FIG. 6. (a) Composition of Bi-tellurides/tellurosulphides from Larga (tetradymite, tsumoite, tellurobismuthite, rucklidgeite), plotted in terms of Bi(+Pb)– Te– (S+Se). (b) Composition of tellurides and tellurosulphides in the Bi₂Te₃-Bi₂Se₃-Bi₂S₃ system demonstrating the extent of solid solution along the Bi₂Te₂S-Bi₂Te₂Se join between tetradymite, Bi₂Te₂S and kawazulite, ideally Bi₂Te₂Se. (c) Compositional variation expressed in terms of Bi-Pb-(S+Se+Te), demonstrating compositions of Pb-free rucklidgeite (vein ores) and rucklidgeite (porphyry mineralization).