Capstone Copper Corp. (“Capstone” or the “Company”) today announced brownfield drill results from the 2021-2022 exploration program at the Cozamin mine in Mexico, and at the Santo Domingo Project in Chile as well as greenfield results at the Planalto Project in Brazil, and provided an update of activities at Copper Cities in Arizona, USA.
Figure 1. MNV West Copper Target Area Open in Multiple Directions. Image Credit: Business Wire
This press release should be read in conjunction with the June 2022 exploration update presentation available at Capstone Copper - Exploration Excellence. To view an interactive presentation including a 3D model of Cozamin, please visit: https://vrify.com/decks/11666?auth=6c97245b-87d3-4cb0-8354-c5483be80d0e
Brad Mercer, SVP, Exploration and Strategic Projects said, “We have an exploration team with a proven track record of excellence and this update highlights the exciting path forward for continued value to be generated through the drill bit. Capstone Copper has significant brownfield exploration potential that points to mine life extensions and expansion opportunities, as well as greenfield potential in Brazil within a great mining jurisdiction. Our exploration portfolio has never been as robust as it is today which will keep us on a sustainable growth path well into the future”.
Cozamin – Underground Resource Expansion Update
Capstone’s 2021-2022 exploration program has focused on the Mala Noche Vein (“MNV”) West copper target, which is located down-dip of historical workings. Drilling in 2021 was performed from surface, with underground drilling added following completion of the West cross-cut in the first quarter of 2022. Since the program started in 2021, approximately 40,000 meters (“m”) of drilling have been completed from 47 holes from surface with an additional 9,000m from 12 holes planned for the remainder of 2022. A proposed lower elevation mine cross-cut will allow expedited infill drilling in 2023 to support an updated resource estimate during the second quarter of 2023. The area can be accessed by refurbishing and deepening existing historic ramps at MNV or laterally from existing Mala Noche Foot Wall Zone haulage ramps and levels.
The 2022 Cozamin exploration program will also include surface drill testing of other targets along strike from San Roberto and San Rafael mine areas at MNV Far West and MNV Far East respectively and at the Vanadio target located north of the San Rafael mine area. All three targets (see Figure 2 for the location of each target) have limited to no previous drilling by Capstone. Both MNV Far East and Vanadio will be drilled below historical workings that mined silver-rich portions of the epithermal system. At MNV Far West, drilling will be located in a covered plateau where the MNV system is inferred to have been down-dropped and not exposed at surface.
A summary of select intervals is shown in Figure 1 and summarized in Table 1.
Figure 2. Cozamin 2022 Brownfield Surface Drilling Targets. Image Credit: Business Wire
Santo Domingo Exploration Program
Capstone’s 2021-2022 Santo Domingo exploration program is the first to be undertaken at the project since 2012. To date, eight holes have identified over 1.5 kilometers (“km”) of mineralization at approximately 500 m depth containing lower-grade copper and high-grade cobalt associated with magnetic iron. The Company believes that further drilling could potentially expand the resource and join the mineralized sequence across the planned Santo Domingo and Iris Norte pits.
Santo Domingo’s oxide mineralization (Figure 3), which is located above the sulphide ore body and is part of the Santo Domingo and Iris Norte’s pre-stripping material, could potentially be processed at the Mantoverde mine’s SX-EW plant, located approximately 35 km southwest of the project. Preliminary metallurgical test results suggest the viability to process oxides in Mantoverde’s existing facilities and if ongoing tests continue to return positive results, a drill program would follow shortly with the aim to complete Santo Domingo’s first oxide mineral resource in the second half of 2023, to be followed by an updated Santo Domingo Feasibility Study.
Additional near-mine brownfields targets have been identified outside the Santo Domingo and Iris Norte current pit designs.
Figure 3. Copper Mineralization in Oxide Zones at Santo Domingo and Iris Norte. Image Credit: Business Wire
Greenfield Exploration
Planalto Project (Carajás, Brazil)
Capstone optioned the Planalto project, in Northern Brazil’s State of Pará, from Lara Exploration Ltd. (“Lara”) and the Company has invested over $4.6 million in the property thus far. Capstone can earn a 70% interest in Planalto by investing up to $5 million, making an additional payment of $400,000, completing a Feasibility Study and subsequently arranging for project financing for Lara. Planalto is located in the Carajás mineral province, one of Brazil’s most prolific mining belts which produces high-grade iron ore, copper, nickel, manganese and gold. To date, 41 holes have been drilled, with a best drill hole intercept of 341 m from 13 m at 0.60% copper, including 108 m at 1.05% copper. PEA-level metallurgical tests indicate +90% copper recovery to a +25% copper concentrate using conventional flotation. In 2021, Lara and Capstone secured options on the Tariana and Zaspir licenses, located on adjoining lands to the north to test open mineralization. At the Cupuzeiro target, five holes with long intervals of over 0.2% copper and significant intervals of over 0.4% copper have been completed.
