冀北张家口地区汉诺坝玄武岩中麻粒岩捕虏体的硫化物相

捕虏体麻粒岩是了解下地壳形成和演化的重要样品。汉诺坝新生代玄武岩中的二辉麻粒岩捕虏体样品中富含各种硫化物相,主要类型有:①孤立产出的球状出溶硫化物;②矿物颗粒之间或颗粒内的粗晶硫化物;③次生硫化物包裹体群;④裂隙充填硫化物。电子探针分析表明,硫化物的矿物成分均为贫镍磁黄铁矿,(Ni+Co+Cu)/Fe(原子比)远小于0.2;(Fe+Cu+Co+Ni)/S(原子比)比地幔岩的磁黄铁矿小,多小于0.875,反映了一种S过饱和环境。各种产状的磁黄铁矿中Au、Ag都有一定的含量,其平均值分别为0.19%～0.22%(Au)、0.01%～0.02%(Ag),反映下地壳的麻粒岩化与金矿化的成因联系。磁黄铁矿的Ni、Co、Cu含量与S正相关,说明微量重金属元素与S具有同源的关系,由于地幔去气伴随S而进入下地壳。     

冀北张家口地区汉诺坝玄武岩中麻粒岩捕虏体的硫化物相

捕虏体麻粒岩是了解下地壳形成和演化的重要样品.汉诺坝新生代玄武岩中的二辉麻粒岩捕虏体样品中富含各种硫化物相,主要类型有:①孤立产出的球状出溶硫化物;②矿物颗粒之间或颗粒内的粗晶硫化物;③次生硫化物包裹体群;④裂隙充填硫化物.电子探针分析表明,硫化物的矿物成分均为贫镍磁黄铁矿,(Ni Co Cu)/Fe(原子比)远小于0.2;(Fe Cu Co Ni)/S(原子比)比地幔岩的磁黄铁矿小,多小于0.875,反映了一种S过饱和环境.各种产状的磁黄铁矿中Au、Ag都有一定的含量,其平均值分别为0.19%～0.22%(Au)、0.01%～0.02%(Ag),反映下地壳的麻粒岩化与金矿化的成因联系.磁黄铁矿的Ni、Co、Cu含量与S正相关,说明微量重金属元素与S具有同源的关系,由于地幔去气伴随S而进入下地壳.     

攀西红格钒钛磁铁矿矿田富钴硫化物中钴的地球化学特征及其地质意义

攀西红格钒钛磁铁矿矿田白草矿区发育富钴硫化物矿物,关于其成因和形成环境方面的研究较为薄弱。本文采用矿物学、矿物化学、地球化学等方法对其进行系统研究。矿石中主要富钴硫化物为磁黄铁矿（Po）、黄铁矿（Py）、镍黄铁矿（Pn）、硫钴镍矿（Se）。磁黄铁矿Co、Ni平均质量分数分别为0.21%、0.42%,Co/Ni平均值为1.10;黄铁矿Co、Ni平均质量分数分别为0.18%、0.29%,Co/Ni平均值为0.77;镍黄铁矿Co、Ni平均质量分数分别为2.67%、34.30%,Ni/Fe平均值为1.08、S/Fe平均值为1.91、M/S^#平均值为1.13;硫钴镍矿Co、Ni平均质量分数分别为24.30%、22.90%,Co/Ni平均值为1.06。根据Po-Py矿物温度计,白草矿区富钴硫化物结晶温度在267~490℃之间,表明其形成于中高温的条件。通过与地幔包体镍黄铁矿S/Fe、M/S^#特征值的对比,结合磁黄铁矿具有陨硫铁（Tr）同质多象晶体的特征,认为白草矿区硫化物具有地幔源的特征,说明成矿物质来源于地幔。白草矿区钴地球化学特征研究表明,在硫化物熔体分离过程中,钴迁移至单硫化物固溶体形成Po-Py固溶体,再由Po-Py固溶体中迁移至Pn、Se,形成了Se、Pn、Po-Py、Ccp（黄铜矿）中Co质量分数依次递减的现象。     

