Oro Silver Resources Ltd.

Oro Silver Resources Ltd.

February 11, 2010 08:00 ET

Oro Silver Targets Silver Potential Below the El Compas Gold Mine, Zacatecas, Mexico

VANCOUVER, BRITISH COLUMBIA--(Marketwire - Feb. 11, 2010) - Oro Silver Resources Ltd. ("Oro Silver or the "Company") (TSX VENTURE:OSR) has completed clay, geophysical, structural geology, and satellite image surveys on its El Compas property within the Fresnillo Trend near Zacatecas, Mexico (see Map 1). These surveys suggest significant potential exists for discovery of high-grade silver below the gold bearing zones at the mine site. These studies have indicated some significant findings:

  • A compilation of the 2009 survey results indicate high-grade silver may exist below the gold bearing zones at El Compas, El Orito, and the northwest trending Escuadra Fault (this theory is supported by a drill hole completed by Hochschild Mining in 2006 which intersected 703 g/t silver and 4.1 g/t gold over 0.9m at 425m below surface).
  • Geological studies at El Compas show epithermal style mineralization similar to other veins systems in the Zacatecas region, including MAG Silver's Juanicipio Project (resource: 238 Million ounces silver).
  • Clay studies indicate that mineralogy can be used at El Compas for target vectoring gold and silver veins. 

"The potential for significant high-grade silver veins exists below the El Compas mine and all the studies seem to support our conceptual model. These surveys have enabled us to plan a carefully designed drill program targeting silver which will get underway this month. It's important to remember that prior to the Mexican revolution, in the 1930's, most mines were located at shallow depths and only recently has modern exploration been applied to these old mining districts. We expect that more announcements like the Juanicipio Project discovery will occur in the Zacatecas area," stated Darren Bahrey, President of Oro Silver.

Summary of the surveys conducted

In order to better understand the geology at El Compas the Company conducted geological bedrock mapping (both on-surface and underground), clay mineralogy surveys, satellite imagery, and geophysical studies over the areas of known mineralization, and elsewhere on the property. The objective of these surveys was to help guide upcoming drilling efforts to test silver targets located beneath the near-surface gold targets. These surveys have been used successfully elsewhere in the Zacatecas district. 


Clays are a component of weathered bedrock, and also may be related to hydrothermal alteration. There are many different types of clay, each having a unique chemical composition. Clay studies can be used in mineral exploration to vector towards mineralized zones since certain clays are found to be located closer than others to precious metal bearing bodies. Clay studies suggest that high-grade silver mineralization may be located at deeper levels below the El Compas mine. 

Eighty-five reconnaissance clay samples were collected within 1.6 km of the El Compas mine and then analyzed by infrared spectroscopy. The results of the sampling indicate clay mineral zonation that is spatially related to known mineralized structures. The zoned alteration assemblage is characterized by: (1) proximal buddingtonite and arsenate/phosphate clay mineral; (2) intermediate kaolinite; and (3) distal smectite. Buddingtonite is part of the advanced argillic alteration assemblage and is strongly associated with the mineralized hangingwall sections of the northwest-trending Escuadra Fault system and not with the north-south trending mineralized structures. At the Fresnillo mine (the world's largest silver mine), located approximately 45 kilometres to the northwest, buddingtonite is associated with northwest structures on the flanks of the deposit. 

In addition to clay sampling, regional scale detection and mapping of clay alteration was carried out using ASTER satellite imagery by multispectral and hyperspectral analysis. Both the multispectral and hyperspectral data identified large areas of clay alteration, especially in the western portion of the El Compas property. Hyperspectral data identified combinations of kaolinite, smectite, illite, and dickite roughly coincident with results of the multispectral analysis. The presence of a large clay alteration zone suggests the upper part of a potentially large epithermal system (see map 2) has been preserved and that the main precious and base metal mineralized zones could exist at depth in the vicinity of the El Compas mine.


