Orthorhombic crystal has the following unit cell parameters
a=b=c ; α=β=γ=90∘
a=b≠c ; α=β=γ=90∘
a≠b≠c ; α=β=γ=90∘
a=b≠c ; α=β=90∘,γ=120∘
Ortho rhombic crystal a≠b≠c;α=β=γ=90∘