The Andrea copper porphyry project is located in northern Chile, 100 kilometres (km) east of the city of La Serena with excellent access to infrastructure. The property is located at the western margin of the Miocene aged El Indio belt that hosts the world-class El Indio and Pascua Lama epithermal gold and silver deposits (Barrick Gold Corporation). This belt was extensively explored for precious metal epithermal deposits in the 1980s – 1990s, but remains highly under-explored for copper porphyry systems.
The Andrea project covers approximately 1,200 hectares at elevations ranging from 3900 – 4900 metres (m). The project is characterized by a 3.5 km by 1 km alteration system, situated along a north-south trending fault zone, that localizes the emplacement of multi-phase porphyry bodies, which are anomalous in copper, gold and molybdenum at an elevation of approximately 4,300 m. Importantly, the majority of the 3.5 km fault zone and associated mineralized porphyries, which represent the primary target area on the property, are situated under post-mineralization landslide and colluvium cover and remain undrilled.
In addition, at higher elevations (4,600 – 4,800 m), to the east of the porphyry system, high-grade gold-silver low - intermediate sulphidation veins were mined historically by small-scale miners and drill tested by LAC Minerals in the 1990s. These epithermal veins, which constitute the Apolinario prospect, are not the focus of Torq’s exploration plans but their presence in conjunction with the mapped porphyries on the project demonstrate a full epithermal – porphyry continuum of the mineralization system is present on the property.
The property is primarily characterized by a north-south trending fault zone that separates Permo-Triassic siliceous volcanics to the east from a Mesozoic volcano-sedimentary package to the west. Multi-staged porphyries that are dioritic to granodioritic in composition are emplaced along this fault zone, with each phase having distinct alteration and mineralization characteristics. These porphyries are characterized by quartz-sericite alteration, quartz-magnetite veining and quartz - copper oxide stockwork veining zones, all of which are characteristics of a potentially productive porphyry system.
Historical grab sampling in the two limited areas where the porphyries are exposed are summarized below in Table 1. The historical grab samples on the Andrea project were collected by Santiago Metals and Noranda Inc. Torq has not conducted any due diligence on whether appropriate QA/QC protocols were followed in the collection of these samples, nor can it confirm their accuracy or repeatability.
The southern cluster of rock samples largely represents a granodiorite phase porphyry that is associated with copper oxide quartz stockwork veins, which have average values of 551 parts per million (ppm) copper, 11.3 ppm molybdenum and 0.1 ppm gold. The northern cluster of rock samples is characterized by disseminated pyrite and minor copper sulphides, and is associated with quartz-magnetite veinlets in a diorite porphyry. Samples from the diorite porphyry average 508 ppm copper, 16 ppm molybdenum and 0.07 ppm gold. Collectively, these two porphyry phases indicate copper endowment along the fault zone and lead to Torq’s technical team’s pursuit of two targeting ideas at this stage: 1) The potential for an enrichment blanket at shallow depths associated with the granodiorite porphyry phase due to the presence of copper oxide on surface, and 2) the identification of a higher-grade porphyry phase under the landslide and colluvium material.
Table 1: Summary of historical rock sampling
|Type||Number of Samples||Au (g/t)||Cu (ppm)||Mo (ppm)|
|Diorite Average Geochem||107||Minimum||0.005||38||0.5|
|Granodiorite Average Geochem||162||Minimum||0.005||89||0.5|
The results from an IP survey of the Andrea property conducted in 2014 demonstrate a robust 2.5 km by 1 km +18 millivolt chargeability anomaly that is largely situated underneath the landslide and colluvium cover, which represents the primary target area of the project (Figure 4). Importantly, internal to the chargeability high is a north-south trending corridor of lower chargeability values that may represent the potential for potassic alteration and high-grade mineralization internal to a pyritic halo that would be characterized by higher chargeability values.
Seven drill holes, totalling 1,371 m and with a maximum depth of 250 m, tested the periphery of the main target area of the Andrea project. Only partial results are available from these drill holes and are listed below in Table 2. These results cannot be validated through assay certificates, however, Torq considers the partial results to be reliable as they were taken directly from historical company reports. The historical results from the drill holes were collected by Lac Minerals. Torq has not conducted any due diligence on whether appropriate QA/QC protocols were followed in the collection of these drill samples, nor can it confirm their accuracy or repeatability.
Importantly, these drill holes did not test the chargeability anomalies that represent an important part of future drill targeting. The most significant intercept reported was 146 m of 980 ppm copper and 46 ppm molybdenum in drill hole DAP-37. Intervals in drill holes DAP-38 and DAP-39 also show discrete zones of elevated molybdenum values ranging between 76 and 203 ppm. The increasing copper and molybdenum values may represent a vector toward a higher-grade portion of the system at depth, which may be associated with the chargeability anomaly.
Andrea Historical Drilling
Andrea Assay Results, Historical Drilling
|Hole ID||From||To||Interval||Cu (ppm)||Au (g/t)||Mo (ppm)|
The Company acquired the rights that constitute the Andrea project through three option agreements. Under these option agreements the Company can acquire 100% interest in the project, subject to net smelter return (NSR) royalties, through cash payments as follows:
|Period from Signing Definitive Agreement||Cash Payments (USD)|
|Within 60 days of signing the Definitive Agreement||$105,000|
|within 12 months||135,000|
|within 24 months||185,000|
|within 36 months||300,000|
|within 48 months||1,000,000|
|within 60 months||4,275,000|
The option agreements each include a NSR of 1.5%, which is buyable for payments totalling US$3,000,000.