In mineralogy and crystallography, crystal structure is a unique arrangement
of atoms or molecules in a crystalline liquid or solid.[1] A crystal structure
is composed of a pattern, a set of atoms arranged in a particular way, and a
lattice exhibiting long-range order and symmetry. Patterns are located upon the
points of a lattice, which is an array of points repeating periodically in three
dimensions. The points can be thought of as forming identical tiny boxes, called
unit cells, that fill the space of the lattice. The lengths of the edges of a
unit cell and the angles between them are called the lattice parameters. The
symmetry properties of the crystal are embodied in its space group.
A crystal's structure and symmetry play a role in determining many of its
physical properties, such as cleavage, electronic band structure, and optical
transparency.
