铂族元素钌(Ru)异常及其地质意义探讨

铂族元素(简称PGE,包括Pt、Pd、Rh、Ru、Ir、Os)的地球化学性质独特,为强烈亲硫的元素,其中,IPGE(Ir,Ru,Os)是高温矿物(橄榄石、尖晶石、铬铁矿等)的相容元素,PPGE(Pt,Pd,Rh)是强不相容元素.     

金川铜镍硫化物矿床岩浆通道型矿体地质地球化学特征

金川铜镍硫化物矿床6行富铜（铂族）矿体曾因Cu、Pt、Pd等含量明显高于相邻其它矿体而被认为是岩浆期后热液叠加作用的产物,研究发现,空间上该矿体受断层构造控制,在矿石组构、矿物组成和硫同位素组成方面与相邻岩浆融离型1号矿体一致,显示了该矿体岩浆成矿作用的特征。在元素地球化学方面,6行富铜（铂族）矿体的Cu、Ni、Pt、Pd含量及Cu/Ni比值明显高于1号主矿体,而Os、Ir、Rh、Ru却明显低于后者,同时,前者相对富含LREE,轻、重稀土分异程度高于后者。根据硫化物结晶分异过程中金属元素分配规律及稀土元素特征,阐明了6行富铜（铂族）矿体为岩浆通道型矿体,是岩浆硫化物晚期结晶的产物。矿区中西部存在的Cu、Ni、Pt、Pd、Au等含量高,而Os、Ir、Rh、Ru含量低的部位,是寻找岩浆通道型矿体的有利部位。     

某岩体含铂矿石锇铱铑品位预报方程的建立

硫化铜镍矿床中伴生的铂族元素以Pt、Pd为主,Os、Ru、Ir、Rh含量通常较低,但价格比Pt、Pd昂贵得多.如何综合评价这些含量较低的伴生铂族元素是普查勘探工作应解决的问题之一.一种作法是将主金属Ni、Cu及6种铂族元素一并列入样品的基本分析项目,这样做便于储量计算,但将增加试金分析工作量,影响矿床勘探速度;另一种作法是只将Ni、Cu、Pt、Pd列入基本分析项目,其余4种伴生铂族元素仅在组合分析样品中进行测定,这样虽节省大量试金分析,却又给储量计算带来困难.本文应用一元线性回归分析方法,尝试依据若干代表性钻孔含铂矿石的基本分析数据,利用Os、Ru、Ir、Rh含量的密切相关关系建立预报方程,以期在只测定矿石中Ru含量的前提下,对Os、Ir、Rh品位进行预报,并讨论了预报的精确度和实际应用的可能性.     

新疆萨尔托海铬铁矿中铂族矿物及硫化物特征

新疆萨尔托海高Al型铬铁矿中几乎不含原生的铂族矿物(PGM)和贱金属硫化物(BMS)包体,显示出成矿岩浆贫硫的特征。BMS多产于铬铁矿铬粒间裂隙、基质及蚀变环带中,主要以赫硫镍矿和针镍矿为主,其次为辉铜矿、砷镍矿、硫砷镍矿、毒砂等。PGM以包体产于BMS或铬铁矿粒间缝隙中,以硫钌矿(RuS2)为主,还包括硫锇矿(OsS2)、硫镍锇矿\[(Os,Ni)S2\]、硫钌锇矿\[(Ru,Os)S2\],锑钯矿(Pd5Sb2)和少量Cu、Pt、Au的硫化物。铬铁矿全岩ΣPGE含量50. 64×10-9~92. 00×10-9,较世界范围内蛇绿岩型铬铁矿低,且具有IPGE较PPGE富集的特点,PdN/IrN在0. 1~0. 9之间,具有Os相对Ir富集的特点。铬铁矿主量元素和原位微量元素显示出与菲律宾阿科杰高Al型铬铁矿以及MORB中尖晶石相似的地球化学特征。根据萨尔托海铬铁矿中PGM及BMS的种类、产出特征,结合铬铁矿全岩PGE及单矿物微量元素地球化学特征,认为铬铁矿的形成与贫硫的拉斑玄武质岩浆与地幔橄榄岩的熔体岩石反应有关。铬铁矿形成后的晚期岩浆阶段使得自形程度较高的PGM(如硫锇矿)和BMS(如赫硫镍矿)形成,随后向热液阶段转变的过程中,由于温压条件改变、热液蚀变,形成了萨尔托海铬铁矿中Fe- Ni- As- S和PGM矿物组合。     

