Mineros Announces Updated Prefeasibility Study for the Porvenir Project and Highlights Emerging Porvenir Polymetallic District

2026-03-31

TSX - Toronto Stock Exchange · Gold · Silver · Zinc · Colombia

(all amounts expressed in U.S. dollars unless otherwise stated)

Mineros S.A. (TSX: MSA, OTCQX: MNSAF, BVC: MINEROS) (“Mineros” or the “Company”) is pleased to announce the results of the updated prefeasibility study for the Hemco Property (the “2026 PFS”) including its 100% owned Porvenir polymetallic project (“Porvenir Project” or “Porvenir”) located within the Company’s Hemco Property in northeastern Nicaragua. In addition, the Company has updated Mineral Resource and Mineral Reserve estimates as of December 31, 2025, for its operating Panama and Pioneer mines.

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Figure 1: Porvenir Polymetallic District, Porvenir, Leticia, Guillermina, San Antonio deposits and exploration targets. Source: Mineros, 2026

A National Instrument 43-101 (“NI 43-101”) technical report entitled, “NI 43-101 Technical Report Hemco Property, Region Autonoma de la Costa Caribe Norte, Nicaragua”, issued and effective March 31, 2026 (“The Hemco Technical Report”), prepared by SLR Consulting (Canada) Ltd. (“SLR”) will be filed on SEDAR+ in accordance with applicable Canadian securities laws.

The 2026 PFS confirms Porvenir as a high-margin, stand-alone underground operation and the cornerstone of an emerging district including the Guillermina, Leticia, and San Antonio deposits.

HIGHLIGHTS:

Robust Economics: After-tax net present value, using a 5% discount rate (“NPV5%”) of $460 million, after-tax internal rate of return (“IRR”) of 37.9% and 2.0-years payback base case 1

After-tax free cash flow at $3,150/oz Au of $727 million for the life of mine

All-in Sustaining Cost (“AISC”) 2 of $1,295/oz of gold equivalent (“AuEq”)

Initial capital cost requirement of $206.8M

Strong Production Profile: Average annual sales of 72.3Koz AuEq, 54.5 Koz Au, 190 Koz Ag, 28 Mlb Zn and 3.75 Mlb Cu over years 1 to 9 (years of full production) of mine life.

Stand-alone operation: A 2,000 tonnes per day (“tpd”) processing plant with associated infrastructure including tailing facility, power supply via dedicated 34.5 kV distribution line and wastewater treatment plant.

Optimized Flowsheet: Metallurgical testing has confirmed a process involving flotation and cyanidation, enabling the recovery of copper and zinc concentrates alongside gold-silver doré.

District Scale Potential: Updated Mineral Resource estimates for Porvenir, Guillermina, Leticia, and San Antonio reinforce a district-scale mineralized system centered on Porvenir infrastructure.

Porvenir Deposit Mineral Reserves: Updated Mineral Reserves as of December 31, 2025: Proven and Probable Mineral Reserves : 6,477 Kt averaging 3.53 g/t AuEq 3 , 2.86 g/t Au, 12.27 g/t Ag, 2.61% Zn and 0.37% Cu, containing 736 Koz AuEq, 596 Koz Au, 2,555 Koz Ag, 372 Mlb Zn, and 52 Mlb Cu. Proven Mineral Reserves: 650 Kt averaging 4.25 g/t AuEq, 3.50 g/t Au, 14.07 g/t Ag, 2.54% Zn and 0.50% Cu, containing 89 Koz AuEq, 73 Koz Au, 294 Koz Ag, 36 Mlb Zn, and 7 Mlb Cu.

Probable Mineral Reserves: 5,827 Kt averaging 3.45 g/t AuEq, 2.79 g/t Au, 12.07 g/t Ag, 2.61% Zn and 0.35% Cu, containing 647 Koz AuEq, 523 Koz Au, 2,261 Koz Ag, 336 Mlb Zn and 45 Mlb Cu.

Daniel Henao, President and Chief Executive Officer of Mineros, commented: “Porvenir's economics are compelling, a $460 million NPV at a 5% discount, near 40% IRR, and 2-year payback speak for themselves. What excites us most is that Porvenir is just the beginning of a confirmed polymetallic district. Nearby deposits like Guillermina, Leticia, and San Antonio sit within striking distance of shared and scalable infrastructure, and we believe we are standing on a district that has the potential to grow Mineros’ operations exponentially over the coming decade.”

