EPR and IR spectral studies of the sea water mussel Mytilus conradinus shells

The electron paramagnetic resonance (EPR) and infrared (IR) spectral studie s have been employed on the periostracum, the prismatic layer and the nacre of the shell of the marine bivalve molluscan Mytilus conradinus of the Sou th Indian origin. All the layers of this shell show Fe3+ ion spin resonance signals in common. The inner layer namely nacre at room temperature shows EPR signals of Fe3+ ions and the heated one exhibits a sextet hyperfme patt ern characteristic of Mn2+ ions. The prismatic layer of the shell also exhi bits a similar spectrum, but of distinct pattern. The spin-Hamiltonian para meters have been evaluated for the prismatic and nacreous layers of this sh ell. Infrared spectra of the two main layers of the shell namely prismatic and the nacre exhibit the characteristic bands of CO32- molecular ion in di fferent symmetries of CaCO3. (C) 2000 Elsevier Science B.V. All rights rese rved.