Los Filos is located in the Guerrero Gold Belt and near the center of a large, approximately 200 km diameter circular shaped feature known as the Morelos Guerrero Sedimentary Basin. The basin is a thick sequence of Mesozoic platform carbonate rocks successively comprised of the Morelos, Cuautla, and Mezcala Formations. The Cretaceous carbonates were intruded by a number of early Tertiary age granitoid bodies. The distribution of intrusive bodies along northwest trending belts is thought to reflect the control on their emplacement by pre-existing northwest trending faults.

Tertiary granodiorites that intrude the carbonate sedimentary units at Los Filos include: the East and West Stocks of the Los Filos Intrusive; the Bermejal Intrusive; the Xochipala Intrusive; and a granodiorite body located in the northeast portion of the property. Mineralization identified within Los Filos is typical of intrusion-related gold-silver skarn deposits. Gold skarns typically form in orogenic belts at convergent plate margins and are related to plutonism associated with the development of oceanic island arcs or back arcs.

Mineralization is geologically controlled by being either hosted by, or spatially associated with, skarn development during contact metamorphism of the carbonates. Massive magnetite, hematite, goethite, and jasperoidal silica, with minor associated pyrite, pyrrhotite, chalcopyrite, and native gold typically occur in the veins and metasomatic replacement bodies that developed at the contacts between the platform carbonates and intrusive rocks. Extensive oxidation of the deposits that occurred at the time of mineralization has altered the mineralization into material that is amenable to cyanidation recovery techniques without the need of pre-treatment by roasting or other methods.

In the Los Filos area, mineralization is associated with two early Tertiary granodiorite stocks that were emplaced in carbonate rocks. Mineralization being mined at the Los Filos Open Pit is associated with a shallowly east dipping sill and with the upper portion of the east stock. The Los Filos Underground is divided into the Los Filos Norte and Sur Sectors along the north and south side of the circular west stock. The principal mining areas in the North Sector are Nukay, Conchita, Peninsular, Chimenea, Independencia-Subida and in the South Sector include Sur, Zona 70 and the Creston Rojo deposits.

Mineralization in the Bermejal area is along the contact of the Bermejal Stock with the carbonate rocks of the Morelos Formation. The Bermejal Open Pit mineralization is typically at the top or on the flanks of the upper portion of the intrusive. Mineralization extends below the Bermejal Open Pit and down the steeply dipping to vertical flanks of the intrusive and at the northern end of the intrusive the mineralization is referred to as the Bermejal Underground deposit.

The total circumference of the Los Filos area intrusive stocks is approximately 8 km and at least half of this has been drilled or developed. The Bermejal Intrusive has a circumference of around 16 km and although the upper portion of the intrusive contact has been mined by open pit, only a few kilometres of this contact have been explored at depth. Mineralization extends from surface to over 700 m depth. The skarn is typically present at the contact of the intrusive with the carbonate rocks and is variable in grade and widths. Additional exploration targets are along the intrusive contacts in the Los Filos and Bermejal areas.

Los Filos comprises the active Los Filos Open Pit and Bermejal Open Pit, the active Los Filos Underground Mine, one planned open pit mine - Guadalupe Open Pit, and one planned underground mine - Bermejal Underground Mine. Development mining at the Bermejal Underground Mine includes establishment of a portal, surface infrastructure and completion of a 1330 m ramp.

During the September quarter 2021, Equinox Gold started mining ore from the new Guadalupe open pit and Bermejal underground deposits at Los Filos.

Open pit mining is by conventional drilling and blasting with loading by excavator and haulage by trucks to a crusher for Crush heap leach processing or directly to a ROM (Uncrush) leach pad.

At Los Filos Underground, the overhand cut-and-fill mining method is used in narrow areas and the overhand drift and fill method is used in the wider areas. All underground ore is trucked by contractors to the crusher. The mining method planned for Bermejal Underground mine is underhand cut and fill.

