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1.
缅甸铂族金属砂矿中的矿物种类 总被引：1，自引：0，他引：1
采用电子探针分析（ＥＰＭＡ），对缅甸铂族金属砂矿中的矿物种类进行了研究。物质组成研究查明：主要组合矿物是Ｐｔ、Ｉｒ、Ｏｓ、Ｒｕ的自然元素和金属互化物。主要矿物是自然铂矿、铁铂合金、钌铱锇矿、等轴锇铱矿和铱锇矿。次要及稀有矿物是铂族金属的硫化物、砷化物、包括（Ｒｈ、Ｐｄ、Ｐｔ）２Ａｓ和（Ｒｈ、Ｐｄ、Ｐｔ、Ｎｉ）２Ａｓ两种陌生矿物、锑化物，以及含铂族元素的Ｆｅ、Ｎｉ、Ｃｕ硫化物。 相似文献
2.
Kreshimir N. Malitch Oskar A. Thalhammer Vladimir V. Knauf Frank Melcher 《Mineralium Deposita》2003,38(3):282-297
We report highly unusual platinum-group mineral (PGM) assemblages from geologically distinct chromitites (banded and podiform) of the Kraubath massif, the largest dismembered mantle relict in the Eastern Alps. The banded chromitite has a pronounced enrichment of Pt and Pd relative to the more refractory platinum-group elements (PGEs) of the IPGE group (Os, Ir, Ru), similar to crustal sections of ophiolites. On the contrary, the podiform chromitite displays a negatively sloping chondrite-normalised PGE pattern typical of ophiolitic podiform chromitite. The chemical composition of chromite varies from Cr# 73-77 in the banded type to 81-86 in the podiform chromitite. Thirteen different PGMs and one gold-rich mineral are first observed in the banded chromitite. The dominant PGM is sperrylite (53% of all PGMs), which occurs in polyphase assemblages with an unnamed Pt-base metal (BM) alloy and Pd-rich minerals such as stibiopalladinite, mayakite, mertieite II, unnamed Pd-Rh-As and Pd(Pt)-(As,Sb) minerals. This banded type also contains PGE sulphides (about 7%) represented by a wide compositional range of the laurite-erlichmanite series and irarsite (8%). Os-Ir alloy, geversite, an unnamed Pt-Pd-Bi-Cu phase and tetrauricupride are present in minor amounts. By contrast, the podiform chromitite, which yielded 21 different PGMs, is dominated by laurite (43% of all PGMs) which occurs in complex polyphase assemblages with PGE alloys (Ir-Os, Os-Ir, Pt-Fe), PGE sulphides (kashinite, bowieite, cuproiridsite, cuprorhodsite, unnamed (Fe,Cu)(Ir,Rh)2S4, braggite, unnamed BM-Ir and BM-Rh sulphides) and Pd telluride (keithconnite). A variety of PGE sulpharsenides (33%) including irarsite, hollingworthite, platarsite, ruarsite and a number of intermediate species have been identified, whereas sperrylite and stibiopalladinite are subordinate (2%). The occurrence of such a wide variety of PGMs from only two, 2.5-kg chromitite samples is highly unusual for an ophiolitic environment. Our novel sample treatment allowed to identify primary PGM assemblages containing all six PGEs in both laurite-dominated podiform chromitite as well as in uncommon sperrylite-dominated banded chromitite. We suggest that the geologically, geochemically and mineralogically distinct banded chromitite from Kraubath characterises the transition zone of an ophiolite, closely above the mantle section hosting podiform chromitite, rather than being representative of the crustal cumulate pile. 相似文献
3.
New data on the composition, assemblages, and formation conditions of platinum-group minerals (PGM) identified in platinum-group
element (PGE) occurrences of the Monchetundra intrusion (2495 +- 13 to 2435 ± 11 Ma) are described. This intrusion is a part
of the Paleoproterozoic pluton of the Monche-Chuna-Volch’i and Losevy tundras located in the Pechenga-Imandra-Varzuga Rift
System. The rhythmically layered host rocks comprise multiple megarhythms juxtaposed to mylonite zones and magmatic breccia
and injected by younger intrusive rocks in the process of intense and long magmatic and fluid activity in the Monchetundra
Fault Zone.
The primary PGM and later assemblages that formed as a result of replacement of the former have been identified in low-sulfide
PGE occurrences. More than 50 minerals and unnamed PGE phases including alloys, Pt and Pd sulfides and bismuthotellurides,
PGE sulfarsenides, and minerals of the Pd-As-Sb, Pd-Ni-As, and Pd-Ag-Te systems have been established. The unnamed PGE phases—Ni6Pd2As3, Pd6AgTe4, Cu3Pt, Pd2NiTe2, and (Pd, Cu)9Pb(Te, S)4—are described. The primary PGM were altered due to the effect of several mineral-forming processes that resulted in the formation
of micro- and nanograins of Pt and Pd alloys, sulfides, and oxides, as well as in the complex distribution of PGE, Au, and
Ag mineral assemblages. New types of complex Pt and Pd oxides with variable Cu and Fe contents were identified in the altered
ores. Pt and Pd oxides as products of replacement of secondary Pt-Pd-Cu-Fe alloys occur as zonal and fibrous nanoscale Pt-Pd-Cu-Fe-(±S)-O
aggregates. 相似文献
4.
Platinum-group minerals (PGM) have been identified as inclusions in chromite from the Bird River Sill, Manitoba. The inclusions are small (<20 microns) and are commonly euhedral. The PGM inclusions are (Ru, Os, Ir) S2, laurite, and (Os, Ir, Ru alloy), rutheniridosmine: Laurites contain up to 2.99 wt. % palladium. Arsenic content is negligible and no platinum or rhodium has been detected. One platinum-group element alloy contains 0.96 wt. % rhodium but neither platinum nor palladium has been detected. Laurite inclusions in chromite from the ultramafic zone record two compositional trends; first increasing and then decreasing Ru/(Ru+Os+Ir) up section. PGM inclusions and other solid inclusions occur as discrete phases in chromite and are part of the chromite precipitation event. Increasing oxygen fugacity by wall rock assimilation or new magma injection initiates chromite precipitation, locally increasing the sulphur content of the magma to convert PGE alloys to sulphides. 相似文献
5.
