Mr. Daniel Wilton reports

FIRST MINING FILES TECHNICAL REPORT FOR THE POSITIVE PRELIMINARY ECONOMIC ASSESSMENT FOR THE DUPARQUET GOLD PROJECT, QUEBEC, CANADA

First Mining Gold Corp. has filed on SEDAR+ an independent preliminary economic assessment (PEA) technical report for its 100-per-cent-owned Duparquet gold project located in the Abitibi region of Quebec, Canada.

The report, entitled "NI 43-101 Technical Report: Preliminary Economic Assessment on the Duparquet Gold Project, Quebec, Canada," was prepared by G Mining Services Inc. of Montreal, Que., in accordance with National Instrument 43-101 Standards of Disclosure for Mineral Projects and has an effective date of Sept. 15, 2023.

The PEA results support a 15,000-tonne-per-day open-pit and underground mining operation over an 11-year mine life. Highlights include:

• $1.07 billion pretax net present value (5 per cent) and $588-million after-tax NPV (5 per cent) at $1,800 (U.S.)/ounce gold;
• 24.9-per-cent pretax internal rate of return and 18-per-cent after-tax IRR at $1,800 (U.S.)/oz Au;
• Annual life-of-mine (LOM) recovered gold production of 233,000 oz;
• Total LOM recovered gold of 2.5 million oz over an 11-year mine life;
• Pretax payback of 3.8 years and after-tax payback of 4.8 years;
• Initial capital costs estimated at $706-million and sustaining and underground development capital costs estimated at $738-million;
• Average annual LOM total cash cost of $751 (U.S.)/oz and average annual LOM all-in sustaining cost (AISC) of $976 (U.S.)/oz.

PEA overview

The Duparquet gold project, located in the Abitibi region of Quebec, Canada, is one of the largest undeveloped gold projects in North America. The project is located immediately north of the town of Duparquet which is approximately 50 kilometres northwest of Rouyn-Noranda, Que., a major mining service centre and home to the only remaining copper smelter in Canada. Duparquet currently hosts 3.4 million ounces of gold in the indicated mineral resource category and 2.6 million ounces of gold in the inferred mineral resource category.

The PEA evaluates recovery of gold from a 15,000-tonne-per-day (tpd) open-pit and underground mining operation, with a process plant that includes crushing, grinding and flotation, producing a concentrate for sale. The PEA only considers the Duparquet gold deposit located on the Beattie, Donchester, Central Duparquet and Dumico claim blocks and does not include the Pitt Gold and Duquesne deposits.

Mineral resource estimate

In September, 2022, the Duparquet gold project mineral resource estimate (MRE) was updated by InnovExplo Inc. in accordance with National Instrument 43-101 (see news release of Sept. 12, 2022, for more details). The Duparquet gold project contains 3.44 million ounces of gold in the measured and indicated category, grading 1.55 grams per tonne Au, and an additional 1.64 million ounces of gold in the inferred category, grading 1.36 g/t Au.

In September, 2023, new updated mineral resource estimates were completed on First Mining's 100-per-cent-owned Pitt Gold and Duquesne projects and have added one million ounces of gold grading 2.32 g/t Au in the inferred category, which will now form part of the larger consolidated Duparquet gold project. During the final validation and completion of the report, minor adjustments were made to the Pitt Gold deposit MRE statement disclosed in the Sept. 7, 2023, press release. The adjustments are presented in the attached tables of this release for the Pitt Gold deposit and the consolidated 2023 MRE, respectively.

Following the updated mineral resource estimate at Pitt Gold and Duquesne, the consolidated Duparquet project now contains 3.44 million ounces of gold in the measured and indicated category, grading 1.55 g/t Au, and an additional 2.64 million ounces of gold in the inferred category, grading 1.62 g/t Au.

Environment and community

The PEA has considered and incorporated the opportunity to leverage the Duparquet gold project development with the reclamation of the brownfield site conditions including the removal and reprocessing of over 4.1 million tonnes of uncontained historical mine tailings. With such measures incorporated into the PEA mine plan, in combination with the ability of the project to collect and treat historically impacted groundwater via the excavation and dewatering of the open pit, the project is positioned to deliver both environmental and socio-economic benefits via employment, contracting and revenue for the municipality of Duparquet. The PEA is anticipated to be refined and optimized based on consultation and input to be received by government, the municipality of Duparquet and other local and regional stakeholders, and local first nation community.

Since acquiring the Duparquet gold project in September of 2022, First Mining has prioritized meeting the people, communities and government representatives on project planning in an open and transparent manner. First Mining published the Mines d'Or Duparquet website to share project information and has recently finished renovations required to open a First Mining community relations office in Duparquet. The project provides an opportunity to address historical environmental aspects at the project site to improve long-term sustainability and economic activity and support sustainable municipal planning and development.

The municipality of Duparquet is in the Abitibi-Temiscamingue region which has been shaped primarily by natural resource-based industries, including mining and forestry, where the mining industry accounts for one in seven jobs in the region.

Qualified persons

The affiliation and areas of responsibility for each of the qualified persons involved in preparing the PEA are as noted herein.

The company cautions that the results of the PEA are preliminary in nature and include inferred mineral resources that are considered too speculative geologically to have the economic considerations applied to them that would enable them to be categorized as mineral reserves. There is no certainty that the results of the PEA will be realized.

Qualified persons

Louis Martin, PGeo (OGQ 0364), a consultant of First Mining, is a qualified person for the purposes of NI 43-101, and he 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 it has commenced a feasibility study and permitting activities are continuing with a draft environmental impact statement (EIS) for the project published in June, 2022, and the Duparquet 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 portfolio of gold project interests including the Pickle Crow gold project (being advanced in partnership with Auteco Minerals Ltd.), the Hope Brook gold project (being advanced in partnership with Big Ridge Gold Corp.) and a large equity interest in Treasury Metals Inc.

First Mining was established in 2015 by Keith Neumeyer, founding president and chief executive officer of First Majestic Silver.

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