Comparison of the Crystallographic Texture of the Recent, Fossil and Subfossil Shells of Bivalves
A crystallographic texture of modern, subfossil and fossils (Upper Pleistocene) shells of bivalves <i>Mytilus galloprovincialis</i>, modern and subfossil <i>Mytilus trossulus</i>, as well as modern and fossils (Upper Pleistocene) <i>Ostrea edulis</i> are studied using neutron diffraction. It is revealed that for shells of mussel species of different ages are characterized by a high ordering of calcite crystals—a sharp texture. Aragonite crystals are poorly distributed, depending on the shape of the valves. In a dry and warm climate, shells of <i>M. galloprovincialis</i> undergo stratification of the shell matter, which violates the crystallographic texture. Under land conditions, the ordering of calcite crystals in <i>M. galloprovincialis</i> shells decreases. In subfossil <i>M. trossulus</i> and fossil <i>M. galloprovincialis</i>, <i>O. edulis</i>, the crystallographic texture intensity of the calcite and aragonite changes over hundreds and thousands years.