Name of the Mine
Cosalá Operations.
Location
Cosalá district, east-central Sinaloa, Mexico.
Mine Owner/s
Americas Gold and Silver.
Brief Description
The Cosalá Operations consist of the San Rafael mine, the Los Braceros tailings storage facility, the EC120 project and the past producing Nuestra Señora mine.
Brief History
Construction started at San Rafael in September 2016, with the mine achieving commercial production in December 2017.
Primary Metals/Minerals
Silver/zinc/lead.
Secondary Metals/Minerals
None stated.
Geology/Mineralisation
The Cosalá mining district is situated along the western edge of the Sierra Madre Occidental, an extensive volcanic province covering about 800 000 km2. The prevolcanic basement comprises an array of tectonic/stratigraphic terranes of Precambrian, Paleozoic and Mesozoic rocks. Within the western Sierra Madre Occidental, the Mesozoic rocks have been altered to recrystallised limestone and skarn in many locations.
An extensional, basin and range-type phase of faulting overprinted the western portion of the Sierra Madre Occidental during the formation of the Gulf of California, in Miocene time. In the Cosalá region, this late-tertiary faulting produced an extensive, north-west-trending graben and related parallel fault system, along with later north-east-trending dextral faults.
Mineralisation within the Cosalá mining district is related to granodioritic or granitic intrusions of the Sinaloa Batholith, a composite gabbroic to granodioritic complex that forced strong contact metamorphism in adjacent sedimentary and volcano-sedimentary units.
Reserves
Total proven and probable silver reserves as June 30, 2021, are estimated at 4.84-million tonnes grading 145 g/t.
Total zinc and lead reserves are estimated at 1.96-million tonnes grading 3.24% and 1.3% respectively.
Total copper reserves are estimated at 2.88-million tonnes grading at 0.42%.
Resources
Total measured and indicated silver resources (exclusive of mineral reserves) as at June 30, 2021, were estimated 7.68-million tonnes grading 93 g/t. Inferred resources were estimated 2.95-million tonnes grading at 107 g/t silver.
Total measured and indicated zinc resources (exclusive of mineral reserves) as at June 30, 2021, were estimated at 5.36-million tonnes grading 2.05%. Inferred resources were estimated at 2.36-million tonnes grading 1.68% zinc.
Total measured and indicated lead resources (exclusive of mineral reserves) as at June 30, 2021, were estimated at 5.36-million tonnes grading 0.92%. Inferred resources were estimated at 2.36-million tonnes grading 1.08%.
Total measured and indicated copper resources (exclusive of mineral reserves) as at June 30, 2021, were estimated at 4.45-million tonnes grading 0.24%. Inferred resources were estimated at 2.61-million tonnes grading 0.25% copper.
Mining Method
Underground – post-pillar cut-and-fill.
Major Infrastructure/Equipment
The Cosalá Operations comprise:
- two surface mine sites and associated facilities, including offices, shops, compressors, fuel storage, electric substations, portals, ventilation fans, run-of-mine storage and a dry facility.
- underground infrastructure, including ramps, ventilation/service raises, explosive magazines, dewatering pumps and underground mobile equipment fleet.
- a main town office, including a shop, diamond drill-core logging and storage facilities, and a meeting room.
- access to the Los Braceros processing plant and tailings storage facility by rural paved and dirt roads.
- grid electric power supply to the San Rafael mine, EC120 project and Los Braceros plant.
Prospects
Mining the silver-rich areas of the Cosalá Operations is expected to significantly increase silver production to more than 2.5-million ounces of silver on an annualised basis.
Contact Details
Americas Gold and Silver
Tel +1 416 848 9503
Email info@americas-gold.com
Website https://www.americas-gold.com/
Sources
Americas Gold and Silver. Technical Report on the San Rafael Mine and the EC120 Preliminary Feasibility Study, Sinaloa, Mexico (May 17, 2019).
Americas Gold and Silver. Americas Gold and Silver Hosts Official Opening Ceremony for Cosalá Operations (January 24, 2022).
Americas Gold and Silver. Website https://www.americas-gold.com/ (accessed February 23, 2022).