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Chert Cliff Property
The Chert Cliff Property is located in the Gold Bar District about 64 kilometres (40 miles) northwest of Eureka, Eureka County, Nevada. Gold Bar, including the property area, occurs within the southern section of the productive Battle Mountain Trend of gold deposits.
Subject to third party net smelter returns royalties, the Chert Cliff Property is 100% controlled by Columbus Gold. The property is subject to a mineral lease with Platte River Gold Inc., providing for annual cash payments to Columbus and a net smelter returns royalty. The Chert Cliff Property forms part of Platte River's Gable Project.
Geology
Geology of the claims area consists of dolomitic siltstones of the Mississippian Webb Formation overriding massive Devonian limestones in thrust fault contact. Disseminated gold occurs in hydrothermally altered Webb siltstones and jasperoid. Drilling in 2008 also encountered gold mineralization in the lower plate Denay Formation.
Past Work
Gold was discovered at Chert Cliff in the mid 1960's during the initial wave of prospecting for carbonate-hosted gold deposits following recognition of the Carlin model in 1961. The most intensive work was carried out by Asarco in the 1980's and succeeded in outlining the Chert Cliff gold deposit, with an historical resource of 1.4 million tons grading 0.04 ounces per ton gold (56,000 ounces of gold) (not NI 43-101 compliant). Anomalous to ore grade intercepts were also encountered in isolated drill holes north and east of the resource area but were never followed up.
In 2008, Platte River drilled seven reverse circulation holes totaling 5,140 feet (1,567 meters) at Chert Cliff. The holes ranged from 300 ft to 1,420 ft (91 m to 433 m) in dept. All of the holes were drilled outside of the Chert Cliff resource defined by Asarco in the 1980's, which is entirely hosted in the Webb Formation.
Drilling by Platte River encountered additional mineralization in the Webb Formation, and also low-grade but significant mineralization in the Lower Plate Denay Formation, which is a host of mineralization at the nearby, multi-million ounce Cortez Hill's gold deposit being developed by Barrick Gold.
The gold mineralization encountered in holes C-4, C-7, and C-8 in the Denay Formation occurs in carbonaceous limestone stratigraphically lower and about 600 ft (183 m) north of the resource delineated by Asarco. The best holes drilled were C-4, which encountered 180 ft (55 m) [from 170 ft to 350 ft (52 m to 107 m] of 0.013 opt gold, including 40 ft (12 m) of 0.025 opt gold, in the Denay Formation, and C-1, with 0-190 ft (0-58 m) of 0.020 opt gold in the Webb Formation.
Planned Program
The confirmation of mineralization in the Denay Formation opens up many additional targets for future drilling.
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