The Coeur d’Alene Mining District, where Hecla was born 125 years ago, is located in North Idaho’s Silver Valley along Interstate 90. Access and infrastructure are excellent. This district has produced more than 1.2 billion ounces of silver in its history – one of the most prolific silver districts in the world. Hecla has a tremendous land position here consisting of about 27-square miles, which is an area roughly the size of Manhattan. On this land position are many historic mines, which in the aggregate have produced more than 340 million ounces of silver, or about 25% of the entire historic production of the Silver Valley.
Even though more than 340 million ounces of silver have been mined from Hecla’s land holdings within the Silver Valley, very little modern surface exploration has actually taken place. Hecla is looking at this old district in a new way and with new exploration tools. Successful exploration of old districts usually comes about as a result of people thinking about the geology differently, and that’s what Hecla’s geologists are doing here. They take the historic information and geologic data and reapply it, but without limiting themselves to historic thinking. They have the advantage of new technologies that allow them to take both a more comprehensive and more detailed look at the whole geologic structure of this great mining district. They are already identifying many prospective targets in this long-term exploration effort.
The geology of the Silver Valley district occurs within the Precambrian meta‐sedimentary rocks of the Belt Supergroup which is comprised of a thick sequence of clastic (argillites, siltites and quartzites) and carbonate sedimentary rocks. These rocks cover a large area of western Montana, most of northern Idaho, northeastern Washington, a large area in southeastern British Columbia, and portions of Alberta.
The district rocks are folded and traversed by long, WNW trending faults that cut the rock stratigraphy and host the economic veins in the area. The best developed mineralization is located where the faults cut favorable rocks that have good competency and break brittlely, such as quartzite. Consequently, some of the best grades and widest veins occur adjacent to thick lenses of quartzite or other competent rocks. The margins of the most mineralized veins have been bleached from hydrothermal processes and have associated silicification, often in conjunction with other types of alteration such as siderite and sericite.
A variety of vein types are recognized in the area including a dominant lead-silver (galena-tetrahedrite) vein, a silver-lead-zinc (tetrahedrite-galena-sphalerite) vein, a zinc (sphalerite) vein and a silver (tetrahedrite) vein. The productive veins can vary in width from four to 20 feet wide and extend along strike up to 1,500 feet. The most striking feature of these veins is the vertical continuity; current and past-producing veins have been mined consistently down-dip over 6,000 feet.
Information with respect to measured, indicated and inferred resources is set forth below.
|(As of December 31, 2019 unless otherwise noted)|
|(000)||(oz/ton)||(oz/ton)||(%)||(%)||(000 oz)||(000 oz)||(Tons)||(Tons)|
|Indicated Resources (1)||1,126||2.9||–||6.2||7.4||3,301||–||69,900||83,410|
|Inferred Resources (1)||3,157||2.9||–||5.6||5.5||9,432||–||178,670||174,450|
- (footnotes)Note: All estimates are in-situ. Resources are exclusive of reserves. Totals may not represent the sum of parts due to rounding.
(1) Indicated and Inferred resources reported using $21 silver, $0.95 lead, $1.10 zinc at a minimum mining width of 4.3 feet and a cut-off grade of $100/ton.
Reporting requirements in the United States for disclosure of mineral properties are governed by the SEC and included in 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). However, 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 being included here 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 and the requirements in Canada under NI 43-101 standards are substantially different. This website contains a summary of certain estimates of the Company, not only of proven and probable reserves within the meaning of Guide 7, which requires the preparation of a “final” or “bankable” feasibility study demonstrating the economic feasibility of mining and processing the mineralization using the three-year historical average price for any reserve or cash flow analysis to designate reserves and that the primary environmental analysis or report be filed with the appropriate governmental authority, but also of mineral resource and mineral reserve estimates estimated in accordance with the definitional standards of the Canadian Institute of Mining, Metallurgy and Petroleum referred to in NI 43-101. The terms “measured resources”, “indicated resources,” and “inferred resources” are Canadian mining terms as defined in accordance with NI 43-101. These terms are not defined under Guide 7 and are 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.
Several decades’ worth of geologic information on the past-producing mines on Hecla’s property has now been converted into digital format by the company. From this data, Hecla’s geologists developed three-dimensional (3D) computer models of more than 15 major mines and mine workings of 200 other underground projects. These models show the spatial relationship between mines and regional structures that control mineral and geologic trends and define highly prospective exploration targets. This information is defining brand-new drill targets, with four large exploration target areas identified so far. Detailed 3D modeling and resource assessment has been completed on the Star mine which closed in 1981 and was operated for a short period in the 1990s.The recent integration of the data in this area has defined previous mine resources and identified adjacent subsidiary structures that represent new mineral resources and strong exploration targets.
One of these exploration targets is the Noonday vein system, where Hecla’s exploration program in 2010 identified an inferred resource in a series of veins. Following up on the success at Noonday, Hecla’s 2011 surface exploration program targeted extensions of the Noonday and Noonday Split veins, as well as the You Like, Lucretia, Star, and Morning veins in the Star area. The 64 surface holes on the Noonday veins have extended the resource outline more than 500 feet along strike to the east and 1,500 feet down dip. To the east along the Noonday vein, there is a distinct increase in silver and lead grade. Success in the surface drilling program prompted Hecla to rehabilitate the underground workings on the Star 700 and 2000 levels in 2011 to provide access for underground drilling. Forty-three underground drill holes completed between 2011 and 2013 targeted the Moffitt, South Moffitt, North, North Star, North Wall, Noonday, Noonday Split, You Like and Wilkie veins, as well as the main Star and Morning veins. Significant silver, lead and zinc mineralization was intersected in each of the veins and several of the targets contribute indicated and inferred resources to the Star Complex.
Underground drilling is complete, and the Star underground infrastructure will be shut down until the Star data is integrated into the Lucky Friday optimization study.
Four major structural trends within the 27-square mile land package define a series of deposits that historically have produced over 350 million ounces of silver. Modern exploration techniques have been used to refine these trends and identify a number of outstanding targets that will be drilled from both surface and underground in the next few years.
One of these targets is located where drilling in 2010 along the You Like / 30 vein trend confirmed the presence of a two-mile long mineralized structure between the Lucky Friday Expansion area and the Star-Morning mine with localized high-grade intervals that have the potential to host a new mining center.