Crystal system
![The diamond crystal structure belongs to the face-centered cubic lattice, with a repeated 2-atom pattern.](/Images/godic/202501/23/Carbon_lattice_diamond2108.png")
![Hexagonal hanksite crystal, with three-fold c-axis symmetry](/Images/godic/202501/23/Hanksite2108.JPG")
In crystallography, the terms crystal system, crystal family, and lattice system each refer to one of several classes of space groups, lattices, point groups, or crystals. Informally, two crystals tend to be in the same crystal system if they have similar symmetries, though there are many exceptions to this.