IR and Raman spectroscopy -Paskin, 2024, tells that infrared and Raman spectroscopy are helpful in vivianite identification. "The IR spectrum of vivianite shows characteristic H-O-H stretching and bending modes at nearly 3430 cm -1 and 1690 cm -1 respectively, the tetrahedral phosphate group shows vibrations at 974 -1037 cm -1 . … . An advantage of using Raman spectroscopy over IR is that data below 400 cm -1 can be obtained. Vivianite shows strong broad O-H stretching bands between 3000 to 3700 cm -1 . The strongest band in the Raman spectrum is at 3262 cm -1 attributable to the OH stretching. A strong band is observed at 951 cm -1 and is due to the Raman active PO stretching. Two intense bands are observed at 236 and 186 cm-1 and these bands are attributable to Fe-O stretching vibrations" (Paskin mentioning .