The Escalones Project is a copper porphyry project comprising oxidized copper mineralization, and is located southeast of Santiago, Chile.
The Escalones copper porphyry project lies 35 km east of El Teniente, one of the world’s largest underground copper mines, and within the renowned Chilean porphyry copper belt that runs north-south in the central Andes Mountains. The project has excellent infrastructure, including road access, electricity, access to seaports, and a gas pipeline that crosses the 70 square km property.
The Escalones deposit was discovered in 1996 through greenfield exploration work by Ralph Fitch, former President and CEO of General Minerals Corporation, and Felipe Malbran, the former Vice President of Exploration, South America.
In 2020, World Copper recognized that the shallow, higher-grade mineralization is significantly oxidized, rendering it mostly acid-soluble and potentially amenable to cost-effective, heap-leach copper production. Redefining the project as a copper oxide deposit significantly enhances its value by lowering costs of capital and operating development options compared to the previously contemplated sulphide flotation project.
Mineralization & Geology
Escalones has Inferred resources of 426 million tonnes of 0.367% copper, based on nearly 25,000 metres of drill core from 53 holes. The 3.45 billion pounds of copper should be amenable to heap leaching with an average recovery of 71%. The mineralization sits within a four square-kilometer area of hydrothermal alteration comprising quartz-sericite, potassic, and calc-silicate alteration assemblages. Coincident copper, gold and silver geochemical anomalies are associated with replacement-style “skarn” mineralization hosted in calcareous sedimentary rocks that flank central porphyritic intrusive rocks with porphyry-style (fracture-fill and disseminated) mineralization.
Copper mineralization at Escalones occurs as the sulphides chalcopyrite, bornite, and covellite, which are partially to completely replaced within about 300m of the surface with secondary copper oxides, sulphates and carbonates. This replacement has led to higher grades at shallower depths, and, since the mineralization sits within a high-standing ridge, makes it ideal for surface mining.
Updated Resource Estimate
Hard Rock Consulting, LLC completed an updated resource estimate for Escalones with an effective date of June 25, 2021. Resources are reported within an optimized pit shell and are considered to have a reasonable potential for economic extraction. A 0.13% total Cu cutoff grade was selected for reporting the mineral resource (Tables 2 and 3). The cutoff grade was calculated based on the following assumptions: a long-term copper price of US$3.50/lb Cu, assumed combined operating ore costs of US$6.50/t (process, general and administrative and mining taxes), refining & shipping costs of US$0.25/lb of Cu, metallurgical recoveries of 71% for copper, and a 2% net smelter returns royalty. The metal prices used in the cutoff represent a 15% increase over the three-year historical average as of June 30, 2021. Table 2 contains cost and other parameters used in the cutoff calculation (all dollar amounts in US dollars).
Escalones Resource Estimate (June 25, 2021)
(1) Mineral resources that are not mineral reserves do not have demonstrated economic viability. Inferred mineral resources are that part of the mineral resource for which quantity and grade or quality are estimated on the basis of limited geologic evidence and sampling, which is sufficient to imply but not verify grade or quality continuity. Inferred mineral resources may not be converted to mineral reserves. It is reasonably expected, though not guaranteed, that the majority of inferred mineral resources could be upgraded to indicated mineral resources with continued exploration. See “Cautionary Note to United States Investors”.
(2) Mineral resources are reported at a 0.13% CuT cutoff. The cutoff is calculated based on a long-term copper price of US$3.50/lb; assumed combined operating ore costs of US$6.50/t (process, general and administrative and mining taxes); refining & transportation costs of US$0.25/lb of Cu; metallurgical recoveries of 71% for copper and a 2% net smelter returns royalty.
(3) Mineral resources are captured within an optimized pit shell and meet the test of reasonable prospects for economic extraction by open pit. The optimization used the same mining costs of US$2.50/t mined and a 50º pit slope.
(4) Rounding may result in apparent differences when summing tonnes, grade and contained metal content.
Mineral resources that are not mineral reserves do not have demonstrated economic viability. Inferred mineral resources are that part of the mineral resource for which quantity and grade or quality are estimated on the basis of limited geologic evidence and sampling, which is sufficient to imply but not verify grade or quality continuity. Inferred mineral resources may not be converted to mineral reserves. It is reasonably expected, though not guaranteed, that the majority of Inferred mineral resources could be upgraded to Indicated mineral resources with continued exploration. Mineral resources are captured within an optimized pit shell and meet the test of reasonable prospects for economic extraction.
Soluble Copper Mineralization
Several programmes of metallurgical testing on Escalones mineralization were completed between 2012 and 2013. Tests focused on the recovery of the copper, gold, silver, molybdenum and gallium by conventional flotation and a combination of flotation followed by acid and acid-brine leaching of sulphide tailings and oxide scavenger concentrates. There was no specific programme to determine the extend of acid-soluble copper mineralization over the full range of mineral zones and rock types.
The standard sulfuric acid leach metallurgical tests achieved average copper extraction of 77%, ranging from 66 to 96% from mixed copper oxide-sulfide mineralization (eight composite samples). Copper sulphide flotation was also successful and rougher-cleaner flotation testing of the porphyry material achieved 25-34% copper concentrate grades at high recovery and low findings of all key impurities.
