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BIRCH-UCHI PROJECT - EXPLORATION HIGHLIGHTS GREEN CAMB SADDED 1050m SWL22-003 Successfully Drill Tested 4 Exploration Targets Swain •Identification of key exploration elements in the Grace Deformation Zone over a structural strike length of 6.5 km; drill intersects of up to 0.64 g/t Au over 5.6 m, and 0.34 g/t Au over 14.9 m (drill hole SWL22- 001) •Discovery of new gold-in-soil anomaly, including a gold assay of 724 ppb Au, with open opportunity for expansion and infill Saddle •Initial drilling campaign returned consistent gold mineralization over meaningful widths that remains open for expansion •Drill intersects include 0.92 g/t Au over 114.0 m in hole SAT23-001, and 0.75 g/t Au over 57.7 meters in drill hole SAT23-002 • 2023 Discovery highlights FIRST MINING GOLD Exploration assay results have identified a new near-surface and high priority structural setting for gold mineralization approximately 375 m from the recently drill tested Saddle target which returned 0.92 g/t Au over 114 m Rock samples assayed at the now-established Challenger target are encouraging, as highlighted by the discovery of two new mineralized occurrences approximately 60 m apart, where grab samples have returned gold values including 25.60 g/t Au, 7.10 g/t Au and 4.42 g/t Au Further gold assays associated with the Challenger target now define an interpreted east-west trending gold mineralized shear structure over an approximately 60 m trend, which remains open both along strike and at depth. 532000 534000 536000 538000 540000 542000 544000 546000 548000 550000 HOR23-004 MOR23-005 HOR23-002 EM PLATES BIR23-001 Horseshoe •Successfully intersected mineralization over a 260-m strike length with drill highlights including 0.48 g/t Au over 48.5 m in drill hole HOR23-001, 0.54 g/t Au over 57 m in drill hole HOR23-002, and 0.64 g/t Au over 24 m and 0.45 g/t Au over 14.5 m in drill hole HOR23-003 5696000- 5694000- Atlantis •Focused on EM plate modelled targets identified in the 2022 airborne geophysics campaign •Drilling aimed at discovering new gold mineralization in analogous structural and stratigraphic settings to other known mineralized occurrences on the property •Technical success on testing newly developed generative targets Further information on the 2023 drilling & Exploration updates can be found at: https://firstmininggold.com/news/ S TSX: FF | OTCQX: FFMGF | FRANKFURT: FMG | www.firstmininggold.com Shabumeni Birch Loke 5692000- Swan Deformation, Horseshoe 5690000- 5688000- n Deformatio Swain Deformation Zone CHALLENGER New Discovery Target Challenger Highlights: Grab samples 25.6 g/t Aut 7.10 g/t Au 4.2 g/t Au Satterly 375m SADDLE Saddle Highlights: Drill Intersects Birch Deformation Zone Cassumi SPRINGPOLE -5696000 -5694000 Horseshoe East Springpole Highlights: Mineral Resource Indicated: 4.6 Moz Au Inferred: 0.3 Moz Au -5692000 Satterly -5690000 Map Extent ONTARIO Timmins 5-5688000 Kenoga Thunder Bay Ottawa Toronto -5686000 542000 544000 546000 548000 550000 5686000- Swain Stargazer 0.92 g/t Au over 114m 0.75 g/t Au over 57.7m $32000 $34000 536000 538000 540000 Legend Springpole Regional geology Source: Ontario Geological Survey Conglomerate Challenger Saddle Deformation Zones First Mining Land Tenure Mafic volcanics Felsic tuff Porphyry FIRST Challenger Target Location Gabbro Syenite MINING GOLD Granite Tonalite Granodiorite Volcano-sedimentary 0 Intermediate tuff Kilometers Wacker | 20

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