Mr. David Strang reports

ERO COPPER ANNOUNCES UPDATE ON NICKEL SULPHIDE EXPLORATION PROGRAM - INTERCEPTS 11.2 METERS GRADING 1.86% NICKEL, INCLUDING 5.0 METERS GRADING 3.71% NICKEL

Ero Copper Corp. has provided an update on its continuing regional nickel sulphide exploration program within the Curaca Valley. Drilling activity over the past several months has focused on delineating the Umburana system, which has a current strike length of approximately five kilometres. Mineralization, which outcrops at surface, remains open to depth, to the north and between the VB and Lazaro (LZ) zones.

To date, the company has received assays on 97 diamond drill holes across the Umburana system, including 63 diamond drill holes within the VB zone and 34 within the LZ zone. New results from drilling conducted since September, 2022, are highlighted by:

• VB zone:
  • VB-41: 11.2 metres at 1.86 per cent nickel, 0.26 per cent copper and 0.05 per cent copper (2.08 per cent nickel equivalent), including five metres at 3.71 per cent Ni, 0.13 per cent Cu and 0.09 per cent Co (4 per cent NiEq);
    • Interval includes 1.9 metres of massive sulphide textures grading 7.09 per cent Ni, 0.18 per cent Cu and 0.18 per cent Co (7.61 per cent NiEq);
  • VB-52: 25.9 metres at 0.69 per cent Ni, 0.18 per cent Cu and 0.02 per cent Co (0.80 per cent NiEq), including 15.5 metres at 1.01 per cent Ni, 0.25 per cent Cu and 0.03 per cent Co (1.17 per cent NiEq);
  • VB-59: 18.7 metres at 0.79 per cent Ni, 0.14 per cent Cu and 0.02 per cent Co (0.90 per cent NiEq), including 6.8 metres at 1.49 per cent Ni, 0.22 per cent Cu and 0.04 per cent Co (1.68 per cent NiEq).
• LZ zone:
  • LZ-25: 46.1 metres at 0.20 per cent Ni, 0.04 per cent Cu and 0.03 per cent Co (0.28 per cent NiEq), including 2.6 metres at 0.75 per cent Ni, 0.18 per cent Cu and 0.06 per cent Co (0.96 per cent NiEq);
  • LZ-32: 11.3 metres at 0.43 per cent Ni, 0.10 per cent Cu and 0.02 per cent Co (0.51 per cent NiEq), including seven metres at 0.61 per cent Ni, 0.14 per cent Cu and 0.03 per cent Co (0.73 per cent NiEq).

In addition to new drill results, the company has commenced metallurgical test work on the Umburana system. While the program is continuing, initial metallurgical tests, completed on three composite samples of varying grades, demonstrate nickel recoveries through the rougher circuit ranging from 77 per cent to 91 per cent across a range of grind sizes, suggesting that the vast majority of nickel within the Umburana system is contained within sulphide minerals with very little nickel encapsulated within silicate minerals that would render the nickel unrecoverable.

Commenting on the update, David Strang, chief executive officer, said: "We are excited by the continuity and growth we are seeing with the Umburana system, which we believe demonstrates the Curaca Valley's potential to be a globally significant magmatic sulphide district for both copper and nickel. Notably, the VB zone has increased from one distinct zone of mineralization to three, with massive sulphide nickel mineralization extending to a depth of approximately 325 metres and remaining open to depth and along strike. Furthermore, our exploration team has identified several new and distinct nickel targets within the Curaca Valley with similar geological signatures to the Umburana system, which we are currently drilling or plan on drilling later this year."

Technical discussion

Detailed geologic mapping, comprehensive multielement soil geochemistry and reinterpretation of the company's available geophysical data sets throughout 2021 and the first half of 2022 resulted in the discovery of a new nickel system, announced in September, 2022, featuring favourable geology with coincident geochemical and geophysical anomalies. To date, detailed exploration has focused primarily on two target areas located at the interpreted northeast and southwest boundary of a five-kilometre system, each characterized by multiple expressions of outcropping nickel mineralization in the form of gossans, geochemical and geophysical anomalies -- all associated with mafic-ultramafic intrusions.

