First Mining Intersects 7.18 g/t Au over 8 m at the Miroir Target and Provides Duparquet Project Update

Press Release

• DUP25-085 returns 3.74 g/t Au over 15.5 m and 7.18 g/t over 8.0 m, including 30.58 g/t over 1.65 m
• DUP25-081 returns 1.56 g/t Au over 33.15 m, including 3.18 g/t Au over 7.6 m
• DUP25-090 returns 4.08 g/t Au over 12.0 m, including 11.20 g/t Au over 1.0 m, extending mineralization to vertical depth of 250 m

March 9, 2026 – Vancouver, Canada – First Mining Gold Corp. (“First Mining” or the “Company”) (TSX: FF) (OTCQX: FFMGF) (FRANKFURT: FMG) is pleased to announce additional results from the 2025 exploration drilling program at its Duparquet Gold Project (“Duparquet Project” or the “Project”) located in the Abitibi region of Quebec, Canada. The Company completed its 2025 drilling program at the Project in October, totaling 16,577 m of drilling. The results reported here are mainly from the Miroir target, a high-priority discovery zone first intersected in the 2024 drill program and subsequently advanced through follow-up drilling in 2025. The latest results extend Miroir mineralization to a vertical depth of 250 m, representing an additional 150 m of down-dip expansion beyond previous drilling. The target currently spans approximately 150 m of strike length and 250 m in depth and remains open at depth and along strike to the east (Figures 1 & 2).

Assay results from drill hole DUP25-081 have returned 1.56 g/t Au over 33.15 m, including 3.18 g/t Au over 7.60 m. Drill hole DUP25-085 returned 3.74 g/t Au over 15.5 m and 7.18 g/t over 8.0 m, including 30.58 g/t over 1.65 m.  DUP25-090 returned 4.08 g/t Au over 12.0 m, including 11.20 g/t Au over 1.0 m. Drilling at the Miroir target has continuously been building potential for a strong resource growth zone returning multiple robust gold intercepts, and it will be a key target to advance in the 2026 drilling campaign.

“The results from our 2025 drilling program at Duparquet and around the Miroir target continue to demonstrate potential for the Project,” stated Dan Wilton, CEO of First Mining. “The Project’s near-surface mineralization footprint continues to be strengthened with our ongoing drilling success while further extending the target at depth, demonstrating Miroir’s potential as a resource-growth area at the Duparquet Project. In addition to our exploration program, we are excited to embark on our environmental baseline program to continue advancing the Project.  The development and reclamation of this Project site represent a tremendous opportunity not only for First Mining, but for the provincial government, City of Duparquet, neighbouring communities and First Nation members.”

Duparquet Project Update

First Mining is pleased announce that it has commenced a comprehensive environmental baseline data collection program at the Duparquet Project to support the information requirements to complete the regulatory approvals process for the Project. The program is led by First Mining’s in-house Sustainability team and supported by Stantec, who both have significant related experience from the successful development of the Greenstone Gold Mine, which recently commenced production in Ontario.

The baseline programs cover all areas of the environment starting with geochemistry and water quality, through to aquatic studies and other biophysical aspects required to advance Project planning. First Mining continues its engagement and collaboration with the City of Duparquet and its residents through the implementation of the Memorandum of Understanding signed in September 2025. Project engineering studies and consultation are planned to advance in 2026 towards optimizing the site plan and the potential publication of a feasibility study building on the success of the 2023 Preliminary Economic Assessment.

Exploration Program Update and Outlook

Drilling activities at the Duparquet Project concluded in October 2025, with a total of 16,577 m completed during the year. While all assays from the 2025 drilling program have been received, outstanding results and interpretations will be disclosed in a future update as ongoing integration and modelling work continues.

The Company is currently reviewing and incorporating the 2025 data into updated geological and exploration target models. In parallel, the 2026 exploration program is being finalized, with a targeted commencement in Q2 2026. Planned drilling will focus on high-priority targets, including Miroir, to further advance its potential as a key resource expansion opportunity.

Additional Drilling Details

Further highlights from the latest drilling results disclosed herein are from the Valentre target area (Figure 2). Drill hole DUP25-074 returned 1.92 g/t Au over 9.3 m, including 2.80 g/t Au over 4.8 m, and DUP25-083 returned 4.26 g/t Au over 3.5 m and 2.41 g/t Au over 10.95 m. The latest results continue to demonstrate the continuity of the CVD target area, with the target currently extending to 480 m below surface and remaining open at depth.

