The La India mine lies within the Sierra Madre Occidental province, an extensive Eocene to Miocene volcanic field extending from the United StatesMexico border to central Mexico. The La India mine lies within the western limits of the Sierra Madre Occidental province in an area dominated by outcrops of andesite and dacitic tuffs, overlain by rhyolites and rhyolitic tuffs that were affected by large-scale north-northwest-striking normal faults and intruded by granodiorite and diorite stocks. Incised fluvial canyons cut the uppermost strata and expose the Lower Series volcanic strata.

The mine area is predominantly underlain by a volcanic sequence comprised of andesitic, dacitic and felsic extrusive volcanic strata with interbedded epiclastic strata of similar composition. The mineral occurrences present in the mine area, and the deposit type being sought, are volcanic-hosted high-sulphidation epithermal-hydrothermal gold, silver and porphyry-related gold deposits. Such deposits may be present as veins and/or disseminated deposits and/or breccias. The La India mine deposit area is one of several high-sulphidation epithermal mineralization centres recognized in the region.

Epithermal high-sulphidation mineralization at the La India mine developed as a cluster of gold zones (Main, La India, El Cochi and North zones) aligned north-south, and El Realito aligned north-east, within a spatially related zone of hydrothermal alteration in excess of 20 square kilometres in area. Gold mineralization is confined to the Late Eocene rocks within zones of intermediate and advanced argillitic alteration originally containing sulphides, and subsequently oxidized by supergene processes. The North and Main zones are within two kilometres of each other. The Main Zone and El Realito are within five kilometres of each other.

Mineralization at Chipriona consists of what appears to be structurally controlled gold- and silver-rich veins, stringers and breccias with significant zinc, lead and copper content in sulphides.

The El Realito mineralization is found in northeast-striking subvertical parallel structural corridors of breccia that appear to have acted as conduits, bringing gold and silver mineralization into the favourable subhorizonal volcanic rock layers (the lower porphyritic dacite). El Realito remains open along strike (northeast and southwest) and shows significant potential at depth.

Surface outcrop mapping and drill-hole data so far indicate that the gold system at the Tarachi deposit is likely best classified as a gold porphyry deposit.

The La India mine is a collection of deposits grouped into three open pits – North, La India (Central) and Main – that provide ore for a heap leach pad located just west of the North pit. Operations use traditional open pit mining techniques with bench heights of 6 m and utilize front-end loaders, trucks, track drills and various support equipment. The potential development of satellite deposits provides an opportunity to extend mine life.

The Main Zone pit is expected to be depleted in the third quarter of 2022. Ore production will then fully transition to the La India pit and the El Realito pit.

La India’s processing flow includes a three-stage crushing process followed by a heap leach operation. Cyanide leach solution percolates through the heap to the lined solution-collection ditch that routes it to a double-lined pregnant collection pond. A zero-discharge water balance is maintained at the heap leach facilities. The gold adsorption, desorption and refining facility (ADR plant) consists of two parallel trains of six 3.5-tonne carbon adsorption columns and a Zadra strip with electrowinning. Gold-silver doré bars are produced in the refinery. The plant is designed to process leach flows from up to 6.0 million dry tonnes of ore per year (16,438 tonnes/day). Ultimate gold recovery is estimated at 69% when leaching is completed.

The La India heap leach pad construction phase III (occupying the now depleted North Zone pit) was completed in the fourth quarter of 2021. The heap leach pad phase III provides sufficient capacity to stack the remaining ore in mineral reserves.