The electrochemically induced nucleation and crystallisation in a glass with t he basic composition (mol%) 52.6 SiO2 - 18.7 Al2O3 - 14.3 MgO - 7,8TiO2 - 4.7 B2O3 - 2.0 CaO leads to the formation of of oriented mullite crystals. Electron microscopy techniques (energydispersive X-ray microanalysis and electron backscatter diffraction) were used to analyse the composition and the orientation of the crystals in the glassy matrix. The mean composition of the mullite crystals matches the formula (formula). The electron backscatter diffraction patten is consistent with data from the literature that needle-like mullite crystals are fast growing parallel to the crystallographic c-axis [001]. The composition of the melt grown mullite crystals does not depend on the melting temperature in the range between 1230C and 1350C.
