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

[R1-12] Ti-Mn unknown mineral from Yakiyama, Iizuka , Fukuoka, Japan

*Seiichiro Uehara¹, Yuki Ishiki ², Yuya Takeda², Satomi Enju³ (1. Kyushu Uni. Museum, 2. Kyushu Univ. Fac. Sci., 3. Ehime Univ. Fac. Sci.)

Keywords:Ti-Mn unknown mineral, Yakiyama Iizuka Fukuoka Japan, Aluminian serpentine, Amesite, Rodingite

A Ti-Mn unknown mineral was found in the low-temperature altered rodingite in Yakiyama serpentinite body, Fukuoka. The X-ray diffraction pattern is similar to the hexagonal CdTi₂O₄(OH)₂, and the lattice constant is a = 5.181, c = 4.562 Å. The chemical composition is MnO (as divalent) 25.8, MgO 6.5, FeO 6.6, SiO₂ 0.6, Al₂O₃ 0.5, CaO 0.3, TiO₂ 48.8, H₂O (calculated value) 6.8 total 95.7 wt%. The empirical formula is (Mn, Mg, Fe, Si, Al, Ca)_Σ1.33Ti_1.63O₄ (OH) ₂. The crystal structure can be estimated from the STEM image observation, and it seems to be a Mn substitution product of CdTi₂O₄(OH)₂.