Icosahedrites

Icosahedrites are a class of quasicrystals characterized by their icosahedral symmetry, meaning they possess rotational symmetry of order five, which is forbidden in conventional crystals. Unlike periodic crystals which exhibit translational symmetry, quasicrystals like icosahedrites have long-range orientational order but no translational periodicity. Their atomic structure is typically described using higher-dimensional lattices, such as a six-dimensional cubic lattice, which are then projected into three dimensions. This projection generates the characteristic complex and non-repeating atomic arrangements observed in icosahedrites.

The discovery of quasicrystals, including icosahedrites, in 1984 by Dan Shechtman revolutionized the understanding of solid-state structures. Initially met with skepticism, their existence was later confirmed and has since been a significant area of materials science research. Icosahedrites are often formed as alloys, with common examples including aluminum-manganese (Al-Mn) alloys and related compositions. These materials can exhibit unique properties such as high hardness, low friction, and unusual electronic behavior, making them of interest for various technological applications. Research continues to explore new compositions, formation methods, and potential uses for these fascinating materials.