Chengdeit
| Chengdeit | |
|---|---|
| General and classification | |
| other names |
IMA 1994-023 |
| chemical formula | Ir 3 Fe |
|
Mineral class (and possibly department) |
elements |
|
System no. to Strunz and to Dana |
1.AG.35 ( 8th edition : I / A.15) 02/01/05/05 |
| Crystallographic Data | |
| Crystal system | cubic |
| Crystal class ; symbol | cubic hexakisoctahedral; 4 / m 3 2 / m |
| Space group | Pm 3 m (No. 221) |
| Lattice parameters | a = 3.79 Å |
| Formula units | Z = 1 |
| Physical Properties | |
| Mohs hardness | 5 ( VHN 50 = 411 to 467, average 452) |
| Density (g / cm 3 ) | calculated: 19.19 |
| Cleavage | is missing |
| Break ; Tenacity | hooked; plastically deformable |
| colour | steel black |
| Line color | black |
| transparency | opaque (opaque) |
| shine | Metallic luster |
| magnetism | strong magnetic |
Chengdeit is a very rarely occurring minerals from the mineral class of "elements (including natural alloys, intermetallic compounds, carbides, nitrides, phosphides and silicides)" with the chemical composition Ir 3 Fe and is thus chemically seen a natural alloy of iridium and iron in the Ratio 3: 1.
Chengdeit crystallizes in the cubic crystal system , but has so far only been discovered in the form of granular aggregates up to about 0.5 mm in size. The mineral is opaque (opaque) and shows a higher metal in any form on the surfaces of the steel grains black gloss . The stroke color of Chengdeit is black. In the reflected light microscope , the mineral shows a strong white color with a yellowish tinge.
Etymology and history
Was first discovered in the Chendeit Cr PGE - deposit Gaositai in county Chengde in the Chinese province of Hebei . The first description was in 1995 by Zuxiang Yu, who named the mineral after its type locality .
Type material, i.e. mineral samples from its type locality, are kept in the Chinese Geological Museum in Beijing .
classification
Already in the outdated but still partially in use 8th edition of the mineral classification by Strunz of Chengdeit belonged to the mineral class of "elements" and then to the Department of "metals and intermetallic alloys (semimetals)" where he collaborated with ferronickel platinum , Isoferroplatin , Nielsenit , Tetraferroplatinum and tulameenite formed the unnamed group I / A.15 .
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 the Chengdeit to the department of "Metals and Intermetallic Compounds". However, this is further subdivided according to the affiliation of the metals involved to certain element families, so that the mineral can be found in the sub-section “ PGE metal alloys” according to its composition , where it is only together with isoferroplatin the “isoferroplatin group” “With the system no. 1.AG.35 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Chengdeit to the class and there in the department of the same name of "elements". Here he is together with isoferroplatinum, rustenburgite , atokit , Zvyagintsevit and Yixunit in the " isoferroplatinum group (room group Pm 3 m) " with the system no. 02/01/05 to be found in the subsection "Elements: Platinum Group Metals and Alloys".
Crystal structure
Chengdeit crystallizes cubically in the space group Pm 3 m (space group no. 221) with the lattice parameter a = 3.79 Å and one formula unit per unit cell .
Education and Locations
Chendeite forms in chromite ores in ultramafic rocks . From there, the mineral is removed by weathering and transported to the corresponding soap deposits . In addition to chromite, the accompanying minerals include erlichmannite , galena , gaotaiite , solid gold , inaglyite , irarsite , isoferroplatinum, laurite , magnetite , osmiridium and ferrous solid platinum.
In addition to its type locality Gaositai in Chengde County, the mineral only appeared in a nearby soap deposit on the Wulie River in China. The only other known site to date is a soap deposit on the Tolovka River on the Ust'-Bel'skii ultrabasite massif in the Koryak Mountains on the Kamchatka Peninsula in Russia's Far East.
See also
literature
- Zuxiang Yu: Chengdeite - ordered natural iron-iridium alloy . In: Acta Geologica Sinica . tape 69 , no. 3 , 1995, p. 215-220 .
- John L. Jambor, Nikolai N. Pertsev, Andrew C. Roberts: New Mineral Names . In: American Mineralogist . tape 81 , 1996, pp. 516-520 ( minsocam.org [PDF; 479 kB ; accessed on December 29, 2017]).
Web links
- Mineral Atlas: Chengdeit (Wiki)
- Mindat - Chengdeite (English)
- American-Mineralogist-Crystal-Structure-Database - Chengdeite (English)
Individual evidence
- ↑ a b c d Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 44 .
- ↑ a b c d e f g Chengdeite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 60 kB ; accessed on December 29, 2017]).
- ↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties . 6th completely revised and supplemented edition. Weise, Munich 2014, ISBN 978-3-921656-80-8 .
- ↑ Webmineral - Chengdeite (English)
- ↑ Find location list for Chengdeit at the Mineralienatlas and at Mindat