M.T. Einaudi B.C. Bostick A. Meibom J. Wooden J.W. Norby M.J.T. Orobona C. P. Chamberlain T.M. Bawden 2003 We identified submicrometer-sized framboidal sphalerite (ZnS) below the base of supergene oxidation in a Carlin-type gold deposit of Eocene age in Nevada, United States, where the framboidal sphalerite forms a blanket-like body containing >400,000 metric tons of zinc. Framboidal sphalerite <0.1 ??m in diameter, formed in the early Miocene, ranges from <0.1 to 0.35 mol% FeS; the ??34S values range from -25??? to -70???, the lowest values measured in a marine or terrestrial environment. These S isotope data demonstrate the involvement of sulfate-reducing bacteria and provide the first documentation that sphalerite can form significant supergene sulfide-enrichment blankets. application/pdf 10.1130/G19831.1 en Extreme 34S depletions in ZnS at the Mike gold deposit, Carlin Trend, Nevada: Evidence for bacteriogenic supergene sphalerite article