Marimaca Announces Updated Mineral Resource Estimate for the Marimaca Oxide Deposit 44% increase in M&I Resource tonnes to 200Mt at 0.45% CuT for 900kt of Contained Copper Inferred Resource of 37Mt at 0.38% CuT for 141kt of Contained Copper
News Release
Marimaca Announces Updated Mineral Resource Estimate for the Marimaca Oxide Deposit
44% increase in M&I Resource tonnes to 200Mt at 0.45% CuT for 900kt of Contained Copper
Inferred Resource of 37Mt at 0.38% CuT for 141kt of Contained Copper
86% of Total Resource Tonnes in Measured and Indicated Categories
Vancouver, British Columbia, May 18, 202 3 – Marimaca Copper Corp. (“Marimaca Copper” or the “Company”)
(TSX: MARI) is pleased to announce an updated Mineral Resource Estimate (“MRE”) for the Marimaca Oxide Deposit (the
“MOD” or the “Project”) located in the Antofagasta region of northern Chile.
The 2023 MRE incorporates 28,374m of new drilling data completed since the 2022 MRE release d in October 2022. The MOD
database now consists of 139,164m of drilling completed since discovery in 2016. New drilling data captured following the 2022
MRE was largely targeted at conversion of Inferred Resources to the Measured and Indicated categories.
The 2023 MRE was prepared in accordance with the Canadian Institute of Mining, Metallurgy and Petroleum ("CIM") Definition
Standards and National Instrument 43-101 - Standards of Disclosure for Mineral Projects ("NI 43-101").
Highlights
• Measured and Indicated Resources of 200.3Mt at 0.45% CuT for 900kt of contained copper
• Inferred Resources of 37.3Mt at 0.38% CuT for 141kt of contained copper
• 86% of the MOD’s total resource tonnes now contained in the Measured and Indicated categories
o Significantly de-risks the Marimaca ore body ahead of the planned Definitive Feasibility Study (DFS)
o Majority of new drilling focused on areas of the northern MOD which previously contained lower density of drilling
(see Figure 1)
• Unique characteristics of the MOD maintained in the 2023 MRE:
o Low strip ratio maintained in the constraining pit shell
o All mineral resources captured in a single continuous pit
• Represents the final phase of oxide resource definition at the MOD ahead of the planned DFS
o Ongoing exploration workstreams will focus on the Marimaca sulphide target and the delineation of near-mine
satellite oxide targets (Mercedes, Cindy, Mititus)
Hayden Locke, President & CEO of Marimaca Copper, commented:
“The 2023 MRE represents the culmination of an exceptionally successful two years of infill drilling at the Marimaca Oxide
Deposit led by Sergio Rivera and his team. We are very pleased with our conversion ratio of Inferred Resources to Measured and
Indicated categories, and today’s result drives significantly improved confidence in the geologic al model and understanding of
the Marimaca ore body.
“The M&I resource estimate at the MOD now stands at approximately 900,000 tonnes of contained metal, and this will support
the assessment of a larger operation in terms of copper cathode production and mine life extension during the Definitive
Feasibility Study. Despite the significant resource growth demonstrated at Marimaca since 2019, the ore body’s core, unique
attributes have been preserved as the deposit has grown – very low strip rati o; a shallow higher-grade core expected to be
accessible in the early mining years; and limited pre-stripping or significant cutbacks expected during operation.
“We continue to progress rapidly forward with development workstreams at the MOD including preparation for our permitting
submissions and the Feasibility Study. Additionally, the first phase of the 2023 sulphide exploration program has been completed
with assays pending and results expected in the near term.”
Summary of 2022 Mineral Resource Estimate
The 2023 MRE was completed by independent consultants NCL Ingeniería y Construcción SpA (“NCL”) and verified by Luis
Oviedo of NCL, a qualified person and independent of Marimaca (within the meaning of such terms under NI 43-101). The 2023
MRE incorporates 139 ,164m of drilling across 554 drill holes completed between 2016 and 2022 and is reported with an
effective date of May 17, 2023. An overview of the infill drilling completed in 2022 and captured in both the 2023 MRE and the
2022 MRE is presented in Figure 1. The Whittle Optimisations were run using the same operating cost parameters as the 2022
MRE and a US$4.00/lb copper price assumption.
Mineral Resource Category and
Type
Quantity CuT CuS CuT CuS
(kt) (%) (%) (t) (t)
Total Measured 96,954 0.49 0.28 473,912 268,628
Total Indicated 103,358 0.41 0.21 425,797 219,690
Total Measured and Indicated 200,312 0.45 0.24 899,709 488,319
Total Inferred 37,289 0.38 0.15 141,252 55,802
Table 1. 2023 Mineral Resource Estimate (reported at 0.15% CuT cutoff)
.
