Information with respect to estimated resources is set forth below.
(as of December 31, 2010)
Tons |
Silver (oz/ton) |
Gold (oz/ton) |
Zinc (%) |
Lead (%) |
Silver (oz) |
Gold (oz) |
Zinc (tons) |
Lead (tons) |
|||
| Estimated Resources (1) |
517,900 |
2.0 |
– |
9.8 |
3.6 |
1,061,500 |
– |
51,000 |
18,600 |
(1) Inferred resources for Noonday and Noonday North Split veins, diluted and factored to minimum mining width.
The United States Securities and Exchange Commission permits mining companies, in their filings with the SEC, to disclose only those mineral deposits that a company can economically and legally extract or produce. We use certain terms on this website, such as "resource," "other resources," and "mineralized materials" that the SEC guidelines strictly prohibit us from including in our filing with the SEC. U.S. investors are urged to consider closely the disclosure in our Form 10-K, included on this website.
overview
The Coeur d’Alene Mining District, where Hecla was born 120 years ago, is located in North Idaho’s Silver Valley along Interstate 90. Access and infrastructure are excellent. This district has produced 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 25-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.
geology
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 curvilinear 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.
exploration
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 80 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 reserves and 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 16 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. Two of the better holes intersected a 9.6-foot horizontal thickness of 13.0 ounces per ton silver and 22.2% lead and a 5.3-foot horizontal thickness of 14.1 ounces per ton silver and 15.3% lead. Further north the Morning vein was intersected and contains significant silver-lead. Finally the North vein which is a northern extension of the Star-Morning vein has a strong lead-zinc intersection. In addition to these highly mineralized veins, the You Like and Lucretia targets hit a high-grade 1.4 foot wide intersection of 48.4 ounces per ton silver, 3.4% lead, and 0.3% zinc, and 1.0 foot wide intersection of 13.3 ounces per ton silver, 15.3% lead, and 8.9% zinc.
Successes at Noonday, coupled with the depth limitations of surface drilling, prompted the re-opening of the Star 2000 level drift in 2011 for underground exploration drilling. The Star 2000 rehabilitation has been successfully completed to allow preparation of two underground drill stations which will be operational in late 2011. An underground drilling program will follow-up on the surface drilling and evaluate extensions of past-producing vein systems (Star, Noonday, Noonday Split, Moffit, Crandall and North) in proximity to historic mine infrastructure. The current understanding of the vein structures suggests potential to define in excess of 25 million ounces of silver with significant zinc and lead above the water table.
The exploration program in 2012 for the Silver Valley will include expanding the Noonday resources along strike; evaluating at least five other vein structures with underground drilling in the Star mine; and drilling extensions of mineralization in the Tamarack Sherman and Hercules areas north of Burke, Idaho.
future upside
Four major structural trends within the 25-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.
In addition, drilling of the Noonday and Noonday Split veins, located near the past-producing Star mine and two miles northwest of Lucky Friday, intersected a number of high-grade silver, zinc, and lead veins that constitute a new resource with significant potential to expand, which we will continue to evaluate.
Drilling in 2010 along the You Like / 30 vein trend also confirmed the presence of a two-mile long mineralized structure between the Lucky Friday Extension and the Star-Morning mine with localized high-grade intervals that have the potential to host a new mining center. Additionally, Hecla is launching the first surface exploration drilling program in decades in the historic Hercules and Tamarack mine areas north of the Star mine.
The exploration program for the Lucky Friday / Silver Valley in 2011 is approximately $8 million.
(Q3 2011)
| Area |
Width (Feet) |
Silver (oz/ton) |
Zinc (%) |
Lead (%) |
||
Noonday Split North Vein Morning
|
3.0 4.0 5.3 5.2 1.4 1.0 9.6 1.9 1.5 5.3 4.0 8.0 5.7 4.3 4.5 |
18.3 13.1 14.1 10.3 18.3 14.0 13.0 16.2 5.2 9.2 7.9 5.1 4.3 2.2 18.3 |
23.2 6.9 15.3 9.8 13.1 15.1 22.2 24.8 5.5 6.0 11.3 3.1 6.4 7.6 23.2 |
0.0 0.0 3.0 0.0 0.0 0.0 0.1 0.0 0.0 0.2 0.2 0.0 0.2 15.3 1.7 |
(Q4 2010)
| Area |
Width (Feet) |
Silver (oz/ton) |
Zinc (%) |
Lead (%) |
||
| Noonday Noonday Noonday Noonday Noonday Noonday Noonday Noonday Split Noonday Split Noonday Split Noonday Split |
2.6 2.8 3.3 1.6 2.5 2.1 5.8 3.1 0.4 8.2 5.1 |
9.3 5.3 4.3 9.3 21.0 0.6 4.4 4.1 2.9 1.3 6.4 |
6.4 14.0 10.7 2.5 27.0 5.3 0.7 16.4 30.9 17.5 47.8 |
2.5 10.2 2.7 6.4 11.8 0.4 4.4 3.4 1.5 2.9 12.7 |
latest assay table results (between Star Mine and 30 Vein)
(Q4 2010)
| Area |
Width (Feet) |
Silver (oz/ton) |
Zinc (%) |
Lead (%) |
||
| Lucretia Lucretia YLK-30 Vein YLK-30 Vein YLK-30 Vein |
1.5 5.0 2.6 2.8 2.5 |
4.3 1.4 19.0 6.6 26.8 |
1.0 0.0 0.1 0.0 0.0 |
0.0 1.3 0.3 0.1 0.5 |