PORVENIR POLYMETALLIC DISTRICT & PORVENIR PROJECT

The 2026 PFS and ongoing exploration work mark an important milestone, supporting Mineros’ view of an emerging polymetallic district with gold, silver, zinc, and copper associated with an intermediate sulphidation epithermal system. The district is centered on the Porvenir Project and includes several nearby deposits and early-stage exploration targets. This clustering highlights the presence of a coherent, district-scale mineralized system.

The 2026 PFS covers the Hemco Property in its entirety. As Panama and Pioneer are producing mines, the study's development focus is on the Porvenir Project, the Company’s principal development-stage project within the district. Concurrently, Mineros has completed updated Mineral Resource estimates for the Guillermina, Leticia, and San Antonio deposits. On a consolidated basis, Porvenir hosts approximately 736 Koz AuEq 3 in Proven and Probable Mineral Reserves. In addition, Measured and Indicated Mineral Resources, exclusive of Mineral Reserves, total approximately 406 Koz AuEq 4 , with a further 313 Koz AuEq classified as Inferred Mineral Resources on all four deposits. Mineros believes centralized infrastructure at Porvenir could serve as a processing hub for the district, with potential to significantly extend mine life beyond the current plan.

Relative to the previous prefeasibility study, this additional technical work has strengthened the project design, supported a better understanding of the underground mine plan, and defined an updated processing flowsheet. The 2026 PFS reflects improved project economics and supports Porvenir’s advancement as a robust underground polymetallic development project within the Hemco operations.

Recent exploration and technical work have highlighted a district-scale mineralized system comprising several spatially related deposits and targets, including:

Porvenir Project : An epithermal gold-silver-zinc-copper system in pre-development stage with updated Mineral Reserves and Mineral Resources, which is the focus of the 2026 PFS.

Guillermina: An epithermal gold-silver-zinc-copper system at an advanced exploration stage, located ~3 km north of Porvenir; open along strike and at depth, with updated Indicated and Inferred Mineral Resources.

Leticia: An epithermal gold-silver-zinc system at an advanced exploration stage, located ~500 m northwest of Porvenir; open along strike and at depth, with updated Indicated and Inferred Mineral Resources.

San Antonio : An epithermal gold-silver-zinc-copper system at an advanced exploration stage, located ~500 m southwest of Porvenir; open along strike and at depth, with updated Inferred Mineral Resources.

Early-stage exploration targets : Mombacho, Pochomil, Apoyo and Madroño, Momotombo which form part of the Company’s broader exploration pipeline within the Porvenir polymetallic district.

The presence of significant polymetallic mineralization distributed throughout the district reinforces the potential for continued resource growth and exploration activities which are focused on expanding Mineral Resources, increasing geological confidence, and advancing the broader district potential centered on the Porvenir Polymetallic district. (See figure 1)

PORVENIR PROJECT OVERVIEW

The Porvenir Project is located within the Bonanza-Siuna-Rosita Mining Triangle in northeastern Nicaragua, approximately 420 km northeast of Managua. The project forms part of the Company’s Hemco Property, which includes the producing Panama and Pioneer underground gold mines, as well as several advanced-stage and early-stage exploration targets across the district.

Mineralization at Porvenir occurs primarily within the Real McKoy and the Porvenir Norte and Porvenir Sur zones and is hosted in epithermal veins associated with intermediate sulphidation mineralization and hydrothermal breccias.

Mining will be conducted using mechanized underground methods. Geomechanical modelling completed as part of the 2026 PFS has been updated to support optimized stope design and improved underground mining parameters, with bench-and-fill and sub-level stoping as the primary extraction methods.

Ore from the Porvenir underground mine will be processed in a new dedicated processing facility incorporating flotation and cyanidation circuits. The optimized flowsheet enables the recovery of copper and zinc concentrates in addition to gold-silver doré.

Economic Analysis

The economic analysis of the Porvenir Project demonstrates that the Mineral Reserves are economically viable at the consensus forecast prices of $3,150/oz Au, $45.00/oz Ag, $4.72/lb Cu, and $1.22/lb Zn over the LOM. The 2026 PFS Update base case economics result in an after-tax NPV at a 5% discount rate of approximately $460 million, an after-tax IRR of 37.9%, and a payback period of approximately 2.0 years from the start of production.

Initial capital costs are estimated at $206.8 million, including contingency. Life-of-Mine (“LOM”) sustaining capital is estimated at $66.2 million, and closure and reclamation costs are estimated at $33.4 million.

