Mithril commenced its maiden 5,000m diamond core drill program at its Copalquin gold silver project, Mexico in July 2020.

The Copalquin project covers the Copalquin Mining District and is located in Sierra Madre Occidental mountain range, Durango State, Mexico, about 80km NNE of the city of Culiacán. The group of contiguous concessions covers an area of 7,005 hectares. The district hosts at least 32 high grade gold/silver mines within a major epithermal centre, with widespread argillic alteration, and evidence of multiple events, frequently associated with large deposits.

Mithril Resources Limited (through its wholly owned Drummond Gold S.A. de C.V. subsidiary) has an option to purchase the Copalquin concessions from Compa├▒ia Minera Copalquin S.A. de C.V. at anytime over a 6 year period while funding and conducting exploration within the concessions.

The maiden diamond core drill program is currently progressing and is scheduled for completion around the end of November 2020. The program will drill test six initial target areas within the central 1,600Ha of the concessions, with most of the drilling focussed in the target areas 1-3, La Soledad-El Refugio-El Cometa.

Drill results from the drilling at La Soledad (~2,000m) has been reported in the following announcements:

Figure 1. The Copalquin Projects is located in the Sierra Madre Trend, which hosts many significant producers.

Two past drilling programmes were completed between 1998 and 2007 by others plus geochemical, rock channel sampling and alteration studies. There are at least 6 drill target areas with one area an advanced pre resource target which was the focus of the previous drilling. Most recent drilling was by UC Resources from 2004 to 2007 with some highlights below.

  • UC-03 from 30.98m to 48.75m, 17.77m @ 45.16 g/t gold and 118.2 g/t silver (El Cometa Mine)
  • UC-24 from 143.10m to 151.0m, 7.9m @ 6.54g/t gold and 140.g/t silver (El Refugio Mine)
  • MP-07-101 from 138m to 142.53m, 4.53m @ 28.99g/t gold and 2,350.3g/t silver (La Soledad Mine)

(reported under Canadian National Instrument 43-101 guidelines. Non JORC 2012 compliant)

Historic Drilling Reports

Past Releases from UC Resources on the Copalquin District


The Copalquin Project lies within the Sierra Madre Occidental physiographic province of north-western Mexico. The project is underlain by andesitic volcanics of the Cretaceous-Tertiary Lower Volcanic Series. A Tertiary granodiorite to monzonite pluton intrudes the andesite and much of the area is capped by Tertiary rhyolite ignimbrites of the Upper Volcanic Series. Mineralisation is thought to be contemporaneous with the eruption of the Upper Volcanic Series.

Semi-continuous low-angle breccia zones have formed within the andesite parallel to the granodiorite contact. These zones include the El Cometa breccia and the Los Reyes breccia. The geometry of these zones is similar to the nearby El Gallo silver deposit of McEwen Mining which is also formed in a series of breccias parallel to the contact between intrusive rocks and Lower Volcanic Series andesite.

A series of high angle normal faults strikes northwest and dips to the northeast including the Refugio, La Soledad and La Constancia structures which host veins mineralised with gold and silver. North-south striking, west dipping faults at San Manuel also host mineralized veins.

Both the low-angle breccias and the high-angle faults host extensive zones of mineralised quartz breccia. It is likely that the low angle zones developed as tectonic breccias during the intrusion of the granodiorite and were later mineralized by hydrothermal activity related to the eruption of the Upper Volcanic Series.

Large areas of argillic alteration occur across the concessions. The alteration forms haloes adjacent to the known structures and large zones where structures have not been identified. Argillic alteration is indicative of widespread penetration of hydrothermal fluids into the surrounding rocks and suggests a long-lived hydrothermal system was active at Copalquin.

The alteration from Refugio to Los Reyes is over 2,000 meters long and from 100 to 400 meters wide. It is expected that the widest zones are related to shallow-dipping portions of the Cometa-Los Reyes structures where the structure is nearer the outcrop surface. Similar alteration is present well to the west at El Platanal and well to the east at Constancia. It cannot be stressed enough that this strong, widespread argillic alteration forming a large-volume halo well out from the veins is the observable geologic characteristic that identifies Copalquin as a major epithermal centre.

Figure 2. Best rock chip channel sample assay and past drill results. 1,600Ha area within the 7,005Ha Copalquin concessions area where the initial exploration activity is focussed.

Figure 3. Copalquin geologic map showing the full concession area and regional upside beyond the central area of work.

Copalquin Mining District History

  • Discovered in the 1848, production ceased during the Mexican Revolution.
  • El Refugio first mined in 1849. By 1897 there were 10 head stamp batteries installed with cyanidation plants.
  • 1935 the company Minera CIBOLA milled ore from the San Manuel and El Cometa mines.
  • Detailed sampling of some workings by Industrial Mineral Mexico S.A. de C.V. (IMMSA) in 1983.
  • 1995 Alta Pimeria and Kennecott outline a potential target of a million ounces of gold and 50 million ounces of silver.
  • 1997, Bell Coast Capital Corp (BCCC) conducted a helicopter supported, 31-hole, 2,500 m diamond drill program from 6 to 8 drill pads. This first-pass drilling program returned excellent results, but BCCC withdrew from the project due to difficulty in acquiring financing during a period of very low gold and silver prices.
  • BCCC completed an extensive program of geochemical sampling and mapping, resulting in the discovery of three large anomalies.
  • UC Resources explored at Copalquin from 2003 – 2007, drilling 39 diamond core holes for 4,200m. UC also completed geochemical sampling and an ASTER study. UC experienced funding difficulties and ceased activities late 2007.

Historic Articles

Articles in the Engineering and Mining Journal 1897 and 1900 give some details about past developments and production of gold and silver from the Copalquin Mining District. Click the links below to open the articles in a separate window. Close the window to return to the site.

Engineering and Mining Journal 12th May 1900
Engineering and Mining Journal 21st August 1897
Engineering and Mining Journal 4th September 1897

The following are some of the historic mines within the Copalquin Project concessions.