R1: Characterization and description of minerals (Joint Session with The Gemmological Society of Japan)

[R1-09] Follow-up report on Chibaite from north Fossa Magna area, central Japan

*Koichi Momma¹, Hiroshi Miyajima², Norimasa Shimobayashi³, Takashi Ishibashi⁴, Nobuyuki Takayama⁵, Toshiro Nagase⁶, Ritsuro Miyawaki¹, Satoshi Matsubara¹, Akira Ijiri⁷, Yoshihiro Furukawa⁸ (1. NMNS, 2. Itoigawa City Council Member, 3. Kyoto Univ., 4. Masutomi Mus. Geo. Sci., 5. Friends of Fossa Magna Museum, 6. Tohoku Univ., Mus., 7. Kobe Univ., 8. Tohoku Univ.)

Keywords:chibaite, silica clathrate, pseudomorph, Fossa Magna

In 2013, we reported occurrence of chibaite from north Fossa Magna area, central Japan. At that time we didn’t report details of the locality to protect the outcrop from collectors. In April, 2021, the locality, silica clathrate minerals, and their pseudomorphs were designated as natural heritage of the Otari village, Nagano Prefecture, Japan. We will report follow-up story of the world’s 2^nd occurrence of chibaite about geology, crystal structure, gas composition in the crystal, and carbon isotope of gas molecules.