chinese loess
    Geochimica et Cosmochimica Acta, 2012
    Co-Authors: Jungwoo Park, Shan Gao, Ian H Campbell, Hujun Gong
    Abstract:

    Abstract Platinum Group Element (PGE) abundances in the upper continental crust (UCC) are poorly constrained with published values varying by up to an order of magnitude. We evaluated the validity of using loess to estimate PGE abundances in the UCC by measuring these Elements in seven Chinese loess samples using a precise method that combines NiS fire assay with isotope dilution. Major and trace Elements of the Chinese loess show a typical upper crustal composition and PGE abundances are consistent with literature data on Chinese loess, except for Ru, which is a factor of 10 lowe than published values. We suggest that the high Ru data and Ru N /Ir N values of Chinese loess reported by Peucker-Ehrenbrink and Jahn (2001) ( Geochem. Geophys. Geosys. 2 , 2001GC000172) are an analytical artifact, rather than a true geochemical characteristic of loess because likely sources of loess are not significantly enriched in Ru and transport and deposition processes cannot preferentially enrich Ru in loess. The effect of eolian fractionation on PGE abundances in loess appears to be limited because Chinese loess from different locations shows similar PGE patterns and concentrations. This conclusion is supported by strong positive correlations between the PGE (except for Pt) and other compatible Elements such as Fe 2 O 3 , Ni, Cr, Co. Using a compilation of PGE data for loess from China, Argentina and Europe, including our data but excluding one sample with an anomalously high Pt content, we propose average PGE abundances for global loess of Ir = 0.022 ppb (ng/g), Ru = 0.030 ppb, Rh = 0.018 ppb, Pt = 0.599 ppb, and Pd = 0.526 ppb, and suggest that these are the best current estimates for the PGE abundances of the UCC.

Thomas Oberthur - One of the best experts on this subject based on the ideXlab platform.

  • Platinum Group Element concentrations in pyrite from the main sulfide zone of the great dyke of zimbabwe
    Mineralium Deposita, 2016
    Co-Authors: Rubén Piña, Sarahjane Barnes, Fernando Gervilla, Rosario Lunar, Thomas Oberthur
    Abstract:

    The Main Sulfide Zone (MSZ) of the Great Dyke of Zimbabwe hosts the world’s second largest resource of Platinum-Group Elements (PGE) after the Bushveld Complex in South Africa. The sulfide assemblage of the MSZ comprises pyrrhotite, pentlandite, chalcopyrite, and minor pyrite. Recently, several studies have observed in a number of Ni-Cu-PGE ore deposits that pyrite may host significant amounts of PGE, particularly Pt and Rh. In this study, we have determined PGE and other trace Element contents in pyrite from the Hartley, Ngezi, Unki, and Mimosa mines of the Great Dyke by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Based on the textures and PGE contents, two types of pyrite can be differentiated. Py1 occurs as individual euhedral or subhedral grains or clusters of crystals mostly within chalcopyrite and pentlandite, in some cases in the form of symplectitic intergrowths, and is PGE rich (up to 99 ppm Pt and 61 ppm Rh; 1.7 to 47.1 ppm Ru, 0.1 to 7.8 ppm Os, and 1.2 to 20.2 ppm Ir). Py2 occurs as small individual euhedral or subhedral crystals within pyrrhotite, pentlandite, and less frequently within chalcopyrite and silicates and has low PGE contents (<0.11 ppm Pt, <0.34 ppm Rh, <2.5 ppm Ru, <0.37 ppm Ir, and <0.40 ppm Os). Py1 contains higher Os, Ir, Ru, Rh, and Pt contents than the associated pyrrhotite, pentlandite, and chalcopyrite, whereas Py2 has similar PGE contents as coexisting pyrrhotite and pentlandite. Based on the textural relationships, two different origins are attributed for each pyrite type. Py1 intergrowth with pentlandite and chalcopyrite is inferred to have formed by late, low temperature (<300 °C) decomposition of residual Ni-rich monosulfide solid solution, whereas Py2 is suggested to have formed by replacement of pyrrhotite and pentlandite caused by late magmatic/hydrothermal fluids.

