IDENTIFICATION OF CALCIUM CARBONATES (CAL CITE, ARAGONITE AND VATERITE) BY RAMAN-CASTAING MICROPROBE - APPLICATION TO BIOMINERALISATIONS

The identification of vaterite by Raman spectrometry is compared to th at of calcite and aragonite. Biomineralisations, commercial reference samples and synthetic vaterite are used. It is demonstrated that the t hree crystalline forms of calcium carbonate can be distinguished by th eir main Raman peak only, especially in the case of vaterite where the peak splits up; this is of particular interest when the quantity of m atter to be analyzed is very limited or when the fluorescence is impor tant, something frequent in the case of biomineralisations. The elemen tal analysis provided by the electron microprobe part of the Raman-Cas taing microprobe rules out any risk of confusion between calcium salts and any other substance.