Amarillo’s land position within the Mara Rosa District primarily covers the Eastern Belt greenstone assemblage with some coverage of the Western and Central belts as well. The Eastern Belt, which in general strikes to the northeast and dips moderately to steeply to the northwest, has a maximum thickness of 6 km. Surface topography over the belt is characterized by moderate relief and locally dissected drainages that follow lithologic or structural weaknesses. Depth to fresh bedrock is generally shallow, ranging from 0 to 15 m. The upper portion of the weathered profile consists of clay-rich latosol and saprolite derived from the underlying bedrock.

Rocks of the Eastern Belt are locally intruded by quartz-feldspar-muscovite & biotite granitoid bodies and associated aplite and pegmatite dykes, small stocks and dykes of hornblende & biotite & magnetite diorites, and, in its north-central portion, a large body of hornblende-plagioclase gabbro. All units exhibit varying degrees of foliation that typically range from weak to moderate, and generally intensify along sheared contacts. The tonalitic orthogneiss which separates the Eastern and Central Belts is composed of coarse-grained plagioclase, hornblende, and biotite with localized patches of biotite schist near its contact with the Eastern Belt.

Structurally the Eastern Belt is dominated by well- developed, penetrative foliation that strikes 30° to 50° and dips 40° to 70° north-west – an orientation subparallel to stratigraphy. Major structural systems include 50° to 65° striking shears and thrusts and associated drag folds. Shears are most commonly developed along zones of elastic disparity such as lithologic contacts. Shear sense is typically reverse-dextral oblique although a sinistral sense is locally observed. A second set of structures consists of late cross cutting north-west to east-northeast striking brittle faults and fractures that locally offset stratigraphy in apparent dextral strike-slip sense.

The mineralisation envelope at Mara Rosa is about 30 m thick and over 1 km long. It is structurally controlled dipping to the NW at about 45°, striking NE-SW. The mylonitic appearance is most noticeable in the footwall where shearing is the most intense. The intense shearing is associated with generally increased sulphide mineralisation (up to about 4%), and a slight increase in metamorphic grade from greenschist to high greenschist facies in the hanging wall through to high greenschist/low amphibolite facies in the footwall (large biotite flakes, some garnets). The best gold values are associated with intense shearing and higher levels of sulphide mineralisation.

The PFS proposes a single open pit mined by conventional shovel and truck methods at a nominal
ore mining rate of 2.5 million tonnes per annum for approximately eight years with Year 1 being the first full year of commercial gold production. A total of 105 MT of material will be mined to produce 19 MT of ore (strip ratio of 4.5:1).

The mine requires 4.5 million tonnes of waste pre-stripping during the pre-production period at a total cost of $14.0 million.

The project will employ contract mining with conventional open-pit mining using drill and blast, hydraulic excavators, haul trucks,and auxiliary mobile equipment to support a mining operation of a nominal 2.5 million tonnes per year of ore and a maximum of 20 million tonnes per year of waste.

The plant consists of a conventional crushing circuit (including tertiary crushing) followed by primary and then secondary milling in closed circuit with cyclones. The final pulp at a P80 of 45 µm is pre-oxidized in agitated tanks using oxygen gas from a PSA oxygen plant at a high pH of 12 for a total of 12 hours to oxidize tellurides to enable successful cyanidation of the gold. The pulp is contacted with cyanide and activated carbon in a typical CIL circuit of six agitated tanks for a total of 24 hours.

Loaded carbon is extracted daily from the CIL circuit and processed in a typical Zadra style elution circuit at up to 140° C with a 4 tonne capacity. The eluted solution is passed continuously the electrowinning cells until efficient desorption has been achieved. At intervals the gold is removed from the cells and smelted into Doré bars for sale. The activated carbon is regenerated in a gas fired rotating kiln before being sent back to the CIL circuit.

The tails ........