 |  | ||||||||||
| |||||||||||
|
|
  The San Martin project, located some 50 km east of the City of Querétaro in Querétaro State, is readily accessible by car in a few hours from Mexico City. The project consists of seven underground mining units (San José I, San José II, San Martin and Cuerpos numbered 28, 29, 30 and 31) and three undeveloped Cuerpos under exploration, numbered 32, 33 and 34, offset by echelon faulting in a north-northeast direction.  Click on map to view enlarged Also the San Pedrito project, located 45 km west of the San Martin mine, is being explored and later, if an economic deposit is outlined, the ore would be trucked to the San Martin mill for processing. High grade mineralization was discovered at San Martin in the 18th Century, and is reported to have been mined over a period of 40 years, however, no production records exist. Between 1900 and 1924, an estimated 250,000 tonnes at a grade of 15 g Au/t and 100 g Ag/t was reportedly mined. In 1982, the area was declared a National Reserve; however, by 1986, Luismin had reached an agreement to conduct exploration/exploitation in the area. Mining began in 1993 at 300 tpd and the production increased on yearly basis to the present rate of 747 tpd with future plans to increase the capacity to 1,100 tpd. Exploration has been concentrated along the breccia zone, but was also been carried out at the San Pedrito project. Two types of orebodies called "mantos and troncos" occur in the San Martin Mine district and the names of the orebodies depend upon their orientation (horizontal and vertical respectively). The mineralization generally is made up of breccia material that normally is concordant with the contact of the volcanic dome thus the mineralization can be projected along the strike and dip of the volcanic dome and this geological feature has been successfully used as a guide to explore for adjacent mantos. Exploration to date has shown that 100% of this horizon has been economic and this geological feature has been used as a guide to determine if the exploration is above, within or below target. Recent exploration has shown that the other side of the dome to also be mineralized and this has opened up considerably the areas for exploration, as to date only one side of the dome has been exploited. The economic breccia mineralization grades from 30 g Ag/to to 250 g Ag/t together with 2.0 g Au/t to 30 g Au/t over widths that vary from 1.0 to 17.0 m but average 4.0 m. The mantos occur as horizontal to 30°E dipping bodies as are clearly observed in orebodies 28, 29, 30 and 31, while the troncos in general dip 50° to 70° SE.  Click on map to view enlarged  Click on map to view enlarged Mineralization occurs in Upper Cretaceous black limestone and calcareous shales of the Soyatal Mexcala Formation as electrum, and silver selenide minerals principally associated with quartz and to a lesser degree with calcite. The deposit is an epithermal, probably high sulphidation precious metal (Ag-Au) type (metal ratio Au:Ag at 1:10), related to a Tertiary dacitic/andesitic intrusive dome. At San Pedrito, numerous epithermal quartz-calcite veins (Paulina, Ramales, Los Cuates, Mina Grande II, Los Cuates II, Los Cuartos, San Eduardo, and Mary) are hosted in andesite, however, much of the mineralization is below the water table and will require the lowering of the water table to be mineable. The city of Querétaro obtains some of its water requirements from wells in the general mine area and talks have been held between city officials and San Martin mine personnel to increase the rate of pumping and drawdown the water table. The level of the water table at San Pedrito is dropping. Until the water table is lowered, the mineralization outlined has been classified as Mineral Resources. Work has been concentrated on the Paulina vein where higher grade silver mineralization occurs, which when processed with the San Martin ores, improves silver recoveries at the San Martin mill. Procedures for sample collection, preparation and estimation of Mineral Resources/Mineral Reserves at San Martin and San Pedrito are similar to those done by Luismin at the other operating mines with the following differences:
For the manto blocks where high values are more homogenous, the high values are cut to the average value and a new average value calculated. A 10% decrease at zero grade is applied to all blocks to account for mine dilution. Manto projections are based on the average width and the average grade of the block. The total Proven and Probable Mineral Reserves estimated as of December 31, 2006 at San Martin are 1.03 million tonnes at a grade of 43 g Ag/t and 3.66 g Au/t as follows: Proven and Probable Mineral Reserves - San Martin
Notes to Reserve Statement 1. Reserves were estimated by Luismin and audited by WGM as of December 31, 2006. 2. Cutoff grade based on total operating cost of US$30.18 per tonne. 3. All reserves are diluted at 10% zero grade, a mining recovery factor has not been applied but WGM estimates that the mining recovery will be approximately 90%. 4. The tonnage factor is 2.7 tonnes per cubic metre. 5. Cutoff values are calculated at a silver price of US$6 per troy ounce and US$400 per troy ounce for gold. Total Inferred Mineral Resources at the San Martin mine (excluding San Pedrito), as of December 31, 2006 estimated and separately reported by Luismin, are about 1.88 million tonnes at an approximate grade of 3.75 g Au/t and 58 g Ag/t. Inferred Mineral Resources are not known to the same degree of certainty as Mineral Reserves and do not have demonstrated economic viability. The Total Inferred Mineral Resource estimated by Luismin at San Pedrito as of December 31, 2006 is about 1.125 million tonnes at an approximate grade of 221 g Ag/t and 0.63 g Au/t. The Mineral Resource estimate at San Martin and San Pedrito was carried out by Luismin in 2006 using the same approach as for their other projects at San Dimas. Luismin has had success transforming the estimated Inferred Mineral Resources at San Martin into Proven and Probable Reserves on a yearly basis. During the period 1997 to August 2003, the transformation of the estimated Inferred Mineral Resources into Mineral Reserves plus production is 133% (i.e. original estimate underestimated the amount of Inferred Resources by 33%). The San Martin mine produced 266,039 tonnes in 2006 at a grade of 52 g Ag/t and 2.82 g Au/t from an underground cut-and-fill operation. Primary access is by adit using LHD equipment. The San Martin mill operated at an average rate of 771 tpd in 2006 yielding an approximate 54% silver recovery and a 92% gold recovery. The mill uses a conventional cyanidation process with zinc precipitation and refinery production of gold and silver doré. The mill also processes on a toll basis the flotation concentrate from La Guitarra, a formerly owned mining operation, as well as another separately owned mining operation. In 2006, the San Martin operation produced 22,004 oz of gold and 235,805 oz of silver. Click here to view a Technical Review of the San Martin Project, Mexico Mar 26, 2007 (PDF 4.7MB)  Click on map to view enlarged * Excerpt from the San Martin 43-101 titled 'A TECHNICAL REVIEW OF THE SAN MARTIN PROJECT, MEXICO' Amended March 23, 2007, Revised February 1, 2007.
 Click on map to view enlarged |
Copyright © 2008 Starcore International Mines Ltd. All Rights Reserved.