新矿物马兰矿——自然界中首次发现三价铂、三价铱与铜的硫化物  

MALANITE——A NEW CUPRIC PLATINUM (Pt^(3+0) AND IRIDIUM (Ir^(3+)) SULFIDE

作　　者：於祖相[1] 

机构地区：[1]中国地质科学院地质研究所

出　　处：《地质学报》1996年第4期309-314,T001,共7页Acta Geologica Sinica

基　　金：国家自然科学基金(编号 49572095)

摘　　要：马兰矿最先在遵化橄榄辉石岩内的浸染状铜、镍硫化物矿石中发现,其后又在燕山双峰村含铂的铬矿石中发现。在前者矿石中马兰矿呈八面体及菱形十二面体,与磁黄铁矿、镍黄铁矿、砷铂矿、硫铂矿等共生。在后者矿石中,它嵌生在硫铱矿的裂隙中,呈块状或他形粒聚晶,与等轴锇铱矿、粗铂矿、硫铱矿等共生。钢灰色,金属光泽,不透明,粉末黑色。H_M5.0,VHN_(20)417kg/mm^2,性脆。解理{111}有时可见。计算密度7.57g/cm^2。反射色为白色微带淡绿,内反射无,均质性,双反射及反射多色性在空气中未见。根据其样品电子探针的分析,其实验式(按原子数7计算)为:(Cu_(0.95)Fe_(0.07))_(∑1.02)(Pt_(1.37)Ir_(0.45)Co_(0.11)Rh_(0.08))_(∑2.01)S3.97。或(Cu_(0.93)Fe_(0.06))_(∑0.99)(Pt_(1.03)Ir_(0.66)Rh_(0.04)Pd_(0.03)Co_(0.21)Ni_(0.03))_(∑2.00)S_(4.03)。马兰矿5条最强粉晶衍射线:hkl,d,I分别为:311,2.98,6;400,2.48,5;333,1.90,7;440,1.75,10;731,1.29,5。根据X射线粉晶指标化的结果,求得马兰矿为等轴晶系,空间群:Fd3m,α0.9940(3)nm,V=0.9821nm^3或α0.9910nm,V=0.9732(3)nm^3,Z=4。马兰矿样品存放在中国地质博物馆。Malanite was found; a) in a magmatic nickel-copper sulfide ore of olivine pyroxenite dikes, about 150 km east of Beijing, associated with pyrrhotite, pentlandite, chalcopyrite, bornite, moncheite, cooperite and sperrylite, and b) as a constituent of placer concentrates, near the village of Shuangfeng, about 200 km NNE of Beijing. Malanite replaces iridisite and is associated with iridosmine, ferric platimum and iridisite.Malanite always occurs in idiomorphic octahedral or dodecahedral crystals 0.1 - 0.2 mm in diameter in magmatic nickel-copper sulfides. In chromite placer concentrates, malanite is massive and tends to occur along the cracks of iridisite (IrS2) and replaces it to form veinlets. Colour steel-grey with black streaks; opaque; lustre metallic. HM5. 0; VHN20 417 kg/mm2; brittle; cleavage [111] observed sometimes; fracture none; magnetism none; density (calc. ) = 7. 57 g/cm3; reflective colour white with a greenish tint; internal reflection none; isotropic; bire-flectance and pleochroism not observed.Five chemical analyses for malanite (sample 2, in chromite placers) were carried out by means of an electron microprobe. The mean analytical results (and ranges) for malanite are- S 22. 6, Fe 0. 7, Co 1. 1, Cu 10. 7, Rh 1. 5, Ir 15. 4, Pt 47. 4, total 99. 4. The empirical formula (based on 7 atoms) is (Cu0.95Fe0.07)21.02 (Pti.37Ir0.45Co0.11Rh0.08)2.01S3.97. Six chemical analyses for malanite (sample 1, in Cu-Ni sulfide ore) gave the results: S 23. 8, Fe 0. 6, Co 2. 2, Ni 0. 3, Cu 10. 9, Rh 0. 7, Pd 0. 5, It 23. 2, Pt 37. 0, total 99. 21. The empirical formula (based on 7 atoms) is (Cu0.93Feo.o6)so.99(Pti.o3lro.66Rho.o4Pdo.o3Coo.2iNio.o3)?ooS4.o3. The simplified formula is CuPt2S4.Malanite has been studied by the osillation method and four circle diffractometer. The unit cell is a 0. 990 nm, with space group Fd3m. Six strongest lines hkl d I are 311, 2. 98, 6; 400, 2.48,5; 333,1.90,7; 440, 1.75,10; 731,1.29, 5. The powder diffractions could be indexed as a cubic unit cell Fd3m (space group) with 0. 9940 nm (

关 键 词：新矿物 马兰矿 铬矿石 铂 铱 铜 

分 类 号：P578[天文地球—矿物学]