As the largest silver mine in the United States, the team at Hecla Greens Creek has demonstrated that its safety record and environmental stewardship are among the best in the world.
Mine Type
Ownership
Silver
Gold
Lead
Zinc
***All metals reflect 2023 production
Hecla’s Greens Creek Mine in southeast Alaska is one of the largest and lowest-cost primary silver mines in the world, and it is the cash generating engine of the Company. In 2023, Greens Creek produced 9.7 million ounces of silver at an All-in Sustaining Cost (AISC), after by-product credits, per silver ounce of $7.14 (a non-GAAP measure), and 60,896 ounces of gold (1). Production in 2023 is expected to be 8.8 – 9.2 million silver ounces.
(1) AISC, after by-product credits, per silver ounce represents a non-GAAP measurement, a reconciliation of which to cost of sales and other direct production costs and depreciation, depletion and amortization, the closest GAAP measurement, can be found in the legal page of this website.
Hecla is the largest private-sector employer and taxpayer in Juneau, Alaska
The Greens Creek ore body contains silver, zinc, gold and lead, and it lies within the Admiralty Island National Monument. The Greens Creek property includes 17 patented lode claims and one patented mill site claim.
The entire project is accessed by boat. It consists of the mine, an ore concentrating mill, a dry stacked tailings facility, a ship-loading facility, camp facilities, and a ferry dock.
At Hecla Greens Creek, virtually everything we do is designed to care for and protect our very special part of Alaska—and the people who live nearby.
The mine holds current proven and probable reserves of 105.2 million ounces for silver, 880 thousand ounces of gold, 250.6 tons of lead and 658.7 tons of zinc. Based on these reserves, Greens Creek has a 14-year mine life. Measured and Indicated resources contain 111.5 million ounces of silver, 239.2 thousand tons of lead and 643.9 thousand tons of zinc; Inferred resources contain 25.9 million ounces of silver, 55.9 thousand tons of lead, and 133.3 thousand tons of zinc.
| Tons(000) | Silver(oz/ton) | Gold(oz/ton) | Lead(%) | Zinc(%) | Silver(000 oz) | Gold(000 oz) | Lead(Tons) | Zinc(Tons) | |
|---|---|---|---|---|---|---|---|---|---|
|
9 |
11.3
|
0.08 |
3.5 |
8.4 |
100 |
1 |
310
|
740 | |
|
10,009
|
10.5 |
0.09 |
2.5 |
6.6 |
105,122
|
880 |
250,270
|
697,990
| |
|
10,018
|
10.5
|
0.09 |
2.5 |
6.6 |
105,222 |
881 |
250,580 |
658,730
| |
|
– |
– |
– |
– |
– |
– |
– |
– |
– | |
|
8,040 |
13.9 |
0.10 |
3.0 |
8.0 |
111,526 |
800 |
239,250 |
643,950
| |
|
8,040
|
13.9 |
0.10 |
3.0 |
8.0 |
111,526 |
800 |
239,250 |
643,950
| |
|
1,930
|
13.4 |
0.08 |
2.9 |
6.9 |
25,891 |
154
|
55,890 |
133,260 |
Totals may not represent the sum of parts due to rounding.
(2) Mineral reserves are based on $17/oz silver, $1600/oz gold, $0.90/lb lead, $1.15/lb zinc, unless otherwise stated. All Mineral Reserves are reported in-situ with estimates of mining dilution and mining loss.
(3) The reserve NSR cut-off values for Greens Creek are $230/ton for all zones except the Gallagher Zone at $235/ton; metallurgical recoveries (actual 2023): 80% for silver, 74% for gold, 82% for lead, and 89% for zinc.
Note: All estimates are in-situ except for the proven reserves at Greens Creek which are in surface stockpiles. Mineral resources are exclusive of reserves.
(12) Mineral resources for operating properties are based on $1,750/oz gold, $21/oz silver, $1.15/lb lead, $1.35/lb zinc and $3.00/lb copper, unless otherwise stated. Mineral resources for non-operating resource projects are based on $1,700/oz for gold, $21.00/oz for silver, $1.15/lb for lead, $1.35/lb for zinc and $3.00/lb for copper, unless otherwise stated.
