ERO.TO · 2025-09-18 12:00:00

Ero Copper Intercepts 115 Meters at 0.98% CuEq1 in Deepest Hole Drilled to Date at Furnas Copper-Gold Project – Phase 2 Drill Program to be Completed in Early Q4 2025

Drill Results Exploration Programs

September 18, 2025

Ero Copper Intercepts 115 Meters at 0.98% CuEq1 in Deepest Hole Drilled to Date at

Furnas Copper-Gold Project – Phase 2 Drill Program to be Completed in Early Q4 2025

Vancouver, British Columbia – Ero Copper Corp. (TSX: ERO, NYSE: ERO) ("Ero" or the

“Company”) is pleased to announce the remaining assay results from its 28,000-meter Phase

1 drill program at the Furnas Copper-Gold Project ("Furnas" or the "Project"), located in the

Carajás Mineral Province in Pará State, Brazil.

Complete results from the Phase 1 program are highlighted by intercepts that continue to

demonstrate high-grade continuity throughout the deposit as well as significantly extend the

known limits of mineralization within the high-grade zones (greater than 1% CuEq 1) to depth.

To date, mineralization has been extended to a depth of approximately 950 meters down-dip

from surface and remains open.

New Phase 1 program drill results are highlighted by:

• FURN-DD-00322: 115 meters at 0.76% copper and 0.47 grams per tonne ("gpt") gold

(0.98% CuEq1), including 46 meters at 0.81% copper and 0.56 gpt gold (1.11% CuEq1)

and 28 meters at 0.91% copper and 0.71 gpt gold ( 1.25% CuEq1). This is the deepest

hole drilled to date in the Southeast zone, drilled approximately 220 meters down-dip

from the previously known extent of mineralization and 950 meters down-dip from

surface.

• FURN-DD-00305: 103 meters at 0.88% copper and 0.80 gpt gold ( 1.26% CuEq 1),

including 27 meters at 1.04% copper and 1.18 gpt gold (1.60% CuEq1), demonstrating

continuity of known mineralization within the high-grade envelope of the Southeast

zone and supporting conversion of the current mineral resource.

• FURN-DD-00321: 115 meters at 0.47% copper and 0.27 gpt gold ( 0.60% CuEq 1),

including 8 meters at 1.13% copper and 0.49 gpt gold ( 1.36% CuEq 1), the deepest

hole drilled in the Northwest zone, approximately 650 meters down-dip from surface,

demonstrating further down-dip potential in the Northwest zone, which has had

limited extensional drilling to date in comparison to the Southeast zone.

• FURN-DD-00300: 80 meters at 1.02% copper and 0.36 gpt gold ( 1.19% CuEq 1),

including 28 meters at 1.67% copper and 0.49 gpt gold (1.90% CuEq1), demonstrating

continuity within the high-grade envelope of the Northwest zone and supporting

conversion of the current mineral resource.

1. Where applicable, copper equivalent ("CuEq") in this press release has been calculated using the following

formula: Cu grade + (Au grade x 0.03215 x ($1,900 gold price x 61.50% gold metallurgical recovery / (0.01 x

$9,259/tonne copper price x 85.00% copper metallurgical recovery)).

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Step-out drilling during the Phase 1 program has now extended the known limits of

mineralization to a depth of approximately 950 meters down-dip from surface. The National

Instrument 43-101 ("NI 43-101") compliant mineral resource estimate for the Project is based

on an average historical depth of drilling of 300 meters (vertical), with a maximum localized

down-dip depth from surface of 580 meters. For additional information on the Project's last

published mineral resource estimate, please refer to the Company's press release dated

October 2, 2024.

Drilling at Furnas continues with eight drill rigs currently on site. Ero expects to complete the

17,000-meter Phase 2 drill program in early Q4 2025, approximately three months ahead of

schedule.

"The full results from the 28,000-meter Phase 1 drill program are highly encouraging and

reinforce the potential for Furnas to be a large-scale, long-life, high-grade copper and gold

mining operation that we believe will fundamentally transform the Company and add

considerable value for our partner, Vale Base Metals" said Makko DeFilippo, President and

Chief Executive Officer. "The Phase 1 program has not only confirmed continuity of high-

grade mineralization, but also exceeded our expectations in demonstrating high-grade

mineralization well beyond the down-dip limits of the last published mineral resource

estimate."

"This year, the majority of our exploration efforts have been dedicated to advancing Furnas as

the next leg of our growth strategy. Following the cumulative 45,000-meter Phase 1 and 2

drill programs, and with eight drill rigs currently on site to support the Phase 3 program and

ongoing engineering studies, we are well-positioned to continue building momentum."

