The face centered cubic (FCC) unit cell begins with a totally different layer, one that is packed much more efficiently. This figure shows the basic layer that will be repeated throughout the entire ...

occupying the octahedral holes. Notice that the octahedral holes are along the edges (for a net of three cations) and in the center of the cube (one more cation). Thus we have four anions (FCC) and ...

Spinel, MgAl 2 O 4 (download cif), is a rare gemstone that was used to imitate rubies. The structure has face-centered cubic symmetry, and is a little heavy to understand. The general formula is AB 2 ...