Next to already mentioned cubic structure there seem to appear also different variations and combinations of basic cubic structures.
An example of such a structure is the crystal of kitchen salt (NaCl) which consists of two face centred cubic structures, of which the first one is constituted of sodium atoms and the second one of chlorine atoms.
The two structures are shifted along the side by half of a side, so that sodium atoms border on chlorine atoms and vice versa.
If sodium atoms and chlorine atoms wouldn't differ form each other, this structure would be a simple cubic structure.
