Global Resource: The Sierra Mojada Project currently has a NI43-101 compliant "measured and indicated" resource of 58.7 million tonnes grading at 3.6% zinc and 50 g/t silver for 4.670 billion pounds of zinc and 90.8 million ounce of silver.
This resource represents an average of the zinc, silver, copper and lead mineralization across the entire ore body and is broken into two parts; 1) A potentially open pittable resource which represents 96% of the total deposit, 2) An additional underground resource which represents mineralization that didn't make it into the open pit due to its depth, but may be economic if mined from underground. A summary of the Global resource is shown below
|GLOBAL NI43-101 COMPLIENT RESOURCE|
- -*NSR, Ag grades, & Ag ounces are from the LG optimized pit only.
- -- Mineral resources that are not reserves do not have demonstrated economic viability.
- -- Mineral resources are reported using a commodity price of US$18.00 silver and US$1.00 zinc with a 75% recovery assumed for silver and a 41% recovery assumed for zinc and reported at a $13.50 NSR cut-off.
- -- Tonnages are reported to the nearest 100,000 tonnes, grades are rounded to the nearest decimal place for Ag, Zn, & Pb and the nearest 2 decimal places for Cu.
- -- Rounding as required by reporting guidelines may result in apparent summation differences between tonnes, grade, and contained metal.
- -- Tonnage and grade are in metric units; contained Zn, Cu & Pb are in imperial pounds.
The resource was modeled using a zinc price of US$1.00 per pound and a silver price of US$18/oz with a recovery of silver estimated at 75% and for zinc at 41%. Mining costs were assumed to be US$1.50/tonne, and silver and zinc processing costs at US$12.00/tonne to give a total NSR cutoff for the resource of $13.50 per tonne. The underground component of the resource was estimated using a 6% cutoff grade.
Figure 1. The Global Resource represents a combined total of the resource defined in the open pit and underground.
The Zinc and Silver Zones: The Global resource encompasses two zones; the zinc zone, and the silver zone and represents an overall average grade for the silver and zinc mineralization across the entire deposit. This average grade does not accurately reflect the discreet, high grade zoning of the silver and zinc mineralization that occurs within the resource. To better reflect these high grade silver and zinc zones which form separate coherent bodies within the larger global resource we have broken out the zinc and silver mineralization using zinc and silver cutoff grades and include;
A high grade "Zinc Zone" of 10.03 million tonnes at an average grade of 11% Zinc at a 6% cutoff for 2.426 billion pounds of zinc.
A high grade "Silver Zone" of 19 million tonnes at an average grade of 102.5 g/t at a 50g/t cutoff for 62.6 million ounces of silver.
The Zinc and Silver Zones at various cutoff grades are shown in the tables below:
Figure 2. The Global resource encompasses two high grade zones, the Zinc Zone and the Silver Zone and shown at various cutoff grades in the above image.
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.
Zinc Zone: a well-defined very high grade zinc oxide ore body situated directly below and adjacent to the Shallow Silver Zone. It is a coherent ore body over 2 kilometers long and remains open to the east and is amenable to both open or underground mining.
Geologic Setting: 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".
The information set forth above constitutes forward-looking statements. See "Cautionary note regarding forward looking statements". We also advise U.S. investors that the terms used above to estimate our mineral reserves are not recognized by the U.S. Securities and Exchange Commission. See "Cautionary note to U.S. investors concerning estimates of Measured, Indicated and Inferred Resources." http://www.silverbullresources.com/s/disclaimer.asp