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

[R1P-09] Ferro-holmquistite in granite pegmatite from Hayama-dake, Tamura, Fukushima Prefecture

*Daisuke Nishio-Hamane¹, Etsuo Hashimoto, Seiji Harada (1. ISSP, Univ. of Tokyo)

Keywords:Ferro-holmquistite, pegmatite, Hayama-dake

Ferro-holmquistite was found in the pegmatite dyke from Hayama-dake, Tamura, Fukushima Prefecture, Japan. The empirical formula is ^B(Li_1.82Na_0.13fromC_0.05)_Σ2^C(Fe²⁺_2.63Mg_0.29Mn_0.19Al_1.69Fe³⁺_0.26)_Σ5.05Si₈O₂₂(OH)₂, and unit cell parameters on space group Pnma are a = 18.377(5) Å, b = 17.782(7) Å, c = 5.300(2) Å, V = 1731.8(11) ų. Tourmaline, a possible host for Li, could not occur in this pegmatite due to a lack of boron by predominant axinite, so that ferro-holmquistite probably occurred by accommodating the excess Li.