Copper Cities (Arizona, USA)
As announced on January 20, 2022, Capstone entered into an 18-month access agreement to conduct drill and metallurgical test work at BHP Copper Inc’s Copper Cities project, located approximately 10 km east of the Pinto Valley Mine. The two-phase 2021-2022 exploration program has been completed. Phase I, comprising approximately 5,500 m in 19 twin holes was completed in early April; Phase II, comprising approximately 3,514 m in eight geology model confirmation holes, was completed in early May. Assaying and Metallurgical studies are underway pointing to a mineral resource estimate tentatively slated for late Q3 2022. To date, the Company has spent approximately $4.3 million of the $6.7 million programmed.
Future Opportunities
Mantos Blancos District and Near Mine Exploration – Oxides & Sulphides
The Mantos Blancos mine’s geology is well understood and Capstone’s team has a long history of mineral resource discovery and conversion into mineral reserves. Near-mine opportunities exist to add additional oxides and sulphides mineral resources, as well as to upgrade existing high-grade inferred resources through additional drilling below the current pit limit.
In addition, many mineralized outcrops have been identified at the Rosario prospect, approximately 15 km south of Mantos Blancos. Exploration targets have been identified through the intersection of faults, geological mapping, geophysics and geochemistry, but limited drilling has been performed to date with the most recent activity in 2017 returning the presence of sub-economic oxide mineralization.
Mantoverde District and Near Mine Exploration – Oxides & Sulphides
Mantoverde has a history of mineral reserves and resources growth through successful exploration. The current mineral resource is open at depth in multiple locations along the main Mantoverde, Santa Clara and Montecristo faults. Future drilling programs will focus on deeper high-grade zones and on sulphide areas in the northern portion of the deposit near the Celso and Manto Russo pits, which are less explored.
Mantoverde also has significant potential to develop a larger mining district and several near-mine resource expansion opportunities exist within the mine’s 23 km land package along the Atacama Fault System. District targets identified to date include the Las Animas, Paloma, Las Juntas, San Manuel and Santa Clara targets, north of the current pit design.
Methodology
Cozamin drill core samples are analyzed at ALS in North Vancouver, Canada after preparation at its facilities in Zacatecas, Mexico. The entire sample is crushed to a minimum of 70% passing 2 millimetres. A 250 g subsample of the crushed material is then pulverized to 85% passing 75 microns. Copper, zinc, lead and silver are determined by ICP analysis after 4 acid digestion of a 0.25 g or 0.4 g subsample of pulverized material. QAQC in each batch of 20 samples include a blank, a certified reference material and a duplicate (one of a field, coarse reject or pulp reject).
Santo Domingo drill core and reverse circulation chip samples are analyzed at ALS in Lima, Peru after preparation at its facilities in Copiapó and La Serena, Chile. The entire sample is crushed to a minimum of 70% passing 2 millimetres. A 1000 g subsample of the crushed material is then pulverized to 85% passing 75 microns. Copper, cobalt and sulphur are determined by ICP analysis after 4 acid digestion of a 0.25 g or 0.4 g subsample of pulverized material and gold is determined by fire assay fusion and an ICP-AAS finish on a 30-gram charge. Iron is determined by ICP-AES after sodium peroxide fusion. QAQC with each batch of 40 samples includes a blank, two to three certified reference materials and a duplicate (one each of a field, coarse reject and pulp reject).
Planalto drill core samples are analyzed at ALS in Lima, Peru after preparation at its facilities in Parauapebas, Brazil. The entire sample is crushed to a minimum of 70% passing 2 millimetres. A 250 g subsample of the crushed material is then pulverized to 85% passing 75 microns. Copper is determined by ICP analysis after 4 acid digestion of a 0.25 g or 0.4 g subsample of pulverized material and gold is determined by fire assay fusion and an ICP-AES finish on a 30-gram charge. Blank, duplicate core or certified gold and copper reference materials were inserted at approximately every 10th sample.