After-Tax cash flow undiscounted for the LOM of $727 million, see Figure 2 , and the average LOM AISC per ounce of gold equivalent sold is estimated at $1,295/oz AuEq.

Mine and Processing Plant Operation

The estimated Mineral Reserves support LOM of 9.2 years at a peak production rate of 2,000 tpd. The LOM plan is designed to minimize upfront capital expenditures without adversely affecting initial cash flow. The mine plan includes a six-month progressive ramp-up period, gradually increasing to 2,000 tpd in year one. Underground development is expected to commence two years prior to the start of production.

The proposed Porvenir Plant is designed as a stand-alone facility with a treatment capacity of 2,000 tpd, placed within a layout with sufficient capacity for future expansions. The plant will utilize an updated metallurgical flowsheet designed to produce three primary products: copper-lead concentrate containing gold and silver, zinc concentrate, and gold-silver doré bars. The comprehensive process includes primary crushing, followed by a grinding circuit featuring a SAG mill and two parallel ball mills. The recovery circuit integrates specialized stages such as flash flotation, conventional Cu-Pb and zinc flotation, and a cyanidation circuit for flotation tailings. The facility includes a Merrill-Crowe recovery system, a cyanide destruction circuit for tailings detoxification, and an industrial wastewater treatment plant equipped with an acid mine drainage module.

The Porvenir Plant is designed to achieve LOM metallurgical recoveries rates of 88.4% for gold, 84.9% for silver, 84.5% for zinc, and 69.9% for copper. Under the 2026 PFS, the Porvenir Project is expected to deliver average annual sales of 72.3 Koz AuEq 1 , 54.5 Koz Au, 190 Koz Ag, 28 Mlb Zn and 3.75 Mlb Cu over years 1 to 9 (years of full production) of mine life. See Figure 3

Sensitivity analysis for the base case is provided in Table 1 .

Table 1: After-tax sensitivity analysis

Gold Price

($/oz Au)

NPV 10%

($000)

NPV 5%

($000)

2,520

152,378

263,836

2,835

221,702

361,851

3,150 (Base Case)

291,026

459,867

3,465

360,238

557,677

3,780

429,309

655,227

The 2026 PFS was managed by Mineros, completed by BISA Ingenieria de Proyectos S.A. of Lima, Peru (“BISA”), and reviewed by SLR. Both BISA and SLR are independent of Mineros.

PORVENIR MINERAL RESOURCES AND MINERAL RESERVES ESTIMATES

Porvenir Deposit Mineral Resources

Porvenir Project Mineral Resources set out in Table 2 were estimated by Mineros and reviewed by SLR. The updated Mineral Resource estimate effective December 31, 2025, accounts for updated metal prices, cost estimates, metallurgical recoveries, and resource reporting using an $80/t NSR cut-off for sub-level stoping resource shapes.

Table 2: Porvenir Mineral Resources – Effective December 31, 2025

Mineral Resource Category

Tonnes

(Kt)

Gold Grade

(g/t Au)

Silver Grade

(g/t Ag)

Zinc Grade

(% Zn)

Copper Grade

(% Cu)

Gold Eq Grade

(g/t AuEq)

Cont. Metal

(Koz Au)

Cont. Metal

(Koz Ag)

Cont. Metal

(Mlb Zn)

Cont. Metal

(Mlb Cu)

Cont.

Metal

(Koz AuEq)

Measured

159

1.86

10.52

1.82

0.43

2.39

Indicated

2,811

1.91

9.02

2.20

0.27

2.44

172

815

137

220

Total M+I

2,969

1.91

9.10

2.18

0.28

2.44

182

869

143

233

Inferred

1,031

2.05

6.77

2.35

0.12

2.64

224

Notes

CIM (2014) definitions were followed for Mineral Resources.

The effective date for the Mineral Resources is December 31, 2025.

Mineral Resources are estimated at an NSR cut-off value of $80/t for sub-level stoping.

Mineral Resources are estimated using a long-term gold price of $2,500/oz Au, a silver price of $28/oz Ag, a zinc price of $1.18/lb Zn, and a copper price of $3.92/lb Cu.

Underground reporting shapes were used to demonstrate Reasonable Prospects for Eventual Economic Extraction.

Bulk density average is 2.73 t/m 3 .

Metallurgical recoveries were applied on a block-by-block basis and average 79.2% for gold, 62.2% for silver, 78.1% for zinc, and 37.1% for copper.

