Quasicrystals are crystals with quasi-periodic order. They might also be described as impossible crystals. The molecules in some quasicrystals are arranged about an axis of 5-fold symmetry. Traditionally, crystallographers have considered this to be impossible since there is no strictly periodic way to make this arrangement work. (Try covering your floor with tiles shaped like regular pentagons. Your pattern will show gaps or overlaps!) Nevertheless, there are crystals that have 5 fold external symmetry and display 5-fold (or 10-fold) diffraction symmetry (when x-rays are passed through them). These structures pose a great challenge to crystallographers.

An example of order without periodicity

In chemistry, biology and materials science - anywhere atomic structure is the key to understanding and controlling chemical and physical properties - crystallographers are making fundamental discoveries and exciting advances.

Preparing for a Career in Crystallography
High School Preparation

Biology, chemistry, physics and mathematics are all important for a career in crystallography, and advanced science courses will help. Mathematics courses should include algebra, trigonometry, geometry, and if possible, calculus. Four years of English are also important, with emphasis on writing skills.

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