S. Yu. Stepanov K. N. Malitch A. V. Kozlov I. Yu Badanina A. V. Antonov 《Geology of Ore Deposits》2017,59(3):244-255
The new data for the geology and mineralogy of the platinum group element (PGE) mineralization related to the chromite–platinum ore zones within the dunite of the Svetly Bor and Veresovy Bor massifs in the Middle Urals are discussed. The geological setting of the chromite–platinum ore zones, their platinum content, compositional and morphological features of the platinum group minerals (PGM) are compared to those within the Nizhny Tagil massif, the world standard of the zonal complexes in the Platinum Ural belt. The chromite–platinum orebodies are spatially related to the contacts between differently granular dunites. Majority of PGM are formed by Pt–Fe alloys that are close in terms of stoichiometry to isoferroplatinum (Pt3Fe), and associated with Os–Ir alloys, Ru–Os and Ir–Rh sulfides, and Ir–Rh thiospinels of the cuproiridsite–cuprorhodsite–ferrorhodsite solid solution. The tetraferroplatinum (PtFe)–tulameenite (PtFe0.5Cu0.5) solid solution and Pt–Cu alloys belong to the later PGM assemblage. The established features of the chromite–platinum ore zones testify to the highly probable identification of the PGE mineralization within the dunite of the Svetly Bor and Vesesovy Bor massifs and could be used in prospecting and exploration for platinum. 相似文献
6.
Gold and platinum group minerals from the gold placers of the South Urals are studied in order to identify the metal sources. In placers from the Main Uralian fault zone (MUF), the primary gold contains Ag (up to 29 wt.%), Cu (up to 2 wt.%) and Hg (up to 4 wt.%) and its fineness ranges from 538 to 997‰. Tetra-auricupride and cupriferous gold (up to 20 wt.% Cu) are common for the Nizhny Karabash placer of the MUF zone. In the eastern part of the South Urals, the placer gold is mainly characterized by high fineness of 900–1000‰ and low Cu contents (max 1.38 wt.%). Most of the placer gold grains consist of the primary domains, which are rimmed by secondary high-fineness gold with diffuse and clear boundaries. The secondary gold also develops along the shear dislocations of primary gold. Gold contains microinclusions of geerite, balkanite, chalcopyrite, Se-bearing galena, sphalerite, pyrite, pyrrhotite, arsenopyrite and hematite.Twenty four (including five unnamed) platinum group minerals (PGMs) were found in 28 placers; those from the Kialim and Maly Iremel placers of the Miass placer zone were studied in details. In the Kialim placer, ruthenium is most abundant PGM, which hosts microinclusions of isoferroplatinum, ferroan platinum, laurite, cupriferous gold, a mineral similar in composition to tolovkite, heazlewoodite and unnamed RhSbS phase. The osmium contains microinclusions of erlichmanite and laurite. The iridium grains hosts various sulfides and arsenides of platinum group elements (PGEs). The inclusion-free PGMs form Ru compositional trend in contrast to Os–Ru trend of the Ir-depleted inclusion-hosted PGMs. The isoferroplatinum from the Maly Iremel placer hosts laurite, rhodarsenite, bowieite, a mineral similar in composition to miassite and unnamed sulfide of Pt (Pt1.11S2.00) and antimonide of Pd ((Pd2.41Rh0.43Fe0.17)3.01(Sb0.91Te0.09)1.00). Ruthenium is a host to isoferroplatinum, PGE sulfides and arsenides, and heazlewoodite. Osmium contains microinclusions of ferroan platinum; iridium is a host to a mineral similar in composition to hongshiite. Three types of PGM intergrowths were identified in the Maly Iremel samples: (1) the intergrowths of platy grains of ruthenium with isoferroplatinum and a mineral similar in composition to tulameenite; (2) the open-latticework intergrowths of platy crystals of ruthenium with interstitial aggregates made up of gold, isoferroplatinum and a mineral similar in composition to xingzhongite and (3) the intergrowths of osmium and irarsite and iridarsenite, which are developed along cleavage of the osmium grains. Nickel sulfides associated with some PGMs contain Ru (11.32 wt.%) and Rh (2.21 wt.%) in millerite and Ir (31.00 wt.%), Ru (5.81 wt.%) and Rh (2.87 wt.%) in vaesite.The primary metal sources were determined on the basis of the mineral assemblages and composition of minerals, taking into account the nearby mineral deposits and directions of rivers. The rodingite-associated gold, gold-bearing massive sulfide and chromite deposits are major sources of gold and PGMs in placers of the Miass placer zone confined to the MUF structure of the South Urals. In the southern part of this structure, gold was mainly originated from orogenic gold–sulfide deposits associated with volcanic/volcaniclastic rocks and listvenite-associated gold deposits. The placer PGMs were derived from the adjacent ultramafic massifs of ophiolitic origin. The distance between the placers and primary deposits varies from 2 to 5 km (up to 20 km in the extended valley of the Miass River). Usage of ore microinclusions and associated PGMs in study of placer gold is far more advanced than an ordinary consideration of gold composition alone. This approach allowed us to identify the concrete sources for individual placers and to predict some mineralogical findings in already known primary occurrences. 相似文献
7.
Summary ?We report, for the first time, the occurrence of five palladium-rich, one palladium bearing and two gold-silver minerals
from podiform chromitites in the Eastern Alps. Minerals identified include braggite, keithconnite, stibiopalladinite, potarite,
mertieite II, Pd-bearing Pt-Fe alloy, native gold and Ag-Au alloy. They occur in heavy mineral concentrates produced from
two massive podiform chromitite samples (unaltered and highly altered) of the Kraubath ultramafic massif, Styria, Austria.
Distribution patterns of platinum-group elements (PGE) in these chromitites show considerable differences in the behaviour
of the less refractory PGE (PPGE-group: Rh, Pt, Pd) compared to the refractory PGE (IPGE-group: Os, Ir, Ru). PPGE are more
enriched in chromitite showing pronounced alteration features. The unaltered chromitite displays a negatively sloped chondrite-normalised
PGE pattern similar to typical ophiolitic-podiform chromitite.
