Low to moderate levels of gold are widely distributed within a distinct member of the Mississippian Keno Hill Quartzite northeast of Mayo Lake, demonstrating characteristics of sediment-hosted disseminated gold deposits. Alteration is pervasively developed within a 20m-thick, moderately dipping quartzite interval that can be traced along strike for 4 km. The unit is distinct in texture and appearance due to the effects of hydrothermal alteration. The altered sandstone is highly porous due to secondary leaching (decalcification), producing a friable unit. Also striking is the bleached white appearance (decarbonatization), which contrasts with the dark grey to black of unaltered graphitic quartzite. Sericite and illite are widespread secondary products of the alteration, and trace amounts of pyrite have been largely oxidized into rusty streaks. Abundant, regular, steep, northeast-striking, vuggy quartz veins are stratabound to the porous interval along its entire length - likely resulting from in-situ hydrofracturing due to elevated pore fluid pressure.