Crystal structure

A crystal structure is a concept fundamental to many areas of science and technology. Along with the unit cell lattice parameters, its space group symbol and the positions of the atoms entirely describe a crystal structure.

Unit cell

The simplest and most symetrical, the isometric system, is represented by the cube. The other six systems, in order of decreasing symetry, are hexagonal, tetragonal, trigonal, orthorhombic, monoclinic and triclinic.

Bravais lattices

There are 14 basic arrangements of atoms in three dimensions, and all crystalline mineral structures recognised till now fit in one of these 14 arrangements.

The fourteen basic structure of minerals are the following:

• triclinic
• monoclinic (simple)
• monoclinic (centered)
• orthorhombic (simple)
• orthorhombic (base-centered)
• orthorhombic (body-centered)
• orthorhombic (face-centered)
• hexagonal
• rhombohedral
• tetragonal (simple)
• tetragonal (body-centered)
• isometric
• isometric (body-centered)
• isometric (face-centered)

The set of atomic positions (xi, yi, zi) are called the asymmetric unit.

Cubic, simple

Cubic, body-centered

Cubic, face-centered

Tetragonal, simple

Orthohombic, simple

Monoclinic, simple

Rhombohedral

Hexagonal

See also

Crystal for a general definition and overview -- Crystallography -- Crystallographic defects

For more detailed information in specific technology applications see materials engineering, materials science, ceramics, metallurgy, or materials physics.

Referenced By