Except for the Pd- and Au-Ag minerals that are generally rare in ophiolites, about 20 other platinum-group minerals (PGM)
have been discovered. They include PGE-sulphides (laurite, erlichmanite, kashinite, bowieite, cuproiridsite, cuprorhodsite,
unnamed Ir-rich variety of ferrorhodsite, unnamed Ni-Fe-Cu-Rh- and Ni-Fe-Cu-Ir-Rh monosulphides), PGE alloys (Pt-Fe, Ir-Os,
Os-Ir and Ru-Os-Ir), PGE-sulpharsenides (irarsite, hollingworthite, platarsite, ruarsite and a number of intermediate species),
sperrylite and a Ru-rich oxide (?). Three PGM assemblages have been recognised and attributed to different processes ranging
from magmatic to hydrothermal and weathering-related.
Pd-rich minerals are characteristic of both chromitite types, although their chemistry and relative proportions vary considerably.
Keithconnite, braggite and Pd-bearing ferroan platinum, together with a number of PGE-sulphides (mainly laurite-erlichmanite)
and alloys, are typical only of the unaltered podiform chromitite (assemblage I). Euhedral mono- and polyphase PGM grains
in the submicron to 100 μm range show features of primary magmatic assemblages. The diversity of PGM in these assemblages
is unusual for ophiolitic environments. In assemblage II, laurite-erlichmanite is intergrown with and overgrown by PGE-sulpharsenides;
other minerals of assemblage I are missing. Potarite, stibiopalladinite, mertieite II, native gold and Ag-Au alloys, as well
as PGE-sulpharsenides, sperrylite and base metal arsenides and sulphides are characteristic for the highly altered chromitite
(assemblage III). They occur either interstitial to chromite in association with metamorphic silicates, in chromite rims or
along cracks, and are thus interpreted as having formed by remobilization of PGE by hydrothermal processes during polyphase
regional metamorphism.
Received August 3, 2000;/revised version accepted December 28, 2000 相似文献
8.
来自蛇绿岩地幔的硫（砷）化物矿物组合 总被引：1，自引：0，他引：1
近来在西藏雅鲁藏布江蛇绿岩带的罗布莎蛇绿岩块的地幔豆荚状铬铁矿中发现一个包括金刚石、柯石英、自然元素、合金、氧化物以及硫(砷)化物组成的地幔矿物群。该矿物群的硫(砷)化物具有特殊化学成分并呈包裹体分布在贱金属(BM)和铂族元素(PGE)或它们的合金中,大量化学成分分析得知它们主要由下列元素组成:S、As、Te、Fe、Ni、Co、Cu、Pt、Pd、Ru、Rh、Os、Ir、Mn和Ti。根据化学成分可辨别出约30种硫(砷)化物矿物:FeS、NiS、(Ni,Fe)S、Fe3S2、Ni3S2、(Ru,Os,Ir)S2、Rh7As3、Rh5Ni(Cu)As4、Pd4Rh3As3、Pd8As2、Pd3TeAs、Pd7Te3、RuAs、PtAs2、Ni4Rh3As3、Rh(As,S)2、(Rh,Ir)(As,S)2、Ir(As,S)2、MnS、Ti7S3、Ti7N3、Rh3.5Se3.5CuS2、RhS、Ir2S3、(Ir,Cu)2、S3(Co,Ni,Fe)2(As,S)3、(Ir,Pt)(As,S)2、Ru3(As,S)7以及(BM)x(PGE)yS10-(x y)等,其中包括已定名和未定名的矿物。由于矿物粒度小(<25μm),缺乏X射线分析资料,有待进一步研究。 相似文献
9.
GUO Guolin YANG Jingsui Paul T. ROBINSON LIU Xiaodong XU Xiangzhen XIONG Fahui 《《地质学报》英文版》2016,90(3):900-912
Voluminous platinum-group mineral(PGM) inclusions including erlichmanite(Os,Ru)S_2, laurite(Ru,Os)S_2, and irarsite(Ir,Os,Ru,Rh)As S, as well as native osmium Os(Ir) and inclusions of base metal sulphides(BMS), including millerite(NiS), heazlewoodite(Ni_3S_2), covellite(CuS) and digenite(Cu_3S_2), accompanied by native iron, have been identified in chromitites of the Zedang ophiolite, Tibet. The PGMs occur as both inclusions in magnesiochromite grains and as small interstitial granules between them; most are less than 10 μm in size and vary in shape from euhedral to anhedral. They occur either as single or composite(biphase or polyphase) grains composed solely of PGM, or PGM associated with silicate grains. Os-, Ir-, and Ru-rich PGMs are the common species and Pt-, Pd-, and Rh-rich varieties have not been identified. Sulfur fugacity and temperature appear to be the main factors that controlled the PGE mineralogy during crystallization of the host chromitite in the upper mantle. If the activity of chalcogenides(such as S, and As) is low, PGE clusters will remain suspended in the silicate melt until they can coalesce to form alloys. Under appropriate conditions of ?S_2 and ?O_2, PGE alloys might react with the melt to form sulfides-sulfarsenides. Thus, we suggest that the Os, Ir and Ru metallic clusters and alloys in the Zedang chromitites crystallized first under high temperature and low ?S_2, followed by crystallization of sulphides of the laurite-erlichmanite, solid-solution series as the magma cooled and ?S_2 increased. The abundance of primary BMS in the chromitites suggests that ?S_2 reached relatively high values during the final stages of magnesiochromite crystallization. The diversity of the PGE minerals, in combination with differences in the petrological characteristics of the magnesiochromites, suggest different degrees of partial melting, perhaps at different depths in the mantle. The estimated parental magma composition suggests formation in a suprasubduction zone environment, perhaps in a forearc. 相似文献
10.
