2021 Annual Meeting of Japan Association of Mineralogical Sciences (JAMS)

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Oral presentation

R4: Mineral sciences of the Earth surface

Thu. Sep 16, 2021 2:00 PM - 5:15 PM Zoom Session 3

Chairperson:Keisuke Fukushi(Kanazawa University), Tadashi Yokoyama(Hiroshima University), Jun Kawano(Hokkaido University), Hiroshi Sakuma(NIMS), Satoshi Utsunomiya(Kyushu University)

4:00 PM - 4:15 PM

[R4-08] Variation of lattice constants with Na substitution in biogenic aragonites

*Taiga Okumura1, Masahiro Yoshimura1, Toshihiro Kogure1 (1. Univ. Tokyo Sci.)

Keywords:biogenic aragonite, sodium, lattice constant, axial ratio, biomineralization

The lattice constants of 14 biogenic and five abiogenic aragonites were measured in this study. The aragonites with larger axial ratios (a/b and c/b) showed a higher concentration of Na. The axial ratios of a marine molluscan shell decreased by heating at 250°C, and Na was diffused out of the aragonite crystals and locally concentrated after heating. These results infer that variation of the lattice constants in biogenic aragonites is caused by the substitution of Na+ for Ca2+.