Crystal systems describe the shape of crystal structures. By reducing the system to the smallest amount that can still be considered a crystal of that type

chemists have found there are only 7

fundamental shapes (called crystal systems). The length of the sides, and the angles that join them describes each system. Consider a simple square box. Each of the axes

length,

width, and

height, are equal and they make right angles with each other, this is

**Cubic** crystal system. If it is

stretched along one direction (lengthen the box) it is

**Tetragonal**, stretch it in two dimensions and it is

**Orthorhombic**. If now this badly stretched box is

skewed (

shear the top and bottom) so that the tops no longer make right angles it becomes

**Monoclinic**, if it is skewed again in another direction so no face is at right angle to any other it becomes

**Triclinic**. Ok now back to the original

cube (all sides equal, all angles equal to 90 degrees) if this cube is skewed exactly the same amount in both directions it is

**Rhombohedral**. Lastly if the original cube is stretched and then skewed to exactly 120 degrees then it is called

**Hexagonal**.

**Here in a nice tabular form are the different crystal systems.**

note:

1)From c programming != means not equal.

2)d = angle between b and c, e between c and a, and f between a and b.

**Name: Axes: Angles(in degrees):**
Cubic a=b=c d=e=f=90
Tetragonal a=b!=c d=e=f=90
Orthorhombic a!=b!=c d=e=f=90
Monoclinic a!=b!=c d=e=90 f!=90
Triclinic a!=b!=c d!=e!=f!=90
Hexagonal a=b!=c d=e=90 f=120
Rhombohedral a=b=c d=e=f!=90