Two additional greenfields exploration targets, Normandie and Lumière, were drill tested in 2025 with a program (Figure 2) targeting geophysical anomalies hosted along favourable lithological contacts. Normandie, a geophysically interpreted structure located 150 m towards the northeast along strike from Miroir, returned 1.39 g/t Au over 4.0 m and 5.22 g/t Au over 1.0 m in DUP25-068, highlighting a favourable area for gold mineralization and further geological modelling and drill testing. Drilling at the Lumière target, located ~300 m northwest of Miroir, returned 7.74 g/t Au over 1.40 m as well as 2.23 g/t Au over 1.50 m near surface in drill hole DUP25-086, successfully demonstrating the presence of favourable mineralization and once further modelled, a favourable target for follow up drilling.

Figure 1: Miroir Long Section, highlighting recent drilling as well as the open-ended potential of the Miroir interpreted structure

Figure 2: Plan view map, highlighting the Miroir, Valentre and other significant targets in the Central Duparquet-Dumico area

The latest reported assays represent approximately 2,550 m of drilling from a total of ~5,000 m across 22 drill holes drilled to date at the Miroir target. These holes were focused on advancing the understanding of mineralization controls at Miroir and extending the target depth while testing the down-dip potential. Assay highlights are provided in Table 1, with the full list of assay results presented in Table 3 and drill collar details in Table 4.  All assay results from this target’s drilling have now been disclosed.

Table 1: Latest Significant 2025 Drill Intercepts

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Additional Details on Miroir, CVD, Aiguille, Lumière, and Normandie Drilling

Miroir

The 2025 drilling at the Miroir target focused on further delineating the extent of near-surface mineralization discovered in 2024. A series of significant intercepts have been returned at Miroir to date (Table 2), with the most recent drilling continuing to confirm and expand the target area, extending mineralization to a vertical depth of 250 m below surface and highlighting multiple near-surface gold zones.

Notable results from the most recent drilling include drill hole DUP25-081 returning 1.56 g/t Au over 33.15 m, including 3.18 g/t Au over 7.60 m. Drillhole DUP25-085 returned 3.74 g/t Au over 15.5 m and 7.18 g/t over 8.0 m, including 30.58 g/t over 1.65 m, and  DUP25-090 returned 4.08 g/t Au over 12.0 m, including 11.20 g/t Au over 1.0 m. These results continue to demonstrate the potential for multiple, high-quality gold zones within the Miroir target and reinforce its potential for further growth.

Table 2: Previous Disclosure Highlights, Miroir target

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High-grade mineralization at the Miroir target is associated with coincident brittle and ductile deformation within a volcanic package proximal to syenite contacts. Mineralized intercepts are spatially correlated with northeast–southwest–striking D2 deformation zones, coincident with a geophysically inferred basalt–syenite contact that plunges to the east.

In the most recent drill holes, mineralization is hosted within brecciated, silica-altered basalt and syenite, with 2–5% very fine-grained disseminated to fracture-controlled bronze pyrite associated with thin smoky quartz veinlets.

Valentre

The 2025 drilling program further confirmed the continuity of the mineralization at the Valentre target and the latest notable results from the most recent drilling include drill hole DUP25-074 returning 1.92 g/t Au over 9.3 m, including 2.80 g/t Au over 4.8 m, and DUP25-083 returning 4.26 g/t Au over 3.5 m and 2.41 g/t Au over 10.95 m. The results continue to demonstrate the continuity of the Valentre target which currently extends to 480 m below surface and remains open at depth.

Gold mineralization at the Central Duparquet-Valentre-Dumico (“CVD”) area is hosted within mineralized silica- and sericite-altered syenite units with very fine-grained disseminated pyrite ranging from 0.5- 3%. Gold mineralization is also coincident with dark smoky quartz veins and veinlets, with up to 3% fine-grained disseminated pyrite mineralization. The gold-mineralized quartz veins are hosted within syenite units and intervals of alternating syenite and mafic and ultramafic volcanic units.

Aiguille

In the 2025 drilling campaign, the up-dip and along-strike opportunities at the Aiguille target were investigated with a sequence of shallow drill holes, targeting a key geological contact to further enhance the resolution for modelling the extent of mineralization. Drill hole DUP25-071 returned 0.62 g/t Au over 1.0 m and DUP25-074 returned 0.48 g/t Au over 1.0 m. These holes successfully demonstrated anomalous gold values in key structures. The down-dip potential of the target continues to remain open at depth and will be validated with further drilling.

Normandie

The Normandie target, located 150 m northeast of Miroir, is a geophysical anomaly interpreted as a structural corridor linking the Miroir target with the greenfield Sid target (see press release dated February 22, 2024). Drilling in 2025 successfully intersected high-grade brecciated and shear-style veining along the syenite–volcanic contact, with hole DUP25-068 returning 1.39 g/t Au over 4.0 m and 5.22 g/t Au over 1.0 m. This maiden drill hole at Normandie validated the geological interpretation, demonstrating geological continuity and a favourable mineralization setting between the Miroir and Sid targets. Follow-up drilling will focus on testing the mineralization footprint along strike and down-dip.