* Pit shell constrained resources with demonstrated reasonable prospects for eventual economic extraction (RPEEE) are generat ed using series of Lerchs-Grossmann
pit shell optimizations completed by NCL
* CuT means total copper and CuS means acid soluble copper. Technical and economic parameters include: copper price US$4.00/l b; base mining cost of US$1.51/t
with a mining cost adjustment factor of US$0.04/t-10m bench; Heap Leach “HL” processing cost US$5.94/t (incl. G&A); Run-of-Mine “ROM” processing cost
US$1.65/t (incl. G&A); SX-EW processing cost and selling cost US$0.16/lb Cu; heap leach recovery 76% of CuT; ROM recovery 40% of CuT; and 4 2°-52° pit slope angle
* Mineral resources which are not mineral reserves do not have demonstrated economic viability. Due to the uncertainty which ma y attach to inferred mineral
resources, it cannot be assumed that all or any part of an inferred mineral resource will be upgraded to an indicated or measured mineral resource as a result of
continued exploration
Cut-off
grade
(% CuT)
Measured Indicated Measured + Indicated Inferred
Quantity
kt CuT [%] CuS [%] Quantity
kt CuT [%] CuS [%] Quantity
kt CuT [%] CuS [%] Quantity
kt CuT [%] CuS [%]
0.40 44.0 0.77 0.44 37.5 0.69 0.38 81.6 0.73 0.41 12.1 0.64 0.24
0.30 60.2 0.65 0.38 55.5 0.58 0.31 115.7 0.62 0.35 18.8 0.54 0.21
0.22 77.8 0.56 0.32 77.0 0.49 0.26 154.9 0.53 0.29 27.2 0.45 0.18
0.20 83.0 0.54 0.31 83.8 0.47 0.25 166.8 0.50 0.28 30.2 0.43 0.17
0.18 88.3 0.52 0.30 91.3 0.44 0.23 179.6 0.48 0.26 33.0 0.41 0.16
0.15 97.0 0.49 0.28 103.4 0.41 0.21 200.3 0.45 0.24 37.3 0.38 0.15
0.10 113.3 0.44 0.24 127.6 0.36 0.18 241.0 0.39 0.21 46.6 0.33 0.13
0.00 146.1 0.35 0.19 178.2 0.27 0.14 324.3 0.31 0.16 72.0 0.24 0.09
Table 2. Mineral Resource Sensitivity
* Pit shell constrained resources with demonstrated reasonable prospects for eventual economic extraction (RPEEE) are generated using series of Lerchs-Grossmann
pit shell optimizations completed by NCL
* CuT means total copper and CuS means acid soluble copper. Technical and economic parameters include: copper price US$4.00/l b; base mining cost of US$1.51/t
with a mining cost adjustment factor of US$0.04/t-10m bench; Heap Leach “HL” processing cost US$5.94/t (incl. G&A); Run-of-Mine “ROM” processing cost
US$1.65/t (incl. G&A); SX-EW processing cost and selling cost US$0.16/lb Cu; heap leach recovery 76% of CuT; ROM recovery 40% of CuT; and 42°-52° pit slope angle
* Mineral resources which are not mineral reserves do not have demonstrated economic viability. Due to the uncertainty which may attach to inferred mineral
resources, it cannot be assumed that all or any part of an inferred mineral resource will be upgraded to an indicated or measured mineral resource as a result of
continued exploration
Figure 1. Plan View of Resource Pit and Infill Drilling
Figure 2. 2023 MRE Block Model Plan View – Resource Category and Block Model
Figure 3. 2023 MRE North-South Long Section – Resource Category and Block Model
Metallurgy Commentary
Marimaca has completed 5 phases of extensive metallurgical test work at Marimaca. A 6th phase of me tallurgical testing is
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 (“HL”)
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 h as 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 he ap leach operations, especially where soluble copper
sulphides such as chalcocite, covellite and bornite are present.
The Marimaca Deposit Commentary
Figure 3 (long section) demonstrates the continuity of the oxide mineralization across the N- S extent of the deposit.
Mineralization is hosted consistently by east-dipping fracture sets with higher grades concentrate d along controlling NW -SE
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 w hich 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 sufficien t drilling to be included in the
2023 MRE.
2023 MRE Estimation Parameters
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 ident ical 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 up on, the 2020 PEA cost assumptions are still
considered to be the most relevant cost assumptions for the 2023 MRE at this stage.
