Gold mineralization in the Santa Rosa Gold Project has characteristics in common with mesothermal or orogenic and intrusion-hosted gold veins. Mineralization of these types consists commonly of quartz and quartz-carbonate veins located in moderately to steeply dipping, brittle-ductile shear zones and locally in shallow-dipping extension fractures. Veins commonly extend along strike and down dip over very significant distances and occur alone or, typically, in complex vein networks and shear zones. Vein minerals are mostly quartz and carbonates with minor native gold, pyrite, and base metals sulfides. Veins are usually massive or ribbon-textured, but vein breccias and drusy, crystalline quartz can also occur. Wall-rock alteration is zoned and consists of carbonate (often ankerite), sericite, and pyrite.

Hypogene gold mineralization within the Santa Rosa Gold Project is generally associated with the shear zones developed in homogeneous diorite country rock, with higher grades occurring in the associated sulfide-mineralized quartz veins or as steep high-grade quartz-sulfide veins. There are also related saprolitic gold deposits and colluvial gold deposits, both of which have been mined by artisanal miners underground and in hydraulically mined areas known locally as “baticiones.” The shear zones and veins are best exposed in adits and baticiones.

In the San Ramon deposit shear zone, mineralization occurs in fractured, brecciated, and ductily deformed rock. ........

The mining method selected is Mechanized Shrinkage with Delayed Fill (“MSDF”). The method is similar to mechanized cut and fill but uses breast blasting of the back between lifts. Then, rather than mucking of ore and backfilling immediately, the MSDF method leaves the ore in place in the stope, only removing enough material from the stope to remove swell (similar to shrinkage stoping but removing the swell from the top instead of the bottom). Access to the stope is provided by establishing an attack ramp. For each
lift, the attack ramp back is blasted to establish access for the subsequent lift. Support is placed in the stope as needed during the drilling and blasting cycle of each lift. Once enough lifts have been drilled and blasted, the ore will be mucked out completely. The last cycle of mining for MSDF stopes is backfilling of the stope from the bottom up, progressively backfilling the attack ramp as well.

Backfill is to be used as required, but not all stopes will be fully backfilled. The backfill will consist of filtered tailings and development waste rock. Tailings will be placed in a single lift, and once the lift of tailings is placed, then a lift of waste rock from development will be placed on top of the tailings. The amount of waste placed on top of the tailings will be sufficient to allow equipment to drive on top of the backfill. It has been assumed that 60% tailings and 40% development waste rock will be a suitable mixture of tailings to waste ........

The process plant design incorporates the following unit process operations:
- Primary crushing with a single toggle jaw crusher (1,100 x 700 mm) to produce a crushed product size of 80% passing (P80) 100 - 120 mm;
- A crushed ore surge bin (30 m3) with a nominal capacity of 1 hour process plant feed of 45 t;
- Single stage SAG mill (5.0 diameter x 3.5 m EGL 1,200 kW) in closed circuit with cyclones to produce a P80 grind size of 125 µm;
- Rougher scavenger flotation (6 x 8 m3 conventional cells) to produce a sulphides/gold concentrate;
- Tower mill (150 kW) for regrind of the concentrate to a P80 grind size of 15 - 20 µm;
- Pre-leach thickener (16 m dia) to minimise carbon in leach (CIL) tankage and reduce overall reagent consumption;
- A hybrid CIL circuit incorporating one leach tank and six adsorption tanks (430 m3 each) with 48 h total residence time;
- A 2 tonne AARL elution circuit with electrowinning and smelting to produce doré bars;