Geophysical surveys were conducted to help understand the geology, structure and possible orientations of the mineralized veins. Induced Polarization (IP) and magnetometry (mag) geophysical orientation surveys were conducted over the El Compas mine and other important target structures, to determine the effectiveness of geophysics as a prospecting and subsurface mapping tool. North-south oriented IP lines identified the northwest trending Escuadra Fault as a strong southwest dipping resistivity low, to a depth of more than 300m. East-west oriented mag lines delineated magnetic lows coincident with the main trend of the El Compas ore body. IP appears to be an effective method for identifying and mapping the Escuadra Fault and possibly other less obvious but potentially important northwest structures. Magnetometry, demonstrated an ability to map alteration zones associated with north-south trending vein systems such as El Compas. These surveys will allow the Company to identify and delineate prospective target structures below the El Compas mine and elsewhere on the property.


The Zacatecas district hosts several, high-grade, silver deposits along the Fresnillo Trend primarily within northwest trending structures. In nearby mines sites such as El Bote, Cozamin, Veta Grande, and Fresnillo, tectonic uplift and subsequent erosion over millions of years has removed the upper gold rich zone; consequently these deposits are all characterized by low gold, high silver, and high base metal content representing the deeper parts of an epithermal system (see maps 2 and 3). More recent discoveries along the Fresnillo Trend include MAG Silver's Juanicipio project.

At both El Compas and Juanicipio, post-mineral erosion has not removed the higher elevation (upper), gold-rich portion of the epithermal vein system (see map 2). At El Compas, one hole completed in 2006, by another explorer, intersected the northwest striking Escuadra Fault. A 0.9-metre wide quartz vein sample within this fault (structure) returned 4.1 g/t gold and 703 g/t silver at a vertical depth of 425 metres below surface. This is similar to the first exploration holes drilled at Juanicipio in terms of width, grade, and depth. Subsequent deeper drilling at Juanicipio discovered a silver-rich bonanza zone about 150 metres below the first exploration holes. Similarities to MAG Silver's Juanicipio property, and past-producing Cantera and El Bote mines (historical production of 250-300 million ounces silver, 7 kilometres to the north) coupled with survey results provide strong support for discovering high-grade silver and gold mineralization at depth below the El Compas mine. Mr. Thomas Bagan, P. Eng is a qualified person as defined by National Instrument 43-101 and has reviewed the content of this press release.

About Oro Silver

Oro Silver is a silver exploration company pursuing early and advanced stage silver-based opportunities in Mexico. Oro Silver's mandate is to develop properties toward silver production through a strategic business arrangement and development plan focused on advanced-stage projects with known silver resources that exhibit potential for expansion. The El Compas mine continues to be the cornerstone for Oro Silver's growth strategy in the Zacatecas silver district. The Zacatecas silver district is the world's largest silver district and is well known for its silver production as the Fresnillo Mine 45km to the northeast, held by Industrias Peñoles, currently produces over 31 million ounces of silver annually from high-grade (23 oz/T Ag plus up to 0.1 oz/T Au) veins. Fresnillo commenced mining around 1560 and has produced about 800 million ounces of silver.


Tom Bagan, P.Eng., Chief Operating Officer

Some statements in this release may contain forward-looking information. These statements include, but are not limited to, statements with respect to future exploration, resource estimation, development and production activities and future expenditures. These statements address future events and conditions and, as such, involve known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the statements. Such factors include, among others, the time and success of future exploration, development and production activities and the timing and amount of expenditures.

To view Map 1:  Zacatecas District, please visit the following link: http://media3.marketwire.com/docs/osr_0211_map_1.pdf

To view Map 2:  El Compas Comparison, Zacatecas District, please visit the following link: http://media3.marketwire.com/docs/osr_0211_map_2.pdf

To view Map 3:  Idealized Vein Model Zacatecas District, please visit the following link: http://media3.marketwire.com/docs/osr_0211_map_3.pdf

Neither the TSX Venture Exchange nor its Regulation Services Provider accepts responsibility for the adequacy or accuracy of this release.

Contact Information

  • Oro Silver Resources Ltd.
    Ariel Cobangbang
    (604) 646-1586
    Oro Silver Resources Ltd.
    Suite 1400-625 Howe Street,
    Vancouver, BC V6C 2T6
    604 646-1585
    604 642-2411 (FAX)