Rhodarsenide, (Rh,Pd)2As, a new mineral

The new mineral rhodarsenide, ideally (Rh, Pd)2As, has been found in concentrates from placers of the Srebrnica river, near the village Veluce in Central Serbia, The associated platinum-group minerals are PGE alloys, Rh-Ir sulpharsenides and sperrylite. Rhodarsenide is present as inclusions (up to 80 x 100 11m) in Pt-Fe and Ru-Os-Ir alloys. In reflected light it is brownish; pleochroism and anisotropy are weak to distinct. Maximum and minimum reflectance values in air for standard wavelengths (470, 546, 589 and 650 nm) are 46.3/45.5, 48.4/47,6, 49.5/48,2 and 51.2/49,8, respectively; values measured in oil are 38,2/32.9 (470), 39.8/35.7 (546),40.4/36.4 (589) and 40.5/36,6 (650). Vickers micro-indentation hardness (VHN2s) is 493-585 kg/mm2, Chemical compositions of individual grains of rhodarsenide vary between Rh 38.53-60,81, Pd 12.10-34.67, Pt 0,00-2,38, Ir 0.09- 0.48, Fe 0,00-0.10, Cu 0.08-0.46, As 23.42-27,96, Sb 0,09-1.60, and Te 0.08-1.20 wt.%, corresponding to: (Rhl.67Pdo.34)L201 ASO.99and (Rhl.07Pdo.94Ptom)L2.04 (ASO.9ISbo.04Teo.0l)m.96. The X-ray powder-diffraction pattern was indexed for an orthorhombic cell with a =5.866 A; b = 3.893 A; c = 7.302 A; a: b: c = 1.507: I: 1.875; V = 166.7 A3, For Z = 4, the calculated density is 11.32 g/cm3, The three strongest lines in the X-ray pattern are 2,237 (10), 2,067 (8) and 2.426 (7) A.