New data on cuprobismutite

Cuprobismutite from Tunnel Extension Number Two mine, Ohio mining district, Utah, was chemically analyzed using the
electron microprobe.  Its empirical formula was determined to be Cu_20.8 Ag_0.97 Pb_0.35 Mn_0.22 Bi_26.7Sb_0.06 Te_0.05 Se_0.55 S_50.4.  The tentative conclusion is that unsubstituted cuprobismutite has the chemical formula 6Cu₂S*6Bi₂S₃ rather than the previously ascribed formula 6Cu₂S*6Bi₂S₃ and that cuprobismutite is therefore not dimorphous with emplectite.