DTA-TGA was used to monitor the evolution of hydration products in unstirred autoclaved metakaolin-lime-quartz slurries with reaction time. Hydrogarnet was always one of the first phases formed at all metakaolin additions and invariably appeared before 11 Angstrom tobermorite. These findings explain apparent inconsistencies in the literature because the continued existence of hydrogarnet depends on such factors as reaction time and bulk composition. DTA-TGA indicated that the lime-quartz reaction was retarded and inferred differences in the precursor silicate anion structure of calcium silicate hydrates with increasing metakaolin addition.