Log InRegister
Home PageAbout MindatThe Mindat ManualHistory of MindatCopyright StatusWho We AreContact UsAdvertise on Mindat
Donate to MindatCorporate SponsorshipSponsor a PageSponsored PagesMindat AdvertisersAdvertise on Mindat
Learning CenterWhat is a mineral?The most common minerals on earthInformation for Educators
Minerals by PropertiesMinerals by ChemistryAdvanced Locality SearchRandom MineralRandom LocalitySearch by minIDLocalities Near MeSearch ArticlesSearch GlossaryMore Search Options
Search For:
Mineral Name:
Locality Name:
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
StatisticsThe ElementsUsersBooks & MagazinesMineral MuseumsMineral Shows & EventsThe Mindat DirectoryDevice Settings
Photo SearchPhoto GalleriesNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day Gallery

Milpillas Mine, Cuitaca, Mun. de Santa Cruz, Sonora, Mexico

This page kindly sponsored by Antoine Barthélemy
Lock Map
Latitude & Longitude (WGS84): 31° 7' 0'' North , 110° 26' 59'' West
Latitude & Longitude (decimal): 31.11667,-110.45000
GeoHash:G#: 9t93n8sg8
Other regions containing this locality:Sonoran Desert, North America
Köppen climate type:BSk : Cold semi-arid (steppe) climate
Name(s) in local language(s):Mina Milpillas, Cuitaca, Mun. de Santa Cruz, Sonora, Mexico

Mine Information: Production started in 2006 with a planned 11 year mine life. By late 2011 most of the 7 principal copper oxide bodies were mined out and company sources indicated that, unless more carbonate-rich ores are found, production will be almost purely chalcocite ores by mid to late 2012. Faults and water courses with secondary copper oxide species extend locally downwards into the supergene sulfide zone, but most post-2012 oxide species have come from upper levels where miners had the opportunity to collect after the areas were abandonded and before back-filling. (2015): Exploration has been successful in finding additional sulfide ores at depth and lateral to the known deposit...they now estimate a total of 12 years [to 2027] of mine life at the 2011 production level (388 kilotons at 26.4 kilotons of copper per year. Only small amounts of additional oxide materials have been found.

Specimen collecting by miners and tours by dealers are actively discouraged.

Geology: The district lies within the NW‐SE trending metallogenic Laramidian (late Cretaceous to Eocene) copper belt of
Southwest North America which extends from Sonora over Arizona to New Mexico. The Milpillas deposit, located in an extensional zone called Cuitaca Graben, is a partially oxidized porphyry copper deposit with a series of alternating copper carbonate-oxide and chalcocite enrichment blankets on top of low grade primary chalcopyrite-bornite mineralization. Mineralization is covered by 250 meters of gravels and extends to 720 meters depth. Most of the copper carbonate oxide ores occur in the top 200 meters of the deposit. Host rocks are volcaniclastic from the Jurassic Henrietta formation and the Laramide Mesa formation in which monzonitic to quartz monzonitic stocks intrude. The sericitically altered stocks and the intruding volcaniclastic rocks host the main copper mineralization.

The supergene profile in Milpillas is made up of 4 principal zones, within which certain overlap exists. They are from top to the bottom as follows:
1. The leached cap is characterized by oxidized rocks: goethite, hematite and jarosite are abundant, copper values are very low (between 0.01 and 0.05 %) with a common thickness of 100 ‐ 300m. Montmorillonite, sericite and kaolinite dominate as secondary alteration minerals of the volcanic hostrock.
2. The oxide zone above the water table is situated at the lowermost part of the leached zone: sub‐horizontal mineralized blankets, made up mostly by copper oxides, copper carbonates and sulfates formed mostly by oxidation of preexisting chalcocite. Minor amounts precipitated from oversaturated groundwater. The mix of different copper species is a result
of at least three supergene enrichment cycles in Milpillas due to uplift or changes in the water level.
3. Supergene enrichment zone: situated at the base of the weathering profile with reducing conditions underneath the paleo water level. In this zone the copper solubility is decreased, which results in the replacement of iron in the primary hypogene minerals: chalcocite dominates together with covellite when copper enrichment is less pronounced. Native
copper can be found at the borderline of reduced and oxidized conditions. 2015: Pyrite crystals to 15 cm with very thin coatings of chalcocite (not bornite as previously described; XRD, SEM-EDS and optically verified; https://www.mindat.org/forum.php?read,11,380551,432315#msg-432315) have emerged from this zone.
4. Hypogene primary mineralization: the surface between this zone and the supergene enriched one is irregularly shaped. In a transition zone different “copper oxide” minerals as well as sulfides can be abundant. Underneath the transition zone the mineralization is primary as it is described above.

Commodity List

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

Mineral List

39 valid minerals.


Mineralization age: Paleocene : 63.5 Ma to 62.6 Ma

Important note: This table is based only on rock and mineral ages recorded below and is not necessarily a complete representation of the geochronology, but does give an indication of possible mineralization events relevant to this locality. As more age information is added this table may expand in the future. A break in the table simply indicates a lack of data entered here, not necessarily a break in the geologic sequence. Grey background entries are from different, related, localities.

Geologic TimeRocks, Minerals and Events
ⓘ Molybdenite (youngest age)62.6 Ma
ⓘ Molybdenite (oldest age)63.5 Ma

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

2.588 - 66 Ma

ID: 2430169

Age: Cenozoic (2.588 - 66 Ma)

Lithology: Conglomerate

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

Miocene - Oligocene
5.333 - 33.9 Ma

ID: 3184329
Cenozoic volcanic rocks

Age: Cenozoic (5.333 - 33.9 Ma)

Comments: Sierra Madre Occidental

Lithology: Ignimbrite(s); felsic volcanic rocks

Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. [154]

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.


Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Berrocal-Lopez, G., and Islas-de la Vega,A. (2009): Geologia del porfido cuprifero de Milpillas, Municipio de Santa Cruz, Sonora, Mexico. in, Clark, K.F., Salas-Piza, G.A., and Cubillas-Estrada, R. editors, Geologia Economica de Mexico, Segunda Edicion, 2009, Asociacion de Ingenieros de Minas, Metalurgistas y Geologos de Mexico, Tegra Color, Mexico D.F., Mexico, p. 857-862.
De la Garza-N., V., Nogues-A., B., and Correon-P., N., 2006, Geology, Mineralization and Emplacement of the Milpillas Secondarily Enriched Porphyry Copper Deposit, Sonora, Mexico, 10p.
Moore, T., and Origlieri, M. (2008): Famous Mineral Localities: The Milpillas Mine, Cananea District, Sonora, Mexico. Mineralogical Record 39(6), 25-34.
Singer, D.A., Berger, V.I., and Moring, B.C. (2008): Porphyry copper deposits of the world: Database and grade and tonnage models, 2008. US Geological Survey Open-File Report 2008-1155.
USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10049594, 10049643 & 10254942.

External Links

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: April 22, 2018 21:05:48 Page generated: April 22, 2018 19:12:29
Go to top of page