Tahuehueto is an active underground polymetallic mine situated in the Mexican state of Durango. The project is owned by Canada-based Luca Mining, formerly Altaley Mining.
A Preliminary Feasibility Study (PFS) was conducted in 2022, building on a previous 2017 study, and provided updated estimates of mineral reserves and resources.
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In July 2024, Luca Mining completed construction of the Tahuehueto gold mine. The project achieved commercial production in March 2025, operating at a throughput rate exceeding 800 tonnes per day (tpd).
The Tahuehueto project is projected to have a 10.9-year mine life. The property features a substantial epithermal gold-silver vein system, encompassing 11km of known veins and mineralised structures. It also has copper, lead and zinc mineralisation.
Luca Mining is actively engaged in an exploration programme aimed at determining the vertical and lateral extent of mineralisation. The programme also targets thick, high-grade mineralised breccia-type ore shoots within the epithermal vein system.
Tahuehueto Mine Location
The Tahuehueto Project is situated in the northwest region of Durango, Mexico, approximately 250km northwest of the state capital, Durango, and 160km northeast of Culiacan, Sinaloa.
It is located about 25km north of the Topia polymetallic-silver mine.
The property spans 7,492.7889 hectares and consists of 28 mining concessions distributed across five non-continuous blocks. These concessions are owned by Real de la Bufa, a Mexican subsidiary of the parent company.
Within this 7,492-hectare area, there are at least 12 mineralised zones within a structurally controlled epithermal system that extends over km.
Geology and Mineralisation
The Tahuehueto project is positioned near the western boundary of the Sierra Madre Occidental, a volcanic plateau extending 1,200km in a north-northwest direction, with a width ranging from 200km to 300km.
The property encompasses four primary rock types: lower volcanic series andesite, granodiorite stocks, polymictic conglomerate, and felsic ash-flow tuffs of the upper volcanic series. The majority of the area is underlain by andesite flows, tuffs, and volcaniclastic rocks of the lower volcanic series.
Mineralisation at Tahuehueto is characterised by polymetallic epithermal veins with multiple mineralising events occurring within the same vein structure.
The primary host rock is the andesite of the lower volcanic series, though the hydrothermal system has also penetrated felsic ignimbrite of the upper volcanic series in at least one instance. Breccias play a key role in the hydrothermal system at Tahuehueto, exhibiting various genetic styles, and many sulfide-mineralised zones show sulfide transport textures.
The upper portions of the mineralised structures are oxidised, comprising minerals such as malachite, azurite, chalcocite, covellite, limonite, and hematite.
Malachite overlays tetrahedrite, while chalcocite and covellite form coatings on sphalerite. The depth of the oxide-sulphide interface varies but is generally less than 100m, with less than 5% of identified mineralisation considered oxidised.
Below the oxidised zone lies sulphide mineralisation, which includes sphalerite, galena, chalcopyrite, tennantite, tetrahedrite, and possibly electrum. Gangue minerals present are quartz, pyrite, chlorite, sericite, and calcite.
A light green phyllosilicate mineral, believed to be celadonite, occurs locally as gangue and is closely associated with high-grade gold and silver mineralisation.
Tahuehueto Project Reserves
The project hosts proven reserves of 2.538 million tonnes (Mt) containing 219,000 ounces of gold at a grade of 2.89 grams per tonne (g/t), 3.937 million ounces of silver at 51.93 g/t, 14.246 million pounds of copper at 0.27%, 61.429 million pounds of lead at 1.18%, and 107.515 million pounds of zinc at 2.07%.
In the probable reserves category, there are 1.227 million tonnes (Mt) containing 75,000 ounces of gold at 1.90 g/t, 1.834 million ounces of silver at 46.48 g/t, 6.304 million pounds of copper at 0.23%, 25.929 million pounds of lead at 0.96%, and 44.125 million pounds of zinc at 1.63%.
Mining and Processing
According to the 2022 PFS, the geometry and orientation of the mineralised veins at the Tahuehueto project are suitable for sublevel stoping. The primary developments at Perdido, Creston, and Rey intersect the veins near the midpoint of the target mineralisation, allowing for both bottom-up and top-down mining sequences.
In contrast, the Santiago and Cinco veins are developed using top-down mining only. The PFS said that a 3m pillar every three sublevels may be used to ensure rock stability and appropriate backfill sequencing.
An Overhand Cut and Fill mining method was assessed in a trade-off study. This method involves conventional drilling, blasting, mucking, hauling, scaling, ground support installation, and backfilling with unconsolidated, mined waste materials. Although this approach improved metal extraction, it required excessive development to access levels off the decline, negatively impacting economic viability.
The processing plant at Tahuehueto uses a conventional crushing, milling, flotation, and filtering process, designed to handle 300,000 tonnes annually over 300 operating days, equating to 1,000 tonnes per day through the grinding and flotation circuits.
This process will produce lead, copper, and zinc concentrates, which will be transported from the site for smelting and refining.
As the operation transitions into commercial production, plant availability stands at 82%, reflecting a phased ramp-up approach as operations stabilise. This results in an average processing rate of 820 tpd, with plans to increase availability to 85%-90% as plant performance improves.
Streaming Agreement
In April 2021, Empress Royalty signed a streaming agreement for production from the Tahuehueto Project.
Under the agreement, the company has the right to purchase 100% of the silver production at 20% of the related off-take price in cash, up to 1,250,000 ounces. Beyond this, Empress Royalty can acquire 20% of the production at the same 20% off-take price. This agreement is set to terminate 10 years from the date of initial production.
As part of the agreement, a payment of $5m was made in two instalments- $2m in April 2021 and $3m in July 2021. In July 2022, Empress Royalty received the first payable silver ounces under the terms of the agreement.