(13) The resource NSR cut-off values for Greens Creek are $230/ton for all zones except the Gallagher Zone at $235/ton; metallurgical recoveries (actual 2023): 80% for silver, 74% for gold, 82% for lead, and 89% for zinc.
Reporting requirements in the United States for disclosure of mineral properties as of December 31, 2020 and earlier are governed by the SEC’s Securities Act Industry Guide 7, entitled “Description of Property by Issuers Engaged or to be Engaged in Significant Mining Operations” (Guide 7). Effective January 1, 2021, the SEC has issued new rules rescinding Guide 7. Mining companies are not required to comply with the new rules until the first fiscal year beginning on or after January 1, 2021. Thus, the Company will be required to comply with the new rules when filing its Form 10-K for the fiscal year ended December 31, 2021. The Company is also a “reporting issuer” under Canadian securities laws, which require estimates of mineral resources and reserves to be prepared in accordance with Canadian National Instrument 43-101 (NI 43-101). NI 43-101 requires all disclosure of estimates of potential mineral resources and reserves to be disclosed in accordance with its requirements. Such Canadian information is included herein to satisfy the Company’s “public disclosure” obligations under Regulation FD of the SEC and to provide U.S. holders with ready access to information publicly available in Canada.
Reporting requirements in the United States for disclosure of mineral properties under Guide 7 compared to the new SEC rules (Item 1300 of Regulation S-K under the Securities and Exchange Act of 1934) and the requirements in Canada under NI 43-101 standards are substantially different. This document contains a summary of certain estimates of the Company, not only of Proven and Probable reserves within the meaning of Guide 7, but also of mineral resource and mineral reserve estimates estimated in accordance with the new SEC rules and definitional standards of the Canadian Institute of Mining, Metallurgy and Petroleum referred to in NI 43-101. Under Guide 7, the term “reserve” means that part of a mineral deposit that can be economically and legally extracted or produced at the time of the reserve determination. The term “economically”, as used in the definition of reserve, means that profitable extraction or production has been established or analytically demonstrated to be viable and justifiable under reasonable investment and market assumptions. The term “legally”, as used in the definition of reserve, does not imply that all permits needed for mining and processing have been obtained or that other legal issues have been completely resolved. However, for a reserve to exist, Hecla must have a justifiable expectation, based on applicable laws and regulations, that issuance of permits or resolution of legal issues necessary for mining and processing at a particular deposit will be accomplished in the ordinary course and in a timeframe consistent with Hecla’s current mine plans. The terms “Measured resources”, “Indicated resources,” and “Inferred resources” are mining terms as defined in accordance with the new SEC rules and NI 43-101. These terms are not defined under Guide 7 and prior to January 1, 2021, were not normally permitted to be used in reports and registration statements filed with the SEC in the United States, except where required to be disclosed by foreign law. The term “resource” does not equate to the term “reserve”. Under Guide 7, the material described herein as “Indicated resources” and “Measured resources” would be characterized as “mineralized material” and is permitted to be disclosed in tonnage and grade only, not ounces. The category of “inferred resources” is not recognized by Guide 7. Investors are cautioned not to assume that any part or all of the mineral deposits in such categories will ever be converted into Proven or Probable reserves. “Resources” have a great amount of uncertainty as to their existence, and great uncertainty as to their economic and legal feasibility. It cannot be assumed that all or any part of such a “resource” will ever be upgraded to a higher category or will ever be economically extracted. Investors are cautioned not to assume that all or any part of a “resource” exists or is economically or legally mineable. Investors are also especially cautioned that the mere fact that such resources may be referred to in ounces of silver and/or gold, rather than in tons of mineralization and grades of silver and/or gold estimated per ton, is not an indication that such material will ever result in mined ore which is processed into commercial silver or gold.