冀北张家口地区汉诺坝玄武岩中麻粒岩捕虏体的硫化物相

捕虏体麻粒岩是了解下地壳形成和演化的重要样品。汉诺坝新生代玄武岩中的二辉麻粒岩捕虏体样品中富含各种硫化物相，主要类型有：①孤立产出的球状出溶硫化物；②矿物颗粒之间或颗粒内的粗晶硫化物；③次生硫化物包裹体群；④裂隙充填硫化物。电子探针分析表明，硫化物的矿物成分均为贫镍磁黄铁矿，（Ni＋Co＋Cu）／Fe（原子比）远小于0．2；（Fe＋Cu＋Co＋Ni）／S（原子比）比地幔岩的磁黄铁矿小，多小于0．875，反映了一种S过饱和环境。各种产状的磁黄铁矿中Au、Ag都有一定的含量，其平均值分别为0．19％～0.22％（Au）、0．01％～0．02％（Ag），反映下地壳的麻粒岩化与金矿化的成因联系。磁黄铁矿的Ni、Co、Cu含量与S正相关，说明微量重金属元素与S具有同源的关系，由于地幔去气伴随S而进入下地壳。     

西藏班公湖地区富镍硫化物超基性岩的成因

班公湖地区富镍硫化物超基性岩位于藏北班公湖-怒江缝合带西段,呈透镜状产出于侏罗系地层中,岩石已完全蚀变为蛇纹岩,恢复其原岩为方辉橄榄岩。地球化学研究表明:相对于原始地幔,该类超基性岩富w(MgO)(40.96%~42.82%),贫w(Al_2O_3)(0.19%~1.76%)、w(CaO)(0.11%~0.38%)和TiO_2(0.02%~0.06%);稀土元素总量低(0.238×10-6~2.044×10-6),远低于原始地幔值,稀土元素配分型式呈U型;强烈亏损高场强元素Y;岩石的锆石年龄为太古代(2 479 Ma±31 Ma)。以上特征表明其为残余地幔橄榄岩成因。富镍硫化物超基性岩中的镍硫化物呈似球状分布于蛇纹石中,主要为镍黄铁矿,偶见与镍黄铁矿共生的赫硫镍矿。电子探针分析结果表明,镍黄铁矿中w(Ni)为36.77%~42.62%,w(Fe)为18.83%~28.84%,w(S)为31.34%~38.3%。赫硫镍矿中w(Fe)为0.91%~13.36%,w(Ni)为60.5%~70.08%,w(S)为25.25%~27.23%。赫硫铁矿Fe含量高(除两件样品外均2%mol),且与镍黄铁矿的接触边界平直。结合前人的实验资料,认为Fe-Ni硫化物形成于高温阶段(300℃),为贫S的地幔Fe-Ni-S熔体捕虏体成因。     

湘黔地区下寒武统黑色岩系中镍-钼矿床黄铁矿的成因

重点研究了贵州遵义中南村和湖南张家界三岔镍-钼多金属矿床的黄铁矿,矿床成因为热水喷流沉积型.黄铁矿样品S/Fe比值的平均值为2.0093-2.048,成分特征均属于铁亏损型,说明其形成温度低.Co/Ni变化范围为0.077~4.5,均值为2.197.据Co/Ni的比值可以判断本区的黄铁矿主要为热液成因,矿化物质来源为热水喷流体系内的热液.成分图解标型显示,黑色岩系中高ω(Co+Ni)/ω(Fe)的黄铁矿和高ω(As+Se+Te)/ω(S)的黄铁矿均大量出现,可能与热水喷流沉积的温差变化范围较大有关.而并非正常沉积的产物.S/Se比值为950.8-1059.9,说明生成环境均一程度较高,而且海水温度比较高.由中南村镍-钼矿床的Se/Te值也能判明其为热液成因.关于黄铁矿的研究对本区镍-钼矿床的寻找有重要意义.     

辉石巨晶中的硫化物及其成因

我国一些地区玄武岩辉石巨晶中的硫化物球泡(0.02-0.05mm)呈点阵式、散布式、定向带状或微裂隙羽状分布。硫化矿物组合是磁黄铁矿-镍黄铁矿-黄铜矿,其中以磁黄铁矿为主(～90％)。根据硫化物的规则排布以及高温矿物组合推测点阵式、散布式硫化物形成于地幔。是由溶解了～1％S的硅酸盐熔体在减压上升过程中析出过饱和的硫所致。     

湘黔地区下寒武统黑色岩系中镍-钼矿床黄铁矿的成因

重点研究了贵州遵义中南村和湖南张家界三岔镍-钼多金属矿床的黄铁矿,矿床成因为热水喷流沉积型。黄铁矿样品S/Fe比值的平均值为2.0093~2.048,成分特征均属于铁亏损型,说明其形成温度低。Co/Ni变化范围为0.077~4.5,均值为2.197,据Co/Ni的比值可以判断本区的黄铁矿主要为热液成因,矿化物质来源为热水喷流体系内的热液。成分图解标型显示,黑色岩系中高ω(Co+Ni)/ω(Fe)的黄铁矿和高ω(As+Se+Te)/ω(S)的黄铁矿均大量出现,可能与热水喷流沉积的温差变化范围较大有关,而并非正常沉积的产物。S/Se比值为950.8~1059.9,说明生成环境均一程度较高,而且海水温度比较高。由中南村镍-钼矿床的Se/Te值也能判明其为热液成因。关于黄铁矿的研究对本区镍-钼矿床的寻找有重要意义。     

