These are the foundation of the many crystal shapes you will come across:
1. Cubic: Can also be Octahedrons and dodecahedrons 2. Tetragonal: Like Cubic, but longer on one axis. Sometimes forms double pyramids and prisms 3. Hexagonal: Six-sided prisms 4. Trigonal: Have a single 3-fold axis of rotation instead of the 6-fold axis the hexagonal possess 5. Orthorhombic: Like tetragonal crystals but not square in cross section, they form dipyramids 6. Monoclinic: Like skewed tetragonal crystals, often forming prisms and double pyramids 7. Triclinic: usually not symmetrical from one side to the other, which can lead to some fairly strange shapes