Calcium carbonate exists in the modifications calcite, aragonite and vaterite. Calcite is the stable, vaterite the most instable modification. In aqueous systems the instable modification is dissolved forming in regard of more stable modifications supersaturated solutions. From aragonit only calcite can be formed, from vaterite either calcite or aragonite. The latter can be transited into calcite. The transition rate is influenced by many parameters. The transition is connected with decreasing the impurities in the precipitates. In the presented paper especially the possibilities of the alteration of the transition rare are emphasized. If could shown that mainly the temperature and the pH value play an important role. The transition products are purity. They differ in their morphology from the starting solids. It is worth noting that the decrease of the impurities also takes place when the transition out in the mother liquor: The transition rate of vaterite into calcite in all studied cases was significantly greater than of aragonite into calcite.