Initial drill testing at the northeast and southwest boundaries of the currently known system has identified nickel sulphide mineralization ranging from disseminated and interstitial nickel sulphides (containing less than 10 per cent sulphides) extending over 50 metres in thickness to patchy net-textured sulphides (containing approximately 10 per cent to 30 per cent sulphides) with localized centimetre up to 1.9-metre-thick massive-sulphide lenses (containing approximately 60 per cent to 80 per cent sulphides) grading up to 7.09 per cent nickel (7.61 per cent NiEq). Mineralization within these zones is hosted by pyroxenite and websterite ultramafic rocks. Sulphide minerals are mainly pyrrhotite, pentlandite (loop-textured where massive sulphide) with lesser pyrite and chalcopyrite. Loop-textured pentlandite is an important geologic indicator commonly observed in magmatic nickel sulphide deposits. The full extent of the system remains unknown at this time with mineralization open to depth and along strike both between the VB and LZ zones and to the north of the Umburana system.

Based upon the exploration techniques used to identify the Umburana system, the company has identified several geographically distinct nickel targets, two of which are currently being drilled. Surface fieldwork and data interpretation are also under way to identify additional targets.

The company has begun evaluating the metallurgical characteristics, recoveries and concentrates grade to determine whether a saleable nickel concentrate is achievable from the Umburana system. While the program is comprehensive and continuing, initial rougher-stage flotation tests demonstrate a range of recoveries of between 77 per cent and 91 per cent depending on grind size (75 to 150 microns). The results of this test work, combined with continuing mineralogy studies, suggest that nickel within the Umburana system is associated primarily with sulphide minerals with very little nickel encapsulated in silicate minerals. Further test work is continuing to determine whether saleable concentrate grades are achievable, and if so, overall nickel recoveries.

Composite samples were prepared based on nickel grades within each zone, and are summarized as follows:

• LZ zone HG composite equivalent to 0.90 per cent;
• Ni LZ zone LG composite equivalent to 0.45 per cent Ni;
• VB zone composite equivalent to 0.92 per cent Ni.

VB zone

At the northeast extent of the Umburana system nickel-bearing ultramafic rocks have been identified over 1.4 kilometres north-south and up to 200 metres east-west using surface mapping supported by soil geochemistry and 30 trenches. To date, 63 diamond drill holes with assay results have been received with nickel mineralization identified starting at surface and to a depth of approximately 450 metres from surface. Mineralization remains open to depth as the majority of holes drilled to date have focused on delineating near-surface open-pittable mineral resources, and remains open to the south trending toward the LZ zone.

Mineralization within the VB zone is characterized by disseminated and patchy net-textured nickel sulphides with three distinct high-grade (north, central and south) zones of massive sulphides featuring localized thickening of up to 1.9 metres grading up to 7.09 per cent nickel (7.61 per cent NiEq). Within the VB zone, higher-grade mineralization continues to be focused at the base of a pyroxenite intrusion. Mineralization occurs predominantly within orthopyroxenites ranging from isotropic to locally banded.

Within the northern high-grade portion of the VB zone, results are highlighted by holes VB-38 and VB-56, both located on the same section, which intercepted small intervals of disseminated, interstitial and patchy net-texture nickel sulphides ranging between approximately three and nine metres grading between 0.63 per cent NiEq and 1.69 per cent NiEq.

Results within the central high-grade zone are highlighted by hole VB-41, which intercepted high-grade massive sulphide of 1.9 metres grading 7.61 per cent NiEq within a broader mineralized interval of 11.2 metres grading 2.08 per cent NiEq.

High-grade mineralization in the southern zone is highlighted by holes VB-52 and VB-59, both located on the same section, which intercepted large intervals of disseminated and interstitial nickel sulphides ranging between approximately 18 and 26 metres grading between 0.80 per cent NiEq to 0.90 per cent NiEq.

The deepest drilling to date within the VB zone is highlighted by hole VB-47 that intercepted two intervals of disseminated nickel sulphide mineralization, 20.7 metres grading 0.47 per cent NiEq and 9.8 metres grading 0.53 per cent NiEq, the latter of which is approximately 450 metres below surface.

There is currently one drill rig active within the VB zone, focused on expanding the current limits of mineralization along strike, and two additional drill rigs testing regional nickel targets.

LZ zone

At the southwest extent of the Umburana system, located approximately 20 kilometres from the company's Caraiba milling operations and approximately 3.2 kilometres southwest of the VB zone, nickel-bearing ultramafic rocks have been identified over 500 metres in strike length and approximately 50 metres in apparent thickness using surface mapping supported by geochemistry, airborne electromagnetic response and eight trenches and has been traced from surface to a depth of 315 metres down dip. Drilling has primarily focused to date on delineating near-surface, open-pittable mineral resources. Mineralization remains open to depth and to the north. To date, 34 diamond drill holes with assay results have been received.

