New data on the dissolution and growth of quartz in acid, nearly neutral and slightly alkaline solutions at ambient conditions are presented. During batch dissolutions, aqueous Si-concentrations increased nonlinearly towards limit values. During parallel growth experiments, however, the high Si-concentrations corresponding to 13-fold supersaturation with respect to quartz did not decreased. To interpret these results, two dynamic models (1) a reaction model and (2) a surface-complexation model, were derived. Both models were focused on (a) reversible dissolution/growth of bulk quartz and b) irreversible dissolution of disturbed quartz (weakly bounded Si-atoms) on new surface.