Sierra Mojada
Overview
Location
The Sierra Mojada project lies within a historical high grade silver, lead, zinc mining district discovered in 1879, located 250km North of the city of Torreon in Coahuila State, Mexico. The project is 100% owned and operated by Silver Bull Resources, Inc. and is part of a large land package consisting of 40 mining concessions totalling 21,167 hectares (52,305 acres). The main zone of mineralization found at Sierra Mojada extends over 6 kilometers in an East-West direction along the base of the Sierra Mojada Range coincident with the Sierra Mojada fault. Over 54 historical mine shafts lie along this strike, mining to depths in-excess of 200 meters. The area has not been mined with modern mining technology and processes.
NI43-101 Resource Estimate
An updated NI43-101 Technical Report ("the Technical Report") currently being completed by JDS Energy & Mining Inc. ("JDS") on the silver and zinc mineralization of the "Shallow Silver" and "Zinc" Zones at the Sierra Mojada Project in Coahuila, Mexico, and is expect to be filed on our about April 15, 2013. Highlights at various cutoff grades for the silver include;
- An Indicated silver resource of 72.9 million tonnes at an average grade of 69.5g/t silver totaling 162.9 million troy ounces of silver at a 25g/t silver cutoff grade.
- An Indicated silver resource of 43.5 million tonnes at an average grade of 93.9g/t silver totaling 131.3 million troy ounces of silver at a 45g/t silver cutoff grade.
- An Indicated silver resource of 23.8 million tonnes at an average grade of 123.3g/t silver totaling 94.5 million troy ounces of silver at an 80g/t silver cutoff grade.
- An Indicated zinc resource of 2.41 billion pounds of zinc at an average grade of 1.50%.
- An Inferred lead resource of 547 million pounds at an average grade of 0.34%.
- An Inferred copper resource of 129 million pounds at an average grade of 0.08%.
| Silver & Zinc Resource Inside the Lerchs-Grossman Optimized Pit | ||||||
|---|---|---|---|---|---|---|
| Category | Silver Cut off Grade (g/t) | Tonnes | Silver Grade (g/t) | Silver (M-Oz) |
Zinc Grade (%) | Pounds Zinc (lbs) |
| INDICATED | >15 | 95,022,002 | 57.9 | 176.9 | 1.34 | 2,807,000,000 |
| >25 | 72,914,248 | 69.5 | 162.9 | 1.50 | 2,411,000,000 | |
| >35 | 55,386,287 | 82.2 | 146.4 | 1.64 | 2,003,000,000 | |
| >45 | 43,492,968 | 93.9 | 131.3 | 1.81 | 1,736,000,000 | |
| >55 | 35,278,796 | 104.4 | 118.4 | 1.99 | 1,549,000,000 | |
| >65 | 29,569,152 | 113.1 | 107.5 | 2.15 | 1,403,000,000 | |
| >80 | 23,827,196 | 123.3 | 94.5 | 2.36 | 1,239,000,000 | |
| >100 | 18,418,873 | 134.0 | 79.4 | 2.63 | 1,067,000,000 | |
In addition to silver and zinc in the "indicated" category, an "inferred" resource of lead and copper was also estimated based on the various silver cutoff grades. The lead and copper resource is as follows:
| Lead & Copper Resource Inside the Lerchs-Grossman Optimized Pit | ||||||
|---|---|---|---|---|---|---|
| Category | Silver Cut off Grade (g/t) | Tonnes | Lead Grade (%) | Pounds Lead (lbs) | Copper Grade (%) | Pounds Copper (lbs) |
| INFERRED | >15 | 95,022,002 | 0.3 | 628,000,000 | 0.07 | 147,000,000 |
| >25 | 72,914,248 | 0.34 | 547,000,000 | 0.08 | 129,000,000 | |
| >35 | 55,386,287 | 0.39 | 476,000,000 | 0.09 | 110,00,000 | |
| >45 | 43,492,968 | 0.43 | 412,000,000 | 0.10 | 96,000,000 | |
| >55 | 35,278,796 | 0.46 | 358,000,000 | 0.11 | 86,000,000 | |
| >65 | 29,569,152 | 0.49 | 320,000,000 | 0.11 | 72,000,000 | |
| >80 | 23,827,196 | 0.53 | 278,000,000 | 0.12 | 63,000,000 | |
| >100 | 18,418,873 | 0.58 | 235,000,000 | 0.12 | 49,000,000 | |
Mineralization
The Sierra Mojada project contains 2 distinct zones:
Shallow Silver Zone: a near surface silver oxide zone (+/- zinc & lead) hosted along the Sierra Mojada fault system. Supergene processes have re-mobilized and re-constituted an original sulphide mineralization as oxides into the current 'manto' deposit style we see today hosted in the fault system. It is a coherent ore body that is 3.8km long, up to 200m wide and 140m thick with an average grade of 70g/t Ag (25g/t cutoff), consisting of 162.9Moz silver.
Zinc Zone: a well-defined zinc oxide ore body situated directly below and adjacent to the Shallow Silver Zone, containing 2.41Blbs of indicated zinc metal at an average grade of 1.50% Zn. Mining out the silver resource above decreases the strip ratio to mine the zinc oxide and dramatically improves the economics of extraction.
Geologic Settings
The geology is composed of a well preserved Cretaceous carbonate platform typical of a marine transgression deposited on top of Jurassic 'San Marcos' Red Bed conglomerates. The main zone of mineralization is hosted along the Sierra Mojada fault which lies at the base of the Sierra Mojada Massif and cross cuts the rock package in an east-west direction.
The mineralization at Sierra Mojada has strong analogies with a number of different deposit styles which includes; Carbonate Replacement Deposits (CRD), Irish-type deposits, and possibly Mississippi Valley Type (MVT). Although an intrusive system has yet to be found, elevated copper, molybdenum, arsenic, and mercury in the area all point to a likely intrusive source.
A second step in the forming of the main zone at Sierra Mojada has seen supergene processes re-mobilize and re-constitute the original sulphide mineralization as oxides into the current 'manto' deposit style we see today. This cyclical leaching over a long period of time has in particular mobilized the silver and zinc in the system and re-deposited them into the fracture and cavern (karst) systems developed along the Sierra Mojada fault zone. The different solubility of these metals has resulted in a crude "zoning" within the ore body, creating zones that are "silver rich", and "zinc rich".