金川超大型铜镍矿床钴的赋存状态与富集过程研究

金川矿床位于龙首山隆起带东段，是中国最大的岩浆镍钴（铂族元素）矿床。该矿床中最重要的金属硫化物组合是磁黄铁矿、镍黄铁矿和黄铜矿，仅局部含有微量的辉钴矿等独立钴矿物。全岩成矿元素分析显示：矿石中Co与S、Ni之间呈良好的正相关性，与As相关性较差，Co/Ni随硫化物含量的增加而降低。电子探针分析结果表明：镍黄铁矿中Co含量较高，其含量为0.32%～1.93%，平均为0.81%；磁黄铁矿和黄铜矿（方黄铜矿）中Co的含量较低，变化范围分别为0.02%～0.11%和0.01%～0.08%。元素面扫描结果表明：Co含量较高的部位与镍黄铁矿范围完全一致，说明Co主要赋存于镍黄铁矿中。金川矿床整体Co/Ni平均值为0.042，与全球典型橄榄岩相地幔Co/Ni值（0.055）相似，表明其岩浆源区主要为橄榄岩相。高程度的部分熔融可能是导致其母岩浆中Co绝对含量较高，但Co/Ni值相对较低的原因之一。硫化物熔离时，Co更倾向于进入硫化物；但相对于Ni，进入硫化物的Co较少，导致不同矿石类型之间S含量与Co/Ni值之间呈明显的负相关性。硫化物分离结晶作用进一步促使Co向镍黄铁矿中富集。     

青海化隆地区拉水峡铜镍矿床地质、 地球化学特征及成因

拉水峡铜镍矿床位于化隆基性—超基性岩带中,岩体几乎全岩发生铜、镍硫化物矿化,且已遭受强烈蚀变,以角闪岩为主。岩浆期主要金属硫化物矿物组合为磁黄铁矿、黄铜矿、镍黄铁矿;热液蚀变期主要有紫硫镍矿、黄铁矿、黄铜矿、针镍矿等;氧化表生期主要为含镍高岭石、含镍绿泥石、孔雀石等。矿石轻稀土元素富集和负Eu异常明显,说明岩浆演化过程中发生了大量斜长石等的分离结晶作用。∑PGE含量平均为2460.46×10-9,(Pd+Pt)/(Os+Ir+Ru)值为0.40~2.00,表明铂族元素与岩浆深部熔离作用密切相关;但Pt/Pd(0.01~2.62)、Pd/Ir(0.91~8.77)说明热液作用对铂族元素具有一定的富集作用。S同位素组成变化范围很小,δ34S平均值为2.24‰,硫化物中的S以地幔S为主。拉水峡矿床的形成经历了岩浆融离贯入、热液叠加改造及表生氧化作用3个阶段。     

江苏六合新生代玄武岩中地幔捕虏体的硫化物相研究

江苏六合一带碱性玄武岩中的出露有以尖晶石二辉橄榄岩为主的地幔捕虏体,这些地幔矿物中普遍有硫化物相出现：（１）被寄主矿物捕获的早期硫化物颗粒。（２）产于矿物晶粒边界或次生裂隙充填物,（３）硫化物包裹体,包括单相硫的包裹体、硫化物－玻璃两相熔体包裹体和ＣＯ／２－硫化物－玻璃（含硅酸盐子矿物）的多相包裹体,电子探针分析表明,硫化物包裹体比例隙中硫化物具有更高的相对Ｆｅ和Ｓ含量,较低的Ｎｉ含量。硫化物包裹     

中国吉林长白山地区地幔捕虏体中硫化物熔体包裹体

Mantle xenoliths are common in the Cenozoic basalts of the Changbaishan District,Jilin Province,China.Sulfide assemblages in mantle minerals can be divided into three types:isolated sulfide grains,sulfide-meh inclusions and filling sulfides in fractures.Sulfide-meh inclusions occur as single-phase sulfides,sulfide-silicate melt,and CO_2-sulfide-silicate melt inclusions. Isolated sulfide grains are mainly composed of pyrrhotite,but cubanite was found occasionally.Sulfide-meh inclusions are mainly composed of pontlandite and MSS,with small amounts of chalcopyrite and talnakhite.The calculated distribution coefficient K_(D3)for lherzolite are similar to that of mean experimental value.The bulk sulfides in lherzolite were in equilibrium with the enclosing minerals, indicating immiscible sulfide melts captured in partial melting of upper mantle.Sulfide in fractures has higher Ni/Fe and(Fe Ni)/S than those of sulfide melt inclusions.They might represent later metasomatizing fluids in the mantle.Ni/Fe and(Fe Ni)/S increase from isolated grains,sulfide inclusions to sulfides in fractures.These changes were not only affected by temperature and pressure,hut by geochemistry of Ni,Fe and Cu,and sulfur fugacity as well.     

