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.
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
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
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/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.
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$0.16/lb Cu; heap leach recovery 76% of CuT; ROM
recovery 40% of CuT; and 42°-52° pit slope angle* Mineral resources
which are not mineral reserves do not have demonstrated economic
viability. Due to the uncertainty which may attach to inferred
mineral resources, it cannot be assumed that all or any part of an
inferred mineral resource will be upgraded to an indicated or
measured mineral resource as a result of continued exploration
Parameter |
2022 MRE |
2023 MRE |
Mining cost (US$/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 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 InformationFor further
information please visit www.marimaca.com or contact:
Tavistock +44 (0) 207 920
3150Emily 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.
Photos accompanying this announcement are available at
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