RAMAN-SPECTRA OF VATERITIC CALCIUM-CARBONATE

The Raman spectrum of polycrystalline vaterite is presented and compar ed to spectra of calcite and aragonite, the other two common CaCO3 pol ymorphs; Raman spectroscopy easily distinguishes between these three p olymorphs. An important feature of the Raman spectrum of vaterite is s plitting of both the vl and v(4) peaks. The splitting of the v(1) peak implies two distinct site symmetries for the CO3-2 groups. A definiti ve crystal structure determination of vaterite is not yet available, b ut none of the three proposed structures for vaterite show such a feat ure.