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Icosahedrite

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Formula:
Al63Cu24Fe13
Colour:
dark grey-black
Lustre:
Metallic
Crystal System:
Icosahedral
Name:
Named for the icosahedral symmetry of its internal atomic arrangement, as observed in its diffraction pattern.
The first quasicrystal (http://en.wikipedia.org/wiki/Quasicrystal) described as a mineral species.

Chemically similar to 'Unnamed (Al-Cu-Fe Alloy)' and 'Unnamed (Al-Cu-Fe Alloy II)'.

The vast majority of minerals are crystalline materials, with structures in which a particular arrangement of atoms repeats regularly by translation, like a 3-D wallpaper pattern. Only certain types of rotation axes in the crystal symmetry are compatible with this: 2-fold, 3-fold, 4-fold and 6-fold rotations, and the combination of four 3-fold axes with additional 2- and/or 4-fold axes that gives rise to "cubic" symmetry.

Quasicrystals are a recently discovered type of solid material that use quite different organising principles for arranging their atoms. They do not have an atomic arrangement which repeats regularly by translation, but they do have rotational symmetry about axes which can be of "crystallographically forbidden" orders such as 5-fold, 8-fold, 10-fold and 12-fold, as well as the combination of six intersecting 5-fold axes that is characteristic of the Platonic dodecahedron and icosahedron. Despite the absence of a straightforward, regular repeat unit, they retain a high degree of organisation. Quasicrystalline structures can be made by using more than one type of building block, which fit together via stringent rules so that there are no gaps, no overlaps, but also no repetition. There is still enough regularity in the structure that sharp periodicities occur in the diffraction pattern, albeit with a fractal distribution rather than uniform spacing of frequencies.

Quasicrystal diffraction patterns were first obtained from synthetic aluminium-manganese alloys by Dan Shechtman in 1982, but early observations were regarded with considerable scepticism, even by such eminent crystallographers as Linus Pauling. However, more and more examples were discovered independently by
several research teams, and thermodynamic stability in a quasicrystal alloy was first shown in 1987. Hundreds of synthetic quasicrystal materials are now known, along with chemically similar "approximant" compounds in which regular repeating mistakes convert the quasicrystal atomic arrangement into a normal crystal.

Although quasicrystals can have a well-defined point group ("crystal class") symmetry, they are aperiodic, so other conventional crystallographic concepts such as "lattice type", "space group","unit cell parameters" and "unit cell content" do not apply to the structure as normally considered in three dimensions. However,
it is mathematically possible to generate quasicrystalline structures by taking 3-D slices that are precisely but irrationally oriented through higher-dimensional structures that are periodic: the icosahedral-symmetry quasicrystalline structure of icoashedrite can then be described as a carefully chosen slice through a 6-dimensional hypercubic (hyper)crystal!

In 2011, Dan Shechtman received the Nobel Prize in Chemistry for his discovery of the first quasicrystal. The year previously, Luca Bindi's icosahedrite, the first naturally-occuring quasicrystal, was approved as a new mineral by the Commission on New Minerals and Mineral Classification (IMA 2010-042).

In 2012, Bindi's group published evidence that natural icosahedrite is extraterrestrial in origin. It occurs with other Cu-Al-Fe alloys and a suite of silicates and oxides such as diopside, forsterite, spinel and the extremely high-pressure SiO2 polymorph stishovite (which contains icosahedrite as inclusions!). The assemblage and oxygen isotopic composition are consistent with formation not on Earth, but in a refractory calcium-aluminium-rich inclusion in a CV3 chondritic meteorite.


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Classification of IcosahedriteHide

Approved
Approval Year:
2010

Physical Properties of IcosahedriteHide

Metallic
Transparency:
Opaque
Colour:
dark grey-black
Streak:
gray
Fracture:
Irregular/Uneven
Comment:
The density could not be determined.

Optical Data of IcosahedriteHide

Type:
Isotropic
Type:
Isotropic
Bireflectance:
None
Comments:
Reflectance percentages (Rmin = Rmax) for the four standard COM wavelengths are 62.3 (471.1 nm), 60.6 (548.3 nm), 58.1 (586.6 nm), and 56.0 (652.3 nm), respectively.

Chemical Properties of IcosahedriteHide

Formula:
Al63Cu24Fe13
Common Impurities:
Al62.2Cu25.7Fe10.7Si0.4Ni0.1Cr0.1

Crystallography of IcosahedriteHide

Crystal System:
Icosahedral
Class (H-M):
5 3m - point symmetry group
Space Group:
Fm 3 5
Morphology:
Anhedral to subhedral grains <0.1mm in the type specimen.
Comment:
The structure is not reducible to a single three-dimensional unit cell, so neither cell parameters nor Z can be given. The X-ray powder pattern was indexed on the basis of six integer indices, as conventionally used with quasicrystals, where the lattice parameter (in six-dimensional notation) is measured to be a6D = 12.64 Å, with probable space group Fm-3-5.

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
3.41 (25)
2.006 (100)
2.108 (90)
1.238 (30)

Type Occurrence of IcosahedriteHide

Synonyms of IcosahedriteHide

Other Language Names for IcosahedriteHide

Common AssociatesHide

AluminiumAl
ChromiteFe2+Cr3+2O4
CopperCu
CorundumAl2O3
HercyniteFe2+Al2O4
IronFe
MagnetiteFe2+Fe3+2O4
NaquiteFeSi
NickelNi
StolperiteAlCu
Suessite(Fe,Ni)3Si
Taenite(Fe,Ni)
Unnamed (Al-Cu-Fe Alloy II)Al78Cu15Fe5
XifengiteFe5Si3

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for IcosahedriteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Ma, C., Lin, C., Bindi, L., Steinhardt, P.J. (2016): Discovery of new Al-Cu-Fe minerals in the Khatyrka CV3 meteorite. 79th Annual Meeting of the Meteoritical Society, PDF no. 6017. [http://www.hou.usra.edu/meetings/metsoc2016/pdf/6017.pdf]
Bindi, L. et al. (2009): Natural quasicrystals. Science: 324: 1306-1309.
Bindi, L., Steinhardt, P.J., Yao, N., Lu, P.J. (2011): Icosahedrite, Al63Cu24Fe13, the first natural quasicrystal. American Mineralogist: 96: 928-931.
Bindi, L., Eiler, J. M., Guan, Y., Hollister, L. S., MacPherson, G., Steinhardt, P. J., & Yao, N. (2012). Evidence for the extraterrestrial origin of a natural quasicrystal. Proceedings of the National Academy of Sciences: 109(5): 1396-1401.

Internet Links for IcosahedriteHide

Localities for IcosahedriteHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
Russia
 
  • Far-Eastern Region
    • Koriak Autonomous Okrug
Science 324,1306(2009)
        • Iomrautvaam Massif
          • Chetkinvaiam tectonic melange
            • Khatyrka river
              • Listvenitovyi stream
Bindi, L., Steinhardt, P.J., Yao, N., Lu, P.J. (2011) Icosahedrite, Al63Cu24Fe13, the first natural quasicrystal. American Mineralogist, 96, 928-931.
Mineral and/or Locality  
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