Where crystallisation takes place from a co-continuous phase separated glass, a peculiar anhedral morphology may develop. The crystals are typically spherical or ellipsoidal and incorporate one of the original glass phases without change in geometry. This phenomenon requires that the crystal nuclei widely spaced in comparison to the wavelength of the original amorphous phase separation and that the growing crystal be similar in composition to one of the original glass phases. This form of microstructure may result in better mechanical properties in glass ceramics of high glass content than are typically obtained with standard microstructures. Examples of this anhedral morphology are found in mullite, zinc-stuffed B-quartz and fluormica glass ceramic systems.
