Observation has been made of the forming behavior of precipitated calcium carbonate polymorphs following changes in supersaturation. Based on the fact that supersaturation in precipitation reaction depends on the ion concentration of the reactants present in the solution, the forming behavior of calcium carbonate through changes in the concentration of the main reactants, $Ca^{2+};and;CO_3^{2-}$, at $75^{circ}C$, was observed. The rate of supersaturation was adjusted to three different levels: high, medium and low. At the highest level of supersaturation the free energy necessary for nucleation decreased, promoting the formation of a sphere-shaped vaterite, while at the medium level, aragonite and calcite were seen to co-exist. At the lowest level of supersaturation, the production yield of aragonite was at its highest although a minimal amount of calcite co-existed. Therefore, in the synthetic reaction of precipitated calcium carbonate, it is believed that adjustments made to the concentration of $Ca^{2+};and;CO_3^{2-}$ ions should facilitate the control of polymorphs as well as the size of particles and the distribution of granularity.