Five 2D lattices Centered Rectangle unit cell. Primitive a≠by=90° Centered Five 2D lattices Parallelogram Square Rectangle a b 日≠bY≠90°， a=by=90° ≠120° a≠by=90° Centered Rectangle Hexagonal a 2≠by=90° a=by=120° unit cell. Primitive Centered There are literally thousands of crystalline materials, there are only 5 distinct planar latticesFive 2D lattices unit cell a≠b γ=90° Centered Primitive Five 2D lattices a=b γ=90° a≠b γ=90° a≠b γ=90° a=b γ=120° a≠b γ ≠ 90° , γ ≠ 120° unit cell Centered Primitive There are literally thousands of crystalline materials, there are only 5 distinct planar lattices