Mineralization within the Curaçá Valley is hosted by a series of irregular-shaped, layered or zoned mafic-ultramafic intrusive bodies of Archean to Proterozoic age. Determination of genetic models for the deposition of copper has been complicated by the multiple episodes of metamorphism and deformation. These deposits are generally believed to be magmatic sulphide deposits and interpreted to be similar to those found in O’okiep, South Africa, Mayer and Barnes (1996).

Mineralization at the Surubim Mine is hosted by the ultramafic rocks of pyroxenitic composition and lesser gabbroic composition. Pyroxenite is commonly altered to phlogopite schist. This mafic- ultramafic package occurs intruded between the Arapuá banded gneisses and the gneisses of Bom Despacho formation. Granites crosscut the gneiss and mafic-ultramafic rocks

The mafic-ultramafic intrusive rocks were subjected to intense alteration in the Surubim area. Dominant alteration minerals include phlogopite, silica, chlorite, K-feldspar, epidote, serpentine and carbonate.

Two main systems of anastomosing faults occur at the mine: NNE-SSW and NNW-SSE dipping to the east. These structures define the strike and dip of the mineralized body.

Mineralization at Surubim Mine occurs as lenses that are hosted by phlogopite-altered pyroxenite. Ore minerals are chalcopyrite and bornite in a ratio of 4:1 that mainly occur as disseminations and semi-massive commonly interpreted as remobilized. Chalcocite, covellite and cubanite also occur as minor sulphides associated with the ore. Magnetite and minor pyrite and pyrrhotite are associated with mineralization.

The district of Surubim has a north-south length of approximately 20 km and a width of approximately 12 km.

The mineralized bodies dip 50º to the northwest in the central to northern part of the open pit and are sub-vertical towards the south.

The Surubim OP Mine is located approximately 33 km north of the Pilar UG Mine and Caraíba Mill. The mine is currently in operation and is forecast to produce a total of approximately 4,939 tonnes of contained copper during 2018.

The final pit, incorporating geotechnical design constraints, was optimized with MineSight Economic Planner software applying the Lerchs-Grossmann algorithm.

Ore is currently loaded by hydraulic loaders with bucket capacities of 4.5 tonnes and transported from the pit to the Surubim OP Mine ore stockpile by 35 tonne trucks. Transportation from the stockpile to the primary open pit crusher at the Caraíba Mill is performed by 70-tonne double axle haul trucks. All drilling is being conducted by a Sandvik DX800. Auxiliary support equipment includes: a D6 bulldozer, wheel loader, fuel truck, water truck, and hydraulic rock breaker.

All required supporting infrastructure is available at the Surubim OP Mine and is in good condition, having been last used to support operations from 2010 to 2018.

Ore from the Surubim OP Mine has been processed by the Caraíba Mill previously. Actual plant performance serves as the guide for forecast metallurgical results. Recoveries of 81.0% are forecast for Surubim at the average feed grade of 0.83% Cu.

The Caraíba Mill is of a conventional three- stage crush, milling and flotation design. Three-stage crushing is used to prepare a nominal 12.5mm crushed feed for the ball milling circuit prior to being sent to flotation for the recovery of copper-bearing minerals. Final flotation concentrate is filtered to a design target of 7.5% moisture and is transported via highway for smelting and refining either (i) locally at Paranapanema company, located in Dias D’Ávila, or (ii) sold via international export markets from Salvador’s port, both approximately 475km from the Caraíba Mill.

There are two primary crushing operations. Ore from open pit mining is delivered to the surface primary cone crusher, featuring a nominal capacity of 1,600t/h. Ore from underground mining is crushed underground by one of two primary jaw crushers with a nominal capacity of 400t/h each. Feed enters the primary crushing operations with maximum size of 48” and is discharged with maximum size of 10”.

The blended product of the primary crushing operations is transported via conveyors to an apron feeder stockpile with a capacity of 12,000 tonnes and fed to one of two secondary cone crushers (seven-foot (“ft.”) standard Symons; 1,400t/h of capacity each) set to 28mm aperture. The secondary discharge feeds two primary double deck screens, configured with 100mm gaps on the top and 40mm gaps on the bottom decks. Screen undersize passes to the collection conveyor while oversize material passes to the secondary crushers in an open circuit configuration.

The flotation circuit at Caraíba consists of a conventional rougher-cleaner-scavenger flotation process. The rougher circuit consists of three rougher banks divided into two stages of flotation (rougher, cleaner) with four cells in each unit operation. The first four cells of each bank produce a rougher concentrate that passes to the four cleaner cells. In practice, the concentrate of second rougher stage is returned to the head of the circuit to increase total rougher mass pull and retention time. Rougher concentrate is fed to the cleaner circuit and tails are fed to the scavenger circuit.