Cuprobismutite group minerals (cuprobismutite, hodrušhite, kupčíkite and padĕraite), other Bi–sulfosalts and Bi–tellurides from the Obari mine, Yamagata Prefecture, Japan

Abstract

Cuprobismutite group minerals have been discovered for the first time in Japan from the Obari mine, Yamagata Prefecture. Furthermore, many kinds of Bi–sulfosalts and Bi–tellurides have been found from this mine. Cuprobismutite occurs as irregular particles which are intergrown with makovickyite. The empirical formula of cuprobismutite is (Cu_7.71Fe_0.41)_∑8.12(Bi_12.17Ag_1.57Pb_0.07Sb_0.07)_∑13.88(S_23.95Se_0.06)_∑24.01 (based on total atoms = 46). Hodrušhite, kupčíkite and padĕraite occur as euhedral to subhedral blade–shaped crystals with parallel intergrowth. The empirical formulae of these minerals are (Cu_7.64Fe_0.36)_∑8.00(Bi_11.18Cu_0.35Ag_0.26Pb_0.07Sb_0.07)_∑11.93(S_21.98Se_0.09)_∑22.07 (based on total atoms = 42), (Cu_3.56Fe_0.50Zn_0.04)_∑4.10(Bi_4.84Sb_0.03)_∑4.87(S_10.00Se_0.03)_∑10.03 (based on total atoms = 19) and Cu_7.00[(Cu_0.50Ag_0.17)_∑0.67Pb_1.27Bi_11.01Sb_0.05]_∑13.00(S_21.91Se_0.09)_∑22.00 (based on total atoms = 42) for hodrušhite, kupčíkite and padĕraite, respectively. The content of trace elements (Ag, Fe and Pb) in each cuprobismutite group mineral is consistent with the characteristics shown by previous works.