Changchengit
| Changchengit | |
|---|---|
| General and classification | |
| other names |
MA 1995-047 |
| chemical formula | IrBiS |
|
Mineral class (and possibly department) |
Sulfides and sulfosalts |
|
System no. to Strunz and to Dana |
2.EB.25 ( 8th edition : II / D.17) 02.12.03.14 |
| Crystallographic Data | |
| Crystal system | cubic |
| Crystal class ; symbol | tetrahedral-pentagon-dodecahedral; 23 |
| Room group (no.) | P 2 1 3 (No. 198) |
| Lattice parameters | a = 6.16 Å |
| Formula units | Z = 4 |
| Physical Properties | |
| Mohs hardness | 3.5 |
| Density (g / cm 3 ) | calculated: 11.96 |
| Cleavage | Please complete |
| colour | steel gray to black |
| Line color | black |
| transparency | opaque |
| shine | Metallic luster |
Changchengit is a very rare mineral from the mineral class of " sulfides and sulfosalts ". It crystallizes in the cubic crystal system with the idealized composition IrBiS, so from a chemical point of view it is an iridium - bismuth sulfide,
Changchengit could so far only be found in the form of massive aggregates up to about 2 mm in size from steel gray to black in color with black streak color .
Etymology and history
Changchengit was first discovered in an unnamed soaps - deposit on Luan River near Chengde in China. The mineral was described in 1997 by Yu Zuxiang , who named the mineral after the Chinese word for "Great Wall" due to its proximity to the Great Wall of China .
classification
Already in the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the Changchengite belonged to the mineral class of "sulfides and sulfosalts" and there to the department of "sulfides with the molar ratio of metal: sulfur, selenium, tellurium <1: 1", where he along with Aurostibit , cattierite , Dzharkenit , Erlichmanit , Fukuchilit , Geversit , Hauerit , Insizwait , Krutaite , Laurit , Maslovit , Mayingit , Michenerit , Padmait , Penroseite , pyrite , Sperrylith , Testibiopalladit , Trogtalit , Vaesit and Villamaninit with the "pyrite group" the system no. II / D.17 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 Changchengit to the class of “sulfides and sulfosalts”, but there in the department of “metal sulfides with M: S ≤ 1 : 2 “a. This section is further subdivided according to the exact molar ratio and the predominant metals in the compound, so that the mineral can be found in the subdivision "M: S = 1: 2, with Fe, Co, Ni, PGE etc." according to its composition is where it together with cobaltite , Gersdorffit , Hollingworthit , Irarsit , Jolliffeit , Kalungait , Maslovit, Mayingit, Michenerit, Milotait , Padmait, Platarsit , Testibiopalladit, Tolovkit , Ullmannit and Willyamit the "Gersdorffitgruppe" with the system number. 2.EB.25 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Changchengit to the class of "sulfides and sulfosalts" and there in the department of "sulfide minerals". Here it is together with cobaltite, Gersdorffit, Ullmannit, Willyamit, Tolovkit, Platarsit, Irarsit, Hollingworthit, Jolliffeit, Padmait, Michenerit, Maslovit, Testibiopalladit, Milotait and Kalungait in the "Cobaltitgruppe (cubic or pseudo-cubic crystals)" 02:12:03 within the Subdivision " 02.12 Sulphides - including selenides and tellurides - with the composition A m B n X p , with (m + n): p = 1: 2 " can be found.
Education and Locations
Changchengit formed as a displacement product of Laurit and Iridisit in hydrothermally formed chromite - ore bodies in dunite or is found in platinum soaps deposits, usually associated with solid iridium and gold and chromite, cooperite , Irarsit, Laurit, Mayingit, Shuangfenit and Sperrylith.
So far (as of 2012) Changchengit could only be found at its type locality , the soap deposit on Luan He.
Crystal structure
Changchengit crystallizes cubically in the space group P 2 1 3 (space group no. 198) with the lattice parameter a = 6.16 Å and 4 formula units per unit cell .
See also
literature
- Yu Zuxiang (1997): Changchengite - a new iridium bismuth-sulfide from the Yanshan Mountains , in: Acta Geologica Sinica , Volume 71 (4), pp. 336–339 (in Chinese with a brief English description) doi : 10.1111 / j.1755 -6724.1997.tb00387.x
Web links
Individual evidence
- ↑ 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. 105 .
- ↑ a b c John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols: Changchengite , in: Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 57.7 kB )
- ^ Mindat - Changchengite