What is "icosahedrite"

n. (context mineral English) A mineral, Al₆₃Cu₂₄Fe₁₃, that is the only known naturally occurring quasicrystal phase.

Icosahedrite is the first known naturally occurring quasicrystal phase. It has the composition AlCuFe and is a mineral approved by the International Mineralogical Association in 2010. Its discovery followed a 10-year-long systematic search by an international team of scientists led by and Paul J. Steinhardt to find the first natural quasicrystal.

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. A geological expedition has identified the exact place of the original discovery and found more specimens. The Al-Cu-Fe quasicrystal phase was originally created in the laboratory by Japanese experimental metallurgists in the late 1980s.