Investigation on the Infrared Absorption Spectrum of Pearl and Nacre

The infrared absorption spectra of some saltwater pearl and shell are investigated; the micrographs of the pearl and nacre layer are viewed. The result shows that infrared absorption spectra of pearl and nacre comprise the spectra of nanophase CaCO3 and other unidentified material, this can evidence that nacre is a kind of biologic composite material composed of nanophase calcium carbonate.