The reaction kinetics of crystallization of tetrasilicic flourmica in DICOR(R) glass was followed non-isothermally by differential thermal analysis (DTA), and analysed using Johnson-Mehl-Avrami equation for determining the activation energy, reaction order, and the pre-exponential parameters. The DTA curves showed a single exothermic crystallization peak in the temperature range of 745-850 degrees C, just above the glass transition temperature. The activation energy E(c), the reaction order n, and the pre-exponential factor nu, of crystallization were computed to be 203 kJ mol-l 3.4 +/- 0.20, and 2.88 x 10(11) s(-1) respectively. These observations suggest that the crystallization of mica in DICOR(R) glass occurs by a cellular precipitation mechanism where the nucleation occurs only at the start of the transformation.