Porphyry copper deposit, its main mineralized body is oxidized in a mineralized zone, mainly Chrysocolla, Black and Atacamite oxides in low presence, deposited under sterile coverage of post mineral gravels with an average thickness of 50 m.

Three lithological suites are recognised at Gaby Sur (Aguilar, 2000; Camus, 2001):

Volcano-sedimentary sequence, a set of stratified rocks composed of sandstones, fine, tuffs and andesites, all subject to varying degrees of low grade metamorphism. The sequence generally strikes north-south and dips at ~45° to the W, in the West sector of the mine area. Its sedimentary facies have been correlated with the Quebrada Escondida Formation, while the volcanic components are equated with the Del Bordo Formation.

Elvira Pampa Intrusive Complex, composed of granodiorite and tonalite and is cut by mafic dykes. It is the most areally extensive unit, within the Gaby Sur deposit area, and intrudes the volcano-sedimentary sequence. U-Pb dating of zircons from the complex yielded ages of 278±1.8 and 280±1.2 Ma (Martin, 1999; Aguilar, 2000), which confirmed the K-Ar ages of from 280 to 270 Ma (Mpodozis et al., 1993), while sericite was dated at 267±3.64 Ma (40Ar-39Ar; Dilles et al., 2000).

Gaby Intrusive Complex, composed of the following lithotypes: Intrusive Breccia, present as a number of separate bodies composed of polymictic fragments (but predominantly granodiorite) set in a fine-grained matrix of biotite and quartz, occurring as irregular, discrete masses that are distributed through the west-central part of the stock. On the basis of the presence in its matrix of abundant secondary biotite, K feldspar, quartz and minor copper sulphides, it is interpreted to be associated with the late-magmatic stage of the system. The sediment-breccia contact often has associated subparallel arrays of thin fragments of intrusive rock.

Tonalite Porphyry, which corresponds to irregular bodies, in part dykes, which are found in the central section the deposit, where they intrude the granodiorite of the Elvira Pampa Intrusive Complex and Volcano-sedimentary sequence. It has a porphyritic texture with 50% of phenocrysts set in a phaneritic matrix. The tonalite porphyry has been dated at 41.9±0.2 and 41.7±0.4 Ma (U-Pb zircon; Martin, 1999).

Gaby Porphyry, that consists of a set of porphyritic diorite dykes, with phenocrysts of feldspar and mafic minerals set in a matrix of quartz and biotite, and is mostly located in the central part of the complex, where it intrudes to all other units. It has been dated at 41.8±0.3 Ma (U-Pb zircon; Martin, 1999).

The deposit lies in a graben, delimited by high-angle boundary faults, and is covered by up to 40 m of gravels (including a ~9.6 Ma tuff; Camus 2001) that completely obscure, all of the units described above. These alluvial gravels comprise subangular, polimictic clasts within a sandy clay matrix, and are cemented by calcrete in the upper 20 m of the profile. The basal section of these gravels is composed of fragments of red sedimentary rocks, which mostly correspond to detritus derived from the Purilactis formation, enclosed in a reddish, cemented matrix that includes sulphates and carbonates.

The upper part of the Gaby Sur deposit below the gravel cover, comprises an up to 180 m thick copper oxide zone, underlain by hypogene sulphides. The oxide zone contains a supergene mineralised suite, mainly oxides of copper and, to a lesser extent, by limonite, which is restricted to an interval immediately below the gravel overburden, coinciding with the area of underlying primary mineralisation. At the interface between the oxidation and hypogene zones, there is a weak and immature chalcocite blanket and a mixed zone of supergene sulphides and poorly developed copper oxides. The average thickness of oxidation is ~150 m, fluctuating between 60 and as locally much as 250 m. The oxide zone mineralised assemblage dominantly composed of chrysocolla with lesser neotocite, atacamite and malachite, present in fractures and replacing feldspars. Towards the margins of the oxide zone, there is an area of leaching with goethite and lesser jarosite (Aguilar, 2000; Camus, 2001). A moderate to weak zone of structurally controlled argillic alteration, represented by kaolinite, smectite and alunite, accompanies the zone of oxide mineralisation.

Gabriela Mistral in it´s 8th Division operates the largest fleet of autonomous trucks in the world. A fleet of 17 Komatsu 930E4 AT Trucks, allowing to transport 210,000 ton / day of materials.

The production process involves different stages: crushing (primary, secondary and tertiary), acid curing in drums, heap leaching, tailings disposal, solvent extraction (SX), electro-winning (EW), and the cathodes produced are transported to the Mejillones port.