The Seven Crystal Systems

The Seven Crystal Systems

All rocks are composed of only seven crystal systems:
Triclinic: no sides equal, no right angles
Monoclinic: no sides equal, one right angle
Orthorhombic: no sides equal, all right angles
Tetragonal: two sides equal, all right angles
Cubic: all sides equal, all right angles
Trigonal: all sides equal, two right angles
Hexagonal: two sides equal, two right angles, one 120 degree angle [NS] {SW}