利用同一化学流程分析地质样品中的铂族元素含量和铼-锇同位素组成

报道了利用一次溶样和同一化学流程分离富集地质样品中铂族元素(Pt、Pd、Os、Ir和Ru)和Re的方法.该化学流程包括以下几个步骤:(1) Carius管溶样法分解岩石样品中富集铂族元素的矿物;(2)四氯化碳萃取法分离出Os;(3)微蒸馏法进一步纯化Os;(4)阳离子交换树脂法将铂族元素(Pt、Pd、Ir和Ru)以及R...     

祁连山拉水峡铜镍硫化物矿床矿物学、地球化学及成因

拉水峡中型铜镍矿床几乎全岩矿化。矿石矿物学、矿床地球化学的研究表明,矿石中金属硫化物以紫硫镍铁矿、黄铁矿、黄铜矿为主,热液作用使原生硫化物组合发生了改变,低温热液特征的元素As、Se、Ag、Te富集; 矿石中Ni含量远高于Cu含量,不同类型矿石均属轻稀土富集型,反映了相同的岩浆成因,部分熔融来源特点。热液改造致使块状矿石中Cu/Ni、Ni/Co比值较高,REE分馏程度明显高于原生浸染状矿石;矿石中铂族元素含量平均为2460.5×10-9,具有较高的Ir含量和低的Pd/Ir比值特点,铂族元素与岩浆深部融离作用密切相关,块状矿石Pd/Ir比值和(Pt+Pd)/(Os+Ir+Ru)比值均高于原生浸染状矿石,表明热液作用对Cu、Pt、Pd金属元素富集具有一定作用;岩浆期后流体属中低温度（180～244℃）、中等盐度（8.81～14.67%NaCl）、中等密度（0.86～0.95g/cm3）范围, CH4+N2+CO2成分组合,具有岩浆流体成分特征。综合分析认为,拉水峡矿床主体成因可能仍以岩浆深部曾有过较彻底的硫化物不混熔作用为主,后期经历了热液作用改造。     

中国西部岩浆岩型铜镍矿床的元素组合特征及伴生金的赋存状态研究

我国西部岩浆岩型铜镍矿床伴生金与主金属元素组合,Au—Cu组合具有同步富集特征,而Au—Ni组合为不相关;伴生金与微量元素组合,Au—Pt、Au—Pd、Au—Se、Au—Te呈正相关Au—Co、Au—Os、Au—Ru、Au—Ir、Au—Rh为不相关的组合特征.该类型铜镍矿床伴生金以矿物态赋存为主,分散金较少,主要载体为黄铜矿及其它硫化物.     

南秦岭大型钡成矿带中硫钒铜矿的特征及成因意义

在南秦岭下寒武统硅岩建造中的毒重石-重晶石矿床中,产出大量硫钒铜矿.硫钒铜矿呈正方形,长方形及不规则状,粒度大小变化较大,一般为0.01 mm～1 mm,最大可达7 mm.反光显微镜下为淡柠檬黄色,显微硬度134.5 kg/mm2～139.8 kg/mm2,相当于摩氏硬度3.46～3.50.主要化学成分为:Cu 47.18～52.02(平均50.44),V 6.50～14.32(平均11.95),Sn 0.00～12.85(平均2.15),S 31.77～34.34(平均33.29),As 0.00～5.12(平均0.86).Fe 0.00～3.27(平均0.77),部分样品含有极少量的Fe,Ni,Co,Sb,Se,Te,In.相应的平均化学分子式为Cu3.04(V0.90,Sn0.07,Fe0.05,As0.04,Sb0.01)1.07(S3.98,Se0.02)4.00,简化式为:Cu3(V,Sn,As,Fe)S4.矿物为等轴晶系.晶胞参数值a=0.539 2nm.成矿带中硫钒铜矿的形成与钒的富集,与有机质演化受热和生物降解作用有密切联系.     

