The seven crystal systems
| Crystal system | Conditions |
|---|---|
| Triclinic | None |
| Monoclinic | α = γ = 90° |
| Orthorhombic | α = β = γ = 90° |
| Tetragonal | a = b; α = β = γ = 90° |
| Trigonal | a = b; α = β = 90°; γ = 120° |
| Hexagonal | a = b; α = β = 90°; γ = 120° |
| Cubic | a = b = c; α = β = γ = 90° |