  • improving recoveries of Platinum and palladium from oxidized Platinum Group Element ores of the great dyke zimbabwe using the biogenic siderophore desferrioxamine b
    Hydrometallurgy, 2015
    Co-Authors: Dennis Kraemer, Thomas Oberthur, Malte Junge, Michael Bau
    Abstract:

    Abstract This study presents results of batch leaching experiments conducted on oxidized (weathered) Platinum-Group Element (PGE) ores from two Platinum mines at the Great Dyke, Zimbabwe. The Great Dyke mafic/ultramafic layered intrusion is, after the Bushveld complex in South Africa, the second largest PGE deposit worldwide. Current mining operations focus on the recovery of PGE from pristine and unweathered ore material from the Main Sulfide Zone (MSZ). Besides pristine ores, there are significant resources of oxidized MSZ material at or near the surface. These oxidized PGE ores are currently not mined because insufficient recoveries using conventional processing techniques render this process option uneconomical. The complex, polymodal mineralogical distribution of the PGE in the oxidized MSZ aggravate to the processing issue. The data presented in this study show that a mild hydrochloric acid leach combined with a subsequent leach with the biogenic siderophore Desferrioxamine B (DFOB) in an aqueous solution efficiently extract Pt and Pd from these ores. Although Pt and Pd extraction during hydrochloric acid pretreatment is rather heterogeneous with a maximum Pt recovery of 30%, it nevertheless facilitates mobilization of Pt and Pd in the subsequent siderophore leaching step. Hydrochloric acid pretreatment of the oxidized PGE ores is a prerequisite for liberating the PGE-bearing host phases from weathering products and for the reduction of the amount of easily-available cations such as Fe in hydroxide minerals, which may compete with Pt and Pd for complexation in the subsequent siderophore leach step. This two-step approach results in a combined extraction of up to 80% of total Pt. Our results further show that Pt and Pd extraction during siderophore leaching is strongly pH-dependent and appears to be most efficient at near-neutral to slightly alkaline conditions, with increasing extraction efficiencies at higher pH. Based on the results of this study, siderophore leaching of oxidized (PGE) ores represents a promising approach for the hydrometallurgical extraction of Pt and Pd from oxidized ores.

  • Platinum Group Element distribution in base metal sulfides of the ug2 chromitite bushveld complex south africa a reconnaissance study
    Mineralium Deposita, 2014
    Co-Authors: Inga Osbahr, Thomas Oberthur, Reiner Klemd, Anja Josties
    Abstract:

    Two drill cores of the UG2 chromitite from the eastern and western Bushveld Complex were studied by whole-rock analysis, ore microscopy, SEM/Mineral Liberation Analysis (MLA), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis. The top and base of the UG2 main seam have the highest bulk-rock Pd and Pt concentrations. Sulfides mostly occur as aggregates of pentlandite, chalcopyrite, and rare pyrrhotite and pyrite or as individual grains associated mostly with chromite grains. In situ LA-ICP-MS analyses reveal that pentlandite carries distinctly elevated Platinum-Group Element (PGE) contents. In contrast, pyrrhotite and chalcopyrite contain very low PGE concentrations. Pentlandite shows average maximum values of 350–1,000 ppm Pd, 200 ppm Rh, 130–175 ppm Ru, 20 ppm Os, and 150 ppm Ir, and is the principal host of Pd and Rh in the studied ores of the UG2. Mass balance calculations were conducted for samples representing the UG2 main seam of the drill core DT46, eastern Bushveld. Pentlandite consistently hosts elevated contents of the whole-rock Pd (up to 55 %) and Rh (up to 46 %), and erratic contents of Os (up to 50 %), Ir (2 to 17 %), and Ru (1–39 %). Platinum-Group mineral (PGM) investigations support these mass balance results; most of the PGM are Pt-dominant such as braggite/cooperite and Pt-Fe alloys or laurite (carrying elevated concentrations of Os and Ir). Palladium and Rh-bearing PGM are rare. Both PGE concentrations and their distribution in base-metal sulfides (BMS) in the UG2 largely resemble that of the Merensky Reef, as most of the Pd and Rh are incorporated in pentlandite, whereas pyrrhotite, chalcopyrite, and pyrite are almost devoid of PGE.

  • Platinum Group Element distribution in base metal sulfides of the merensky reef from the eastern and western bushveld complex south africa
    Mineralium Deposita, 2013
    Co-Authors: Inga Osbahr, Thomas Oberthur, Reiner Klemd, Helene Bratz, Robert Schouwstra
    Abstract:

