The La Colorada deposit is an atypical gold-silver deposit located in the centre of Sonora. It is not similar to the typical epithermal systems of the SMO with a marked northwest control and lesser northeast structures.

Fluid inclusion studies by Albinson (1997) indicated mineralizing temperatures for the deposit were mostly in the high 200°C to mid-300°C range and the system was a relatively hot epithermal environment. Albinson classified the veining at La Colorada as either deep epithermal or high level magmatic-mesothermal in origin. He went on to state that the system was likely related to shallow level plutons emplaced above a copper porphyry system. His studies also identified two styles of mineralization. The first was the main structurally-controlled primary hydrothermal quartz vein system with associated gold-silver and base metal mineralization. The second represented an overprinting supergene enrichment of gold. This younger gold event is hosted by cross cutting fractures with associated iron oxides. In the samples studied, he identified high-grade zones of coarse gold with oxides that filled cross cutting vugs and fractures. Albinson theorized that the gold was leached out of adjacent primary veins.

The La Colorada vein system is post-intrusive and post-skarn in age and may be termed either deep epithermal or high-level magmatic-mesothermal in origin and developed above a copper porphyry system.

The significant mineralized occurr ........

Production at La Colorada has been ongoing since 2012 with the majority of ore being sourced from the Gran Central open pit. Mining ceased in Gran Central in 2018 and production is sourced from the El Creston and Veta Madre open pits.

Pit Design
The open pit designs were created by Argonaut regional staff in Hermosillo and transferred to La Colorada for implementation by both operations and mine contractors. Mine design is comprised of four mine phases. The first was mined and finished in 2019 and Phase 2 was finished in 2020. Phase 3 is actively being mined and Phase 4 is the final layback. Veta Madre consists of four phases for eventual extraction and Phase 1 is actively being mined. Phases 2 and 3 will extend the open pit to the west and Phase 4 will be the final layback.

For the El Crestón and Veta Madre pits, the ramp width was sized at 25 m (truck factor of 3.5) which can safely support Cat 777 (or equivalent) sized mining trucks. One-way access of 15 m was applied at the pit bottom after stripping requirements were met.

El Crestón Pit Parameters:
Inter-ramp Slope: 51°, 41°, 49°, 46º;
Bench Face Slope: 67°, 65°, 70°;
Berm Width: min.5 m max.7 m;
Bench Mining Height: 5 m;
Bench Height: 15 m;
Ramp Width: 2 Ways 25 m;
Ramp Width: 1 Way 15 m;
Ramp Gradient: 10%.

Veta Madre Pit Parameters:
Inter-ramp Slope: 46º, 48°, 51º, 53º;
Bench Face Slope: 67°;
Berm Width: 7 m;
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