Keg Mining District, Juab County, Utah, USAi

Regional Level Types
Keg Mining District	Mining District
Juab County	County
Utah	State
USA	Country

The Keg mining district, on the northwest flank of the Keg Mountains, is located about 44 mi west of Eureka in central Juab County of west-central Utah. The Keg mineral occurrences were not discovered until the 1970s and there has been no recorded production.
The Keg district lies on the Deep Creek–Tintic mineral belt in the Basin and Range Province. Prospecting from the 1970s to the 1990s, primarily by Bob and Terry Steele, located numerous mineral occurrences, which have since been explored by several prospect pits and drill programs. These properties have been investigated by Getty Mining Company, Freeport Minerals, Western Strategic Minerals Company, Kennecott Exploration, Crown Resources, and Inland Explorations since the late 1970s. The eastern part of the district has been explored principally for base metals (Lead Hill area) and the west end for Ag (Dome Hill) (Venable, 2009).
The geology of the Keg Mountain area is quite complex. The oldest exposed units in the area are Lower Cambrian Prospect Mountain Quartzite, thrust over Middle Cambrian carbonate rocks, and overlain by Eocene andesitic and latitic volcanic rocks, volcanic megabreccia, and finally by Miocene Topaz Mountain Rhyolite. During the latest Eocene, a cauldron subsided on the north side of the district and several small porphyry stocks (~36 Ma) were intruded to the southeast (Shubat, 1987). These porphyries range in composition from granodiorite to high-silica rhyolite (>75% SiO2). Mineralization in the Keg district appears to be related to these porphyry stocks and associated pebble dikes. A zone of pyritic alteration wraps around the northeast side of the northeasternmost granodiorite porphyry. Mineralization may have been deposited by hydrothermal solutions derived from the granodiorite porphyry of Dead Ox Wash (Shubat, 1987).
The Dome Hill Ag prospect has high-grade rock samples assaying to over 1000 ppm Ag and generally low Au values (Au:Ag about 1:150). A low northwest-trending ridge of Prospect Mountain Quartzite occurs as a horst surrounded by Tertiary volcanic rocks and alluvium. Bedding in the quartzite strikes to the northwest and dips moderately to the southwest. Mineralization at Dome Hill consists of a northwest-trending quartz-sulfide stockwork from 2 to 10 ft wide in the Prospect Mountain Quartzite (Venable, 2009).