Crystal Systems

The seven crystal systems include triclinic, monoclinic, orthorhombic, tetragonal, trigonal, hexagonal, and cubic. Each differs by the symmetries present. A crystal’s symmetry will imply certain constraints on its basis vectors (i.e., lattice constants), and it is these constraints that are often used to determine or even define the crystal system; however, it should always be remembered that it is the symmetry, not the lattice constants, that determines the crystal system of any given crystal.