Greens Creek | Admiralty Island, Alaska
Hecla’s 100%-owned and operated Greens Creek mine in southeast Alaska is one of the largest and lowest-cost primary silver mines in the world, last year producing 7.8 million ounces of silver at a cash cost, after by-product credits, per silver ounce of $2.89 (a non GAAP measure)(1). Production in 2015 is expected to be 7.3 million ounces.
In 2014, at Greens Creek, definition drilling replaced or added reserves at the NWW and Deep 200 South. Definition and exploration drilling made progress in refining the NWW and West Wall resources, extending the Deep 200 South trend and defining a potential resource at the Gallagher Fault Block area. Drilling of the Deep 200 South in the past few years has defined three stacked folds of high-grade mineralization that represent up to 600 feet of down-dip continuity. The 200 South and Deep 200 South zones currently represent a mineralization trend that extends over 3,000 feet along strike and over 1,000 feet of dip. Recent drill intersections of the Deep 200 South include 49.8 oz/ton silver, 0.08 oz/ton gold, 3.4% zinc and 1.6% lead over 11.1 feet and 30.5 oz/ton silver, 0.05 oz/ton gold, 15.5% zinc and 8.0% lead over 13.9 feet. Drill intersections continue to be very encouraging, and mineralization remains open to the south.
Definition drilling tested the lower limits of both folds of the NWW Zone and confirmed the fold limbs below the current resource. Recent drilling of the NWW Zone includes 21.0 oz/ton silver, 0.34 oz/ton gold, 30.3% zinc and 8.4% lead over 14.9 feet and 25.8 oz/ton silver, 0.00 oz/ton gold, 1.9% zinc and 1.0% lead over 8.0 feet. Drill intercepts of the West Wall Zone suggest thicker and more consistent mineralization than currently modeled, and intercepts including 29.9 oz/ton silver, 0.23 oz/ton gold, 19.7% zinc and 6.7% lead over 11.0 feet are 400 feet further down dip then the previous resource model.
An aggressive underground drilling program is anticipated at Greens Creek in 2015 with plans for three drills to be active all year. Definition drilling is budgeted at $5.8 million and includes 126,700 feet that concentrate on the Lower NWW, Deep 200 South, East Ore, Deep Southwest and 9a zones and will consist mainly of in-fill drilling in order to develop mine plans in all of these areas. Exploration drilling includes 46,000 feet of drilling and budgeted at $2.4 million in order to test for mineralization: 1) along the Deep 200 South, 5250 and 9a zones trends, 2) down-plunge of the Central West and East ore zones, and 3) along the Southwest Bench upper contact and Gallagher Fault Block area. A planned 10,000 foot surface drilling program should continue to evaluate a broadly defined, mineralized stockwork veins and horizons at Killer Creek which is about a mile west-northwest of the mine. This surface program is also expected to assess the High Sore target which has surface base metal mineralization and is less than a mile southeast of the mine.
The mine holds current proven and probable silver reserves of 94.0 million ounces, 739,000 ounces of proven and probable gold reserves, as well as 240,850 tons of lead and 639,930 tons of zinc in proven and probable reserves.
There are an additional 9.1 million ounces of silver measured and indicated resource and 46.8 million ounces of silver inferred resources. Measured and indicated gold resources measure 102,000 ounces and inferred gold resources measure 315,000 ounces.
Drilling efforts over the past 11 years have replaced production and added new reserves. Exploration efforts are ongoing along the trend of numerous orebodies underground and aggressively exploring the highly prospective 27-square-mile land package on surface.
(1) Cash cost, after of by-product credits, per silver ounce is a non-GAAP measurement. A reconciliation of cash cost to cost of sales and other direct production costs and depreciation, depletion and amortization (GAAP) can be found in the legal page of this website.