Drills expand Greens Creek beyond 2030
Mining Explorers 2019 – Published Nov. 1, 2019
Last updated 8/14/2020 at 9:21am
Hecla Mining Company's Greens Creek Mine in Southeast Alaska has enough reserves to keep the high-grade underground silver mine in operation until 2030.
The Greens Creek Mine now has 9.23 million tons of proven and probable reserves averaging 11.5 oz/t (107.1 million oz) silver; 0.09 oz/t (840,000 oz) gold; 7.6 percent (706,470 tons) zinc; and 2.8 percent (227,740 tons) lead.
This marks the highest silver reserves for Greens Creek since Hecla bought full ownership of the underground mine in 2008.
An updated NI 43-101 technical report completed this year for Greens Creek details an optimized mine plan that accelerates access to higher-grade ore, which will allow some of the highest-margin reserves to be extracted in the earlier years of the mine plan, which is now estimated to extend out to 2030.
This major increase in reserves comes on top of replacing the 845,398 tons of ore containing 10.3 million oz of silver, 79,087 oz of gold, 63,116 tons of zinc and 23,656 tons of lead that was processed through the Greens Creek Mill last year.
What is equally as impressive is the property hosts roughly as much material in resources, which can potentially be elevated to reserves and further extend the life of the mine.
Going into 2019, Greens Creek hosted 7.47 million tons of measured and indicated resources averaging 13 oz/t (97.4 million oz) silver; 0.1 oz/t (726,000 oz) gold; 8.2 percent (609,350 tons) zinc; and 3.1 percent (227,740 tons) lead.
This is a 66.1 million oz (211 percent) jump in the amount of silver and 467,700 oz (181 percent) rise in the amount of gold reporting to measured and indicated resources since the beginning of 2018. This rise comes from bringing the West, Southwest, 9A, and 200 South zones into the measured and indicated resources category – partially offset by losses from elevating resources in the Gallagher and East zones to reserves.
Despite the amount of resources being elevated to higher confidence categories, the amount of silver in inferred resources increased by 3.3 million oz, while the gold in this lowest resource category decreased by 3,200 oz.
Hecla's 2019 exploration at Greens Creek continues to focus on expanding and upgrading resources.
"At Greens Creek we could see reserve increases again this year as the resources are upgraded," said Hecla Mining President and CEO Phillips Baker, Jr.
Toward this objective, definition drilling during 2019 is targeting the East Ore, NWW, 9A and 200 South zones.
Exploration drilling this year is testing extensions of 200 South Zone and the Deep Southwest.
Hecla is also exploring Kinskuch, a large silver project southeast of Stewart, British Columbia. Drilling completed by Hecla last year defined silver-enriched, base metal mineralization over a three-mile-long stretch of the Illiance Valley at Kinskuch.
Historical rock chip and grab samples collected from several occurrences along the Illiance River trend returned values of up to 3,761 g/t silver, 17 percent zinc and 7.6 percent lead.
Trenching and channel sampling completed in 2011 include a 2.2-meter-wide interval averaging 530 g/t silver, 4.52 percent zinc and 5.5 percent lead; and a 1.9-meter interval averaging 373 g/t silver, 10.4 percent zinc and 16 percent lead.
Four core holes were drilled in 2011 tested the depth extensions of the surface trenching.
Hole KN11-02, drilled in the southern portion of the trend, cut 2.8 meters averaging 318 g/t silver, 6.5 percent zinc, 2.2 percent lead and 0.4 g/t gold.
KN11-03, drilled 500 meters to the south, cut 3.9 meters averaging 268 g/t silver, 6.5 percent zinc, 1.3 percent lead and 0.20 g/t gold.
KN11-04, drilled from the same pad as hole KN11-03 but angled a bit further south, cut 9.7 meters averaging 77 g/t silver, 3.9 percent zinc and 1.4 percent lead.
While Hecla has not published results from its 2018 drilling at Kinskuch, the Idaho-based miner said the high-grade zones identified in the Illiance Valley appear to have continuity and may represent two parallel mineralized structures or two limbs of a folded body. A preliminary resource model is being prepared for Kinskuch.