Figure 3: Plan view map highlighting the Normandie target area and showing the 2^nd vertical derivative magnetics geophysical product

Lumière

The Lumière target, located approximately 300 m northwest of Miroir (Figure 2), was drill tested in 2025, with hole DUP25-086 returning 7.74 g/t Au over 1.4 m and 2.23 g/t Au over 1.5 m near surface. Drilling targeted a geophysical anomaly and syenite–volcanic contacts along the northern margin of the syenite body.

High-grade gold values are associated with brecciated and sheared volcanic units with fracture-controlled silica alteration. Structural and geochemical interpretations will be integrated to update the 3D geological model along the contact and identify priority areas for follow-up drilling.

Table 3: Latest Assay Results from 2025 Drill Program

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*Reported intervals are drilled core lengths (true widths are estimated at 75-85% of the core length interval; assay values are uncut)

Table 4: Latest 2025 Drill Hole Locations

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Note: Collar coordinates in UTM NAD 83 z17

About the Duparquet Gold Project

The Duparquet Project is situated in the southern part of the Abitibi Greenstone Belt and is geographically located approximately 50 km northwest of the city of Rouyn-Noranda. The Project benefits from easy access and proximity to an existing workforce and infrastructure, including road, rail and hydroelectric grid power. The Duparquet Project currently hosts an NI 43-101 compliant gold resource of 3.44 million ounces in the Measured & Indicated category, grading 1.55 g/t Au, and an additional 2.64 million ounces in the Inferred category, grading 1.62 g/t Au. First Mining completed a Preliminary Economic Assessment¹ (“PEA”) on the Project in 2023.

The Duparquet Project totals approximately 5,800 hectares focused on an area of 19 km of strike length along the prolific Destor-Porcupine Fault Zone, along with numerous mineralized splays and influential secondary lineaments. The Duparquet Project includes the past-producing Beattie, Donchester and Duquesne mines as well as the Central Duparquet, Dumico and Pitt Gold deposits.

¹ Further details on the Duparquet PEA can be found in the technical report entitled “NI 43-101 Technical Report: Preliminary Economic Assessment, Duparquet Gold Project, Quebec, Canada” dated October 20, 2023, which was prepared for First Mining by G Mining Services Inc. in accordance with NI 43-101 and is available under First Mining’s SEDAR+ profile at www.sedarplus.ca

Analytical Laboratory and QA/QC Procedures

All sampling completed by First Mining within its exploration programs is subject to a Company standard of internal quality control and quality assurance (QA/QC) programs which include the insertion of certified reference materials, blank materials and a level of duplicate analysis. Core samples from the 2025 drilling program at Duparquet were sent to AGAT Laboratories, with sample preparation in Val d’Or, Quebec and analysis in Thunder Bay, Ontario, where they were processed for gold analysis by 50 gram fire assay with an atomic absorption finish. Samples from selected holes were sent to AGAT Laboratories in Calgary, Alberta, for multi-element analysis (including silver) by inductively coupled plasma (ICP) method with a four acid digest. AGAT Laboratories systems conform to requirements of ISO/IEC Standard 17025 guidelines and meets assay requirements outlined for NI 43-101.

Qualified Person

James Maxwell, P.Geo., VP, Exploration and Project Operations for First Mining, is a “Qualified Person” for the purposes of NI 43-101 Standards of Disclosure for Mineral Projects and has reviewed and approved the scientific and technical disclosure contained in this news release.

About First Mining Gold Corp.

First Mining is a gold developer advancing two of the largest gold projects in Canada, the Springpole Gold Project in northwestern Ontario, where we have commenced a Feasibility Study and permitting activities are on-going with a final Environmental Impact Statement / Environmental Assessment for the project submitted in November 2024, and the Duparquet Gold Project in Quebec, a PEA-stage development project located on the Destor-Porcupine Fault Zone in the prolific Abitibi region. First Mining also owns the Cameron Gold Project in Ontario and a 30% project interest in the Pickle Crow Gold Project.

First Mining was established in 2015 by Mr. Keith Neumeyer, founder and CEO of First Majestic Silver Corp.

ON BEHALF OF FIRST MINING GOLD CORP.
Daniel W. Wilton
Chief Executive Officer and Director

For further information, please contact:
Toll Free: 1 844 306 8827 | Email: info@firstmininggold.com
Paul Morris | Director, Investor Relations | Email: paul@firstmininggold.com

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