The mining newspaper for Alaska and Canada's North
The mining newspaper for Alaska and Canada's North
Greens Creek leads the way, has reserves to last until 2031 North of 60 Mining News – February 7, 2020
Workers at Hecla Greens Creek silver mine near Juneau, Alaska. Based on current production levels, this underground operation has enough reserves to feed the mill until 2031.
Continuing a tradition of growth, Hecla Mining Company has increased its reserves of silver, lead, and zinc to historic levels.
Hecla goes into 2020 with 37.08 million metric tons of proven and probable reserves averaging 212.2 million ounces of silver, 2 billion pounds of zinc, 1.6 billion lb of lead and 2.71 million oz of gold.
Hecla replaced the 12.6 million oz of silver produced from ore containing 15.4 million oz and increased reserves by 11 percent during 2019, despite using a conservative US$14.50/oz silver price to calculate the reserves.
Over the last 12 years, Hecla has not only replaced silver production but added 234 million oz through exploration.
Hecla's exploration also more than replaced the zinc and lead the company produced during 2019 –increasing zinc reserves by 8 percent and lead reserves by 5 percent.
"The foundation of value creation for any mining company is increasing reserves, and Hecla's silver, lead and zinc reserves are the most in our 129-year history," said Hecla Mining President and CEO Phillips S. Baker, Jr. "Despite using what we believe is the industry's most conservative price assumption and spending our second lowest amount on exploration in the last 10 years, Hecla grew silver reserves 11 percent last year, with Greens Creek having its most reserves since 2001."
The reserve growth at Greens Creek is even more impressive when you consider that the Southeast Alaska mine accounted for roughly 79 percent of the silver, nearly 21 percent of the gold and most of the zinc and lead Hecla produced in 2019.
Greens Creek growth
The increase in Greens Creek silver reserves means the exploration team outpaced a banner year of production at this Southeast Alaska mine.
During 2019, the Greens Creek Mine produced 9.9 million oz of silver from 846,076 tons of ore containing 12.4 million oz of silver, 81,223 oz of gold, 125.7 million lb of zinc and 49.4 million lb of lead.
Exploration replaced and increased reserves of all four metals.
As a result, Greens Creek now hosts 10.72 million tons of proven and probable reserves averaging 12.2 oz/t (130.9 million oz) silver; 0.09 oz/t (932,000 oz) gold; 7.3 percent (1.6 billion lb) zinc; and 2.8 percent (610 million lb) lead.
This is enough ore to keep the Juneau area mine in operation until 2031 and there are plenty of additional resources that can be upgraded to reserve status with drilling.
In addition to the reserves, Greens Creek hosts 8.65 million tons of measured and indicated resources averaging 11.7 oz/t (101 million oz) silver, 0.1 oz/t (835,000 oz) gold, 8.1 percent (1.4 billion lb) zinc, and 2.8 percent (488 million lb) lead; and 1.85 million tons of inferred resource averaging 13.7 oz/t (25.4 million oz) silver, 0.09 oz/t (159,000 oz) gold, 7.4 percent (272 million lb) zinc and 3.1 percent (113 million lb) lead.
This provided the Greens Creek exploration team plenty of resources to upgrade to reserves as they seek out new areas of mineralization to keep Hecla's flagship asset operating deep into the 21st century.
Strong definition drilling assay results received in the fourth quarter have upgraded and expanded the East Ore and 200 South zone resources.
Resource upgrade drilling continued to confirm inferred resources at the north end of East Ore, a zone that comes to surface at the Big Sore outcrop that led to the Greens Creek discovery. Highlights from definition drilling include:
• 4.3 feet (1.3 meters) averaging 56.6 oz/ton silver, 0.13 oz/ton gold, 4.5 percent zinc and 1.5 percent lead;
• 1.9 feet (0.6 meters) averaging 228.4 oz/ton silver, 0.35 oz/ton gold, 2.1 percent zinc and 0.2 percent lead; and
• 6.4 feet (two meters) averaging 10.4 oz/t silver, 0.58 oz/ton gold, 13.2 percent zinc and 4.6 percent lead.
Definition drilling at 200 South, a much deeper zone at the underground mine, encountered mineralization over 200 meters of strike at the northern end of the 200 South Bench. This includes one hole that cut 22.4 feet (6.8 meters) averaging 16.8 oz/ton silver, 0.24 oz/ton gold, 12.7 percent zinc and 6.1 percent lead.
Hecla said its definition drilling at Greens Creek during the first quarter of 2020 will continue to focus on further defining the East Ore and 200 South zones.
The company's fourth quarter exploration at Greens Creek also focused on 200 South. This drilling expanded upper bench mineralization 350 feet (107 meters) and lower contact mineralization 800 feet (244 meters) down-plunge from the current resource model, which could add new resources to the mine.
Recent intersections from the upper bench mineralization include:
• 15.3 feet (4.7 meters) averaging 11.5 oz/ton silver, 0.06 oz/ton gold, 6.6 percent zinc and 3.6 percent lead;
• and 12 feet (3.7 meters) averaging 50.5 oz/ton silver, 0.05 oz/ton gold, 1.5 percent zinc and 0.7 lead.
Recent intersections from the lower contact mineralization include four feet (1.2 meters) averaging 4.5 oz/ton silver, 0.05 oz/ton gold, 7.7 percent zinc and 3.6 percent lead.
Exploration drilling at Greens Creek during 2020 is expected to target East, 9A, West, Upper Plate and 200 South zones and explore down-plunge of the Gallagher Zone.
Over his more than 16 years of covering mining and mineral exploration, Shane has become renowned for his ability to report on the sector in a way that is technically sound enough to inform industry insiders while being easy to understand by a wider audience.
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