Crystallographic texture of crossed-lamellar structure in Cymbiola nobilis shell

Abstract

The crossed-lamellar structure is known to exhibit a fantastic microarchitecture and excellent fracture resistance. Despite a similar morphology, this structure belongs to a family of homeomorphic microstructures with complex and varied crystallographies. In the present study, the crystallographies of different parts in Cymbiola nobilis shell were studied. The width of the first building blocks becomes increasingly thicker from the top to bottom of inner and middle layers. All the crystallites tend to align their c-axes towards the shell surface, and two twinned crystals share the c-axis at the top of inner and middle layers, while at the bottom the 001 pole figure shows two orientation components with c-axes inclined, and four preferential b-axis orientations distributed into two pairs. Texture analysis provides important information about the nature of shell growth, and suggests that the shape of the building blocks may be controlled by the crystallographic arrangement during the aragonite deposition.