铂双峰矿—双峰矿的新变种

铂双峰矿产在纯橄榄岩铝矿体中。在铝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自形晶，与疏钻矿、含锇自然铱紧密共生。脉状的宽20～301μm，长400～500μm，一般10μm×20μm。金属光泽。条痕黑色。HM=3．05。VHN20=92kg／mm2（平均）。{0001}解理完全。性脆。计算密度为10．21g／cm2。反射色；亮黄白带淡蓝色。内反射无。非均质性中等，偏光色为淡蓝或淡黄。双反射或反射多色性在空气中或油中均未见。5个电子探针分析数据平均（wt％）：Cu0．2，Te57.2，Ir24.5，Pt17．2，Bi0．4，总量99．5。实验式为：（IR0．57Pt0.39Cu0.01）0．98（Te1.99Bi0.01）2.00。简化理论式为（11，Pt）Te2。4条最强X射线粉晶衍射线hkl，d，I为：101，2．87（100）；102，2．10（70）；110，1．98（60）；103，1．58O（50）。根据X射线粉晶数据进行指标化，获得铂双峰矿晶胞数据：三方晶系，P3ml，a=0．3973（5），c＝0．5315（5）um，V＝0．0727nm3，Z=1。铂双峰矿是笔者对双峰矿研究的继续与补充。

PLATINOSHUANGFENGITE, A NEW VARIETY OF SHUANGFENGITE

The mineral shuanfengite was found as a constituent of placer concentrates and crushedores of a chr0mite deposit. Colour: black-Streak: black. H. = 3. 05. VHN20 = 92kg/mm2 (78 ~144kg/mm2). Cleavage: {0001}perfect. Fracture: none. Brittle- Density could not be measured be-cause of its small grain size. Density (cal- ) = 10. 21g/cm2. Colour: bright yellowish-white with abluishtint. Internal reflection: none. Anisotropism: moderately week with a bluish or yellowishtint. Bireflectance and pleochroism:not observed in air or oil-Five chemical analyses were carriedout by means of an electron microprobe using the following standards: pure metals: S, Cu, Te,Os, Ir, Pt, Bi, pyrite (S), sperrylite (As ). The mean analytical results (wt % ) are: Cu 0. 2, Te57- 2, Ir 24. 5, Pt 17. 2, Bi 0. 4, totalling 99. 5. The empirical formula (based on 3 atoms) is:(Ir0.57, Pt0.40, Cu0.01 )0. 98(Te2.01. Bi0.01 )2.01. The simplified formula is (Ir, Pt )Te,. Single-crystal X-raystudies could not be carried out because of its small crystal size, but the X--ray powder diffractiondata were indexed by analogy with those of moncheite PtTe,. Four strongest line hkl, d and I ofthe X-ray diffraction powder are: 1O1, 2- 87 (100); 102, 2. 01 (70) j 110, 1. 98 (60); and 103, 1. 580(50). Unit cell data (parameters refined from the powder data): trigonal, P3ml, a = 0. 397 3 (5)nm, c = 0. 531 5 (5)nm- V = 0. 072 7 (5 )nm3, Z= 1. Morphology: c: a ratio calculated from the unitcell parameters is 1. 34.