The Fazenda Brasileiro gold deposit is an epigenetic, structurally controlled and hydrothermally altered Precambrian quartz vein hosted lode gold deposit that has been subjected to greenschist facies metamorphism. There is some suggestion of a partial syngenetic origin for the gold because of the anomalous gold content (0.05 g/t Au to 0.10 g/t Au) throughout visibly unmineralized CLX.

Gold mineralization is related to multi-phase quartz veining events. The gold occurs in at least three textural settings at MFB: as particles attached to sulphide grains, as particles within fractures in sulphide grains, and as particles within fractures in quartz/albite gangue. Gold grains typically contain less than 5% silver.

The bulk of the mineralization is hosted by quartz-albite-sulphide veins within the chlorite schist (CLX) unit. Individual veins vary from one to four centimetres thick, have irregular margins, and are typically oriented sub-parallel to the predominant east-west trend of the felsic and mafic schists. The veins occur in multiple vein sets which vary in true width from 1.5 m to 40 m and in horizontal mining width from a minimum 3 m to 40 m. The veins are generally arcuate in an east-west trend and south dipping at 40° to 70°, with a shallow to moderate east plunge. The plunge, however, is quite variable, with some zones plunging westerly.

Mineralization is also found stratigraphically below the CLX unit in the CLX2 and Canto horizons. Econ ........

The mining methods used at Fazenda include conventional truck and shovel for the open pit mining and mechanized sublevel stoping method for the underground mining.

Open Pit Mine
Currently, several small open pits are in operation and being mined by contractors. These small pits are 25 to 80 m deep and are being developed using air-track drills for grade control drilling, backhoe excavators for mining, and highway-type trucks for haulage to the mill. Pit depths are dependent on the economics of stripping overlying waste. Mineralization exceeding pit depths is considered for underground mining.

• Narrow vein shallow open pits have historically supplemented the underground production
• Open pits have been excavated to extract the near-surface portion of the main mineralized zones (CLX-1, CLX-2, Canto);
• Open pit mining is done by contractors, typically using 3 m³ - 3.5 m³ excavators and 30 t - 40 t industrial haul trucks;
• Average mining rate is ~4.6 Mtpa, with a maximum of 5.7 Mtpa (ore and waste);
• Strip ratio of 9:1 (waste:ore);
• Anticipate five years of open-pit production at ~0.5 Mtpa of ore - Potential for open pit mine life extension based on mining of crown pillar with orebodies FW, G, C North and C South;
• Two main ore types to mine: chloritic schist (CLX1, CLX2) and carbonaceous schist (Canto);
• Nine pits have been developed along the mineralized trend: Canto 1, Canto 2, C North, C South, PPQ, FW ........

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