A type of ionic crystal structure in which the cations have a face-centred cubic arrangement, with anions occupying all the octahedral holes. It can equally be described as a f.c.c array of anions with cations in the octahedral holes. Each type of ion has a coordination number of 6. Examples of compounds that have the structure are NaCl, KBr, AgCl, AgBr, HgO, CaO, FeO, NiO, and SnAs.
http://www.chemtube3d.com/solidstate/_rocksalt(final).htm An interactive version of the structure