The molecular structure of the three vivianite-structure, compositionally related phosphate minerals vivianite, baricite and bobierrite of formula M32+(PO4)2.8H2O where M is Fe or Mg, has been assessed using a combination of Raman and infrared (IR) spectroscopy.

Figure 1 is Raman spectra of the hydroxyl-stretching region of (a) vivianite, (b) baricite and (c) bobierrite.

Figure 2 is IR spectra of the hydroxyl-stretching region of (a) vivianite, (b) baricite and (c) bobierrite.

Figure 3 is IR spectra of the water HOH-bending region of (a) vivianite, (b) baricite and (c) bobierrite.

Figure 4 is Raman spectra of the phosphate-stretching region of (a) vivianite, (b) baricite and (c) bobierrite.

Figure 5 is IR spectra of the PO4-stretching region of (a) vivianite, (b) baricite and (c) bobierrite

Figure 6 is Raman spectra of the low-wavenumber region of (a) vivianite, (b) baricite and (c) bobierrite.