Icosahedrite

Icosahedrite
General
Category Native element mineral, alloy
Formula
(repeating unit)		 Al63Cu24Fe13
Identification
Color Dark grey, black
Crystal habit Subhedral to anhedral grains
Crystal symmetry Icosahedral,
H-M symbol: 5 3m
Space group: Fm 3 5[1]
Fracture Irregular
Luster Metallic
Streak Grey
Diaphaneity Opaque
Optical properties Isotropic
References [2]

Icosahedrite is the first known naturally occurring quasicrystal phase. It has the composition Al63Cu24Fe13 and is a mineral approved by the International Mineralogical Association in 2010.[1][3] Its discovery followed a 10-year-long systematic search by scientists to find the first natural quasicrystal.[4]

X-ray diffraction pattern of the natural Al63Cu24Fe13, icosahedrite.

It occurs as tiny 0.1 mm grains in a small terrestrial rock sample labelled "khatyrkite, Khatyrka ultramafic zone, Koryak-Kamchatka area, Koryak Mountains, Russia", collected from an outcrop of weathered serpentinite (catalog number 46407/G, housed in The Museum of Natural History, University of Florence, Italy). The rock sample also contains spinel, diopside, forsterite, nepheline, sodalite, corundum, stishovite, khatyrkite, cupalite and an unnamed AlCuFe alloy. Intriguingly, evidence suggests icosahedrite is extraterrestrial in origin, possibly delivered to the Earth by a CV3 carbonaceous chondrite asteroid that dates back 4.5 Gya.[5][4] A geological expedition has identified the exact place of the original discovery and found more specimens.[6][7] The Al-Cu-Fe quasicrystal phase was originally created in the laboratory by Japanese experimental metallurgists in the late 1980s.[8]

References

  1. 1 2 Bindi, L.; Paul J. Steinhardt; Nan Yao; Peter J. Lu (2011). "Icosahedrite, Al63Cu24Fe13, the first natural quasicrystal" (PDF). American Mineralogist 96: 928–931. doi:10.2138/am.2011.3758.
  2. ↑ Mindat.org
  3. ↑ Commission on New Minerals and Mineral Names, Approved as new mineral
  4. 1 2 Bindi, Luca; John M. Eiler; Yunbin Guan; Lincoln S. Hollister; Glenn MacPherson; Paul J. Steinhardt; Nan Yao (2012-01-03). "Evidence for the extraterrestrial origin of a natural quasicrystal". Proceedings of the National Academy of Sciences. Bibcode:2012PNAS..109.1396B. doi:10.1073/pnas.1111115109. Retrieved 2012-01-04.
  5. ↑ Paul J., Steinhardt (2012-09-15). "Quasicrystals: a brief history of the impossible, paper presented at the conference "The Centennial of X-Ray Diffraction (1912–2012)", held at Accademia Nazionale dei Lincei in Roma on May 8 and 9, 2012." (PDF). Rend. Fis. Acc. Lincei. doi:10.1007/s12210-012-0203-3. Retrieved 2012-09-22.
  6. ↑ Nadia Drake, Prospecting for Quasicrystals, Science News, Print edition: Nov. 3, 2012; Vol.182 #9 (p. 24)/ Web edition: October 19, 2012
  7. ↑ A second natural quasicrystal with a different (decagonal) structure has been identified in the samples, Bindi L., and al, Natural quasicrystal with decagonal symmetry, Nature - Scientific Reports 5, Article number: 9111 doi:10.1038/srep09111,
  8. ↑ Tsai, An-Pang; Akihisa Inoue; Tsuyoshi Masumoto (1987-09-20). "A Stable Quasicrystal in Al-Cu-Fe System". Japanese Journal of Applied Physics 26 (Part 2, No. 9): L1505–L1507. Bibcode:1987JaJAP..26L1505T. doi:10.1143/JJAP.26.L1505. ISSN 0021-4922. Retrieved 2012-01-04.
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