Fig. 1

a FTIR spectra and (b) Raman spectra of paste and stone deposits, where both correspond to hydroxyapatite. The peaks in the Raman spectra correspond to the ν₃ (1071 cm⁻¹), ν₁ (960 cm⁻¹), ν₄ (586 cm⁻¹) and ν₂ (435 cm⁻¹) vibrational modes of phosphate ions present in the hydroxyapatite