The Cerro Matoso deposit is located to the south of Cordoba and north of Antioquia provinces, where three peridotite bodies are present in a north-south orientation, referred to as the Cerro Matoso nickel belt. The peridotites are associated with a Cretaceous ophiolite complex, located along the northern extension of the regional NNE–SSW-oriented Cauca-Romeral fault system. Tertiary age argillaceous sediments with local coal horizons surround the peridotites.

The peridotites are present in the following areas:
- Cerro Matoso mine area, comprising the current mine and possible extensions below sedimentary cover;
- Planeta Rica License area, located 40 km north of Cerro Matoso mine; and
- Uré License area, located 15 km south of Cerro Matoso mine.

The local geological setting of Cerro Matoso is characterised by a complex set of rock types that have been grouped into a number of major rock sets.

This geological basis for the rock type grouping is critical, as the local laterite profile is characterised not only by the evolutionary products of a typical tropical laterite weathering profile, but by several unique lithologies that also occur, including tachylite and very dark (black) saprolite units.

The resulting vertical layering is based on common physical and chemical features and from top to bottom consists of four zones – a sedimentary cover, a limonitic zone, a saprolitic zone and fresh peridotite bedrock.

The Cerro Matoso nickel operation is a well-established open cut mining operation. Its business model is predominantly owner-operator. The Main Pit is broken into a number of pit areas. The trucks, loading units, blasthole drills, blasting units and ancillary equipment are owned by CMSA. Some of the maintenance operations, such as drill maintenance, are completed by specialty contracting services.

Cerro Matoso uses a traditional truck-and-shovel mining approach. The operation is a mix of selective and bulk mining areas in both ore and waste. The pit design is relatively shallow from ground level (~60 masl), (approximately 70 m to the base of Pit 6 (-7 masl); however, the original hill height was approximately 200 m above the surrounding surface level (260 masl) The mining operation is constrained by the Uré River which has a water level of approximately 44 masl.

Due to the lateral extent of the orebody and the trend of Ni grade lowering with depth, the Cerro Matoso pit has generally been mined in a “top-down” method – which is appropriate for this style of orebody. The mining method is traditional truck-and shovel utilising shovel, excavator and front end loaders (FELs) as required for both primary digging and stockpile rehandle. The excavator in backhoe configuration is the primary loading unit in ore, while shovels and FELs are used in bulkier materials or stockpile reclaim.

Mining activities include removal of any growth medium (topsoil), f ........

Ore mined is blended with ore from stockpiles before it is passed through a two-stage crushing sequence. The two stages of crushing reduce the size from a nominal minus 600 mm to minus 50 mm.

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