Los Filos Open Pit production benches are designed to be 9 m in height and stacked in double benches of 18 m. The standard haul road width is 25 m to allow for two-way traffic, but is narrowed to allow only one-way traffic when extracting the lowest benches of the pit. The maximum haul road gradient is 10% and the minimum mining width is 50 m

The Los Filos Underground operations are focused on the mineralized skarn on the perimeter of the Los Filos intrusive and are accessed by multiple portals that are located outside of the current open pit operations. The main ramps are driven at a gradient of 12.5% and have a profile of 4.5 m x 4.5 m to accommodate 10-wheel, 14 m3 class highway dump trucks. The main ramps are located in the hanging wall, in competent limestone, at a distance of 60 to 100 m from the ore to minimize geotechnical issues. The main ramps provide access to ore zones that are separated by subeconomic material (i.e., waste rock). The ore and the immediately adjacent waste zones have a poor rock quality and require increased ground support for stability.

The primary mining methods are OHCAF and OHDAF, with the latter being used in wide areas of the orebody. Ore drives typically have a profile of 3.5 m wide x 4.0 m high. Underground development waste rock is used for backfill. When adequate development waste rock is not available, rock from open pit waste dumps is dropped into the underground mine through 3 m diameter vertical borehole raises.

For all of the mining method configurations, a short access (attack) ramp is driven exterior to a targeted portion of the skarn to begin stoping. The attack ramp is typically developed in seven passes, in 3 m vertical lifts, and begins from the bottom of a planned stope and progresses upward as each successive lift of the stope is mined out. The bottom ramp of an attack ramp system is developed at a gradient of -15%, and each subsequent ramp is built upon development waste rock that is backfilled into the completed level and the attack ramp.

Ore Delivery and Crushing
Ore that is classified as low-grade is stacked as Uncrush ore on Pad 1 for leaching. Medium and high-grade ore is crushed to 80% minus (P80) 19 mm, agglomerated with lime and cement, and transported by conveyors as Crush ore to Pad 2 for leaching. The Pad 2 ore is placed in 5-m lifts.

The crushing circuit has a maximum operating capacity of 1,500 t/h, but depending on ore supply, crusher feed size distribution and moisture content, the circuit normally operates between 830 to 875 t/h for 16 to 18 h/d based on 2016 to 2018 production rates.

Medium and high-grade open pit ore is end-dumped from 136-t capacity mine haulage trucks near the primary crusher into a 200,000-tonne stockpile without significant blending of ore types. Underground ore is end-dumped in a separate stockpile by 20-t capacity dump trucks.

The ore is delivered to the jaw crusher feeder hopper, which is equipped with a 400 mm grizzly and fed by a dedicated CAT 992 front-end loader from the stockpile. The separately stockpiled underground ore is fed to the crusher as a weekly campaign, one day per week. Grizzly oversize material is broken down with a remotely operated stationary rock breaker on the grizzly or by a track-mounted rock breaker.

The major components of the crushing plant include a primary jaw crusher (Sandvik JM 311), which is set at a 100 mm opening, and two secondary cone crushers (Metso HP-800) operated in closed circuit with double-deck banana screens to produce a final P80 19 mm final crushed product.

A scalping screen with 100 mm openings precedes the jaw crusher. Crusher tonnage is measured by a weightometer on the No. 1 conveyor, which is calibrated monthly by Los Filos technicians and checked annually by the manufacturer. A cross-belt sampling system is used at the discharge end of one of the intermediate conveyors. The sampler cross-cuts the discharge stream every 15 minutes throughout the shift. The collected sample is then reduced in size, dropping by gravity through a series of riffle splitters. The final shift sample weighs 150 kilograms and is then taken to the laboratory for preparation and analyses. The shift samples are analyzed in the site laboratory for gold, silver and moisture content. A portion of the sample is retained and is used as part of the weighted monthly average composite sample for column leach testing.

Ore is processed by conventional heap leaching methods to recover the contained gold and silver. In addition, installation of CIL cyanidation processing facilities to recover gold and silver from higher grade ore sourced primarily from the future Bermejal Underground mine is being investigated.

Heap Leach Operations
Ore is sourced from three areas: Los Filos and Bermejal Open Pits and Los Filos Underground. Eventually heap leach ore will also be sourced from the Guadalupe Open Pit, which will be developed as an extension of the Bermejal Open Pit. There are several ore types being mined from these deposits, including oxides, intrusives, carbonates, endoskarn (altered intrusives) and sulphides. Mineralization from the open pit and underground operations is classified as either low-grade or high-grade ore. Low grade ore is heap leached as Uncrush ore (ROM) and medium-high grade ores are heap leached as Crush ore.

Heap Leach Pads 1 and 2 are currently in opera ........