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

[R1-11] Willemseite from the Hamayokawa mine, Nagano Prefecture, Japan

*Satoshi Matsubara¹, Koichi Momma¹, Norio Yanagisawa², Yoko Kusaba¹, Akiko Tokumoto¹, Ritsuro Miyawaki¹ (1. National Museum of Nature and Science, 2. Geological Survey of Japan, AIST)

Keywords:suzukiite, willemseite, Hamayokokawa mine

Rare mineral, suzukiite, was reported from the metamorphosed manganese ore deposit of the Hamayokawa mine (Hirowatari & Yoshie, 1978). Althogh some specimens from the Hamayokokawa mine, Nagano Prefecture, Japan donated by amature mineralogists in the National Museum of Nature and Science and the Geological Survey of Japan are registered as suzukiite, but recent our analyses reveal they are not suzukiite but willemseite [(Ni₃Si₄O₁₀(OH)₂] which is first found in Japan.