The crystallization of diabase glass

The crystallization behaviour of diabase glass at elevated temperatures was studied in samples prepared by melting the diabase rock. DTA and X-ray analyses revealed the crystallization of diopside (CaO · MgO · 2SiO₂) at 865 ‡C and anorthite (CaO · Al₂O₃ · 2SiO₂) at 1060 ‡C. Further, the kinetics of crystallization of diopside were studied. The phenomenological Johnson-Mehl-Avrami equation was used and the exponentn=3/2 determined from the dependency of the volume fraction of the crystal phase (diopside) on time. The activation energy of crystallization of diabase glass 248 kJ mol^-1 was estimated on the basis of DTA measurements carried out at different heating rates and found to be in good agreement with literature data for similar glass.