Rhod arsenide
| Rhod arsenide | |
|---|---|
| General and classification | |
| other names |
IMA 1996-030 |
| chemical formula | (Rh, Pd) 2 As |
|
Mineral class (and possibly department) |
Sulfides and sulfosalts |
|
System no. to Strunz and to Dana |
2.AC.25b ( 8th edition : II / A.05) 02.04.19.01 |
| Crystallographic Data | |
| Crystal system | orthorhombic |
| Crystal class ; symbol | Please complete |
| Lattice parameters | a = 5.87 Å ; b = 3.89 Å; c = 7.30 Å |
| Formula units | Z = 4 |
| Physical Properties | |
| Mohs hardness | 4 to 5 |
| Density (g / cm 3 ) | calculated: 11.32 |
| Cleavage | Please complete |
| colour | brownish with a tinge of light green |
| Line color | Please complete |
| transparency | opaque |
| shine | Please complete |
Rhod arsenide is a very rarely occurring mineral from the mineral class of " sulfides and sulfosalts ". It crystallizes in the orthorhombic crystal system with the chemical composition (Rh, Pd) 2 As, whereby the elements rhodium and palladium indicated in the round brackets can represent each other in the formula ( substitution , diadochy), but always in the same proportion to the arsenic involved stand.
Rhodarsenid could so far only in the form of 80 x 100 micron sized inclusions in platinum - iron - and ruthenium - Osmium - Iridium - alloys are found. In incident light, the mineral has a brownish color with a tinge of light green.
Etymology and history
Rhodarsenid was first discovered in platinum metal-containing soap deposits of Srebrnica near Veluce in central Serbia . Mahmud Tarkian, Saša Krstić, Karl-Heinz Klaska and Wilfried Ließmann described the mineral in 1997 and named it after the predominant elements in the compound.
The type material of the mineral is deposited in the Mineralogical Museum of the University of Hamburg .
classification
In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the rhod arsenide belonged to the mineral class of "sulfides and sulfosalts" and there to the department of "alloys a. alloy-like compounds ", where he together with Arsenopalladinit , Atheneit , Genkinit , isomertieite , Majakit , Menshikovit , Mertieit-I , Mertieit-II , Miessiit , Naldrettit , Palladoarsenid , Palladobismutoarsenid , Palladodymit , Polkanovit , stibiopalladinite , Stillwaterit , Ungavait and Vincentit the" Arsenopalladinit -Group "with the system no. II / A.05 .
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns rhod arsenide to the category of "alloys and alloy-like compounds". However, this is further subdivided according to the metals involved in the connection, so that the mineral can be found in the sub-section "Alloys of semi-metals with platinum group elements (PGE)", where it is the only member of the unnamed group 2 .AC.25b forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns rhod arsenide to the class of “sulfides and sulfosalts” and there to the “sulfide minerals” division. Here it can be found together with palladodymite in the unnamed group 02.04.19 within the subsection “Sulphides - including selenides and tellurides - with the composition A m B n X p , with (m + n): p = 2: 1”.
Education and Locations
Rhodarsenid is found in the form of 80 x 100 micron sized inclusions in platinum - iron - and ruthenium - Osmium - Iridium - alloys in placer deposits. Accompanying minerals include platinum-iron and ruthenium-osmium-iridium alloys, hollingworthite , irarsite , sperrylite .
In addition to its type locality Srebrnica in Serbia, Rhodarsenid could also be found on the Pustaya near Kamchatka in the East Asian part of Russia and near the Maandagshoek Farm in the Bushveld complex of South Africa.
Crystal structure
Rhodarsenide crystallizes orthorhombically, but the exact space group has not yet been determined. The lattice parameters are a = 5.87 Å ; b = 3.89 Å and c = 7.30 Å and 4 formula units per unit cell .
See also
literature
- Mahmud Tarkian, Saša Krstić, Karl-Heinz Klaska, Wilfried Ließmann : Rhodarsenide, (Rh, Pd) 2 As, a new mineral , in: European Journal of Mineralogy , Volume 9, pp. 1321-1325 ( PDF 279.4 kB )
Web links
Individual evidence
- ↑ a b c d Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 61 .
- ↑ Mindat - Rhodarsenide