Icosahedrite
Chemical compound
>
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. Wikipedia
Crystal habit: Subhedral to anhedral grains
Crystal system: Quasicrystal
Optical properties: Isotropic
Space group: Icosahedral; H-M symbol: 5 3m; Space group: Fm 3 5