The Binchuan area of Yunnan is located in the western part of the Emeishan large igneous province in the western margin of the Yangtze Block.In the present study,the Wuguiqing profile in thickness of about 1440 m is mainly composed of high-Ti basalts,with minor picrites in the lower part and andesites,trachytes,and rhyolites in the upper part.The picrites have relatively higher platinum-group element（PGE） contents（ΣPGE=16.3-28.2 ppb）,with high Cu/Zr and Pd/Zr ratios,and low S contents（5.03-16.9 ppm）,indicating the parental magma is S-unsaturated and generated by high degree of partial melting of the Emeishan large igneous province（ELIP） mantle source.The slightly high Cu/Pd ratios（11 000-24 000） relative to that of the primitive mantle suggest that 0.007%sulfides have been retained in the mantle source.The PGE contents of the high-Ti basalts exhibit a wider range（ΣPGE=0.517-30.8 ppb）.The samples in the middle and upper parts are depleted in PGE and haveεNd（260 Ma） ratios ranging from -2.8 to -2.2,suggesting that crustal contamination of the parental magma during ascent triggered sulfur saturation and segregation of about 0.446%-0.554% sulfides,and the sulfide segregation process may also provide the ore-forming material for the magmatic Cu-Ni-PGE sulfide deposits close to the studied basalts.The samples in this area show Pt-Pd type primitive mantle-normalized PGE patterns,and the Pd/Ir ratios are higher than that of the primitive mantle（Pd/Ir=1）,indicating that the obvious differentiation between Ir-group platinum-group elements（IPGE） and Pd-group platinum-group elements（PPGE） are mainly controlled by olivine or chromites fractionation during magma evolution.The Pd/Pt ratios of most samples are higher than the average ratio of mantle（Pd/Pt=0.55）,showing that the differentiation happened between Pt and Pd.The differentiation in picrites may be relevant to Pt hosted in discrete refractory Pt-alloy phase in the mantle;whereas the differentiation in the high-Ti basalts is probably associated with the fractionation of Fe-Pt alloys,coprecipitating with Ir-Ru-Os alloys.Some high-Ti basalt samples exhibit negative Ru anomalies,possibly due to removal of laurite collected by the early crystallized chromites. 相似文献
11.
F. Melcher 《Mineralogy and Petrology》2000,68(1-3):177-211
Summary ?A mineralogical classification of sulfides containing base metals (BM) and platinum group elements (PGE) is proposed based
on BM-PGE ratios. Group A comprises BM sulfides carrying PGE as trace or minor elements (e.g., pentlandite). Group B is characterized
by BM/PGE > 1 comprising kharaelakhite and some poorly defined minerals (thiospinels and monosulfides) which are described
in detail. In group C, all sulfides with BM/PGE < 1 are summarized, comprising PGE-rich thiospinel, minerals related to the
thiospinel group (e.g. xingzhongite, konderite, inaglyite), and the Pd-Pt±Ni sulfides.
A number of BM-PGE sulfides are described from podiform chromite occurrences in ultramafic portions of ophiolite complexes
in the southern Urals (Kempirsai, Kazakhstan) and the Eastern Alps (Kraubath, Austria). Copper- and (Ir, Rh, Pt)-rich thiospinel
(general formula AB2S4, with A = Cu, Ni, Fe and B = Ir, Rh, Pt) is present in complex assemblages in Kraubath, usually intergrown with laurite,
Pt-Fe alloy and Rh sulfide. These thiospinels are commonly associated with lamellae and inclusions of Ni-and/or Fe-rich (Ir,
Rh) sulfide showing either monosulfide or BM-rich thiospinel stoichiometry. In massive chromitite from Kempirsai, (Ni,Cu,Fe,Ir,Rh,Os)
sulfides are intergrown with laurite-erlichmanite, Ir-Os alloy, and rarely, PGE sulfarsenides (e.g. irarsite), and usually
have monosulfide (BM,PGE)S compositions. A small number of grains have (BM+PGE)/S matching PGE-rich thiospinel (cuproiridsite)
and BM-rich thiospinel (Ni,Cu,Fe)1.5(Ir,Rh)1.5S4. In the occurrences studied, monosulfides exhibit sulfur-deficient stoichiometries (e.g., (BM,PGE)1−xS) and are characterized by BM/PGE ranging from 0.8 to 2.2. Although anisotropic in reflected light, their reflectance spectra
(Y% = 33–38) differ only slightly from those of isotropic cuproiridsite and cuprorhodsite (Y% = 36–38). At least three groups
of monosulfides can be distinguished on chemical grounds using literature data: monosulfides dominated by Ni and Ir (“iridian
millerite”) with BM/PGE ranging from 1.6 to 5.9, monosulfides dominated by Fe and Rh (“rhodian pyrrhotite”) with BM/PGE ranging
from 1.6 to 7.1, and monosulfides dominated by Cu, Ir or Rh (“xingzhongite”-type) with BM/PGE ranging from 0.6 to 1.1. While
the first two types presumably crystallize in a hexagonal NiAs structure and exhibit extensive solid solution between each
other, xingzhongite is cubic (BM-rich thiospinel?) and usually poor in Ni and Fe. Monosulfides and thiospinel may form from
PGE-rich base metal sulfide liquids after cooling and equilibration in chromite-precipitating magmatic systems.