未定名矿物（Ru,Fe）2O3的发现及初步研究

未定名矿物(Ru,Fe)_2O_3产自我国西藏东巧超基性岩铬铂矿中。呈粒状、柱状、粒径8—42μm。具弱电磁性。与硫钌矿和等轴铁铂矿连生。反光下星灰黄色-灰白带棕色。双反射明显,强非均质性,有的呈3—10μm的微晶集合体。3个颗粒15个点的电子探针分析平均值(%):Ru 58.32,Fe 16.21,Os 2.71,Ir 1.78,O 20.97,矿物的化学式为(Ru,Fe)_2O_3。由于未能获X射线结构资料,暂未定名。     

黔西玄武岩铂、钯地球化学特征与存在状态

黔西玄武岩中铂族元素丰度较高，其含量变化顺序为Pt〉Pd〉Ru〉Ir〉Rh，表现为Pt、Pd富集，而Os、Ir、Ru、Rh亏损，说明在地幔熔融形成玄武岩的过程中，铂族元素已发生了明显的分异。在分析黔西玄武岩中Pt、Pd岩石载体所处的大地构造背景、含铂（族）矿床的可能类型和岩石化学特征与Pt、Pd可能存在状态的关系的基础上，研究了黔西玄武岩中Pt、Pd存在状态。结果表明，其状态分属硫化物态．金属互化物态、类质同像亲石态和吸附态，且各状态丰度值依次减少。     

Composition and evolution of PGE mineralization in chromite ores from the Il’chir ophiolite complex (Ospa–Kitoi and Khara-Nur areas,East Sayan)

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.     

铂族元素矿物共生组合(英文)

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?     

Diversity of platinum-group mineral assemblages in banded and podiform chromitite from the Kraubath ultramafic massif,Austria: evidence for an ophiolitic transition zone?

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.     

缅甸铂族金属砂矿中的矿物种类

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。     

Genesis of the Jinchuan PGE deposit, China: evidence from fluid inclusions, mineralogy and geochemistry of precious elements

Summary The Jinchuan deposit is a platinum group element (PGE)-rich sulfide deposit in China. Drilling and surface sampling show that three categories of platinum group element (PGE) mineralization occur; type I formed at magmatic temperatures, type II occurs in hydrothermally altered zones of the intrusion, and type III in sheared dunite and lherzolite. All ore types were analyzed for Os, Ir, Ru, Rh, Pd, Pt and Au, as well as for Cu, Ni, Co and S. Type I ore has (Pt + Pd)/(Os + Ir + Ru + Rh) ratios of <7 and relatively flat chondrite-normalized noble metal patterns; the platinum group minerals (PGM) are dominated by sperrylite and moncheite associated with chalcopyrite, pyrrhotite and pentlandite. Type II has (Pt + Pd)/(Os + Ir + Ru + Rh) ratios from 40 to 330 and noble metal distribution patterns with a positive slope; the most common PGM are sperrylite and Pd bismuthotelluride phases concentrated mostly at the margins of base metal sulfides. Type III ores have the highest (Pt + Pd)/(Os + Ir + Ru + Rh) ratios from 240 to 710; the most abundant PGM are sperrylite and phases of the Pt–Pd–Te–Bi–As–Cl system. It is concluded that the Jinchuan deposit formed as a result of primary magmatic crystallization followed by hydrothermal remobilization, transport, and deposition of the PGE.     

