Original paper

Occurrence and mineral chemistry of bismuth sulfide-telluride-selenide solid solutions (ingodite, joseite, and unnamed phase) in the Nakdong deposit, South Korea

Shin, Dong-Bok; Lee, Chan-Hee; Lee, Kwang-Sik

Abstract

Bismuth sulfide – telluride – selenide solid solutions, such as ingodite (Bi(S, Te)), joséite–A (Bi4TeS2), selenian joséite–B (Bi4(Te,Se,S)3), and an unnamed phase (Bi2(Te,Se)) were formed during the As–Bi mineralization in the Nakdong deposits, South Korea. Ingodite, a rarely reported mineral, has the general composition, Bi1.94Sb0.01Ag0.04Te1.03Se0.03S1.08, which is regarded as Te-rich ingodite. Compiled data of previous work indicates that joséite–A from the Nakdong deposits extends its compositional range toward joséite–B and there still remains an obvious compositional gap in the range of 19.7 to 24.6 at % S + Se and 16.4 to 21.9 at % Te between the two phases. Selenian joséite–B has an intermediate compositional range between Bi4Te2S and Bi4Te2Se through the exchange between S and Se. The unnamed phase, Bi1.97Sb0.02Te0.83Se0.12S0.01, with constant Bi/(Te + Se + S) ratio close to 2 but a variable Te/(Se + S) ratio from 5.7 to 8.2, is placed in the compositionally intermediate range between the two unnamed phases of Bi2Te and Bi2 (Te, Se) of Gu et al. (2001). Coexistence of native bismuth with joséite–B and the unnamed phase constrains their formation temperature below 266 °C.

Keywords

bismuth mineralsingoditejoseite-aselenian joseite-bunnamed phasesouth korea