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dark grey-black
Named for the icosahedral symmetry of its internal atomic arrangement, as observed in its diffraction pattern.
The first 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.

Classification of Icosahedrite

Approval Year:

Occurrences of Icosahedrite

Type Occurrence of Icosahedrite

Geological Setting of Type Material:
Associated Minerals at Type Locality:

Physical Properties of Icosahedrite

Diaphaneity (Transparency):
dark grey-black
The density could not be determined.

Crystallography of Icosahedrite

Crystal System:
Class (H-M):
5 3m - point symmetry group
Space Group:
Fm 3 5
Anhedral to subhedral grains <0.1mm in the type specimen.
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 Diffraction Data:
3.41 (25)
2.006 (100)
2.108 (90)
1.238 (30)

Optical Data of Icosahedrite

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 Icosahedrite

All elements listed in formula:
Analytical Data:
Empirical formula concerns the relatively fine-crystalline material associated with hollisterite and stolperite
Empirical Formula:
Common Impurities:

Relationship of Icosahedrite to other Species

Other Names for Icosahedrite

Name in Other Languages:

Other Information

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 Icosahedrite

Reference List:
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. []

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 Icosahedrite URL:
Please feel free to link to this page.

Localities for Icosahedrite

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.
(TL) indicates type locality for a valid mineral species. (FRL) indicates first recorded locality for everything else. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
  • 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.
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