Recent studies by World Copper indicate that most of the shallow copper mineralization at Escalones could be amenable to heap leach processing, which would result in lower operating costs as well as significantly lower capital costs. The sulphide copper mineralization is partially to completely replaced and enriched from surface to depths of approximately 300m from surface by secondary copper oxides, sulphates and carbonates, resulting in higher grades at shallower depths. The base of oxidized copper enrichment is currently defined by a database review of core photos, assays and core logs, and supported by almost 1200 sequential copper leach tests, representing 2040 metres of core, or roughly 16% of all oxidized intervals. In addition, 55 acid consumption tests were completed. the visual down-hole limits of oxidized and secondary copper sulphide minerals.
Bottle roll leach tests will be undertaken to confirm the positive preliminary findings.
Exploration - Escalones Expansion Targets
The Escalones deposit remains open to expansion laterally to the south, east and west, with only roughly half of the alteration zone drilled to date. The Mancha Amarilla lithocap (“Mancha Amarilla”) extends one kilometre south from the main Escalones deposit. Evidence indicates this southern half of the Escalones alteration system is also deeply oxidized and could contain significant soluble copper mineralization. Geophysical and geochemical anomalies indicate there is also substantial expansion potential to skarn zones on both east and west flanks of the porphyry mineralization.
A geochemical sampling and mapping crew was mobilized in late February 2021 to evaluate these targets. During the sampling programme, 336 samples were collected from the untested Mancha Amarilla lithocap and the East Skarn, which is a large gossanous wedge of mineralized sandstone and porphyry sills. Further details can be found in the August 12, 2021 news release.
Top: Panorama looking west over the Escalones ridge and areas sampled
Bottom: close-up of copper oxide mineralization in the East Skarn sandstone.
Exploration - Northern Targets
The Escalones Project contains what may be one of the last remaining untested mineralized porphyry clusters in Chile; no drilling has been carried out on these distal targets. Three significant hydrothermal alteration zones, each measuring between 2,000m and 3,000m in diameter, lie from 5 to 10km to the north of the main discovery, and were first recce mapped and sampled by General Minerals Corporation (“GMC”) in 1999. GMC discovered disseminated and fracture-controlled copper-oxide and sulphide mineralization within the Rio Negro target.
World Copper sampled and recce mapped the three anomalies in early 2021, confirming the presence of porphyry and skarn mineralization. The large anomalies are intense quartz-sericite, argillic and gossanous alteration of porphyritic and granitic intrusions, as well as skarn in volcanic and sedimentary units. The Northern Targets have significant potential, with surface alteration zones on the same scale as that of the main Escalones deposit.
Ridge and spur character rock sampling at an average spacing of 200m has defined two porphyry centres that are now considered drill targets. Rio Negro is the primary target, with excellent copper mineralization at surface and will be the priority for further exploration. The eastern target, Argüelles Este, is larger and more deeply weathered, and more sampling will be carried out to determine its potential. Sampling of the third target, Argüelles, was limited, and further work programmes by the Company are expected to follow up on this work. Results of the exploration programmes will be released as information becomes available.
Panorama looking south over northern target cluster.
Rio Negro Target; north side looking northwest over quartz-sericite altered porphyry intrusions.
Arguelles Este Target: looking south over main colour anomaly.
Gridded 4m character rock sampling results over the northern targets. Typical porphyry deposits have elevated Au-Mo and depressed Zn-Mn over 1km in width.
Rio Negro Target Details
At the Rio Negro target, argillic and quartz-sericite alteration occurs within lower dacite/monzonite porphyries intruding overlying clastic sedimentary rocks. Copper oxide mineralization is most apparent in the centre of the alteration where multiple samples returned over 5000 ppm (0.5%) copper, with five samples returning over 1% copper (Figures 2 and 3). This central area covers an area 800x1000m and will be a focus of more detailed geochemical sampling and mapping this field season.
It is considered a priority porphyry copper target for future drill programmes.
Rio Negro Target; north side looking northwest with location of character samples.
Cautionary Note Regarding Forward-Looking Statements
Forward Looking Information: this webpage and linked content includes certain information that may be deemed “forward looking information”. Forward-looking information can generally be identified by the use of forward-looking terminology such as “may”, “will”, “expect”, “intend”, “estimate”, “anticipate”, “believe”, “continue”, “plans” or similar terminology. All information in this release, other than information of historical facts, including, without limitation, the potential of the general future plans and objectives for the Escalones project, the completion of the Plan and receipt of shareholder and regulatory approval therefor, the likelihood of receipt of value from the Retained Right, the availability of financing to World Copper Ltd. (“the Company”) and the Company’s plan in relation to its listing review are forward-looking information that involve various risks and uncertainties. Although the Company believes that the expectations expressed in such forward-looking information are based on reasonable assumptions, such expectations are not guarantees of future performance and actual results or developments may differ materially from those in the forward-looking information. Forward-looking information is based on a number of material factors and assumptions. Factors that could cause actual results to differ materially from the forward-looking information include changes in project parameters as plans continue to be refined, future metal prices, availability of capital and financing on acceptable terms, general economic, market or business conditions, regulatory changes, delays in receiving approvals, and other risks detailed herein and from time to time in the filings made by the Company with securities regulatory authorities in Canada. Mineral exploration and development of mines is an inherently risky business. Accordingly, actual events may differ materially from those projected in the forward-looking information. For more information on the Company and the risks and challenges of our business, investors should review our continuous disclosure filings which are available at www.sedar.com. Readers are cautioned not to place undue reliance on forward-looking information. The Company does not undertake to update any forward looking information, except in accordance with applicable securities law.
John Drobe P.Geo., World Copper's Exploration Manager, and a qualified person as defined by National Instrument 43-101, has reviewed the technical information that forms the basis for this webpage.