One of the seven crystal systems, with two sets of edges of the same length and a third which is either longer or shorter than the other two. The lattice may be referred to three crystallographic axes, a₁, a₂, and c (or x, y, and z) where a₁ and a₂ (or x and y) are equal, and c (or z) may be longer or shorter. All three axes are at right angles.

Tetragonal