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, 2023 -- InvestorsHub
NewsWire -- 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 released 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
- Significantly de-risks the Marimaca ore body ahead of
the planned Definitive Feasibility Study (DFS)
- 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:
- Low strip ratio maintained in the constraining pit
shell
- 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
- 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 geological 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 ratio; 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.
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 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
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
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/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
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 metallurgical
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 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.
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 concentrated 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 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.
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 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.
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
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
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
experience. 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, has
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
marimaca@tavistock.co.uk
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 prove 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 number of assumptions and estimates
that, while considered reasonable by Marimaca Copper, are
inherently subject to significant business, economic, competitive,
political and social uncertainties and 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 on 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, exploration and development of mineral properties, the
uncertainties involved in interpreting drilling results and other
geological data, fluctuating metal prices, the possibility of
project delays or cost overruns or unanticipated excessive
operating costs and expenses, uncertainties related to the
necessity of financing, uncertainties relating to regulatory
procedure and timing for permitting reviews, the availability of
and costs of financing needed in the future as well as those
factors disclosed in the annual information form of the Company
dated March 27, 2023 and other filings made by the Company with the
Canadian securities regulatory authorities (which may be viewed
at www.sedar.com).
Statements regarding the Company’s planned DFS on the Project and
the Company’s plans and expectations regarding the
6th phase of its metallurgical test work at the
Project are forward-looking information and may not be realized.
Accordingly, readers should not place undue reliance on
forward-looking statements. Marimaca Copper undertakes no
obligation to update publicly or otherwise revise any
forward-looking statements contained herein whether as a result of
new information or future events or otherwise, except as may be
required by law.
Neither the Toronto Stock Exchange nor the Investment Industry
Regulatory Organization of Canada accepts responsibility for
the adequacy or accuracy of this release.
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