富碲马营矿[Ir（Te,Bi）2]——马营矿的新变种

富碲马营矿产在纯橄榄岩铬矿体中。在铝矿石及矿体附近的砂矿中均可找到。呈粒状自形结构,直径0．01～0．15mm。与硫铱矿（IrS2）、双峰矿、高台矿、马营矿及（Fe,Ni）9Cu3Ir6S20等紧密共生。有的呈脉状,宽0．1～0．2mm,长1．2mm。金属光泽。不透明,钢灰色,粉末黑色。HM＝3．7。VHN50＝161kg／mm2（范围132～215kg／mm2）。无解理。无断口。性脆。计算密度为12．2g／cm3。反射色亮白带淡黄色调,内反射无,均质性,双反射与反射多色性无。5个电子探针分析数据平均为（％）：Cu0．3,Te32．9,Ir34．7,Pt2．7,Bi28．2,总量98．9。实验式根据原子数3计算为：（Ir(0．92)Pt(0．92)Cu(0．01)）;(1．00)Bi(0．68)Te(1．31)。简化后的理论式为Ir（Te,Bi）2,而（Ir：Bi：Te＝3：2：4）。6条富碲马营矿是强X射线衍射hki、d、I为：210,2．89（60）;311,1．95（100）;511,1．246（70）;520,1．204（60）;440,1．145（60）;533,0．9891（60）。根据X射线粉晶指标化求得马营矿为等轴晶系,空间群：Pa3,a＝0．6486（4）um,V＝0．2729nm3,Z＝4。富碲马营矿是本文作者对马营矿研究的继续与补充。     

Platinum-group element distribution in base-metal sulfides of the Merensky Reef from the eastern and western Bushveld Complex, South Africa

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.     

A laser ablation ICP-MS study of platinum-group and chalcophile elements in base metal sulfide minerals of the Jinchuan Ni–Cu sulfide deposit,NW China

The paper presents concentrations of the platinum-group and chalcophile elements in the base metal sulfides (BMS) from the Jinchuan Ni–Cu sulfide deposit determined by laser ablation-inductively coupled plasma-mass spectrometry. Mass balance calculations reveal that pentlandite hosts a large proportion of Co, Ni and Pd (> 65%), and that pentlandite and pyrrhotite accommodate significant proportions of Re, Os, Ru, Rh, and Ag (~ 35–90%), whereas chalcopyrite contains a small amount of Ag (~ 10%) but negligible platinum-group elements. Iridium and Pt are not concentrated in the BMS and mostly occur in As-rich platinum-group minerals. The enrichments of Co, Ni, Re, Os, Ru, and Rh in pentlandite and pyrrhotite, and Cu in chalcopyrite are consistent with the fractionation of sulfide liquid and exsolution of pentlandite and pyrrhotite from the mono-sulfide solid solution (MSS). The Ir-bearing minerals exsolved from the MSS, depleting pentlandite and pyrrhotite in Ir, whereas sperrylite exsolved from the residual sulfide liquid on cooling. Diffusion of Pd from residual sulfide liquid into pentlandite during its exsolution from the MSS and crystallization of Pt-bearing minerals in the residual sulfide liquid resulted in the enrichment of Pd in pentlandite and decoupling between Pd and Pt in the Jinchuan net-textured and massive ores.     

Base metal – platinum-group element sulfidesfrom the Urals and the Eastern Alps:characterization and significance formineral systematics

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.

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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.

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Received June 17, 1998;/Revised version accepted July 1, 1999     

新矿物双峰矿—铱的二碲化物

双峰矿产在纯橄榄岩体铬矿体中。在铬矿石及矿体邻近的砂矿中均可找到，呈块状聚集体或板片状与硫铱矿、锇自然铱矿紧密共生。直径０．５￣０．２ｍｍ，脉状的宽０．０５￣０．１０ｍｍ，长０．５￣１．０ｍｍ。金属光泽。条痕黑色。Ｈ（Ｍ）３。ＶＨＮ２０１０８ｋｇ／ｍｍ＾２（平均）。解理：（０００１）完全。性脆。计算密度为１０．１４ｇ／ｃｍ＾３。反射色：亮黄白带蓝色调。内反射无。非均质性中等，偏光色为淡蓝或淡黄。双