Gold-Mineralization in the 144 Zone at Sterling: Stratigraphically and structurally controlled, Carlin-type epithermal gold mineralization in the Southern Walker Lane

The 144 Zone is located on Imperial Metals’ Sterling property, in the Bare Mountain
range in Nye County, Nevada. Bare Mountain is part of the southern Walker
Lane, aNNW-trending lineament in westernNevada hosting many precious metal deposits.
Historically, the open pit and underground Sterling mine produced 200,000
troy ounces of gold at an average grade of 0.217 oz/st between 1980 and 1997. Gold occurs
in silicified hydrothermal breccia at the thrust contact between overlying
siltstones of the Wood Canyon Formation and underlying dolostone of the Bonanza
King Formation, both of Early Cambrian age. In 2001, exploration drilling from surface
south of the Sterling mine discovered a new, deeper zone of mineralization called
the 144 Zone, at the contact between silty dolostones of the basal Bonanza King Formation
and underlying limestone of the Carrara Formation, on the west side of a 13.9
Ma quartz latite dike which is also altered and mineralized. Significant gold grades
range from 0.1 to 2 oz/st. Drilling from 2001 to 2003 produced a small mineral resource
supportive of further exploration activity. In 2007, a 3,352 foot decline was excavated
into the 144 Zone for underground drilling access and potentially for future
mining. A 2008 underground diamond drill program expanded the 144 Zone, and established
a significant extension on the eastern side of the latite dike; gold up to 0.145
oz/st was also discoveredwithin the dike. These results led to the lengthening by 80 feet
of one of the drift branches to explore the 144 Zone down-dip to the north, beneath the
former mine workings.