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) |
1,142,500 |
8.0 |
0.010 |
4.4 |
2.9 |
9,186,200 |
14,300 |
49,900 |
33,000 |
(1) Inferred resources, Hugh Zone (Deep Francine), diluted and factored to minimum mining width. Also includes 2.1% copper (23,500 tons)
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
Our concession holdings cover approximately 85,000 hectares (325 square miles), including the Francine vein, the Hugh Zone, and the Don Sergio-Andrea vein system and multiple outlying active exploration areas in the middle of the prolific Mexican Silver Belt. Production from the Francine intermediate sulfidation epithermal vein consisted of high-grade silver with significant gold credits. Production from the Don Sergio low sulfidation epithermal vein consisted of near-surface, high-grade gold with some silver credits. Mineral concession titles are obtained and held under the laws of Mexico, and are valid for 50 years with the possibility of extending another 50 years. There are work assessment and tax requirements that are variable and increase with the time that each concession is held.
Underground development along the Francine vein started in May 2001, and reached full production during the second quarter of 2002. Mining of economic ore on the upper Francine vein was completed during the first quarter of 2005. The mine has been placed on care and maintenance as exploration continues on the property, including the Hugh Zone, which is located 100 to 600 meters below historic mining. Mining of economic ore on the Don Sergio vein was completed in the fourth quarter of 2005 and reclamation of this portion of the mine site was completed during 2006. San Sebastian’s life-of-mine production over four years was 11.2 million ounces of silver and 155,937 ounces of gold. The Hugh Zone currently has a resource consisting of 1,142,500 tonnes grading 274.24 g/t Ag, 0.342 g/t Au, 2.9% Pb, 1.82% Cu, and 4.4% Zn and contains 9,186,200 oz Ag, 14,300 oz Au, 33,000 tonnes Pb, 24,193 tonnes Cu, and 49,900 tonnes Zn.
geology
Similar to numerous world-class mines in the Mexican Silver Belt, mineralization in the Francine and Don Sergio vein systems in the Saladillo district is hosted in Mesozoic sedimentary rocks and is closely associated with Tertiary volcanic and intrusive rocks. Two NW-WNW oriented regional scale structural features that pass through the Saladillo district are known to be important controls of mineralization throughout the Mexican Silver Belt and at the Saladillo district. In contrast to the NW and WNW oriented structures, a set of NE oriented district to regional scale faults traverse the center of the district. The confluence of these deep-seated WNW, NW and NE structures appears to be an important factor for the localization of the mineralizing systems at the Saladillo district.
Several intermediate sulfidation epithermal veins occur within the Saladillo Valley and include the Francine, Profesor, Middle and North vein systems. These veins are proximal to each other, and are hosted within a series of shales with interbedded fine-grained sandstones interpreted to be the Cretaceous Caracol Formation. The Don Sergio, Jessica, Andrea and Antonella veins located in the Cerro Pedernalillo area, about five kilometers from Francine, are end member low sulfidation epithermal veins hosted by the same formation with the addition of dioritic intrusive rocks.
The past-producing Francine vein strikes northwest and dips southwest, and is located on the southwestern limb of a doubly plunging anticline. The vein ranges in true thickness from more than four meters to less than one meter, and consists of several episodes of banded quartz, silica-healed breccias and minor amounts of calcite. Hugh Zone mineralization contains chalcopyrite, sphalerite, galena, argentite, acanthite, tetrahedrite, polybasite, stephanite, freibergite, and pyrargyrite.
exploration
In Mexico, the Hugh Zone is a high-grade, base metals-rich zone located 150 meters down dip from the deepest levels mined on the past-producing Francine Vein. A scoping study was initiated to update the 2005 Hugh Zone scoping study. The Andrea vein is an expanding, silver and gold-rich resource about six miles from the Francine vein.
The Andrea vein is a high-grade, exclusively silver and gold-rich epithermal vein system. Recent drilling at the Andrea vein included three core rigs, drilling in-fill holes along the Andrea vein to complete a resource by year-end. The Andrea drilling program results have more than doubled the strike length to 1.7 kilometers since late 2010. Drilling to date has defined two higher-grade gold and silver zones within this vein including the shallower northwest zone and the deeper southeast zone. The gold dominant northwest zone northwest zone outcrops at surface, is oxidized for the first 75 meters, and can be traced for 800 meters. The veins range from 0.5 to 4.5 meters in width with grades ranging between 0.5 to 4.5 grams per ton gold and 20.4 to 378.4 grams per ton silver. The deeper silver gold-rich southeast zone is currently 700 meters in strike length at a depth of 250 to 600 meters but is open at depth to the southwest. The Andrea vein in this zone varies from 1.5 to 6.51 meters and has precious metal grades that vary from 0.2 to 4.0 grams per ton gold and 15.2 to 418.0 grams per ton silver.
Recent intersections of precious-metal veining on the Andrea vein are included in the latest assay table to the right. Up to three drills will be providing both in-fill and exploration holes in the third and fourth quarters to refine and expand a precious-metal resource along the Andrea vein.
Although the Don Sergio vein was partially mined in 2002 to 2005 the remaining portions may be economically viable at today’s commodity prices. Initial 3D and economic modeling indicate that remnant Don Sergio mineralization and the newly intersected Andrea vein may represent an economically viable target due to their close proximity and integration with the Hugh Zone vein.
Hecla has dedicated a budget of $6 million for the 2011 exploration program at San Sebastian within the Saladillo district.
future upside
The San Sebastian property encompasses highly favorable terrain, with mineralization styles ranging from precious-metal epithermal veins to near-surface bulk tonnage mineralization. The Hugh Zone is a high-grade depth extension of the past-producing Francine vein and in combination with new discoveries will be the focus of new scoping and feasibility work and potential production at San Sebastian. Recent high-grade, gold-silver drill intersections at the Andrea vein has necessitated a re-examination of the nearby, past-producing Don Sergio mine. With continued drilling success, a new resource and conceptual mine plan combining the Andrea and Don Sergio veins into an independent mining unit could emerge in early 2012. A shallow drilling program at Cerro Santiago has been completed and the drilling has defined a multiple vein system that extends for at least one kilometer.
(Q3 2011)
| Area |
Width (meters) |
Silver (g/tonne) |
Gold (g/tonne) |
||
Southeast |
4.37 6.51 4.20 4.41 1.15 4.08 1.79 0.77 0.50 |
418.0 194.8 59.0 57.5 378.4 15.9 214.5 213.1 253.3 |
4.0 0.7 0.4 0.5 2.2 0.9 2.5 2.1 0.8 |
(Q1 2011)
| Area |
Width (meters) |
Silver (g/tonne) |
Gold (g/tonne) |
||
PED-14 |
4.72 1.01 1.24 1.93 1.30 |
178.9 284.4 340.6 140.9 261.2 |
1.947 0.911 0.586 1.155 2.392 |
(Q4 2010)
| Area |
Width (meters) |
Silver (g/tonne) |
Gold (g/tonne) |
||
| PED-08 PED-09 PED-11 |
1.79 0.28 1.22 |
214.5 241.0 779.1 |
2.532 8.510 3.101 |