The complete results from the Phase 1 drill program will serve as the foundation for an

updated NI 43-101 compliant mineral resource estimate as well as a preliminary economic

assessment ("PEA") of the Project. The PEA, which was initiated earlier this year, remains on

track for completion during the first half of 2026. Please refer to the Company's July 10, 2025

press release in conjunction with the current release for complete results of the Phase 1

program.

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ABOUT THE FURNAS COPPER-GOLD PROJECT

Furnas is an iron oxide copper-gold deposit located approximately 50 kilometers southeast of

Vale Base Metal's ("VBM") Salobo operations and approximately 190 kilometers northeast of

Ero's Tucumã Operation. Covering an area of approximately 2,400 hectares, the Project sits

within fifteen kilometers of extensive regional infrastructure, including paved roads, an

industrial-scale cement plant, a power substation and Vale S.A.'s railroad loadout facility.

In July 2024, the Company signed a definitive earn-in agreement ("Agreement") with Salobo

Metais S.A, a subsidiary of VBM, to earn a 60% interest in the Project upon completion of

several exploration, engineering and development milestones over a five-year period. In

exchange for its 60% interest, Ero will solely fund a phased work program during the earn-in

period and grant VBM up to an 11.0% "free carry" on future Project construction capital

expenditures. For additional details on the key terms and execution of the Agreement, please

refer to the Company's press releases dated October 30, 2023 and July 22, 2024.

Prior to the commencement of the Phase 1 drill program, the Company published an initial NI

43-101 compliant mineral resource estimate on the Project, based on approximately 90,000

meters of historical drilling. This estimate underscored the significant potential of the Project.

Using a 1.00% copper equivalent cut-off grade, the mineral resource estimate, effective June

30, 2024, totaled:

• Indicated Mineral Resource: 35.2 million tonnes grading 1.04% copper and 0.69 gpt

gold (1.36% CuEq 1), containing an estimated 364,700 tonnes of copper and 775,300

ounces of gold

• Inferred Mineral Resource: 61.3 million tonnes grading 1.06% copper and 0.63 gpt

gold (1.36% CuEq1), containing an estimated 647,400 tonnes of copper and 1,235,600

ounces of gold

For additional information on the Project's mineral resource estimate, please see the

Company's press release dated October 2, 2024 as well as the corresponding technical

report titled “Furnas Copper Project – Para State, Brazil – NI 43-101 Mineral Resource

Estimate Technical Report”, dated November 18, 2024 with an effective date of June 30,

2024, prepared for the Company by Anderson Gonçalves Candido, FAusIMM of RPMGlobal

Canada Limited (“RPM”).

1. Where applicable, copper equivalent ("CuEq") in this press release has been calculated using the following

formula: Cu grade + (Au grade x 0.03215 x ($1,900 gold price x 61.50% gold metallurgical recovery / (0.01 x

$9,259/tonne copper price x 85.00% copper metallurgical recovery)).

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Figure 1: Furnas Plan View Map, including drill collar locations. Rock types include:

HCS Calcic-sodic hydrothermal rock

GRA Granite

DIO Diorite

RCL HD Chlorite-rich hydrothermal rock

GMF HD Grunerite-garnet-magnetite hydrothermal rock

GMF HD-2 Grunerite-garnet-magnetite hydrothermal rock

XTA Aluminous schist

RSL Host Quartz-rich rock

GMF RSL Magnetite-rich hydrothermally altered rock / Quartz-rich rock

Abbreviation Rock Type

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Figure 2: Cross section within the high-grade SE Zone of Furnas. Rock types include:

Abbreviation Rock Type

HDM Magnetite-rich hydrothermally altered rock

RSL Host Quartz-rich rock

GMF RSL Magnetite-rich hydrothermally altered rock / Quartz-rich rock

XTA Aluminous schist

RCL HD Chlorite-rich hydrothermal rock

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Figure 3: Cross section within the high-grade NW Zone of Furnas. Rock types include:

Abbreviation Rock Type

GRA Granite

HDCS Calcic-sodic undifferentiated mafic rock

HDM Magnetite-rich hydrothermally altered rock

RSL Host Quartz-rich rock

GMF RSL Magnetite-rich hydrothermally altered rock / Quartz-rich rock

RCL HD Chlorite-rich hydrothermal rock

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DRILL RESULTS - SOUTHEAST ZONE