Mineral Resource Category and Type Quantity CuT CuS CuT CuS
(kt) (%) (%) (t) (t)
Measured
Brochantite 31,293 0.62 0.45 194,890 141,442
Chrysocolla 24,252 0.44 0.33 105,594 79,863
Wad/Black oxides 10,727 0.29 0.15 30,599 16,116
Mixed 18,626 0.51 0.13 95,159 23,431
Enriched 12,056 0.40 0.06 47,669 7,776
Total Measured 96,954 0.49 0.28 473,912 268,628
Indicated
Brochantite 29,084 0.56 0.41 162,753 117,847
Chrysocolla 13,591 0.38 0.28 51,332 37,674
Wad/Black oxides 19,880 0.28 0.15 56,382 29,649
Mixed 17,193 0.41 0.11 71,109 18,654
Enriched 23,611 0.36 0.07 84,221 15,867
Total Indicated 103,358 0.41 0.21 425,797 219,690
Measured and Indicated
Brochantite 60,376 0.59 0.43 357,643 259,290
Chrysocolla 37,843 0.41 0.31 156,927 117,536
Wad/Black oxides 30,607 0.28 0.15 86,981 45,765
Mixed 35,819 0.46 0.12 166,268 42,085
Enriched 35,667 0.37 0.07 131,891 23,643
Total Measured and Indicated 200,312 0.45 0.24 899,709 488,319
Inferred
Brochantite 4,950 0.46 0.32 22,892 15,710
Chrysocolla 4,488 0.36 0.26 16,250 11,695
Wad/Black oxides 8,727 0.29 0.15 25,180 12,799
Mixed 5,979 0.36 0.11 21,548 6,541
Enriched 13,145 0.42 0.07 55,381 9,057
Total Inferred 37,289 0.38 0.15 141,252 55,802
Table 3. 2023 MRE by Mineralization Type
* Pit shell constrained resources with demonstrated reasonable prospects for eventual economic extraction (RPEEE) are generated using series of Lerchs -Grossmann
pit shell optimizations completed by NCL
* CuT means total copper and CuS means acid soluble copper. Technical and economic parameters include: copper price US$4.00/lb; base mining cost of US$1.51/t
with a mining cost adjustment factor of US$0.04/t-10m bench; Heap Leach “HL” processing cost US$5.94/t (incl. G&A); Run-of-Mine “ROM” processing cost
US$1.65/t (incl. G&A); SX-EW processing cost and selling cost US$0.16/lb Cu; heap leach recovery 76% of CuT; ROM recovery 40% of CuT; and 4 2°-52° pit slope angle
* Mineral resources which are not mineral reserves do not have demonstrated economic viability. Due to the uncertainty which may attach to inferred mineral
resources, it cannot be assumed that all or any part of an inferred mineral resource will be upgraded to an indicated or meas ured mineral resource as a result of
continued exploration
Parameter 2022 MRE 2023 MRE
Mining cost (US$/t mined) $1.51 base ($1.76 avg.) $1.51 base ($1.76 avg.)
Mining Cost Adjustment Factor (US$/t-10m bench) $0.04 $0.04
Heap Leach Cost (including G&A and mining cost
component from pit to Heap Leach) US$5.94/t processed US$5.94/t processed
Run-of-Mine Cost (including G&A and mining cost
component from pit to ROM) US$1.65/t processed US$1.65/t processed
SX-EW processing cost and selling cost (US$/lb Cu) $0.16 $0.16
Heap Leach Recovery (% CuT) 76% 76%
ROM Recovery (% CuT) 40% 40%
Pit Slope angle 42 - 52° 42 - 52°
Table 4. Summary of Inputs – 2023 MRE (no changes from 2022 MRE)
The Company intends to file an updated technical report to support the updated 2023 MRE on SEDAR within 45 days of this
news release or such earlier time in accordance with NI 43-101.
Qualified Person
The technical information in this news release, including the information related to geology, drilling, mineralization, modeling
and estimation has been reviewed and approved by Luis Oviedo, an independent Consulting Geologist with more than 45 years
of ex perience. Mr. Oviedo is a member of the Colegio de Geólogos and the Institute of Mining Engineers of Chile and is
independent and a qualified person (within the meaning of such terms under NI 43-101).
Mr. Oviedo confirms he has visited the project area, h as reviewed relevant project information, is responsible for the
information contained in this news release, and consents to its publication.
Contact Information
For further information please visit www.marimaca.com or contact:
Tavistock
+44 (0) 207 920 3150
Emily Moss / Adam Baynes
Forward Looking Statements
This news release includes certain “forward-looking statements” under applicable Canadian securities legislation. There can be
no assurance that such statements will prov e to be accurate, and actual results and future events could differ materially from
those anticipated in such statements. Forward-looking statements reflect the beliefs, opinions and projections on the date the
statements are made and are based upon a numb er of assumptions and estimates that, while considered reasonable by
Marimaca Copper, are inherently subject to significant business, economic, competitive, political and social uncertainties an d
contingencies. Many factors, both known and unknown, could cause actual results, performance or achievements to be
materially different from the results, performance or achievements that are or may be expressed or implied by such forward -
looking statements and the parties have made assumptions and estimates based o n or related to many of these factors. Such
factors include, without limitation: risks related to share price and market conditions, the inherent risks involved in the mining,