After 2 hours of reaction (Figure ), P solid-state NMR reveals the crystallization of the system as a sharp resonance corresponding to brushite CaH2PO4 . 2H2O is observed. Note that the temperature strongly influences the 31 P chemical shift of brushite as it decreases from 1.6 to 0.8 ppm when the temperature is lowered from ambient to -120°C (Figure ). Hence, preliminary recording of solidstate NMR spectra of reference crystalline phases at low temperatures is essential to identify the final crystalline phases unambiguously in mineralizing solutions. Brushite 31 P resonance is observed together with a broad resonance centered around 2 ppm (in agreement with the final pH 5.9), indicating the presence of remaining free phosphate ions in the solution. The crystallization is supported by calcium potential monitoring where a second transition is observed circa 300s, corresponding to the transformation of ACP into brushite, leadining to a final [Ca 2+ ]free around 5 mM (Figure ).