The mining newspaper for Alaska and Canada's North
The mining newspaper for Alaska and Canada's North
President, Sumitomo Metal Mining Pogo: Katsuya Tanaka
Pogo General Manager: Chris Kennedy
Pogo Geology Manager: Ken Puchlik
Sumitomo Metal Mining Pogo LLC - a joint venture between Japanese firms Sumitomo Metal Mining Company (85 percent) and Sumitomo Corp. (15 percent) - is preparing to mine East Deep, a new zone of high-grade gold discovered in the shadow of the mill at the Pogo Mine in Interior Alaska.
Since 2008, this high-grade underground mine, situated some 85 miles (137 kilometers) southeast of Fairbanks, has produced roughly 1,000 ounces of gold per day and is on track to produce 352,000 ounces of gold in 2013.
With 2.4 million ounces of gold in reserves (5.06 million metric tons of ore averaging 13.58 grams per metric ton gold) and 2.4 million ounces of gold in resources (6.84 million metric tons averaging 10.83 g/t gold), it is currently expected that the mine will maintain this pace into 2019.
The ongoing expansion of East Deep and other nearby deposits will likely add several years to this projection.
Since the Interior Alaska gold mine went into production in 2008, the feedstock for the mill has primarily been mined from the Liese zone - three flat-lying, parallel quartz veins that carry high-grade gold.
The gold-rich veins of the Liese zone end abruptly where they come in contact with a gold-barren body of diorite to the northeast.
In 2010, the Pogo exploration team decided to drill-test an area just north of the diorite.
This exploration drilling tapped East Deep, a zone of quartz-vein structures with grades and thickness that are strikingly similar to those that have provided feedstock for the Pogo mill over the past six years.
Through the end of 2012, 75 holes drilled into East Deep have outlined reserves of 2.36 million metric tons averaging 12.7 g/t (964,000 ounces) of gold and resources of 1.23 million metric tons averaging 13 g/t (514,000 ounces) gold at the newly discovered zone.
This drilling provides strong evidence that the Liese and East Deep zones were once a contiguous ore body that became separated when the diorite split the two zones as it intruded along the Liese Creek fault about 95 million years ago.
These zones are believed to converge at the North zone, a high-grade gold deposit located at the northwestern end of the diorite.
The North zone is distinctive due to the vertical orientation of the veins found there.
These narrower but higher grade veins are believed to be feeders that provided a conduit to deliver the gold-rich fluids to the Liese zone to the south and the East Deep zone to the east.
The 2013 exploration drilling at Pogo is focused on tracing East Deep to the North and Liese zones.
With the mill sitting about where these three zones meet, accessing the ore at East Deep will be essentially the same as the zone for which the operation was built.
In 2012, Sumitomo drove two drifts through the some 300 meters of diorite that separate Liese from East Deep.
These access drives have provided a platform for further expanding the new zone as well as early access to the gold-rich ore found here.
A bulk sample of East Deep ore was processed during the third quarter of 2013.
To mine the high-grade gold at East Deep, Sumitomo is developing the 2150 portal.
With permits in-hand, Sumitomo Metal Mining Pogo plans to begin processing ore from East Deep in 2014.
In addition to expanding East Deep westward to the North Zone, Sumitomo Metal Mining Pogo said the deposit remains open to the north, a target of future exploration.
Expanding East Deep and other nearby deposits is expected to augment the reserves at Pogo, ensuring the underground deposit continues to contribute some 1,000 ounces a day to Alaska's gold production for years to come.
Ownership:
Sumitomo Metal Mining Co. (85 percent)/Sumitomo Co. (15 percent)
PO Box 145
Delta Junction, Alaska
USA 99737
Tel: 907-895-2841
Fax: 907-895-2866
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