What Are Quasicrystals? How They Differ from Regular Crystals

Quasicrystals are a rare class of solid materials that possess an ordered atomic structure but lack periodicity—a defining feature of traditional crystals. This means their atomic patterns never repeat exactly, even though they exhibit long-range order. This unique arrangement allows quasicrystals to display symmetries that are mathematically forbidden in normal crystals, such as five-fold, eight-fold, or ten-fold rotational symmetry.

A Ho-Mg-Zn icosahedral quasicrystal, shaped like a pentagonal dodecahedron with 12 regular pentagonal faces, the geometric dual of the icosahedron. Unlike the irregular pentagonal faces of pyrite’s pyritohedron (a cubic-system crystal), this quasicrystal’s perfect 5-fold symmetry is unique, defying the rules of traditional crystallography.

The discovery of quasicrystals in 1982 by Israeli scientist Dan Shechtman, for which he was awarded the 2011 Nobel Prize in Chemistry, revolutionized crystallography. Until then, it was thought that all crystals must be periodic—repeating in space like tiles on a bathroom wall. Quasicrystals proved that matter could be organized in ways previously considered impossible.

While traditional crystals can only exhibit certain symmetries—such as two-fold, three-fold, four-fold, or six-fold—quasicrystals can display symmetries incompatible with periodic tiling, like five-fold or ten-fold symmetry. This is analogous to trying to tile a floor with regular pentagons: the shapes fit together locally, but gaps appear over larger areas. Yet in quasicrystals, atoms are arranged in such a way that these symmetries are maintained without repeating, through complex mathematical rules such as Penrose tiling.

The concept of quasicrystals was formalized in 1984 by physicists Dov Levine and Paul Steinhardt, shortly after Shechtman’s discovery. Since then, over 100 types of synthetic quasicrystals have been created in the laboratory—usually from metallic alloys like aluminum–copper–iron—using rapid cooling techniques that prevent the formation of periodic crystals.

For many years, it was believed that quasicrystals could not form in nature. That changed in 2009, when a team led by Luca Bindi and Paul Steinhardt discovered the first natural quasicrystal in a fragment of the Khatyrka meteorite, found in eastern Russia. Remarkably, its atomic structure matched one that had previously been synthesized in the lab. In 2021, the same team reported a second natural quasicrystal from the same meteorite—but this one had a completely novel composition, never before seen in either nature or laboratory experiments. This discovery confirmed that quasicrystals can form under extreme natural conditions, such as those produced during high-energy collisions in space.

While some have speculated that such materials could theoretically form deep within Earth's mantle under ultra-high pressures, no terrestrial examples have yet been found. Quasicrystals remain scientifically important not only for challenging the classical rules of crystallography but also for their unusual physical properties, such as low thermal conductivity, high hardness, and non-stick surfaces, which offer potential for advanced industrial applications.

Because of these differences, quasicrystals require very specific formation conditions—such as rapid cooling or high-pressure impacts—which are rarely present within Earth's interior. While it is theoretically possible for quasicrystals to form deep within the mantle under extreme pressure and reducing conditions, to date, all verified natural quasicrystals have been found in meteorites, not in terrestrial rocks.