These crystallites (q.v.) show that the glassy rock has a tendency to crystallize which is inhibited only by the very viscous state of the glass and the rapidity with which it was cooled.
The self-alignment of crystallites manifests itself as patterns of optical birefringence when the liquids are viewed between crossed polars.
crystallites formed during these processes often have a unique chemistry and morphology as a result of the controls imposed by the organisms.
Here, crystallites of large size have ' seeded ' themselves on scratches in the sapphire substrate.