Chemqueries: What are the 7 types of Crystals

# 7-types of crystals:

On the basis of axial length in x,y, z-direction, and interfacial angles between them,unit cell can be classified into seven types which are called Seven Crystal System.
 7- Crystal Habits Axial Length Interfacial Angles Cubic a = b = c α = β = γ = 90˚ Tetragonal a = b ≠ c α = β = γ =90˚ Orthorhombic(Rhombic) a ≠ b ≠ c α = β = γ =90˚ Monoclinic a ≠ b ≠ c α = γ =90˚ ,  β ≠ 90˚ Triclinic a ≠ b ≠ c α ≠ β ≠ γ ≠ 90˚ Hexagonal a = b ≠ c α = β = 90 ˚ , γ =120˚ Rhombohedral a = b = c α = β = γ ≠ 90˚
Where a,b,c is the length of x,y and z-axis respectively.
α,β,γ  is the interfacial angle between x-axis and y-axis, y-axis and z-axis, z-axis and x-axis respectively.

### Note:

Most symmetric crystal -Cubic Crystal
Most unsymmetric crystal -Triclinic Crystal
To remember this crystal system we have derived a formula and i.e.
CUTE OUR MOTHER
CU-Cubic
TE-tetragonal
OUR-Orthorhombic
MO-Monoclinic
T-Triclinic
HE-Hexagonal
R-Rhombohedral