Phosphorus-bearing sulfides and their associations in CM chondrites

Phosphorus-bearing Fe and Ni sulfides represent a new type of phosphorus compounds and are characteristic accessory phases of CM chondrites. The proportions of atoms in the sulfides can be approximated by the equation (Fe + Ni)/P = 0.965 ± 0.003 (1σ) · S/P + 1.255 ± 0.036 (1σ). Sulfides with high S/P ratios are systematically richer in Fe and poorer in Ni compared with low-S/P sulfides. Their characteristic minor elements are Cr, Ca, Co, K, and Na. The contents of Cr and Ca may reach several weight percent, but their incorporation does not affect the relation between (Fe + Ni)/P and S/P. This is also true of light elements (O and H), which probably occur in the P-bearing sulfides in certain amounts. The sulfides are usually associated with schreibersite, barringerite, eskolaite, and daubreelite. A negative correlation was observed between the Fe/Ni ratios of coexisting P-bearing sulfides and phosphides. Metallic iron was never found in association with the sulfides. It can be suggested that P-bearing sulfide is a primary phase rather than a secondary alteration product formed under the conditions of the CM chondrite parent body. This phase had to be stable in the solar nebula after the formation of Ca-Al inclusions and before the condensation of Fe-Ni metal. At high temperatures, P-bearing sulfide with low Fe/Ni and S/P ratios coexists with schreibersite in the solar gas. During condensation schreibersite is replaced by barringerite, which is accompanied by a decrease in the Fe/Ni ratio of phosphides and an increase in the S/P and Fe/Ni ratios of P-bearing sulfides. Trace element data suggest that the P-bearing sulfides could be formed in the solar nebula by the sulfidization of a precursor phase of extrasolar origin.     

浙江新昌地幔岩捕虏体中的硫化物包裹体初步研究

浙江新昌一带晚第三纪碱性玄武岩中地幔岩（二辉橄榄岩）捕虏体内存在大量硫化物熔体包裹体。电子探针分析表明,硫化物相成分主要为镍黄铁矿,次为磁共铁矿。硫化物包裹体的Ｎｉ／Ｆｅ值与寄主地幔岩的橄榄石含量呈正相关。同一包裹体的硫化物相成分不均一,自中心至边缘硫化物的Ｎｉ／Ｆｅ、（Ｆｅ＋Ｎｉ）／Ｓ值和Ｎｉ呈均呈增加趋势。通过与中国汉诺坝、德国ＷｅｓｔＥｉｆｅｌ东欧Ｎｏｇｒａｄ－Ｇｏｍｏｒ地区资料的综合分析,     

Sulfide oxidation as a process for the formation of copper-rich magmatic sulfides

Typical magmatic sulfides are dominated by pyrrhotite and pentlandite with minor chalcopyrite, and the bulk atomic Cu/Fe ratio of these sulfides is typically less than unity. However, there are rare magmatic sulfide occurrences that are dominated by Cu-rich sulfides (e.g., bornite, digenite, and chalcopyrite, sometimes coexisting with metallic Cu) with atomic Cu/Fe as high as 5. Typically, these types of sulfide assemblages occur in the upper parts of moderately to highly fractionated layered mafic–ultramafic intrusions, a well-known example being the Pd/Au reef in the Upper Middle Zone of the Skaergaard intrusion. Processes proposed to explain why these sulfides are so unusually rich in Cu include fractional crystallization of Fe/(Ni) monosulfide and infiltration of postmagmatic Cu-rich fluids. In this contribution, we explore and experimentally evaluate a third possibility: that Cu-rich magmatic sulfides may be the result of magmatic oxidation. FeS-dominated Ni/Cu-bearing sulfides were equilibrated at variable oxygen fugacities in both open and closed system. Our results show that the Cu/Fe ratio of the sulfide melt increases as a function of oxygen fugacity due to the preferential conversion of FeS into FeO and FeO_1.5, and the resistance of Cu₂S to being converted into an oxide component even at oxygen fugacities characteristic of the sulfide/sulfate transition (above FMQ?+?1). This phenomenon will lead to an increase in the metal/S ratio of a sulfide liquid and will also depress its liquidus temperature. As such, any modeling of the sulfide liquid line of descent in magmatic sulfide complexes needs to address this issue.     

