Palladodymite

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Palladodymite
General and classification
other names

IMA 1997-028

chemical formula (Pd, Rh) 2 As
Mineral class
(and possibly department) 		Sulfides and sulfosalts
System no. to Strunz
and to Dana 		2.AC.25c ( 8th edition : II / A.05)
02.04.19.02
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol orthorhombic-dipyramidal; 2 / m 2 / m 2 / m
Room group (no.) Pnma (No. 62)
Lattice parameters a  = 5.91  Å ; b  = 3.90 Å; c  = 7.34 Å
Formula units Z  = 4
Physical Properties
Mohs hardness 5.5
Density (g / cm 3 ) Please complete!
Cleavage Please complete!
colour Please complete!
Line color Please complete!
transparency opaque
shine Metallic luster

Palladodymite 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 (Pd, Rh) 2 As, whereby the elements palladium and rhodium 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.

So far, palladodymite could only be found in the form of 30 μm × 70 μm inclusions in ruthenium . Under the incident light microscope , palladodymite has a brownish-gray color with a bluish tinge.

Etymology and history

Palladodymite was first discovered in a soap deposit on the Miass in the Russian Oblast of Chelyabinsk and described in 1999 by Britvin, Rudashevsky, Bogdanova and Shcherbachev that the mineral is based on its composition and the fact that it is a palladium analogue of rhodarsenide in the figurative sense Gemini is ( Greek δυμο [dymo]), given the name palladodymite .

classification

In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the palladodymite belonged to the mineral class of "sulfides and sulfosalts" and there to the department of "alloys and alloys". alloy-like compounds ", where he together with Arsenopalladinit , Atheneit , Genkinit , Miessiit ( IMA 2006-013 ), Majakit , Menshikovit , Mertieit-I , Mertieit-II , Palladoarsenid , Palladobismutoarsenid , Polkanovit , Rhodarsenid , stibiopalladinite , Stillwaterit , Ungavait and Vincentit the unnamed group II / A.05 formed.

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 palladodymite to the class of "sulfides and sulfosalts" and to the department of "alloys and alloy-like compounds". However, this section is further subdivided according to the metals involved in the connection, so that the mineral can be found according to its composition 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.25c forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the palladodymite to the class of "sulfides and sulfosalts" and there in the department of "sulfide minerals". Here it can be found together with rhod arsenide 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

The accompanying minerals included ruthenium , isoferroplatinum , cherepanovite , rhodium-containing irarsite , honshiite , sperrylite , tulameenite and some unnamed iridium - arsenic - tellurium compounds.

In addition to its type locality Miass in Russia, palladodymite could so far (as of 2012) only be found near Pefki in the Pindos Mountains in Greece.

Crystal structure

Palladodymite crystallizes orthorhombically in the space group Pnma (space group no. 62) with the lattice parameters a  = 5.91  Å ; b  = 3.90 Å and c  = 7.34 Å and 4 formula units per unit cell .

See also

Web links

Individual evidence

  1. ↑ a b c d e 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 .
  2. ↑ Webmineral - Palladodymite
  3. ↑ Mindat - Palladodymite