Material within 10 m of the topographic surface has been excluded from Porvenir Mineral Resources to allow for artisanal mining.

The NSR $/t value for each block was calculated using the following NSR factors:

$75.88/g x g/t Au x gold recovery

$0.744/g x g/t Ag x silver recovery

$12.93/% x % Zn x zinc recovery

$53.07/% x % Cu x copper recovery

10.

The formula used to calculate the AuEq grade is Au g/t + (Ag g/t * silver AuEq factor) + (Zn% * zinc AuEq factor) + (Cu% * copper AuEq factor), where:

silver AuEq factor = (0.74 * silver recovery) / (75.88 * gold recovery)

zinc AuEq factor = (12.93* zinc recovery) / (75.88 * gold recovery)

copper AuEq factor = (53.07 * copper recovery) / (75.88 * gold recovery)

11.

Gold Grade stated on an AuEq basis and AuEq Contained Metal have been calculated for purposes of this press release and are not disclosed in the Hemco Technical Report.

12.

Mineral Resources are exclusive of Mineral Reserves.

13.

Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.

14.

Numbers may not add due to rounding.

Porvenir Deposit Mineral Reserves

Mineral Reserves were estimated by BISA and reviewed by SLR, set out in Table 3 , using the updated Mineral Resource estimate, and Deswik stope optimizer software to prepare stope designs for bench-and-fill and sub-level long hole stoping of the deposit. Mine access designs assume the use of mechanized equipment for mucking and haulage and conventional ventilation and backfill systems. Dilution was added to the footwall and hanging wall of stopes and mining extraction factors were included to account for pillars and practical ore extraction from stopes. Allowances were made for sill and rib pillars within the designs.

Table 3: Porvenir Mineral Reserves – Effective December 31, 2025

Mineral Reserve

Category

Tonnes

(Kt)

Gold Grade

(g/t Au)

Silver Grade

(g/t Ag)

Zinc Grade

(% Zn)

Copper Grade

(% Cu)

Gold Eq Grade

(g/t AuEq)

Cont. Metal

(Koz Au)

Cont. Metal

(Koz Ag)

Cont. Metal

(Mlb Zn)

Cont. Metal

(Mlb Cu)

Cont. Metal

(Koz AuEq)

Proven

650

3.50

14.07

2.54

0.50

4.25

294

Probable

5,827

2.79

12.07

2.61

0.35

3.45

523

2,261

336

647

Total P+P

6,477

2.86

12.27

2.61

0.37

3.53

596

2,555

372

736

Notes

CIM (2014) definitions were followed for Mineral Reserves.

Mining methods at Porvenir include bench-and-fill stoping and sub-level stoping.

Minimum mining width for Porvenir is 1.80 m.

Mineral Reserves are based on NSR cut-off values ranging approximately between $96/t and $110/t depending on mining method and mining area.

Mineral Reserves were estimated using long-term metal prices of $2,150/oz Au, $24/oz Ag, $1.01/lb Zn, and $3.33/lb Cu.

Metallurgical recoveries were applied on a block-by-block basis and average 88.4% for gold, 84.9% for silver, 84.5% for zinc and 69.9% for copper.

The NSR $/t value for each block was calculated using the following NSR factors:

$65.25/g x g/t Au x gold recovery

$0.638/g x g/t Ag x silver recovery

$9.83/% x % Zn x zinc recovery

$41.14/% x % Cu x copper recovery

The formula used to calculate the AuEq grade is Au g/t + (Ag g/t * silver AuEq factor) + (Zn% * zinc AuEq factor) + (Cu% * copper AuEq factor), where:

silver AuEq factor = (0.638 * silver recovery) / (65.25 * gold recovery)

zinc AuEq factor = (9.83* zinc recovery) / (65.25 * gold recovery)

copper AuEq factor = (41.14 * copper recovery) / (65.25 * gold recovery)

Gold Grade stated on an AuEq basis and AuEq Contained Metal have been calculated for purposes of this press release and are not disclosed in the Hemco Technical Report.

10.

Totals may not add due to rounding.

PORVENIR POLYMETALLIC DISTRICT MINERAL RESOURCES

Porvenir Polymetallic District Mineral Resources

Mineral Resources were estimated by Mineros and reviewed by SLR, set out in Table 4 . The updated Mineral Resource estimate effective December 31, 2025, accounts for updated metal prices, cost estimates, metallurgical recoveries, and resource reporting using a $80/t NSR cut-off for sub-level stoping resource shapes. Mineral Resources at Guillermina, Leticia and San Antonio are classified based on drill hole spacing, using criteria comparable to those applied at Porvenir due to the similar deposit style.

