The Probert Encyclopaedia of Rocks & Minerals

FOLIATION

In geology, the term foliation refers to the property, possessed by some crystalline rocks, of dividing into plates or slabs, which is due to the cleavage structure of one of the constituents, as mica or hornblende. It may sometimes include slatey structure or cleavage, though the latter is usually independent of any mineral constituent, and transverse to the bedding, it having been produced by pressure.
Research Foliation