Guanajuato District

Guanajuato, Mexico

Main commodities: Ag Au
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The Guanajuato mining district is located in the state of Guanajuato, some 400 km NW of Mexico City, Mexico.

Mining has been carried on in the district continuously for over 400 years to yield to 1990 a total of 34 850 tonnes Ag and 175 tonnes of Au.

Three extensive NW-SE trending mineralised fault systems are known in the district, cutting the 850 m thick Tertiary volcanics and clastics of the Sierra Madre Occidental, up to but not including the Oligocene member.   These volcanics overlie a Mesozoic sequence of black mudstones with local micritic limestone bands.

The most extensive of the three vein systems extends over a strike length of 25 km and widths of up to 90 m, with associated mineralised breccias.   Veins are made up of bands of amethyst, chalcedony and clear quartz, interlayered with base and precious metal sulphides and sulphosalts, with ore occurring as a series of shoots within the vein.   The breccias are developed in flexures in the vein systems and consist of silicified fragments of all host lithologies, quartz and vein ore in a quartz and chalcedony matrix.

Ore minerals are predominantly silver sulphides and sulphosalts, electrum, galena, sphalerite, chalcopyrite and pyrite.

Production in 1990 was 35 000 tonnes of ore per month @ 150 g/t Ag, 1.5 g/t Au.

For more detail consult the reference(s) listed below.

The most recent source geological information used to prepare this summary was dated: 1991.    
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd.   Unauthorised copying, reproduction, storage or dissemination prohibited.

  References & Additional Information
   Selected References:
Mango H, Zantop H, Oreskes N  1991 - A fluid inclusion and isotope study of the Rayas Ag-Au-Cu-Pb-Zn mine, Guanajuato, Mexico: in    Econ. Geol.   v86 pp 1554-1561

Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge.   It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published.   While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo takes no responsibility what-so-ever for inaccurate or out of date data, information or interpretations.

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