Marimaca Copper Corp. Announces Updated Mineral Resource Estimate for the Marimaca Oxide Deposit
underway which is expected to define the optimized process design flowsheet ahead of the planned DFS. Results from Phase 5 were announced on June 15, 2022 following a rigorous program including full-scale column testing, mini-column testing, container-leach testing, sulfation tests, acid sensitivity testing, Iso-pH testing, and head characterization for heap leach and run-of-mine ("ROM") samples. In-line with results from Phases 1-4, Phase 5 recoveries in the column and bottle roll tests generally exceeded the solubility ratio (CuS/CuT) and leaching potential of the samples, indicating a potentially larger proportion of total copper will be recovered in industrial-scale operations. The leaching potential of copper ores is defined as acid soluble copper (CuS) plus cyanide soluble copper (CuCN) divided by total copper (CuT). The acid solubility ratio (CuS/CuT) for copper oxides such as atacamite, brochantite and chrysocolla, which dissolve quickly when exposed to acid, is a good predictor of leachability. However, where the mineralization has several copper bearing minerals with different dissolution characteristics under these leaching conditions (such as Marimaca's black oxide (wad) component), the copper acid solubility ratio may materially underestimate the acid leaching potential for heap leach operations, especially where soluble copper sulphides such as chalcocite, covellite and bornite are present. structures and splays. Higher grade green oxide mineralization (brochantite, atacamite, chrysocolla) dominates the core of the deposit and is located near-surface. High grade zones of oxides, mixed and enriched mineralization extend at depth beneath the green oxide zones. The MOD is exposed at surface which is expected to drive a low strip ratio during the mine's potential
operational phase. Exploration for sulphide mineralization down-dip of the MOD to the east is ongoing and results will be released when available. The MOD oxide potential remains open to the east and southeast and further exploration may be planned in due course. Satellite oxide discoveries made in 2021 (Mercedes, Cindy, Roble) have not received sufficient drilling to be included in the 2023 MRE. Grade estimates were completed using ordinary kriging with nominal block size measuring 5m by 5m by 5m. Resources have been classified by their proximity to sample locations and number of drill holes and samples within different search ellipsoids, and are reported according to the CIM Definition Standards for Mineral Resources and Mineral Reserves and NI 43-101. The technical and economical parameters used for the 2023 MRE are identical to the 2022 MRE and were informed by the 2020
Preliminary Economic Assessment ("PEA") assumptions. Although the PEA no longer reflects the current economic potential of the project and should be seen as historical in nature and should not be relied upon, the 2020 PEA cost assumptions are still considered to be the most relevant cost assumptions for the 2023 MRE at this stage.