Beitrag
Rhodarsenide, (Rh,Pd)2As, a new mineral
Tarkian, Mahmud; Krstiö, Saša; Klaska, Karl-Heinz; Ließmann, Wilfried
European Journal of Mineralogy Volume 9 Number 6 (1997), p. 1321 - 1326
12 Literaturangaben
veröffentlicht: Dec 2, 1997
Manuskript akzeptiert: Sep 15, 1997
Manuskript erhalten: Jul 10, 1997
DOI: 10.1127/ejm/9/6/1321
Abstract
Abstract 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 × 100 μm) 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 (VHN25) 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: (Rh1.67Pd0.34)Σ2.01 As0.99 and (Rh1.07Pd0.94Pt0.03)Σ2.04 (As0.91Sb0.04Te0.01)Σ0.96. The X-ray powder-diffraction pattern was indexed for an orthorhombic cell with a = 5.866 Å; b = 3.893 Å; c = 7.302 Å; a: b: c = 1.507: 1: 1.875; V = 166.7 Å3. 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) Å.
Schlagworte
rhodarsenide • new mineral • PGM placers • Central Serbia