Mineralization within the LZ zone primarily comprises disseminated nickel sulphide mineralization with intercalated intervals of interstitial and patchy net-textured sulphides. Within the 500-metre identified strike length, a zone of higher-grade mineralization has been identified within the footwall of the mafic-ultramafic intrusion associated with a websterite layer.

Results within the footwall are highlighted by hole LZ-25 that intercepted a broad interval of mineralization covering 46.1 metres grading 0.28 per cent NiEq from approximately 230 metres down hole. Hole LZ-32 intercepted 11.3 metres grading 0.51 per cent NiEq from approximately 295 metres down hole. Together, these intercepts demonstrate continuity of nickel sulphide mineralization down dip.

The deepest drilling to date is highlighted by hole LZ-33 that intercepted disseminated nickel mineralization over 2.6 metres grading 0.70 per cent NiEq, from approximately 350 metres down hole. At the bottom of this mineralized intercept, an extension of the high-grade websterite layer of the footwall zone, approximately 320 metres below surface, was intercepted over 1.6 metres grading 1.03 per cent NiEq, indicating continuity, albeit thinner, to depth. There are no drill rigs currently working within the LZ zone, as exploration efforts are focused on the VB zone and other regional nickel targets within the Curaca Valley identified using systematic geological mapping, soil geochemistry, trenching and ground electromagnetic (EM) surveys.

Note on National Instrument 43-101 compliant technical report(s)

The conversion of drill results presented in this press release into NI 43-101 compliant mineral resources and mineral reserves all require additional work and analysis that are continuing. To date, there has been insufficient exploration and accompanying analysis to define a mineral resource and it is uncertain if further exploration will result in this nickel system being delineated as a mineral resource. Accordingly, the results herein may not be included in future NI 43-101 compliant mineral resources or mineral reserves depending on the results of this additional work and analysis, and other technical and/or economic reasons.

Quality assurance and quality control

In support of its continuing Umburana system exploration program, the company is currently drilling on surface using third party contracted core drill rigs. During the period from September, 2022, through May, 2023, third party drill rigs were operated by Major Drilling do Brasil Ltda., DrillGeo Geologia e Sondagem Ltda. and Layne Christensen Co., all of whom are independent of the company. Drill core is logged, photographed and split in half using a diamond core saw at the secure core logging and storage facilities of Mineracao Caraiba SA (MCSA). Half of the drill core is retained on site and the other half core is used for analysis, with samples collected on one-metre sample intervals unless an interval crosses a geological contact. All sample preparation is performed in MCSA's secure on-site laboratory. Total nickel and copper is determined using a nitric-hydrochloric acid digestion and atomic absorption spectrometry and/or titration at the on-site laboratory. All sample results during the period have been monitored through a QA/QC program that includes the insertion of certified standards, blanks, and pulp and reject duplicate samples. Check assays for nickel and copper were submitted to ALS Brasil Ltda.'s facility located in Vespasiano, Minas Gerais, Brazil, at a rate of approximately 5 per cent. ALS Brasil is a subsidiary of ALS Ltd. and is independent of the company.

Cid Goncalves Monteiro Filho, SME RM (04317974), MAIG (No. 8444), MAusIMM (No. 3219148) and resource manager of the company, who is a qualified person within the meanings of NI 43-101, has reviewed and approved the disclosure of technical information, including verification of the sampling, analytical and testing data in this press release. Quarterly reviews entail sampling and laboratory procedure review as well as verification of original assay certificates associated with a selection of samples from company's internal database included in this press release.

About Ero Copper Corp.

Ero is a high-margin, high-growth, clean copper producer with operations in Brazil and corporate headquarters in Vancouver, B.C. The company's primary asset is a 99.6-per-cent interest in the Brazilian copper mining company MCSA, 100-per-cent owner of the company's Caraiba operations (formerly known as the MCSA mining complex), which are located in the Curaca Valley, Bahia state, Brazil, and include the Pilar and Vermelhos underground mines and the Surubim open-pit mine, and the Tucuma project (formerly known as Boa Esperanca), an IOCG-type (iron oxide copper-gold) copper project located in Para, Brazil. The company also owns 97.6 per cent of NX Gold SA, which owns the Xavantina operations (formerly known as the NX Gold Mine), comprising an operating gold and silver mine located in Mato Grosso, Brazil.

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