Received June 17, 1998;/Revised version accepted July 1, 1999 相似文献
Zusammenfassung ?Buntmetall-PGE-Sulfide aus dem Ural und den Ostalpen: Charakterisierung und Bedeutung für die Mineral-Systematik In diesem Beitrag wird eine Einteilung von Sulfiden mit bedeutenden Konzentrationen von Buntmetallen (BM) und Platingruppenelementen (PGE) aufgrund ihrer BM/PGE-Verh?ltnisse vorgestellt. Gruppe A enth?lt Buntmetallsulfide mit Spuren- oder Nebenelementgehalten von PGE (z.B. Pentlandit). Sulfide der Gruppe B sind charakterisiert durch BM/PGE-Verh?ltnisse > 1, z.B. Kharaelakhit sowie einige schlecht definierte Minerale (Thiospinelle und Monosulfide), die im folgenden n?her beschrieben werden. In Gruppe C werden alle Sulfide mit BM/PGE < 1 zusammengefasst, wie z.B. PGE-reiche Thiospinelle, einige mit Thiospinell verwandte Minerale (z.B. Xingzhongit, Konderit, Inaglyit), sowie die Pd-Pt±Ni Sulfide. Verschiedene BM-PGE Sulfide treten als Einschlüsse in ophiolitischen podiformen Chromiten im Südural (Kempirsai, Kasachstan) und in den Ostalpen (Kraubath, ?sterreich) auf. In Kraubath sind Cu- und (Ir, Rh, Pt)-reiche Thiospinelle (generelle Formel AB2S4, mit A = Cu, Ni, Fe und B = Ir, Rh, Pt) in Verwachsung mit Laurit, Pt-Fe Legierungen und Rh-Sulfiden recht h?ufig. Soche Thiospinelle sind manchmal mit Lamellen und winzigen Einschlüssen eines Ni- und/oder Fe-reichen (Ir, Rh)-Sulfids assoziiert, das st?chiometrisch entweder einem Monosulfid oder einem BM-reichen Thiospinell entspricht. In massiven Chromititen von Kempirsai sind (Ni, Cu, Fe, Ir, Rh, Os)-Monosulfide mit Laurit-Erlichmanit, Ir-Os Legierungen und selten PGE-Sulfarseniden (Irarsit) vergesellschaftet. Die (BM+PGE)/S Verh?ltnisse einiger K?rner entsprechen denen von PGE-reichem Thiospinell (Cuproiridsit) bzw. BM-reichem Thiospinell [(Ni,Cu,Fe)1.5(Ir,Rh)1.5S4]. In den meisten F?llen weisen die Monosulfide leichte Schwefeldefizite auf [z.B. (BM,PGE)1−xS] und sind charakterisiert durch BM/PGE Verh?ltnisse von 0.8 bis 2.2. Obwohl sie im Auflicht, soweit erkennbar, schwach anisotrop sind, differieren ihre Reflexionsspektren (Y% = 33–38) nur schwach von isotropem Cuproiridsit und Cuprorhodsit (Y% = 36–38). Zumindest drei chemische Gruppen von Monosulfiden konnten anhand einer Literaturrecherche identifiziert werden: Ni- und Ir-dominierte Monosulfide (“Iridium-Millerit”) haben BM/PGE Verh?ltnisse von 1.6 bis 5.9; Fe- und Rh-dominierte Monosulfide (“Rhodium-Magnetkies”) haben BM/PGE Verh?ltnisse von 1.6 bis 7.1; Cu-, Ir oder Rh-dominierte Minerale vom “Xingzhongit-Type” habben BM/PGE-Verh?ltnisse von 0.6 bis 1.1. Die ersten beiden Typen kristallisieren wahrscheinlich in einer hexagonalen NiAs-Struktur und weisen weitgehende Mischbarkeiten miteinander auf. Xingzhongit dagegen ist kubisch (BM-reicher Thiospinell?) und hat general niedrige Ni- und Fe-Gehalte BM-PGE-Monosulfide und Thiospinelle bilden sich wahrscheinlich aus kleinen PGE- und BM-reichen Sulfidschmelztropfen bei der Abkühlung und ?quilibrierung von Chromit.
Received June 17, 1998;/Revised version accepted July 1, 1999 相似文献
12.
E. M. Spiridonov A. A. Ariskin E. V. Kislov N. N. Korotaeva G. S. Nikolaev I. V. Pshenitsyn V. O. Yapaskurt 《Geology of Ore Deposits》2018,60(3):210-219
The near-bottom part of the Yoko-Dovyren layered ultramafic-mafic intrusion host the Baikal deposit of Cu–Ni sulfide ores with Pt–Pd mineralization, whereas horizons and pockets of low sulfide ores with Pt–Pd mineralization occur at higher stratigraphic levels, including the boundary between strata of troctolite and gabbronorite, within these rocks, as well as in strata of peridotite at the lower part of the intrusion. This paper represents a new (for the Yoko-Dovyren intrusion) type of “refractory IPGE-mineralization” discovered in the lower peridotite ranging from two-pyroxene-plagioclase-bearing lherzolite. This mineralization occurs in thin intercalations of plagioclase lherzolite containing as much as 7% of alumochromite, up to 50 ppb Ru, 15 ppb Ir, and 60 ppb Pt. Crystals of cumulate alumochromite with 0.2–0.8 wt % TiO2 contain hexagonal plates of Ir-osmium up to 5 m in size. Crystals of cumulate alumochromite with 1.2–2.8 wt % TiO2 host pentagonal dodecahedrons of laurite up to 4 m in size. One of the alumochromite crystals with an inclusion of Os-poor laurite was found inside a crystal of cumulate olivine Fo86. Intergrowth of laurite and Ir-osmium enclosed in alumochromite with 1.1% TiO2 was observed in one case. Laurite from Yoko-Dovyren contains 93–66%, predominantly 92–82%, RuS2 endmember (n = 10); 3–20, predominantly 5–12%, OsS2 endmember; 4–5% IrS2 endmember; and up to 0.7% Pd and 0.5% Au. Ir-osmium is divided into two groups by composition. The first group is enriched in Os (58–73 wt %, on average 64 wt %) and Ru (3–8 wt %, on average 5 wt %), contains 24–34 wt % Ir (n = 4), up to 1.4 wt % Au, and no Pt. Compositions of the second group have 57–58 wt % Os, 27–30 wt % Ir, 1.5–5.5 wt % Ru, approximately 10 wt % Pt (n = 3), and up to 0.2 wt % Pd. The Cr# and Fe2+/(Fe2+ + Mg) values, which range within 58–69 and 61–72, respectively, are identical in alumochromite with both enclosed laurite and Ir-osmium. Alumochromite, relatively enriched in Ti, crystallized slightly later, suggesting later crystallization for hosted laurite. Occurrence of Ir-osmium seems to indicate a picritic magma undersaturated with sulfide sulfur during bulk crystallization of alumochromite Judging from the diagram from (Brennan and Andrews, 2001), intergrowths of laurite and Ir-osmium, evidence that their probable crystallization temperature did not exceed 1250°C. The presence of own minerals of Ru, Os, Ir in the rocks, containing the first ppb of these PGE shows startling degree of magmatic differentiation. In the matrix of plagioclase lherzolites, containing laurite and Ir-osmium, in association with phlogopite, pargasite, pentlandite, troilite and chalcopyrite there were found the smallest crystals of geversite, sperrilite, insizwaite, niggliite, naldrettite, zvyagintsevite, in association with serpentine and chlorite–native platinum, Pd-platinum, osarsite, irarsite, platarsite. 相似文献
13.
