McEwen Copper Inc. holds a 100% interest in the Los Azules Project through its Argentine subsidiary, Andes Corporación Minera S.A. (ACM). ACM controls all required mining and surface rights, as well as easements and access routes, with fully established legal and administrative standing.
McEwen Copper Inc. is 46.4% owned by McEwen Inc. Other owners are:
• FCA Argentina S.A. (Stellantis) - 18.3%,
• Nuton (Rio Tinto) - 17.2%,
• Evanachan Limited (Rob McEwen) - 12.7%,
• Victor Smorgon Group - 3%,
• Others - 2.4%.
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Summary:
Los Azules is located within the Central Chile segment (400 km-long) of the Miocene-early Pliocene porphyry copper belt (6,000 km-long) of the north and Central Andes.
Los Azules exhibits characteristics typical of Andean-style porphyry copper deposits. It consists of a barren leached zone, an underlying supergene enrichment zone, and hypogene mineralization extending at least 1,000 m in depth. The hydrothermal system spans 5 km by 4 km NNW along a structural corridor, with its ultimate extent concealed beneath volcanic cover to the north. Mineralization limits along strike and depth remain undefined, with some drill holes terminating in mineralized zones above the resource cut-off grade.
Key minerals include chalcopyrite, bornite, chalcocite-digenite and idaite. Copper sulfides rarely exceed 2% to 3% of rock volume, with hypogene copper grades typically ranging from 0.1% to 0.35%. Silver is present at approximately 1 gram/tonne, along with trace amounts of gold and molybdenum.
Porphyry copper deposits in this sub-belt are 23 to 3 Mya in age and include the world-class Los Pelambres (Cu-Mo), Rio Blanco-Los Bronces (Cu-Mo), and El Teniente (Cu-Mo) porphyry deposits in Chile, the Maricunga belt porphyries (Cu-Au) in Chile, and El Pachón (Cu) and Bajo de la Alumbrera (Cu-Au) in Argentina, as well as numerous other porphyry and related deposits (Sillitoe and Perello, 2005).
Panteleyev (1995) describes the common features of porphyry deposits as large zones of hydrothermally altered rock containing quartz veins and stockworks, sulfide-bearing veinlets, fractures, and lesser disseminations in areas up to 10 km2 in size. These are commonly associated with hydrothermal and/or intrusion breccias and/or dike swarms.
Volcanic Country Rocks (host)
Los Azules is hosted within volcanic lithologies of the Choyoi group, believed to be of Triassic age. These rocks include rhyolite and crudely bedded pyroclastics, ranging from fine-grained tuffs to coarse breccias.
Early Mineralized Porphyry Dike (EMP)
The Early Mineralized Porphyry Dike (EMP) is a rhyodacite intrusion trending NNW and dipping steeply east (Zurcher, 2008a). It measures ~3.6 km in length and 20-400m in width, and it forms the prominent La Ballena ridge due to its resistance to erosion. The dike exhibits a “crowded” texture, with closely packed feldspar, hornblende, biotite, and quartz phenocrysts, the latter showing resorbed or cracked textures.
Inter-Mineral Porphyry Dikes (IMP)
Following the emplacement of the EMP, a series of dacitic porphyry dikes (IMP) intruded the diorite pluton, trending NNW and dipping steeply east. The most prominent IMP is located east of the EMP, measuring 1.9km in length and 20-70 m in width, with minor intrusive bodies west of the EMP.
Magmatic – Hydrothermal Breccias
Breccias at Los Azules are predominantly magmatic-hydrothermal in origin and are associated with both the EMP and IMP. They occur as two types: early breccias related to the EMP and later breccias associated with the IMP. Both breccia types host hypogene mineralization, with early breccias generally exhibiting higher copper grades.
Early breccias are composed of fragments of porphyry and diorite in a quartz-cemented porphyritic matrix. They are generally characterized by potassic alteration with secondary biotite, potassium feldspar, magnetite, and anhydrite. The early breccias are found as small, high-grade zones along the edges and cupola zones of the EMP.
Mineralization
Mineralization at Los Azules is Andean-Cordilleran, late Miocene, (quartz-) diorite-hosted, oxidized porphyry copper style with a well-developed leached cap and supergene chalcocite-covellite blanket. Los Azules displays numerous features in common with other porphyry deposits.
The supergene mineralization at Los Azules consists of a sub-horizontal chalcocite-covellite blanket that overlays hypogene sulfide mineralization. This enriched zone is capped by a leached oxidized layer with minimal copper content (<0.10%). The leached cap, ranging from 0 m to 260 m thick, is characterized by spots of jarosite, goethite, and hematite. Beneath this, a mixed sulfide-oxide zone transitions to the supergene blanket, where hypogene sulfides are replaced by chalcocite and minor covellite.
The supergene blanket extends approximately 4,400 meters north-south and up to 1,800 meters wide, with a thickness ranging from 60 m to 250 m, penetrating to over 400 m deep along structures. Copper grades in the enriched zone range from 0.4% to over 1.0% in the north-central area, tapering to 0.2 - 0.4% in the southern and peripheral zones. This supergene mineralization is the most economically significant at Los Azules.
Potential gold-silver mineralization near Los Azules includes late-stage, intermediate-sulfidation epithermal quartz veins, with minor sphalerite and galena, as described by Pratt (2010). Although precious metal deposits often occur around porphyry copper systems, the district remains largely unexplored for this style of mineralization.
At Los Azules, a leached cap and supergene chalcocite blanket indicate copper oxidation, dissolution, and vertical transportation, with subsequent redeposition within the system. Copper may have also been transported laterally and redeposited as “exotic” copper mineralization nearby (Sillitoe, 2010).
Hydrothermal alteration and Mineralization
Potassic alteration includes widespread hydrothermal biotite replacing mafics, Early Halo veins (Early dark Micaceous, Pale Green Sericite veins and Grey Green sericite), potassium feldspar normally accompanied by quartz in veins, veinlets and pervasive replacements (aplites) and coarse-grained occurrences (pegmatites). Phengitic (Mg-rich) sericite is a common component of high temperature potassic alteration. It is present in Early Halo veins, miarolitic cavities, replacing mafics and normally growing with hydrothermal (secondary) biotite. Chalcopyrite dominates in these zones, with bornite appearing at greater depths and reaching a one-to-one ratio with chalcopyrite at 400-500 m.