R1: Characterization and description of minerals

[R1-11] A re-examination on kobeite-(Y) for the redefinition

*Ritsuro Miyawaki¹, Toshiaki Shimura², Koichi Momma¹, Satoshi Matsubara¹, Akira Kato¹ (1. National Museum of Nature and Science, 2. Yamaguchi Univ.)

Keywords:kobeite-(Y), zirconium, zirconolite

Kobeite-(Y) was re-examined with a specimen from the type locality, Kobe, Kyoto, Japan. DTA/TG curves revealed 4 steps of weight loss of dehydrations. The metamictized kobeite-(Y) crystallized into a cubic phase, and then, transited into another trigonal phase of zirconolite-3T type structure at 775°C. The trigonal morphology and Zr as an essential constituent in kobeite-(Y) verified that kobeite-(Y) should be redefined as YZr(TiFe³⁺)O₇, the Y-analogue of zirconolite, CaZrTi₂O₇.