Platinum-Group Minerals from the Durance River Alluvium,France 总被引：2，自引：2，他引：0
Dr. Z. Johan Dr. M. Ohnenstetterl M. Fischer J. Amossé 《Mineralogy and Petrology》1990,42(1-4):287-306
Summary Platinum-group minerals were discovered, during gold recovery, in the Durance river alluvium, near Peyrolles (Bouches-du-Rhône). The PGM grains (average size 130 microns) are strongly flattened (average thickness 64 microns). The PGM concentrate consists primarily of (Pt, Fe) alloys (92%), (Os, Ir, Ru) alloys (3.5%), and native gold and (Au, Cu, Ag) alloys (4.5%). The following minerals were observed: isoferroplatinum, ferroan platinum, native osmium, native iridium, iridosmine, rutheniridosmine, osmiridium, ruthenian osmium, osmian ruthenium, cuprorhodsite, guanglinite, shandite, tetrauricupride, native gold, bornite, heazlewoodite, (Pt, Pd)2Cu3, Pt(Cu, Au), (Ni, Pt)Sn, (Cu, Fe)1–x (Pd, Rh, Pt)2+xS2, (Pt, Pd)4–xCu2As1–x. Isoferroplatinum contains numerous inclusions of alloys, sulphides, arsenides, Pd-tellurides, and partly devitrified silicate glass droplets. Most of the non-silicate inclusions also exhibit a drop-like shape indicating their original entrapment in a liquid state.Cuprorhodsite crystals (up to 20 microns) are associated with bornite included in Pt3Fe. Rarely, Pd- and Cu-sulphides, and Pd-tellurides appear in this association. Complex droplet-like arsenide inclusions in isoferroplatinum are composed of Pt bearing guanglinite and (Pt,Pd)4+xCu2As1–x. Native iridium shows exsolutions of Ir-bearing isoferroplatinum and (Pt,Pd)2Cu3. In places, concentrations of Sn (up to 3 wt.%) were observed in (Au, Cu) alloys. Shandite and (Ni, Pt)Sn inclusions occur in (Au, Cu, Ag) alloys. Silicate-glass inclusions are TiO2-poor and occasionally K-rich (plotting in the shoshonitic field). Taking into account mineralogical and chemical pecularities of the PGM association occurring in the studied concentrate, it seems highly probable that its primary source should be an Alaskan-type intrusion.
With 4 Figures and 2 Plates 相似文献
Platingruppen Minerale aus dem Alluvium der Durance, Frankreich
Zusammenfassung Minerale der Platingruppe wurden im Zuge von Goldgewinnung im Alluvium der Durance in der Nähe von Peyrolles (Bouches-du-Rhône) entdeckt. Die PGM Körner (durchschnittliche Korngröße 130m) sind flach gepreßt (durchschnittliche Dicke 64m). Die PGM Konzentrate bestehen vorwiegend aus (Pt, Fe) Legierungen (92%); (Os, Ir, Ru) Legierungen (3,5%), sowie gediegen Gold und (Au, Cu, Ag) Legierungen (4,5%). Folgende Minerale wurden beobachtet:Isoferro-Platin, Fe-Platin, gediegen Osmium, gediegen Iridium, Iridosmium, Rutheniridosmium, Osmiridium, Ru-Osmium, Os-Ruthenium, Cuprorhodsit, Guanglinit, Shandit, Tetrauricuprit, gediegen Gold, Bornit, HeazIewoodit, (Pt, Pd)2 Cu3, Pt(Cu, Au), (Ni, Pt)Sn, (Cu, Fe), (Pd, Rh, Pt)2+xS2, (Pt, Pd)4+xCu2As1–x.Isoferro-Platin enthält zahlreiche Einschlüsse von Legierungen, Sulfiden, Arseniden, Pd-Telluriden und teilweise devitrifzierte Silikatglaströpfchen. Die meisten nichtsili katischen Einschlüsse sind ebenfalls tröpfchenförmig. Dies weist darauf hin, daß sie in flüssigem Zustand eingeschlossen wurden.Cuprorhodsitkristalle (bis zu 20m) sind gemeinsam mit Bornit in Pt3 Fe einge schlossen. Selten sind Pd- und Cu-Sulfide, sowie Pd-Telluride mit diesen vergesellschaftet. Bei den komplexen tröpfehenförmigen Arsenideinschlüssen im Isoferro-Platin handelt es sich um Pt-führenden Guanglinit und (Pt, Pd)4+xCu2 As1–x. Gediegen Iridium zeigt Entmischung von Ir-führendem Isoferro-Platin und (Pt, Pd)2Cu3. Stellenweise wurden Konzentrationen von Sn (bis zu 3%) in den (Au, Cu) Legierungen beobachtet. Shandit und (Ni, Pt) Sn Einschlüsse kommen in (Au, Cu, Ag) Legierungen vor. Silikatische Glaseinschlüsse sind TiO2-arm und manchmal K-reich (im Shoshonitfeld liegend).Auf Grund der mineralogischen und chemischen Eigenheiten der untersuchten PGM Konzentrate ist eine Intrusion des Alaska-Typs als primäre Quelle sehr wahrscheinlich.
With 4 Figures and 2 Plates 相似文献
14.
