Mineralization in the Keno Hill (KH) comprises carbonate vein-hosted polymetallic silver-lead-zinc as described by Boyle (1965), Cathro (2006), Murphy (1997), and Roots (1997). Mineralized zones typically exhibit a succession of hydrothermally precipitated minerals deposited in veins or veinlets resulting from multiple pulses of hydrothermal fluid boiling events, probably related to repeated depressurization due to movement along the host fault structures. As a result, a progressive series of differing mineral depositional stages, assemblages, and textures can be identified. To a minor extent, supergene alteration may have further changed the nature of the mineralogy in the veins, although this may have been largely removed due to glacial erosion.
In general, common gangue minerals include (manganiferous) siderite and, to a lesser extent, quartz, and calcite. Silver occurs predominantly in argentiferous galena and argentiferous tetrahedrite (freibergite) with associated native silver, and the silver-bearing sulfosalts polybasite, stephanite, and pyrargyrite are other important silver-bearing minerals. Lead occurs in galena and zinc in sphalerite, which can be either an iron-rich or iron-poor variety. Other sulfides include pyrite, pyrrhotite, arsenopyrite, and chalcopyrite.
Historically, it was believed that economic mineralization in the Keno Hill mining camp was restricted to a shallow zone of approximately 120 m thickness. However, the 370 m depth of ........