The Ogee zone at the past-producing Pinson mine project in northeastern Nevada is starting to live up to its name for operator Atna Resources (ATN-T).
Recent underground drilling on the recently discovered zone is highlighted by an impressive 58.5-ft intersection (beginning 156.5 ft. downhole) running 1.69 oz. gold per ton in hole no. 10; the first 15.9 ft. of the hole (from 50 ft. downhole) contain 1.23 oz. gold per ton.
The hole was collared around 50 ft. above hole no. 4 sunk late last year. That hole was the first underground hole drilled in the Ogee zone, and returned a 147.5-ft. intersection grading 0.97 oz. gold, including 54.6 ft. of 1.29 oz. gold and a 37.3-ft. interval of 1.32 oz.
The mid-point of the 147.5-ft. intersection is located 145 ft. north and 175 ft. below adit-level channel samples that averaged 34 ft. grading 0.69 oz. gold.
Two other more recent holes returned intervals with grades exceeding 1 oz. per ton, including hole no. 5, which intersected a 7.5-ft. section (from 214.5 ft.) running 1.18 oz. gold, and hole no. 7 which yielded 25.2 ft. (from 78 ft.) of 1.17 oz. The five remaining holes of the recent batch generally returned around 0.3-0.75 oz. gold over widths of 2-12 ft.
Atna says that more drilling is required to determine the size and shape of the irregular zone before a resource estimate can be made. To that end, the company has resumed drilling with two underground drill rigs.
The Ogee zone occurs in a decalcified limestone-siltstone collapse breccia within the lower member of the Ordovician Comus Formation, which is the principal host rock for mineralization at Pinson. Mineralization appears best developed near the intersection of the Ogee structure and the CX-West fault within the limy sequence below the capping shale.
Existing measured and indicated resources in the parallel Range Front and CX zones at Pinson total 1.75 million tons grading 0.3 oz. gold per ton, using a 0.15 oz. cutoff grade, while inferred resources add another 4.2 million tons of 0.32 oz. gold. At a cutoff grade of 0.25 oz., measured and indicated resources amount to around 1.1 million tons averaging 0.35 oz., with another 3.05 tons of inferred material running 0.36 oz.
The estimates do not include the Ogee zone mineralization.
The Ogee structures lies between the Range Front and CX zones, and Atna believes it may provide an early mining opportunity owing to its high grades and ready access from the existing adit.
The zone was first encountered last August during underground development of an adit being cut from near the bottom of the existing CX pit to allow for drilling to test for extensions of the Range Front and CX zones down-dip and along strike.
The Pinson project is situated in the Getchell gold belt and has produced almost 1 million oz. gold from shallow oxidized pits before mining ceased in 2000. The ‘Carlin-type’ gold system features micron-gold hosted in altered, fine-grained sedimentary rocks.
Atna holds rights to earn a 70% interest in the project from a subisidary of Barrick Gold (ABX-T, ABX-N).
Completion of the ongoing underground exploration and development program would see Atna meet its earn-in expenditure requirement of US$12 million. It will also provide data for a prefeasibility study, also an earn-in requirement.
Based on measured and indicated resources at a 0.25-oz. cutoff, Atna initially envisages annual production of 88,000 oz. of gold over 4 years at Pinson. The proposed underground operation would generate pre-tax cash flow of $13.2 million per year.
Shares in Atna were as much as 38, or 17%, higher at a long-time high of $2.56 in early trading in Toronto on Jan. 12. By mid-afternoon the shares eased and were trading 12 better at $2.30.
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