Table 4: Porvenir Polymetallic District Mineral Resources – Effective December 31, 2025

Mineral Resource Category

Deposit

Tonnes

(Kt)

Gold Grade

(g/t Au)

Silver Grade

(g/t Ag)

Zinc Grade

(% Zn)

Copper Grade

(% Cu)

Gold Eq Grade

(g/t AuEq)

Cont. Metal

(Koz Au)

Cont. Metal

(Koz Ag)

Cont. Metal

(Mlb Zn)

Cont. Metal

(Mlb Cu)

Cont.

Metal

(Koz AuEq)

Porvenir

159

1.86

10.52

1.82

0.43

2.39

Measured

Guillermina

Leticia

San Antonio

Porvenir

2,811

1.91

9.02

2.20

0.27

2.44

172

815

137

220

Indicated

Guillermina

1,763

0.97

27.33

6.61

0.21

2.37

1,549

257

134

Leticia

300

3.40

13.31

1.71

0.54

3.98

129

San Antonio

Porvenir

2,969

1.91

9.10

2.18

0.28

2.44

182

869

143

233

M+I

Guillermina

1,763

0.97

27.33

6.61

0.21

2.37

1,549

257

134

Leticia

300

3.40

13.31

1.71

0.54

3.98

129

San Antonio

Total M+ I

Porvenir Polymetallic

5,033

1.67

15.74

3.71

0.27

2.51

270

2,546

411

406

Porvenir

1,031

2.05

6.77

2.35

0.12

2.54

224

Inferred

Guillermina

1,118

1.44

30.15

5.50

0.17

2.66

1,084

136

Leticia

137

2.81

8.53

0.82

0.36

3.15

San Antonio

1,313

2.23

12.33

0.32

0.93

2.82

521

119

Total Inferred

Porvenir Polymetallic

3,599

1.95

16.13

2.53

0.44

2.70

226

1,866

200

313

Notes

CIM (2014) definitions were followed for Mineral Resources.

The effective date for the Mineral Resources is December 31, 2025.

Mineral Resources are estimated at an NSR cut-off value of $80/t for sub-level stoping.

Mineral Resources are estimated using a long-term gold price of $2,500/oz Au, a silver price of $28/oz Ag, a zinc price of $1.18/lb Zn, and a copper price of $3.92/lb Cu.

Underground reporting shapes were used to demonstrate Reasonable Prospects for Eventual Economic Extraction.

Bulk density average is 2.73 t/m³ for Porvenir, 2.73 t/m 3 , 2.71 t/m 3 for Guillermina, 2.77 t/m 3 for Leticia, and 2.76 t/m 3 for San Antonio.

Metallurgical recoveries for Porvenir were applied on a block-by-block basis and average 79.2% for gold, 62.2% for silver, 78.1% for zinc, and 37.1% for copper.

Metallurgical recoveries for Guillermina were applied on a block-by-block basis and average 83.9 % for gold, 69.3 % for silver, 81.8 % for zinc and 47.0 % for copper.

Metallurgical recoveries for Leticia were applied on a block-by-block basis and average 73.3 % for gold, 60.6 % for silver, 62.2 % for zinc and 44.1 % for copper.

10.

Metallurgical recoveries for San Antonio were applied on a block-by-block basis and average 79.3 % for gold, 68.3 % for silver, 27.9% for zinc and 56.9 % for copper.

11.

Material within 10 m of the topographic surface has been excluded from Porvenir Mineral Resources to allow for artisanal mining.

12.

The NSR $/t value for each block was calculated using the following NSR factors:

$75.88/g x g/t Au x gold recovery

$0.744/g x g/t Ag x silver recovery

$12.93/% x % Zn x zinc recovery

$53.07/% x % Cu x copper recovery

13.

The formula used to calculate the AuEq grade is Au g/t + (Ag g/t * silver AuEq factor) + (Zn% * zinc AuEq factor) + (Cu% * copper AuEq factor), where:

silver AuEq factor = (0.74 * silver recovery) / (75.88 * gold recovery)

Mineros Announces Updated Prefeasibility Study for the Porvenir Project and Highlights Emerging Porvenir Polymetallic District

Earlier from Mineros S.A.