Yixunite and Damiaoite—A Twin of New Native Alloys of Indium and Platinum from the Yanshan Mountains

Abstract

AbstractYixunite and damiaoite were found in a cobalt‐ and copper–bearing platinum ore vein of a contact metasomatic deposit. The chief ore minerals are bornite, chalcopyrite, magnetite and carrollite. The platinum minerals include moncheite, sperrylite, daomanite, cobalt malanite and cooperite. Yixunite and damiaoite occur as immiscible globules, 1.0 to 2.0 mm in diameter. Yixunite is always in the central part of a globule. It is opaque with metallic lustre, bright white colour and black streak. HM=5.8; VHN50 = 634 kg/mm2 (573–681 kg/mm2); insoluble in HCl, HNO3, HF or H3PO4; no cleavage; no magnetism. Density is hard to measure because of small grain size. Calculated density = 18.21 g/cm3. Reflective colour is bright white with a yellowish tint. Isotropic. The mean analytical results (ranges) (%) are: Pt 82.8 (81.8–83.6), In 16.4(15.6–17.1) and total 99.2. The empirical formula (based on 4 atoms) is Pt2.993 In1.007. The five strongest lines of X–ray diffraction (hki, d, I) are 111, 2.30 (100); 200, 1.99(60); 202, 1.411 (40); 311, 1.203 (80); 222, 1.151(40). Space group: Pm3m with a = 0.3988(3) nm and Z= 1. Damiaoite occurs as single globules or was exsolved from yixunite. Opaque with metallic lustre; bright white colour with black streak; HM = 5.3; VHN50 = 485 kg/mm2 (434–529 kg/mm2); insoluble in HCl, HNO3, HF or H3PO4; cleavage: no; magnetism: no. Density: hard to measure because of small grain size. Calculated density = 10.95 g/cm3. Reflective colour is bright white with a yellowish tint. Isotropic. The mean analytical results (ranges) (%) are Pt 45.6 (45.4–46.0), In 53.5 (52.4–53.9), total 99.1. The empirical formula (based on 3 atoms) is P1.002 In1.998. The six strongest lines of X–ray diffraction (hkl. d. I) are 220,2.25 (100); 311,1.92 (60); 400,1.59 (60); 422,1.299 (80); 440,1.125 (60); 620,1.006 (70). Space group: Fm3m with a = 0.6364 (3) nm and Z = 4.