The monoclinic crystal system is characterised by a unit cell with lower symmetry than the cubic or hexagonal systems, resulting in a more distorted geometric form. In a monoclinic lattice, the unit cell has three edges of unequal length. Two of the angles between these edges are 90°, while the third angle is inclined (that is, not 90°). This produces a unit cell that appears skewed rather than orthogonal. Because of this reduced symmetry, monoclinic crystals typically possess only a single two-

The tetragonal crystal system is defined by a unit cell shaped like a stretched or elongated cube. In this system, two of the three edges are equal in length, while the third is either longer or shorter. All angles between the edges are 90°, so the cell is still a rectangular prism but with a square base and a different height. The tetragonal system has higher symmetry than monoclinic or orthorhombic systems but less than cubic. Its main symmetry feature is a single four-fold rotational axis alo