The 100% owned 35,000 hectare Santa Rosa gold project is an intrusive hosted structurally-controlled quartz stockwork system within the prolific Antioquia Batholith. Gold mining within the Santa Rosa project pre-dates the 17th century when an estimated 30 million tonnes were mined. The San Ramon gold deposit (a single shear zone within the Santa Rosa project) trends east-west, dips 70o to the north, extends over 2 kilometres, is up to 50 metres in width and is mineralised from surface. 45,000 metres have been drilled to date to a vertical depth of over 600 metres with mineralisation remaining open at depth.
The high potassic alteration, anomalous geochemistry and drill results all confirm and are coincident with the historic workings. Other than the San Ramon deposit, numerous additional drill targets have been identified within the Santa Rosa gold project.
Geology within the Santa Rosa gold project is dominated by hornblende-biotite diorite and quartz diorite of the Antioquia batholith. The batholith is a calc-alkaline, plutonic intrusive complex belonging to an early- to mid-Cretaceous magmatic arc. Basement geology is a complex elongated mosaic of Palaeozoic and younger autochthonous and allochthonous terranes that were accreted to the South American continent and subjected to transpressional tectonics and episodic subduction-related magmatism. Mineralisation is contained within numerous mesothermal veins and stockworks structurally related to east-west and north-north-west corridors.
Exploration to date has entailed:
The September 2014 Feasibility Study outlines a 1,000 tonne per day operation producing an average annual production of 50,000 ounces over an eight year mine life. Initial capital costs are $74 million. Cash costs are $596/ounce or $84/tonne.
Current reserves are 2,424,000 tonnes at a grade of 5.2 g/t gold for 405,000 ounces.
San Ramon is an underground mine using conventional shrinkage stoping mining methods with delayed backfill. Processing incorporates single-stage crushing, SAG milling and floatation with concentrate re-grinding followed by conventional carbon-in-leach processing the combined float tails and reground concentrate to produce gold dore with 96% recoveries.
Assuming a long-term forecast gold price of $1,300/ounce gold: post-tax Net Present Value (5%) is $104 million, Internal Rate of Return is 53% and payback is 1.3 years.
Major equipment and layout has been designed with built-in capacity to accommodate an expansion to double the throughput rates without without disrupting production.