crystals, according to the classical crystallographic restriction theorem, can possess only 2, 3, 4, and 6-fold rotational symmetries, the Bragg diffraction pattern of quasicrystals shows sharp peaks with other symmetry orders, for instance 5-fold.
Although 20th-century physicists were surprised by the discovery of quasicrystals, their mathematical descriptions were already well established. For example, tiles in a medieval Islamic mosque in Isfahan, Iran, are arranged in a quasicrystalline pattern, suggesting that their designers achieved a mathematical breakthrough 500 years earlier than Western scholars.
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