Donate now to keep mindat.org alive!Help mindat.org|Log In|Register|
Home PageMindat NewsThe Mindat ManualHistory of MindatCopyright StatusManagement TeamContact UsAdvertise on Mindat
Donate to MindatSponsor a PageSponsored PagesTop Available PagesMindat AdvertisersAdvertise on Mindat
What is a mineral?The most common minerals on earthMineral PhotographyThe Elements and their MineralsGeological TimeMineral Evolution
Minerals by PropertiesMinerals by ChemistryAdvanced Locality SearchRandom MineralRandom LocalitySearch by minIDLocalities Near MeSearch ArticlesSearch GlossaryMore Search Options
Search For:
Mineral Name:
Locality Name:
Keyword(s):
 
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
StatisticsThe ElementsMember ListBooks & MagazinesMineral MuseumsMineral Shows & EventsThe Mindat DirectoryDevice Settings
Photo SearchPhoto GalleriesNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day Gallery

Platosa Mine, Bermejillo, Mun. de Mapimí, Durango, Mexico

This page is currently not sponsored. Contact us for sponsorship opportunities.
 
Latitude & Longitude (WGS84): 25° 55' 38'' North , 103° 39' 29'' West
Latitude & Longitude (decimal): 25.92748,-103.65815
Owned/operated by:Excellon Resources (100%)
Köppen climate type:BWh : Hot deserts climate
Name(s) in local language(s):Mina la Platosa, Bermejillo, Municipio Mapimi, Durango, Mexico


Platosa is a typical Mexican Carbonate Replacement Deposit lying approximately 5 km northwest of the town of Bermejillo, Durango. Platosa lies on the northeast flank of the Sierra Bermejillo, less than 2 km off the Pan American Highway. Although it is in the Municipality of Mapimi it has no apparent relationship to the Ojuela Mine area of the Mapimi Disrict.

The historic workings of the Platosa Mine are a series of flat-lying stopes, connected by tabular open zones developed along NW-SE faults and fractures. The deposit was found in outcrop, probably in the mid-1600s when Ojuela was just getting started and early mining focused on very high-grade oxidized silver-lead-zinc-copper ores. Mineralogically, these ores consisted dominantly of argentiferous cerussite and anglesite, with some remnant galena) and probably at least trace chlorargyrite. The oxides also contain small amounts of schulenbergite, orthoserpierite, malachite, linarite and serpierite.

Post-mineral ground-water movement along the NW-SE faults dissolved large open caverns up to 8 m wide, 30 m high and 250 m long. These contain very large gypsum crystals...to 2.5 m long, often characterized by dark brown to black phantoms of organic material. Many also show pale yellow-white phantoms under SWUV, probably also reflecting included organic materials. A fair number of these gypsum crystals are partially encrusted with hydrozincite and a small number are studded with light blue rice-grain smithsonites to 4 mm. Many gypsum specimens from Platosa have been misattributed to Naica...the fluorescent phantoms are diagnostic however.

Sulfur isotope analyses indicate that the gypsum in the crystals is derived from gypsum-rich evaporite deposits that lie deep in the local stratigraphic section. Field relations and extensive collapse breccias indicate that the deep gypsums were dissolved to form large caverns that ultimately collapsed creating breccia chimneys that subsequent fluids...themselves dissolving gypsum...followed and partially to completely filled with gypsum.

In 1997, exploration drilling by Excellon Resources found the unoxidized faulted continuations of the Platosa mantos essentially just below cover at the base of the mountain. These mantos have been proven to contain over 1 million tonnes of very high-grade silver-lead-zinc mineralization in the form of massive galena, sphalerite, acanthite and minor pyrite with trace copper sulfosalts. In the 5 Manto, silver grades locally exceeded 2% silver in areas rich in proustite. Proustite crystals to 1 cm in diameter and 3 cm long were found, many encaased in limpid crystallinee gypsum. Barite and celestine are locally abundant with clear evidence of galena replacing celestine in several places.

There are a multitude of celestine and barite showings throughout the Sierra Bermejillo, the majority forming as infillings of collapsed caverns. Most have been prospected and produced, although little specimen-quality material has been found. The cross-cutting relationships indicate the celesto-barite mineralization was early, formed from brines expelled from the nearby Central Mexico Basin. The silver-lead-zinc mineralization is clearly younger, probably forming in the mid-Tertiary.

Other oxidized metallic deposits occur in the area, some with adamite, mimetite, wulfenite and copper oxide species.

The 2015 Excellon PEA for Platosa says: Gypsum occurs as fairly late stage fracture-fillings and veins throughout the district. Collector quality
gypsum crystals have been extracted from open fractures in the historic Platosa Mine, and are what originally led Excellon to the property. The gypsum commonly cuts across mantos and cements large areas of sulphide breccia. Crystalline gypsum containing extremely fine grained inclusions of galena dust is often found tens of metres from these breccias and is a reliable indicator of proximity to coherent sulphides. Cross-cutting relationships and sulphur isotopic analyses indicate that the gypsum is probably not genetically related to the mineralizing event, but is most likely derived from the solution and reprecipitation of gypsum derived from the underlying Acatita Formation evaporates.


Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.


Mineral List


22 valid minerals.

Regional Geology

This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.

Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org

Early Cretaceous
100.5 - 145 Ma



ID: 2434746

Age: Early Cretaceous (100.5 - 145 Ma)

Lithology: Limestone

Reference: Instituto Nacional de Estadística, Geografía e Informática. Conjunto de Datos Vectoriales Geológicos. Continuo Nacional. Escala 1:1’000,000. [63]

Data and map coding provided by Macrostrat.org, used under Creative Commons Attribution 4.0 License



This page contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.

References

Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Megaw and Ramirez, 2010: Geologia Economica de Mexico: Clark, K.F., and others, editors. Servicio Geologico Mexicano Publication.
Cox J.J., Ross D., and Michaud R.L. (2015) Technical Report on the Preliminary Economic Assessment of the Platosa Mine, Durango State, Mexico: Excellon Resources Limited website under Technical Reports.

Mineral and/or Locality  
Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2018, except where stated. Mindat.org relies on the contributions of thousands of members and supporters.
Privacy Policy - Terms & Conditions - Contact Us Current server date and time: January 21, 2018 02:56:22 Page generated: December 24, 2017 07:30:40
Go to top of page