# Unit cell of hcp structure

It is given in my book that the structure in figure-1 is the unit cell of hcp structure.
So why then is the structure in figure-2 not the unit cell as we can repeat the structure in figure-2 to get the original hcp structure?
Also the structure in figure-1 is not a Bravais lattice so how then can it be called a unit cell?

• A unit cell is just the smallest representation of a mineral that can be said to be repeated without any change in orientation or configuration, your second 'unit cell' does not repeat in the same configuration but needs to be oriented at different angles. Apr 13 '21 at 11:15
• @Safdar Faisal figure-1 is not a bravais lattice so how then can it be called a unit cell? Apr 13 '21 at 11:25
• It can't. Your book uses the old convention, which needs to be cancelled, spat upon, and forgotten. Apr 13 '21 at 11:33