Chaméanite
| Chaméanite | |
|---|---|
| General and classification | |
| chemical formula |
|
|
Mineral class (and possibly department) |
Sulfides and sulfosalts |
|
System no. to Strunz and to Dana |
2.LA.35 ( 8th edition : II / C.11) 02/03/08/01 |
| Crystallographic Data | |
| Crystal system | cubic |
| Crystal class ; symbol | cubic-hexakistrahedral; 4 3 m |
| Room group (no.) | I 4 3 m (No. 217) |
| Lattice parameters | a = 11.04 Å |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | 4.5 (VHN 25 = 247 to 292) |
| Density (g / cm 3 ) | calculated: 6.17 |
| Cleavage | Please complete |
| colour | - |
| Line color | Please complete |
| transparency | opaque |
| shine | Metallic luster |
Chaméanite is a very rare mineral from the mineral class of "sulfides and sulfosalts". It crystallizes in the cubic crystal system with the chemical composition (Cu, Fe) 16 As 4 Se 16 , so it is a copper - iron - arsenic - selenite . The elements copper and iron indicated in the round brackets can represent each other in the formula ( substitution , diadochie), but are always in the same proportion to the other components of the mineral. Since the selenium can also be partially replaced by sulfur , the formula is given in more recent sources as (Cu, Fe) 4 As (Se, S) 4 .
Chaméanite is opaque and so far has only been found in the form of irregular grains up to about 30 micrometers in size, dark gray in color and metallic luster .
Etymology and history
Chaméanite was first discovered in the Chaméane uranium deposit in the Puy-de-Dôme department in the Auvergne region of France and described in 1982 by Z. Johan, P. Picot and F. Ruhlmann, who named the mineral after its type of locality .
classification
Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the chaméanite belonged to the mineral class of "sulfides and sulfosalts" and there to the department of "sulfides with metal: S, Se, Te ≈ 1: 1", where it together with Argentotennantit , Argentotetraedrit , Freibergit , Giraudit , Goldfieldit , Hakit , Mgriit , tennantite and Tetraedrit the "Tetraedrit group" with the system number. II / C.11 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), classifies chaméanite under the category of “unclassified sulfosalts”. This is further subdivided according to the possible presence of lead (Pb) in the compound, so that the mineral can be found according to its composition in the sub-section “without Pb”, where it is the only member of the unnamed group 2.LA.35 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , classifies chaméanite in the “sulfosalts” department. Here he is the only member of the unnamed group 02/03/08 within the subsection “ Sulphosalts with the ratio z / y = 4 and the composition (A + ) i (A 2+ ) j [B y C z ], A = metals , B = semi-metals, C = non-metals ”.
Education and Locations
Chaméanite is formed by hydrothermal processes in granite or selenium-containing polymetallic deposits . As accompanying minerals may include Ankerit , Bukovit , cadmoselite , Eskebornite , Geffroyit , Giraudit , Hakit and Umangite occur.
In addition to its Chaméane type locality in France, only Předbořice in Černíny in Okres Kutná Hora in the Czech Republic and the "Tumiñico Mine" in the Sierra de Cacho in the Argentine province of La Rioja are known to have been found as chaméanite (as of 2013).
Crystal structure
Chaméanite crystallizes cubically in the space group I 4 3 m (space group no. 217) with the lattice parameter a = 11.04 Å and two formula units per unit cell .
See also
literature
- Z. Johan, P. Picot, F. Ruhlmann: Evolution paragénétique de la minéralisation uranifère de Chaméane (Puy-de-Dôme), France: chaméanite, geffroyite et giraudite, trois séléniures nouveaux de Cu, Fe, Ag et As. In: Tschermaks Mineralogische und Petrographische Mitteilungen. Volume 29 (1982), pp. 151-167 (in French)
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. 122 .
- ↑ a b IMA / CNMNC List of Mineral Names; October 2013 (PDF 1.5 MB)
- ↑ a b c d Webmineral - Chaméanite
- ↑ a b Chaméanite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 60.2 kB )
- ↑ location list for the Chaméanit Mineralienatlas and Mindat