Zaïrite in quartz veins from Ishidera area, Wazuka, Kyoto Prefecture, Japan

Abstract

Zaïrite was found from the quartz vein penetrating into the metamorphosed mudstone of the Wazuka Unit in Ishidera area, Wazuka–cho, Kyoto Prefecture, Japan, which is the first occurrence in Japan. Zaïrite occurs as bright–yellow granular crystals (20–30 µm) in a cavity formed by the leaching of fluorapatite with native bismuth inclusion. The chemical composition of zaïrite from Ishidera was closer to the ideal chemical composition, comparing with the zaïrite from type locality including Al. The empirical formula from electron probe microanalyzer (EPMA) analysis on the basis of O = 8, OH⁻ = 6 was (Bi_0.70Ca_0.23)_Σ0.93Fe³⁺_2.91(P_2.04S_0.09O₈)(OH)₆. The unit cell parameters obtained from the X–ray diffraction (XRD) pattern were a = 7.311(3) Å and c = 16.407(7) Å, larger than the type locality due to difference in chemical composition.