`NaCl` exhibits this type of structure. In the rock salt structure, `Cl^(-)` ions exists in FCC pattern and `Na^+` ions occupy all octahedral voids. There are `4` effective `Na^+` ions and `4` effective `Cl^(-)` ions in a unit cell of `NaCl`. So, the general formula is `Na_4Cl_4` or `NaCl` as per the effective ions in a unit cell. The co - ordination number of `Na^+` ion is `6` and co- ordination number of `Cl^(-)` ion is also `6`. So, the general formula (using co - ordination number of ions) is `Na_6Cl_6` or `NaCl `....The other substances having this kind of a structure are halides of all alkali metals except cesium halides and oxides of all alkaline earth metals except beryllium oxide.

This structure is shown by `ZnS`. Sulphide ions are face centered cubic position and Zinc is present in alternate tetrahedral voids. Formula is `Zn_4S_4` i.e, `ZnS` Coordination number of `Zn` is `4` and that of sulphide is also `4`. Other substance that exists in this kind of a structure is `BeO`.

This structure is exhibited by `CaF_2`. Calcium ions are face centered cubic position and fluoride ions are present in all the tetrahedral voids. There are four calcium ions and eight fluoride ions per unit cell. Therefore the formula is `Ca_4Fa`. (i.e, `CaF_2`). The coordination number of fluoride ions is four (tetrahedral voids) and thus the coordination number of calcium ions is eight. Other substances which exist in this kind of structure are `UO_2`, and `ThO_2`.

This structure is shown by `Li_2O`. Oxide ions are face centered cubic position and lithium ions are present in all the tetrahedral voids. There are four oxide ions and eight lithium ions per unit cell. As it can be seen, this unit cell is just the reverse of Fluorite structure, in the sense hat. the positions of cations and anions is interchanged. Other substances which exist in this kind of a structure are `Na_2O, K_2O` and `Rb_2O`.

This structure is shown by `CsCl`. Chloride ions are primitive cubic while the Cesium ion occupies the center of the unit cell. There is one chloride ion and one cesium ion per unit cell. Therefore the formula is `CsCl`. The coordination number of cesium is eight and that of chloride ions is also eight. Other substances which exist in this kind of a structure are all halides of cesium.

Spinel is a mineral `(MgAl_2O_4)` . Generally they can be represented as `M^(2+)M_2^( 3+)O_4` where `M^(2+)` is present in one-eighth of tetrahedral voids in a FCC lattice of oxide ions and `M^(3+)` ions are present in half of the octahedral voids. `M^(2+)` is usually `Mg, Fe, Co, Ni, Zn` and `Mn; M^(3+)` is generally `Al, Fe, Mn, Cr` and `Rh`. Examples are `ZnAl_2O_4`, `Fe_3O_4, FeCr_2O_4` etc. Many substances of the type have this structure. In an inverse spinel the ccp is of oxide ions, `M^(2+)` is in one-eight of the tetrahedral voids while `M^(3+)` would be in one-eight of the tetrahedral voids and one-fourth of the octahedral voids.