(years ended December 31)
|
2019 |
2020 |
2021 |
2022 | 2023 | |
|---|---|---|---|---|---|
|
Silver (ounces) |
9,890,125 |
10,494,726 |
9,243,664 | 9,741,935 |
9,731,752
|
|
Gold (ounces) |
56,625 |
48,491 |
46,088 | 48,216 |
60,896
|
|
Lead (tons) | 20,112 | 21,400 |
19,873 | 19,480 |
19,578
|
|
Zinc (tons) |
56,805 | 56,814 |
53,648 | 52,312 |
51,496
|
The 2023 exploration program successfully expanded mineralization at Greens Creek. Four underground drills focused on resource conversion and exploration that extended or confirmed mineralization of known resource areas. Drilling was focused in the 9a, 200 South, 5250, East, 9a, West, Upper Plate, Gallagher, and Gallagher Fault Block zones.
In 2024, of the $25.4 million planned for exploration and pre-development spend, 35% is planned for Greens Creek. Definition and exploration drilling from underground will focus on the 200S, 9A, Gallagher, SW, and Upper Plate zones. Surface exploration drilling will target near-mine areas at Upper Plate, East Ore Offset, and Gallagher West. Surface drilling is also planned for the recently acquired Mammoth Claims northwest of the mine. Surface mapping and surface and airborne geophysics are also planned for the Greens Creek property.
Greens Creek is exploring a number of areas on the 23-square-mile land package which could potentially lead to additional reserves and resources, further extending the mine life or even leading us to find another deposit like Greens Creek. There are over 30 miles of mine horizon where mineralization has been identified and projected along surface on our property.
The Greens Creek deposit is a polymetallic, stratiform, massive sulfide deposit. The host rock consists of predominantly marine sedimentary and mafic to ultramafic volcanic and plutonic rocks, which have been subjected to multiple periods of deformation. These deformational episodes have imposed multiple folding of the orebodies to create a complex geometry. Mineralization occurs discontinuously along the contact between a structural hanging wall of quartz mica carbonate phyllites, and a structural footwall of graphitic and calcareous argillite.
Ore lithologies fall into two broad groups: massive ores with over 50% sulfides and white ores with less than 50% sulfides. The massive ores are further subdivided as either base-metal or pyrite dominant. Massive ores vary greatly in precious-metal grade from uneconomic to bonanza Au (>.5 opt) and Ag (>100 opt). White ores are subdivided into three groups by the dominant gangue mineralogy: white carbonate, white siliceous, and white baritic ore. These ores tend to be base-metal poor and precious-metal rich. Important minerals include pyrite, sphalerite, galena, and tetrahedrite/tennanite.
Greens Creek is an underground mine that produces approximately 2,300 tons of ore per day. The primary mining methods are cut and fill and longhole stoping.
The Greens Creek unit has historically been powered completely by diesel generators located on site. However, since 2006, Hecla has purchased excess hydroelectric power from the local power company, Alaska Electric Light & Power Company (“AEL&P”). This project has reduced production costs at Greens Creek when hydroelectric power has been available. Since 2009, hydropower has provided 77% of Greens Creek’s energy needs.
There are three main phases to the mining process: development, production, and backfilling.
Development – the tunneling or accessing phase
Using plans from the geology and engineering departments, miners drive tunnels 15ft high by 15ft wide to access the various ore zones to be mined.
Production – the extraction phase
The method of extraction depends upon the geological nature of the orebody involved. Some of the smaller, more contorted orebodies are extracted using the same tunneling procedure as the development phase. In other more massive orebodies, larger scale extraction methods are used, sometimes producing voids of up to 150ft long, 25ft wide and 120ft deep.
Backfilling – the replacement phase
The voids created during the production phase are filled up with a combination of mill waste (tailings) and cement. This “backfilling” process stabilizes the production voids and allows extraction of the ore beside, above, and even below the backfilled area.
Hecla is the largest private-sector employer and taxpayer in Juneau, and we are proud to be a strong community partner. Our employees regularly volunteer in the community, and in 2022, we made a direct economic impact in local communities of more than $219 million, including approximately $76.8 million in wages, $29 million in taxes and fees, and $112 million in purchases from vendors.
