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The Providencia property, covering 152,400 acres, is located to the northeast of Sabinas Hidalgo on the main road to Laredo, Texas. It contains a number of high-target prospects--including the Vallecillo prospect and the La Blanca prospect. The Vallecillo prospect, named after the nearby village, is part of a historical mining district and contains six past producing mines. The La Blanca prospect, with additional old Spanish-era underground workings and more recent surface trenching (approximately 30 years old), is located an additional 25 kilometers to the north of Vallecillo.
Access to Providencia is gained through secondary but readily passable gravel roads north of the village of Vallecillo. Past Spanish workings at Vallecillo are located to the immediate north of the main highway and are accessible through all-season gravel roads.
Trenching work has recently been completed at the Vallicello and the La Blanca projects. Twenty-eight samples were taken from the mineralized part of the structure at La Blanca and returned silver values ranging from 897 g/t silver to 4,110 g/t silver with an average value of 2,112 g/t silver.Lead from these samples ranged up to 83 percent. Trenching results for the Vallecillo project have not yet been announced.
The first ever drilling has begun on these projects.
Geology & Mineralization
The Providencia property is located in the province of the Sierra Madre Oriental. It is underlain by a series of Cretaceous sediments consisting of laminated and massive limestones, lutites and some conglomerates. Most of the eastern part of the license area is of low topographic relief, and is covered by flat-lying Tertiary conglomerates.
The only exposed bedrock is located in the Vallecillo area, a 4-kilometer-long mining district of thin manto and vein deposits aligned along a northeast-trending structural zone. The mineralization consists of a series of northeast-trending, vein- and manto-type occurrences over a strike length of several kilometers. There are a number of shafts, underground workings and surface open-cuts.
The La Blanca prospect was exposed several decades ago in a now water-filled surface open-cut. Silver-zinc-lead mineralization, possibly north-northwest-trending, is hosted in claystone.
History
The Vallecillo mines, located in the southwest portion of the Providencia property, were originally worked by Spanish colonizers who apparently abandoned operations due to a combination of water problems and "constant incursions" by local peoples. The Vallecillo Silver Mining Company of New York bought the deposits in 1851. That company began operations at the old Jesus Maria mine, but water problems forced them to move about four kilometers to the east, to another Spanish-era operation, the Delores shaft.
By 1885 there were four shafts and an incline at the bottom of one of the shafts at Vallecillo within a distance of about 400 meters along the vein. The main working was the 150 meter deep Santiago shaft. Two other shafts had been sunk further to the west of this area, bringing the total known surface extent of the vein to approximately 500 meters. The Spanish had mined to a depth of about 50 meters and, as of 1885, mining had been done on five levels to a depth of about 120 meters. Workings had been developed to about 550 meters to the west, and 360 meters to the east of the Santiago shaft. It is unclear when production at Vallecillo ended.
In October 1982, the Consejo de Recursos Minerales conducted a study of the immediate Vallecillo area. The study briefly discussed the La Magnolia Mine, the Nuevo Mexico Mine, the La Colorada Mine, the Carmencita, the Indian and the La Cucaracha. They carried-out regional geologic mapping over an area of 286 square kilometers and completed a geologic-topographic study of the six mines mentioned above which covered a strike length of 772 meters and, in addition, visited three prospects and four collapsed and inaccessible mines as well as numerous shallow openings.
Exploration Work
Vallecillo displays significantly more lead-zinc-silver mineralization than La Blanca and is therefore considered to be a higher-priority target area for future exploration.
Exploration work includes:
- interpretation and integration of historic geologic data with newly generated information from surface and subsurface mapping and sampling
- generation of new geologic and assay data from all the projects through surface and underground geochemical sampling programs
- detailed surface geological mapping of the district at workable scables
- acquisition of data sets available to the public from private or government sources for the concessions
- evaluate the utilization of various geophysical survey techniques on various targets to determine response characteristics of the mineralization and host rocks
Mexican Silver Mines continues to maintain strong working relationships with the government's geological department to facilitate access to state data.
Howe recommended that after zones of mineralization have been identified and located, an initial bulldozer trenching program be implemented for sampling purposes to identify the most favorable targets for follow-up diamond drilling. Initial limited drilling (Phase 1) is recommended to test for vein and mantos mineralization at depths of up to 200 meters.
For La Blanca, Howe recommends a program to attempt to accurately determine the characteristics of mineralization through trenching. A specific plan for this area would include:
- draining and cleaning out the original trench with a bulldozer or backhoe
- detailed mapping and sampling of trenches
- limited Phase 1 drilling under the La Blanca occurrence to determine the geological setting and potential for mineralization at depth
As work proceeds, the airborne geophysical survey for La Blanca should be re-interpreted, especially for the possibility of regional structures crossing the immediate area and the area under the salt lake to the north of the original trench.
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