R4: Mineral sciences of the Earth surface

[R4-08] Crystallographic characteristics of vaterite in fish otolith

[Presentation award entry]

*Gen Takahashi¹, Taiga Okumura¹, Takayoshi Nagaya¹, Michio Suzuki ², Toshihiro Kogure¹ (1. Univ. Tokyo, Sci., 2. Univ. Tokyo, Agri.)

Keywords:biomineralization, calcium carbonate, vaterite, otolith

Bony fishes have three kinds of otoliths, and generally they adopt different crystal polymorphs: lapillus and saggita adopt aragonite, and asteriscus adopts vaterite. Otolithic vaterite was analyzed mineralogically and compared with synthesized ones. There was no significant difference between them in the XRD peak positions and phase transition temperature measured by TG-DTA. Moreover, EBSD and TEM analyses revealed similar crystallographic aspects: mosaic-like crystallographic feature and preferential crystal growth along the a_i-axes.