• (n.) The quality or state of being schistose.
mode of foliation that occurs in certain metamorphic rocks as a consequence of the parallel alignment of platy and lath-shaped mineral constituents. ... [2 related articles]
The parallel arrangement of platy or prismatic minerals in a rock that is caused by metamorphism in
Schis·tos'i·ty noun [ Confer French schistosité .] (Geol.) The quality or state of being schistose. 
The type of foliation that characterizes schist, resulting from the parallel arrangement of coarse-grained platy minerals, such as mica, chlorite, and talc.
The parallel arrangement of shaly or prismatic minerals like micas and amphiboles resulting from nonhydrostatic stress in metamorphism.
The foliation in a schist, due largely to the parallel orientation of micas.