a) In clay science, exfoliation involves a degree of separation of the layers of a host structure where units, either individual layers or stacking of several layers, are isotropically dispersed (freely oriented and independent) in a solvent or polymer matrix (Bergaya et al., 2011). This may be achieved by intercalation, by mechanical means, or by other methods. Where delamination or exfoliation cannot be distinguished, use “intercalation” or “delamination/exfoliation” to describe the process. See intercalation, delamination, 1:1 layer, 2:1 layer. (From AIPEA Nomenclature Committee, 2011, unpublished)

b) a process of physical weathering where large granitic plutons break into onion-like sheets along joints that lie parallel to the exposed surface.