FURN-DD-00280 458 523 65 0.79 0.40 0.98 51.2

incl 491 523 32 0.85 0.54 1.11 27.2

FURN-DD-00281 488 599 111 0.63 0.40 0.82 70.0

incl 519 539 20 0.81 0.62 1.11 16.2

FURN-DD-00283 429 523 93 0.80 0.32 0.95 74.7

incl 429 447 18 1.51 0.46 1.73 26.7

incl 489 512 23 1.33 0.71 1.67 30.5

FURN-DD-00291 174 271 97 0.50 0.25 0.62 48.7

incl 174 190 17 0.93 0.35 1.10 15.4

incl 252 271 19 0.75 0.39 0.94 14.4

FURN-DD-00292 196 248 52 0.57 0.56 0.84 29.7

incl 212 248 36 0.59 0.68 0.91 21.2

incl 235 248 13 0.63 0.95 1.08 8.1

FURN-DD-00294 556 639 83 0.56 0.39 0.75 46.2

incl 570 617 47 0.63 0.46 0.85 29.3

FURN-DD-00296 119 200 81 0.42 0.13 0.48 34.1

incl 182 200 18 0.89 0.23 1.00 16.2

FURN-DD-00297 297 389 92 0.91 0.65 1.22 83.9

incl 297 344 47 1.04 0.30 1.18 49.0

incl 359 389 30 1.10 1.48 1.81 33.1

FURN-DD-00298 329 423 94 0.90 0.57 1.17 84.6

incl 353 379 26 1.34 0.63 1.64 34.8

incl 399 421 22 0.99 0.98 1.46 21.8

FURN-DD-00299 422 483 62 0.76 0.57 1.03 46.8

incl 444 460 16 0.92 1.05 1.42 14.7

FURN-DD-00302 315 366 51 0.74 0.38 0.92 37.5

incl 334 361 27 0.97 0.42 1.17 25.7

FURN-DD-00303 243 289 46 1.31 0.44 1.52 60.8

incl 260 289 29 1.67 0.50 1.91 48.8

FURN-DD-00304 370 444 74 0.95 1.04 1.45 70.3

incl 391 441 50 1.00 1.40 1.67 50.5

FURN-DD-00305 352 455 103 0.88 0.80 1.26 90.6

incl 408 435 27 1.04 1.18 1.60 28.1

FURN-DD-00307 290 310 20 0.69 0.20 0.79 13.8

Hole ID From (m) To (m) Length (m) Cu (%) Au (g/t) CuEq (%)

%Cu Grade

x Thickness

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FURN-DD-00307 355 407 52 0.63 0.35 0.80 32.8

FURN-DD-00309 91 147 56 1.28 0.24 1.39 71.7

incl 116 139 23 1.86 0.31 2.01 42.8

FURN-DD-00310 121 150 29 0.80 0.36 0.97 23.2

FURN-DD-00311 356 419 63 0.74 0.45 0.95 46.6

incl 361 389 28 0.88 0.53 1.13 24.6

FURN-DD-00313 279 364 85 0.61 0.40 0.80 51.9

FURN-DD-00314 113 167 54 0.72 0.42 0.92 38.9

incl 149 167 18 1.22 0.79 1.60 22.0

FURN-DD-00316 492 592 100 0.67 0.36 0.84 67.0

incl 540 578 38 0.74 0.67 1.06 28.1

FURN-DD-00318 150 196 46 1.23 0.52 1.48 56.6

FURN-DD-00319 125 158 33 1.65 0.38 1.83 54.5

FURN-DD-00322 647 761 115 0.76 0.47 0.98 87.3

incl 661 707 46 0.81 0.56 1.11 37.3

incl 733 761 28 0.91 0.71 1.25 25.8

FURN-DD-00323 167 229 62 0.91 0.52 1.16 56.3

FURN-DD-00324 323 385 62 0.80 0.59 1.08 49.6

incl 323 339 16 1.14 0.92 1.58 18.2

FURN-DD-00325 457 522 65 0.72 0.43 0.93 46.8

incl 459 469 10 1.13 0.73 1.48 11.3

FURN-DD-00327 138 192 54 0.68 0.42 0.88 36.7

incl 150 175 25 1.02 0.53 1.27 25.5

FURN-DD-00328 473 530 57 0.70 0.47 0.92 39.9

incl 473 481 8 1.06 0.72 1.40 8.5

FURN-DD-00330 421 466 44 0.82 0.50 1.06 36.4

incl 421 451 30 0.98 0.54 1.24 29.3

FURN-DD-00331 74 115 42 0.61 0.92 1.05 25.4

incl 94 102 8 1.27 1.77 2.11 10.5

Hole ID From (m) To (m) Length (m) Cu (%) Au (g/t) CuEq (%)

%Cu Grade

x Thickness

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