The kinetics of vaterite (CaCO3) crystallization on calcite in the presence of the aminoacids alanine, glycine, lysine as well as on lysine, polyglycine, polytyrosine and polymethionine was investigated by the constant composition method. The presence of the above mentioned aminoacids stabilizes this calcium carbonate polymorph. The number of ions forming the critical nucleus, the surface energy as well as the apparent growth order for the forming phase was estimated. (C) 2002 Elsevier Science B.V. All rights reserved.