The Altar copper-gold project is a cluster of several, intermediate composition porphyry intrusive centres occurring within an area of approximately 5 km by 8 km and emplaced during Middle to Late Miocene times (ca. 12 to 10 Ma). Basement rocks in the area correspond to the Pachón Formation, which consists of a thick sequence of intercalated bimodal composition subvolcanic and volcanic-sedimentary units, deposited, and emplaced during the Early Miocene. This sequence consists of a stratigraphically lower member mainly fine-grained andesite flows and pyroclastic units intercalated in the upper portion with layers of rhyolitic rocks progressively increasing in thickness and frequency. The top of this sequence is overlain by a several hundreds of meters of rhyolitic ignimbrite flows that cover the eastern half of the project area.
The Altar project contains copper ± gold ± molybdenum sulphide mineralization that was deposited in an environment that transitions from the basal roots of a high-sulphidation epithermal lithocap to the sub-volcanic porphyry copper environment at depth. Mineralization at the Altar project is described as telescoped because of the close spatial distance between the porphyry and high-sulphidation alteration systems. High- and intermediate-sulphidation epithermal characteristics of the Altar porphyry system have been preserved locally at higher topographic elevations and are most notable along the arcuate ridge at the eastern margins of Altar East. There are currently no reliable published dates for the epithermal mineralization that overlies the copper-gold porphyry systems and therefore any direct temporal genetic link between the two types of mineralization remains conjectural.
Six main mineralized zones have been defined for exploration purposes and are from west to east: QDM Gold, QDM Porphyry, Radio Porphyry, Altar North, Altar Central, and Altar East. The currently reported Mineral Resource at the Altar Project comes from one large conceptual open pit that incorporates mineralization from Altar Central and Altar East porphyry centres, and second, smaller open pit centred on the QDM Gold zone located approximately 3 km west of Altar Central.
The Altar project is part of a more regional-scale cluster of large porphyry deposits that includes: Los Pelambres (Antofagasta Minerals) in Chile, and El Pachón (Glencore) and Los Azules (McEwen Mining) in Argentina; all of which are within 60 km or less of Altar.