    Base-metal sulfides in magmatic Ni-Cu-PGE deposits are important carriers of Platinum-Group Elements (PGE). The distribution and concentrations of PGE in pentlandite, pyrrhotite, chalcopyrite, and pyrite were determined in samples from the mineralized portion of four Merensky Reef intersections from the eastern and western Bushveld Complex. Electron microprobe analysis was used for major Elements, and in situ laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) for trace Elements (PGE, Ag, and Au). Whole rock trace Element analyses were performed on representative samples to obtain mineralogical balances. In Merensky Reef samples from the western Bushveld, both Pt and Pd are mainly concentrated in the upper chromitite stringer and its immediate vicinity. Samples from the eastern Bushveld reveal more complex distribution patterns. In situ LA-ICP-MS analyses of PGE in sulfides reveal that pentlandite carries distinctly elevated PGE contents, whereas pyrrhotite and chalcopyrite only contain very low PGE concentrations. Pentlandite is the principal host of Pd and Rh in the ores. Palladium and Rh concentrations in pentlandite reach up to 700 and 130 ppm, respectively, in the samples from the eastern Bushveld, and up to 1,750 ppm Pd and up to 1,000 ppm Rh in samples from the western Bushveld. Only traces of Pt are present in the base-metal sulfides (BMS). Pyrrhotite contains significant though generally low amounts of Ru, Os, and Ir, but hardly any Pd or Rh. Chalcopyrite contains most of the Ag but carries only extremely low PGE concentrations. Mass balance calculations performed on the Merensky Reef samples reveal that in general, pentlandite in the feldspathic pyroxenite and the pegmatoidal feldspathic pyroxenite hosts up to 100 % of the Pd and Rh and smaller amounts (10–40 %) of the Os, Ir, and Ru. Chalcopyrite and pyrrhotite usually contain less than 10 % of the whole rock PGE. The remaining PGE concentrations, and especially most of the Pt (up to 100 %), are present in the form of discrete Platinum-Group minerals such as cooperite/braggite, sperrylite, moncheite, and isoferroPlatinum. Distribution patterns of whole rock Cu, Ni, and S versus whole rock Pd and Pt show commonly distinct offsets. The general sequence of “offset patterns” of PGE and BMS maxima, in the order from bottom to top, is Pd in pentlandite → Pd in whole rock → (Cu, Ni, and S). The relationship is not that straightforward in general; some of the reef sequences studied only partially show similar trends or are more complex. In general, however, the highest Pd concentrations in pentlandite appear to be related to the earliest, volumetrically rather small sulfide liquids at the base of the Merensky Reef sequence. A possible explanation for the offset patterns may be Rayleigh fractionation.

  • Platinum-Group Element distribution in the oxidized Main Sulfide Zone, Great Dyke, Zimbabwe
    Mineralium Deposita, 2010
    Co-Authors: Marek Locmelis, Frak Melcher, Thomas Oberthur
    Abstract:

    In the Great Dyke mafic/ultramafic layered intrusion of Zimbabwe, economic concentrations of Platinum-Group Elements (PGE) are restricted to sulfide disseminations in pyroxenites of the Main Sulfide Zone (MSZ). Oxidized ores near the surface constitute a resource of ca. 400 Mt. Mining of this ore type has so far been hampered due to insufficient recovery rates. During the oxidation/weathering of the pristine ores, most notably, S and Pd are depleted, whereas Cu and Au are enriched. The concentrations of most other Elements (including the other PGE) remain quite constant. In the oxidized MSZ, PGE occur in different modes: (1) as relict primary PGM (mainly sperrylite, cooperite, and braggite), (2) in solid solution in relict sulfides (dominantly Pd in pentlandite, up to 6,500 ppm Pd and 450 ppm Pt), (3) as secondary PGM neoformations (i.e., Pt–Fe alloy and zvyagintsevite), (4) as PGE oxides/hydroxides that replace primary PGM as the result of oxidation, (5) hosted in weathering products, i.e., iron oxides/hydroxides (up to 3,600 ppm Pt and 3,100 ppm Pd), manganese oxides/hydroxides (up to 1.6 wt.% Pt and 1,150 ppm Pd), and in secondary phyllosilicates (up to a few hundred ppm Pt and Pd). In the oxidized MSZ, most of the Pt and Pd are hosted by relict primary and secondary PGM; subordinate amounts are found in iron and manganese oxides/hydroxides. The amount of PGE hosted in solid solution in sulfides is negligible. Considerable local variations in the distribution of PGE in the oxidized ores complicate a mineralogical balance. Experiments to evaluate the PGE recovery from oxidized MSZ ore show that using physical concentration techniques (i.e., electric pulse disaggregation, hydroseparation, and magnetic separation), the PGE are preferentially concentrated into smaller grain size fractions by a factor of 2. Highest PGE concentrations occur in the volumetrically insignificant magnetic fraction. This indicates that a physical preconcentration of PGE is not feasible and that chemical, bulk-leaching methods need to be developed in order to successfully recover PGE from oxidized MSZ ore.