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.

Underground Mining
Underground mining employs blasthole stoping from sublevels developed in the mineralization footwall. The stoping areas are accessed initially from 5 m wide by 5.5 m high main haulage ramps developed at a 15% road grade in the footwall, which leads to primary development crosscuts with the same dimensions of the main ramps, and secondary development drifts and crosscuts of 4.5 m wide by 4.9 m high. Sublevels are spaced at 20 m vertical intervals. In general, mined-out stopes are not backfilled.

From the sublevels, access drifts are developed into the stoping areas, and fan drilling of blastholes into the mineralization is used to further define the boundaries of the mineralization and design the ultimate blast patterns. After blasting, remote-controlled, 10 tonne-capacity load-haul dump (LHD) machines are used to load and haul ........

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