Lomas Bayas is a low grade Cu-Mo deposit resulting from the intrusion of several porphyry and breccia systems that were later exposed to leaching and subsequent supergene enrichment and in situ oxidation. Green copper oxides, copper sulphates in various forms and less partially mixed ores are the main source of ore for the existing SX/EW operation. The copper oxidessulphate mineralisation is the basis of the Lomas Bayas Ore Reserves (Lomas Bayas I).

The deposit is located in a structural framework formed by three sets of faults along an ENE bend in the Tertiary strike-slip San Cristóbal Fault system. The deposit area is mainly underlain by granodiorite that has been intruded by a cluster of small granodiorite and/or granite to dacite porphyry bodies of the Lomas Porphyry. Later events, focused by the structural framework, include the emplacement of breccia pipes and zones as well as hydrothermal alteration and copper mineralisation.

The deposit area is characterised by a structural regime, the main structural elements of which are NNE, NW, north-south and WNW-trending high-angle faults and fractures, as well as west to SW-dipping, low-angle faults and fractures that occur to the north of the ENE-trending South Fault Zone.

Both primary and supergene mineralisation occurs at Lomas Bayas. The upper parts of the orebody are generally oxidised, with a few zones of mixed oxide-sulphide, and it is principally exploited as a heap-leach operation. C ........

The Lomas Bayas open cut operations are located in the centre of the Atacama Desert copper belt approximately 115 km to the northeast of the town of Antofagasta in Chile.

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