The crystallization of cordierite from stoichiometric glass is observed in situ in the scanning electron microscope. A heating stage was, therefore, operated at 1000 and 1100 A degrees C. The surface crystallization of well-separated crystals was recorded. Surprisingly, at the late stage of crystallization, the formation of cracks as well as a squeezing out of a low viscous phase took place. To our knowledge, this has not been reported before and gives rise to new considerations of the crystallization mechanism of cordierite from glasses.