The 100% owned Rubi Project was staked by Mirasol through its Chilean project generation program in 2007 and is located within the Eocene- Oligocene age porphyry belt of northern Chile that hosts many world class porphyry copper deposits. It is situated adjacent to the giant El Salvador copper mining district in northern Chile.
Mirasol has completed field evaluation and targeting programs at Rubi identifying three large-scale copper, molybdenum and gold targets at the Lithocap, Zafiro, and Portezuelo prospects. The targets were defined by integrated analysis, including re-logging of drill holes and the re-interpretation of geophysics and geochemistry from exploration work conducted by a previous JV partner (First Quantum Mining Inc). This work was combined with recent Mirasol geological mapping, rock chip sampling and target vector modelling from field-based measurements of alteration mineralogy.
The Rubi project lies at relatively low elevation within 20 km of El Salvador and Portrerillos porphyry copper-molybdenum-gold mines, with highly favourable infrastructure such as year-round access, adjacent townships with a trained mining workforce, nearby roads, power, water grid and an operating mill and smelter.
Rubi has a prospective geological setting centered on structural intersections with the Domeyko Fault System, a through-going regional-scale structure and the Ojos del Salado trans-orogen structure, interpreted to have influenced the emplacement of the near-by giant El Salvador and Potrerillos deposits.
Mirasol has systematically consolidated claims holdings at Rubi over the past 12 months and has expanded the claim area to a total of nearly 26,000 ha.
The Rubi Lithocap (“Lithocap”) target covers a 3.5 km by 2.0 km area centred on a large, deeply weathered, advanced argillic alteration zone, surrounded by thin gravel cover. Geochemically barren lithocap alteration zones of the type seen at Rubi can form above or adjacent to large porphyry copper deposits.
At Lithocap, previous explorers have drilled peripheral to, but not beneath or adjacent to the post-mineral gravel covered western edge of the anomaly. New Mirasol mapping and re-logging of previous drill holes has defined veining and brecciation with anomalous copper and molybdenum mineralization and alteration patterns that vector toward potentially concealed porphyry mineralization to the north and north-west of the previous drill holes.
This pattern suggests the presence of a deep weathering profile overlying a buried source of the chargeability anomaly, which may indicate the presence of sulfide(s) in the unoxidized basement rocks. This type of deep weathering in porphyry environments in northern Chile is often conducive for the development of supergene enriched copper mineralization akin to the nearby El Salvador mining district.
The Zafiro prospect features a 2.8 km by 2.2 km gravel covered area characterized by a subtle circular magnetic high surrounded by an incomplete, doughnut-shaped magnetic low. This magnetic signature may be indicative of a large gravel-covered intrusive with an alteration halo. The gravel cover in this area ranges from approximately 25 m to more than 200 m in thickness concealing the central target area. However, a large canyon 1 km to the north of the target cuts through the gravel profile exposing the basement rock. Mirasol’s stream sediment sampling of gullies that traverse this area have returned widespread strongly anomalous copper up to 1,030 ppm (0.1%), suggesting either an “exotic” source of copper in the gravels and / or a primary porphyry source for the copper in the gravel-covered basement of the Zafiro prospect.
High grade “exotic” copper or a supergene enriched porphyry are both attractive exploration targets at the Zafiro prospect. Significant ore bodies of these types of mineralization occur at the nearby El Salvador mining district.
At the Portezuelo prospect, the 4.5 km by 2.7 km target area is characterized by relatively thin gravel cover and intermittent outcropping. Analysis of Mirasol and previous JV partner data shows widespread anomalous copper and molybdenum in soils, spatially associated with an oval-shaped magnetic feature that may represent a partially gravel-covered intrusive complex. Strongly oxidized, porphyry-like stock-works and sheeted veining with anomalous molybdenum and copper, is locally exposed in road cuts and has been recently identified by Mirasol outcropping in creek beds in the north of the target area.
A limited number of reverse circulation (RC) holes from prior operators were drilled into the southern part of the Portezuelo target prior to Mirasol staking these claims. The RC holes are estimated to have been drilled in the late 1980’s to early 90’s. The assays for these drill holes are not available to Mirasol, however sampling of residual RC chips on the drill pads returned anomalous molybdenum and copper assays. Reconnaissance mapping and sampling to the southwest of the target has identified a multi-kilometre long zone of gold-silver base metal veinlets that may represent a style of polymetallic mineralization commonly developed in the halo surrounding a porphyry centre.
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