Djerfisherite in xenoliths of sheared peridotite in the Udachnaya-East pipe (Yakutia): origin and relationship with kimberlitic magmatism

Djerfisherite, a Cl-bearing potassium sulfide (K₆Na(Fe,Ni,Cu)₂₄S₂₆Cl), is a widespread accessory mineral in kimberlite-hosted mantle xenoliths. Nevertheless, the origin of this sulfide in nodules remains disputable. It is usually attributed to the replacement of primary Fe–Ni–Cu sulfides when xenoliths interact with a K-and Cl-enriched hypothetical melt/fluid. The paper is devoted to a detailed study of the composition and morphology of djerfisherite from a representative collection (22 samples) of the deepest mantle xenoliths—sheared garnet peridotite, taken from the Udachnaya-East kimberlite pipe (Yakutia). Four types of djerfisherite were distinguished in the mantle rocks on the basis of morphology, spatial distribution, and relationships with the rock-forming and accessory minerals in the nodules. Type 1 was found in the rims of polysulfide inclusions in the rock-forming minerals of the xenoliths; there, it was younger than the primary sulfide assemblage pyrrhotite + pentlandite ± chalcopyrite. Type 2 formed rims around large polysulfide segregations (pyrrhotite+ pentlandite) in the xenolith interstices. Type 3 formed individual grains in the xenolith interstices together with other sulfides, silicates, oxides, phosphates, and carbonates. Type 4 was present as a daughter phase in the secondary melt inclusions which occurred in healed cracks in the rock-forming minerals of the xenoliths. Along with djerfisherite, the inclusions contained silicates, oxides, phosphates, carbonates, alkaline sulfates, chlorides, and sulfides. The results indicate that djerfisherite from the xenoliths is consanguine with kimberlite. Djerfisherite both in the sheared-peridotite xenoliths from the Udachnaya-East pipe and in different xenoliths from other kimberlite pipes worldwide formed owing to the interaction between the nodules and kimberlitic melts. Djerfisherite forming individual grains in the melt inclusions and xenolith interstices crystallized directly from the infiltrating kimberlitic melt. Djerfisherite bounding the primary Fe–Ni ± Cu sulfides formed by their replacement as a result of a reaction with the kimberlitic melt.     

来自蛇绿岩地幔的硫（砷）化物矿物组合

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。     

CuFeNiS mineral assemblages in upper-mantle peridotites from the Table Mountain and Blow-Me-Down Mountain ophiolite massifs (Bay of Islands area,Newfoundland): Their relationships with fluids and silicate melts

Plastically deformed ultramafic rocks in the Table Mountain and Blow-Me-Down Mountain ophiolites comprise a basal unit of slightly depleted Iherzolites, an intermediate sequence of strongly depleted harzburgites and an upper zone of dunites, also referred to as a transition zone intensively percolated by basaltic melts or magmatic fluids. Thirty-five samples including all of the above rock types have been investigated on 100 polished thin sections for CuFeNiS mineral assemblages. Most of them contain traces of CuFeNi sulfides, native metals and locally Ni arsenide. Compositional features of opaque assemblages as well as their textural sites in the rocks indicate that the present CuFeNiS minerals derive from an upper-mantle sulfide component through extensive subsolidus re-equilibration down to 100°C. The primitive component (predominant pentlandite, minor pyrrhotite and chalcopyrite) is preserved as sulfide inclusions in chromites of the transition zone, due to a subsolidus re-equilibration in a closed system. On the contrary, sulfide assemblages interstitial to silicates and spinel have extensively reacted with reducing serpentinizing fluids to produce sulfur-deficient sulfides such as heazlewoodite and mackinawite and native metals (native copper and awaruite). Microscale variations of redox conditions and the removal of Fe from the silicate during serpentinization may account for the peculiar “grain-by-grain” equilibrium state of intergranular assemblages. In spite of low-temperature alteration, a gradual depletion in sulfide component has been recognized from the basal lherzolites to the intermediate harzburgites while the sulfide content gradually increases in the transition zone (up to 0.2% by volume). The first pattern is consistent with the low-melting nature of the sulfide component in mantle melting processes. Microstructural criteria such as the absence of sulfide inclusions in olivine neoblasts demonstrate that the sulfide component postdates plastic deformation of the transition zone. The sulfide-enrichment pattern is thus ascribed to the percolation of a sulfur-saturated basaltic magma into residual dunites.     

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