For phyllosilicates, interlayer material separates the 1:1 or 2:1 layers and generally may consist of cations, hydrated cations, organic material, hydroxide octahedra, hydroxide octahedral sheets (see fig. 2), and/or hydroxy-interlayers as a combination of H2O and hydroxyl-coordinated cations. The interlayer material offsets the net negative charge of the layer. In certain cases (e.g., talc, pyrophyllite, where the net layer charge is zero), there is no interlayer material, and an interlayer separating the layers is empty. After Guggenheim et al. (2006).
Cf., layer; hydroxy-interlayer