Spectroscopic characterization of biogenic silica

Amorphous biogenic silicas were studied by FTIR and MAS-NMR spectroscopy. Fossil diatom frustules and sponge spicules exhibit a highly condensed and well-organised silica whereas the silica frustule of living diatoms is much less condensed, suggesting that some condensation process still happens upon fossilisation during the diagenetic evolution of silica. Moreover, the silica network of living diatoms appears to be linked to the bio-organic components of the cell, in agreement with the biosilicification mechanisms suggesting that some proteins or polysaccharides favour the formation of silica.