The formations of mineral phases from human oral-like fluids (saliva, plaque fluid) were studied using a simple precipitation technique. Precipitates were analyzed by means of XRD, IR-spectroscopy and SEM with EDX. The phosphate mineral analogues of dental calculi (brushite, apatite, struvite) were obtained during experiments. It was shown that at the initial stages of crystallization the variation of mineral phase composition of precipitates caused by changing solution composition (ions concentration and pH) were controlled more by kinetic rather than by thermodynamic factors.