《Russian Geology and Geophysics》2014,55(2):259-272
Data are presented on chromitites from the northern and southern sheets of the Il’chir ophiolite complex (Ospa–Kitoi and Khara-Nur (Kharanur) massifs). The new and published data are used to consider similarities and differences between ore chrome-spinel from the chromitites of the northern and southern ophiolite sheets as well as the species diversity of PGE minerals and the evolution of PGE mineralization. Previously unknown PGE minerals have been found in the studied chromitites.Ore chrome-spinel in the chromitites from the northern sheet occurs in medium- and low-alumina forms, whereas the chromitites from the southern sheet contain only medium-alumina chrome-spinel. The PGE minerals in the chromitites from the southern sheet are Os–Ir–Ru solid solutions as well as sulfides and sulfoarsenides of these metals. The chromitites from the northern sheet contain the same PGE minerals and diverse Rh–Pt–Pd mineralization: Pt–Ir–Ru–Os and isoferroplatinum with Ir and Os–Ir–Ru lamellae. Areas of altered chromitites contain a wide variety of low-temperature secondary PGE minerals: Pt–Cu, Pt–Pd–Cu, PdHg, Rh2SnCu, RhNiAs, PtAs2, and PtSb2. The speciation of the PGE minerals is described along with multiphase intergrowths. The relations of Os–Ir–Ru solid solutions with laurite and irarsite are considered along with the microstructure of irarsite–osarsite–ruarsite solid solutions. Zoned Os–Ir–Ru crystals have been found. Zone Os82–99 in these crystals contains Ni3S2 inclusions, which mark off crystal growth zones. Different sources of PGE mineralization are presumed for the chromitites from the northern and southern sheets.The stages of PGE mineralization have been defined for the chromitites from the Il’chir ophiolite belt. The Pt–Ir–Ru–Os and (Os, Ru)S2 inclusions in Os–Ir–Ru solid solutions might be relics of primitive-mantle PGE minerals. During the partial melting of the upper mantle, Os–Ir–Ru and Pt–Fe solid solutions formed syngenetically with the chromitites. During the late-magmatic stage, Os–Ir–Ru solid solutions were replaced by sulfides and sulfarsenides of these metals. Mantle metasomatism under the effect of reduced mantle fluids was accompanied by PGE remobilization and redeposition with the formation of the following assemblage: garutiite (Ni,Fe,Ir), zaccariniite (RhNiAs), (Ir,Ni,Cu)S3, Pt–Cu, Pt–Cu–Fe–Ni, Cu–Pt–Pd, and Rh–Cu–Sn–Sb. The zoned Os–Ir–Ru crystals in the chromitites from the northern sheet suggest dissolution and redeposition of Os–Ir–Ru primary-mantle solid solutions by bisulfide complexes. Most likely, the PGE remobilization took place during early serpentinization at 450–600 ºC and 13–16 kbar.During the crustal metamorphic stage, tectonic movements (obduction) and a change from reducing to oxidizing conditions were accompanied by the successive transformation of chrome-spinel into ferrichromite–chrome-magnetite with the active participation of a metamorphic fluid enriched in crustal components. The orcelite–maucherite–ferrichromite–sperrylite assemblage formed in epidote-amphibolitic facies settings during this stage.The PGE mineral assemblage reflects different stages in the formation of the chromitites and dunite-harzburgite host rocks and their transformation from primitive mantle to crustal metamorphic processes. 相似文献
15.
This study presents compositional features of platinum-group element mineralization derived from the Late Archaean placers in the eastern part of the Witwatersrand basin. The significant presence of platinum-group minerals, formed by polycomponent solid-solution series in the system Ru–Os–Ir–Pt(±Fe), was determined using an electron microprobe analysis. Compositional data indicate that the source for polycomponent solid solutions of the Ru–Os–Ir–Pt–Fe system was the Archaean mantle of the Earth, slightly differentiated with respect to platinum-group elements. 相似文献
16.
Platinum-group Elements and Microstructures of Normal Merensky Reef from Impala Platinum Mines, Bushveld Complex 总被引：11，自引：4，他引：11
The Merensky Reef of the Bushveld Complex contains one of theworld’s largest concentrations of platinum-group elements(PGE). We have investigated ‘normal’ reef, its footwalland its hanging wall at Impala Platinum Mines. The Reef is 46cm thick and consists from bottom to top of leuconorite, anorthosite,chromitite and a very coarse-grained melanorite. The footwallis leuconorite and the hanging wall is melanorite. The onlyhydrous mineral present is biotite, which amounts to 1%, orless, of the rock. All of the rocks contain 0·1–5%interstitial sulphides (pyrrhotite, pentlandite and chalcopyrite),with the Reef rocks containing the most sulphides (1–5%).Lithophile inter-element ratios suggest that the magma fromwhich the rocks formed was a mixture of the two parental magmasof the Bushveld Complex (a high-Mg basaltic andesite and a tholeiiticbasalt). The Reef rocks have low incompatible element contentsindicating that they contain 10% or less melt fraction. Nickel,Cu, Se, Ag, Au and the PGE show good correlations with S inthe silicate rocks, suggesting control of the abundance of thesemetals by sulphides. The concentration of the chalcophile elementsand PGE in the silicate rocks may be modelled by assuming thatthe rocks contain sulphide liquid formed in equilibrium withthe evolving silicate magma. It is, however, difficult to modelthe Os, Ir, Ru, Rh and Pt concentrations in the chromititesby sulphide liquid collection alone, as the rocks contain 3–4times more Os, Ir, Ru, Rh and Pt than the sulphide-collectionmodel would predict. Two possible solutions to this are: (1)platinum-group minerals (PGM) crystallize from the sulphideliquid in the chromitites; (2) PGM crystallize directly fromthe silicate magma. To model the concentrations of Os, Ir, Ru,Rh and Pt in the chromitites it is necessary to postulate thatin addition to the 1% sulphides in the chromitites there isa small quantity (0·005%) of cumulus PGM (laurite, cooperiteand malanite) present. Sulphide liquids do crystallize PGM atlow fS2. Possibly the sulphide liquid that was trapped betweenthe chromite grains lost some Fe and S by reaction with thechromite and this provoked the crystallization of PGM from thesulphide liquid. Alternatively, the PGM could have crystallizeddirectly from the silicate magma when it became saturated inchromite. A weakness of this model is that at present the exactmechanism of how and why the magma becomes saturated in PGMand chromite synchronously is not understood. A third modelfor the concentration of PGE in the Reef is that the PGE arecollected from the underlying cumulus pile by Cl-rich hydrousfluids and concentrated in the Reef at a reaction front. Althoughthere is ample evidence of compaction and intercumulus meltmigration in the Impala rocks, we do not think that the PGEwere introduced into the Reef from below, because the rocksunderlying the Reef are not depleted in PGE, whereas those overlyingthe Reef are depleted. This distribution pattern is inconsistentwith a model that requires introduction of PGE by intercumulusfluid percolation from below. KEY WORDS: Merensky Reef; platinum-group elements; chalcophile elements; microstructures 相似文献
17.
