2022 Annual Meeting of Japan Association of Mineralogical Sciences (JAMS)

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Oral presentation

R5: Extraterrestrial materials

Sat. Sep 17, 2022 9:30 AM - 12:30 PM B251 (Adv. Edu. Res. Bldg. B-2F)

Chairperson: Matsumoto Megumi(Tohoku Univ.), Yusuke Seto(Osaka Metropolitan Univ.)

10:00 AM - 10:15 AM

[R5-03] FIB-TEM observation of co-existing tridymite polymorphs in Moama meteorite

*Atsushi Takenouchi1, Yohei Igami2, Akira Miyake2, Norimasa Shimobayashi2, Takashi Mikouchi3, Haruka Ono3 (1. Kyoto Univ. Museum, 2. Kyoto Univ., 3. The Univ. of Tokyo, Univ. Museum)

Keywords:Silica, tridymite, TEM, thermal metamorphism

Meteorites sometimes contain various combinations of silica polymorphs, and their variations may relate to their thermal metamorphic history. Here, we report the results of the FIB-TEM study focusing on co-existing tridymite polymorphs in Moama eucrite to clarify the occurrence of the polymorphs. Our observation revealed that monoclinic (Aa) and pseudo-orthorhombic tridymite shared their (001) planes, indicating that they were formed by transformation from a single high-temperature tridymite grain.