R1: Characterization and description of minerals

[R1-09] Chemical compositions of katoite from Tadano, Fukushima Prefecture, Japan

*Yasuyuki Banno¹, Michiaki Bunno² (1. AIST, 2. Univ. of Tokyo)

Keywords:katoite, wadalite, Tadano

Microprobe analyses were carried out on katoite in skarn xenoliths in andesites from Tadano, Fukushima Prefecture, Japan. Backscattered electron images indicate that katoite is chemically heterogeneous within a single grain. The empirical formula corresponding to its average composition is {Ca₃}[Al_1.59Fe³⁺_0.20Mg_0.07Ti_0.02]_Σ1.88(Si_1.15S_0.11vacancy_1.74)_Σ3[(OH)_6.99O_4.81F_0.16Cl_0.04]_Σ12 on the basis of Ca = 3. Compositional ranges for S and Al + Fe³⁺ are 0.00-0.20 and 1.61-2.00 apfu, respectively.