A metamorphic texture characterized by the mutual interference of polygonal grains which meet at approximately 120° triple junctions. The texture is produced during solid-state crystal growth as a result of increasing the pressure on or temperature in the rock system. As the grains grow, they have to compromise in their competition for space and hence form the typical polyhedral grains with triple junctions. The texture can be ‘isotropic’ (no grain alignment) where there is no directed stress during metamorphism, or ‘anisotropic’ (with grain alignment) where there is a directed stress during metamorphism.
Subjects: Earth Sciences and Geography.