Icosahedrite
| Icosahedrite | |
|---|---|
| General and classification | |
| other names |
IMA 2010-042 |
| chemical formula | Al 63 Cu 24 Fe 13 |
|
Mineral class (and possibly department) |
Elements - metals and intermetallic alloys |
| Crystallographic Data | |
| Crystal system | icosahedral quasicrystal |
| Crystal class ; symbol | not applicable (quasi-crystal) |
| Space group | Fm 3 5 |
| Lattice parameters | a = 12.64 Å ( a 6D ) |
| Physical Properties | |
| Mohs hardness | (unknown) |
| Density (g / cm 3 ) | (unknown) |
| Cleavage | is missing |
| colour | grey yellow |
| Line color | Gray |
| transparency | opaque |
| shine | metallic |
| Other properties | |
| Special features | only known natural quasicrystal (as of 2012) |
Icosahedrite (English Icosahedrite ) is an extremely rare mineral from the mineral class of the elements, more precisely the metals , intermetallic compounds and alloys . The mineral has the empirical composition Al 63 Cu 24 Fe 13 . Icosahedrite is the first known mineral that exists in the form of quasicrystals . The second known quasicrystalline mineral is decagonite . Both could so far only be detected in the Siberian meteorite Khatyrka .
Etymology and history
The name icosahedrite refers to the macroscopic form of the quasicrystals. These formed icosahedra in the specimens found . The mineral was first described by Luca Bindi and Paul J. Steinhardt using samples from the meteorite Khatyrka, which was found in 1979 on the river of the same name ( Khatyrka in English ) on the Siberian Chukchi Peninsula . This prompted the first describer to embark on an expedition to Siberia in the course of which further fragments of the meteorite, which is now considered the type material for icosahedrite, were found. In the same year the mineral was officially recognized by the IMA .
classification
Icosahedrite is a metal intermetallic compound or alloy. A classification according to Strunz or Dana does not yet exist, as these systematics are based exclusively on crystals, but not on quasicrystals (as of 2012). The Hölzel classification was extended to include quasicrystals. Here the icosahedrite is listed under the number 1.AK.100 (metals, intermetallic compounds and alloys; sub-group quasicrystals).
Crystal structure
Icosahedrite does not form crystals with translational symmetry, but rather quasicrystals . X-ray diffractometric analyzes confirm the five-fold symmetry typical of quasicrystals. According to the analyzes, the samples known so far were not (quasi) single crystals , but aggregates.
The classification is a 6D = 12.64 Å in the 6-dimensional notation usual for quasicrystals . Since there is no in quasicrystals unit cells are only an empirical chemical composition can be given.
properties
Since the icosahedrite is an extremely rare mineral and the quasicrystals found so far had edge lengths of a maximum of 1 to 2 mm, some parameters such as density, hardness etc. have not yet been determined.
Education and Locations
The only previously known site is a meteorite that fell in the Koryak Mountains on the Siberian Chukchi Peninsula . Based on the location, it is assumed that the meteorite hit there around 15,000 years ago, as the remains were found in ice-age sediments. The type material is in the Museo di Storia Naturale of the University of Florence (catalog no. 46407 / G). So far it is not known whether there can be icosahedrite of purely terrestrial origin.
See also
literature
- Williams PA, Hatert F., Pasero M., Mills SJ: IMA Commission on New Minerals, Nomenclature and Classification (CNMNC). Newsletter 6. New minerals and nomenclature modifications approved in 2010 . In: Mineralogical Magazine . tape 74 , no. 6 , December 2010, p. 941–942 , doi : 10.1180 / minmag.2010.074.6.941 ( main.jp [PDF; 54 kB ; accessed on March 1, 2018] Icosahedrite, IMA 2010-042, p. 942).
- Luca Bindi, Paul J. Steinhardt, Nan Yao, Peter J. Lu: Icosahedrite, Al 63 Cu 24 Fe 13 , the first natural quasicrystal . In: American Mineralogist . tape 96 , no. 5-6 , January 5, 2011, pp. 928-931 , doi : 10.2138 / am.2011.3758 .
Web links
- Mineral Atlas: Icosahedrite
- Richard Van Noorden: The quasicrystal from outer space. In: Nature News. January 3, 2012, accessed October 2, 2012 .
- Asteroid brought quasicrystals to earth. Expedition confirms extraterrestrial origin of the unusual metal shape. In: scinexx. August 13, 2012, Retrieved October 2, 2012 (popular science article).
- Nina Weber: Meteorite brought an exotic structure to the earth. In: Spiegel Online . Retrieved October 2, 2012 (popular science article).
Individual evidence
- ↑ Meteoritical Society Database - Khatyrka. Retrieved April 16, 2018 .
- ↑ Mineralienatlas : Type locality Khatyrka meteorite
- ↑ Mindat - type locality Khatyrka meteorite, Listvenitovyi stream, Khatyrka river, Chetkinvaiam tectonic melange, Iomrautvaam Massif, Koryak Upland (Koriak; Koriakskhiye), Koriak Autonomous Okrug, Far-Eastern Region, Russia