A. G. Mochalov 《Geology of Ore Deposits》2013,55(3):145-161
A genetic model has been developed for platinum group minerals (PGM) hosted in plutonic gabbro-pyroxenite-dunite (GPD) complexes of the Koryak Highland. The following mineralogical-geochemical and genetic PGM types have been distinguished: (1) magmatic platinum (Pt), (2) magmatic-fluid-metasomatic platinum (Pt) and osmium-platinum (Pt > Os), (3) fluid-metamorphic iridium-platinum (Pt > Ir), and (4) hydrothermal metasomatic platinum-copper (Pt-Cu). PGM of the magmatic Pt type were formed under conditions of monocyclic petrogenesis of Cr-spinel-olivine and olivine-clinopyroxene cumulates as products of picritic magma fractionation in the conduit chamber. The magmatic-fluid-metasomatic platinum Pt and osmium-platinum Pt > Os types were formed by interaction of these early cumulates with magma. The abundance of these types is proportional to injections of picritic magma into the conduit chamber. PGM of the fluid-metamorphic iridium-platinum Pt > Ir type accumulated as a result of synmagmatic recrystallization of GPD cumulates. Their development depends on (1) mono- or polycyclic GPD cumulative complex and (2) the degree of GPD cumulate recrystallization from partial to complete and the degree of transformation of PGM pertaining to the magmatic and magmatic-fluid-metasomatic Pt types. The monocyclic GPD complexes are low-prospective in respect to magmatic Pt deposit formation. The polycyclic GPD complexes differ in their prospectivity from ore occurrences to unique magmatic-fluid-metasomatic Pt and Pt > Os deposits, as well as deposits of the fluid-metamorphic Pt > Ir type. The genetic types of PGM accumulation imply a multifactor system of ore-forming processes with the participation of platinum-group elements (PGE) in GPD complexes. The genetically different PGM accumulations in GPD complexes should be regarded as self-dependent geological objects of local forecasting. In this connection, it is necessary to renew mineralogical and geochemical criteria for prospecting and exploration of PGM genetic types in GPD complexes as well as their mining conditions. 相似文献
18.
铂族元素矿物共生组合(英文) 总被引：1，自引：2，他引：1
由于铂族元素能有效地降低汽车尾气的污染 ,其需求量日益增加 ,对铂族元素矿床的寻找已是当务之急。着重从矿物矿床学角度对铂族元素的矿物共生特点进行了探讨。铂族元素可呈独立矿床产出 ,主要产于基性超基性层状侵入体、蛇绿岩套及阿拉斯加式侵入体中。铂族元素也伴生于铜镍矿床中 ,该类铜镍矿床主要与苏长岩侵入体、溢流玄武岩及科马提岩有关。产于基性超基性层状侵入体中的铂族矿物有铂钯硫化物、铂铁合金、钌硫化物、铑硫化物、铂钯碲化物、钯砷化物及钯的合金。这些铂族矿物可与硫化物矿物共生 ,也可与硅酸盐矿物共生 ,还可与铬铁矿及其他氧化物矿物共生。产于蛇绿岩套中的铂族矿物主要是钌铱锇的矿物 ,而铂钯铑的矿物则较少出现 ,这些铂族矿物可呈合金、硫化物、硫砷化物以及砷化物 4种形式出现。产于阿拉斯加式侵入体中的铂族矿物主要有铂铁合金、锑铂矿、硫铂矿、砷铂矿、硫锇矿及马兰矿等少数几种 ,其中铂铁合金与铬铁矿及与其同时结晶的高温硅酸盐矿物共生 ,而其他的铂族矿物则与后来的变质作用及蛇纹岩化作用中形成的多金属硫化物及砷化物共生。产于铜镍矿床中的铂族矿物主要是铂和钯的矿物。产于基性超基性层状侵入体、蛇绿岩套及阿拉斯加式侵入体中的铂族矿物的共同特点是它们均与铬铁矿? 相似文献
19.
Total organic carbon content (TOC), trace element and platinum-group element (PGE) concentrations were determined in the black shales of the Lower Cambrian Niutitang Formation in the Nayong area, Guizhou Province, South China, in order to study the polymetallic Ni–Mo–PGE mineralization. The results demonstrate that numerous elements are enriched in the polymetallic ores compared to those of the nearby black shale, particularly Ni, Mo, Zn, TOC and total PGE, which can reach up to 7.03 wt.%, 8.49 wt.%, 11.7 wt.%, 11.5 wt.% and 943 ppb, respectively. The elemental enrichment distribution patterns are similar to those in the Zunyi and Zhangjiajie areas except that the Nayong location is exceptionally enriched in Zn. Whereas positive correlations are observed between the ore elements of the polymetallic ores, no such correlations are observed in the black shale. These positively correlated metallic elements are classified into three groups: Co–Ni–Cu–PGE, Zn–Cd–Pb and Mo–Tl–TOC. The geological and geochemical features of these elements suggest that Proterozoic and Early Palaeozoic mafic and ultramafic rocks, dolomites and/or Pb–Zn deposits of the Neoproterozoic Dengying Formation and seawater could be the principal sources for Co–Ni–Cu–PGE, Zn–Cd–Pb, and Mo–Tl–TOC, respectively. Furthermore, the chondrite-normalized patterns of PGEs with Pd/Pt, Pd/Ir and Pt/Ir indicate that PGE enrichment of the polymetallic ores is most likely related to hydrothermal processes associated with the mafic rocks. In contrast, PGE enrichment in the black shale resembles that of the marine oil shale with terrigenous and seawater contributions. Our investigations of TOC, trace elements and PGE geochemistry suggest that multiple sources along with submarine hydrothermal and biological contributions might be responsible for the formation of the polymetallic Ni–Mo–PGE mineralization in the black shales of the Lower Cambrian Niutitang Formation across southern China. 相似文献
20.
Sarah A. S. Dare Sarah-Jane Barnes Hazel M. Prichard Peter C. Fisher 《Mineralium Deposita》2011,46(4):381-407
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. 相似文献