First Mining Delineates Encouraging Gold Targets at the Birch-Uchi Greenstone Belt Project and Announces Management Change
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NEWS RELEASE
First Mining Delineates Encouraging Gold Targets at the Birch-Uchi
Greenstone Belt Project and Announces Management Change
July 20, 2023 – Vancouver, Canada – First Mining Gold Corp. (“First Mining” or the “Company”) (TSX: FF)
(OTCQX: FFMGF) (FRANKFURT: FMG) is pleased to announce results from its 2023 drill program focused
on the advancement of its Horseshoe and Atlantis drilling targets in the Birch-Uchi Greenstone Belt Project
(“BUGB Project” or the “Project”) located in northwestern Ontario, Canada. Winter drilling at the project
comprised a total of eleven drill holes for 2,760 metres focused on three target areas: Saddle, Horseshoe,
and Atlantis.
First drilling by the Company at the Horseshoe target included five drill holes totalling 1,589 metres which
identified a significant gold mineralization system , with drill highlights including 0.48 g/t Au over 48.5
metres in drill hole HOR23-001, 0.54 g/t Au over 57 metres in drill hole HOR23-002, and 0.64 g/t Au over
24 metres and 0.45 g/t Au over 14.5 metres in drill hole HOR23-003. The Company also completed drilling
at the Atlantis target which focused on EM plate modelled targets identified in the 2022 airborne
geophysics campaign.
Assays for the Saddle target were previously reported and include gold intercepts of 0.92 g/t Au over
114.0 metres and 0.75 g/t Au over 58 metres (see news release dated July 6, 2023).
Project Highlights
• Initial drill program tested multiple mineralization targets within the Horseshoe target area and
successfully intersected mineralization over a 260-m strike length
• Foundational data consolidation and integration with recent airborne geophysics into a
preliminary 3D model to further characterize, advance and identify exploration opportunities
• BUGB Project is proving to be prospective with three of four drilled targets identifying meaningful
gold mineralization
• Continued advancement and prioritization of e xploration opportunities being delivered
throughout the project area with opportunities for increased testing
“Our exploration efforts continue to identify and advance new resource growth opportunities within our
Birch-Uchi Greenstone Belt project, as dem onstrated once again by significant intercepts of meaningful
widths and gold grades in our latest results from Horseshoe” stated Dan Wilton, CEO of First Mining . “The
results from drilling at the Saddle, Horseshoe and Atlantis targets demonstrate robust gold endowment
of this under-explored greenstone belt, all located within proximity of our Springpole Gold Project.”
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Figure 1: Atlantis & Horseshoe Target Locations within First Mining’s BUGB Project
Table 1: Selected Significant Drill Intercept Results at Horseshoe Target
Hole ID From (m) To (m) Length (m) Au (g/t) Target
HOR23-001 159 194 35 0.57 Horseshoe and 221 269.5 48.5 0.48
HOR23-002 158 215 57 0.54 Horseshoe
HOR23-003 150 174 24 0.64 Horseshoe and 183 197.5 14.5 0.45
*Reported intervals are drilled core lengths, true widths are not yet established; assay values are uncut
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Horseshoe Target
The Horseshoe target is located approximately 10 kilometres east-southeast of First Mining’s Springpole
Gold Project (Figure 1) and is characterized by a significantly deformed and altered granodiorite intrusive
unit that occurs in contact with a surrounding series of volcanic and sedimentary units of the Birch -Uchi
Greenstone Belt. Mineralization is associated with increased sericite and silica alteration, moderate to
intensely sheared granodiorite, higher concentrations of deformed quartz veining, and sulphides. The
dominant sulphide mineralization is composed of pyrite and occurs as fine -grained to very fine -grained
disseminations averaging 0.5% - 4%, with localized abundances up to 10%. Veining is typically 1 cm to 5
cm in scale with higher densities corresponding to increased silica alteration. Mineralization is interpreted
to be coincident with potential subparallel shear structures, and increased sulphide mineralized areas.
The 2023 winter drilling campaign was focused on testing the preliminary 3D geological model and to
target sheared, mineraliz ed granodiorite along the Swain Deformation Zone ( “SDZ”) as well as its
continuity down plunge. Modelling of the SDZ proximal to the target area incorporates a series of mapped
splays that are interpreted to support a dilation zone of interest considered favourable for gold
mineralization (Figure 1). Drill hole HOR23 -001 was drilled to test the continuity of the mineralization
between historical drilled holes, with holes HOR23-002 and HOR23-003 stepping east along the SDZ and
testing the extension along strike in confirming continuity in the mineralization. The first three holes
(HOR23-001, HOR23-002 and HOR23-003) all returned significant gold intercepts over a strike length of
260 m, with widths ranging from 14 - 48 m (Table 1 and Table 2) which supports scaleability, and further
opportunities for extension in previously untested areas.
Drill holes HOR23-004 and HOR23-005 are two step-out holes targeting an area that was highlighted by
advanced geophysical modelling of the data from the Company’s 2022 airborne geophysics campaign.
Hole HOR23-004 was targeting the lithological contact of a historically explored gabbro body known to
host polymetallic Cu-Ni mineralization with increasing geochemical gold vectors towards a modeled
contact. Drilling returned a down hole significant intercept that supports the presence of gold
mineralization in the interpreted area, leading to opportunity for follow -up testing in additional
exploration campaigns. Drill hole HOR23 -005 target ed an extension of the SDZ dilation trend where
coincident with geophysical interpretation of the modelled shear. The drill hole encountered breccia units
providing structural insight to the target area, however, no significant gold values were encountered.
Figure 2 shows the location of the 2023 Horseshoe drilling superimposed on the airborne geophysics
imagery.
The Horseshoe target area has been a focus of recent geoscience compilation and target generation
through First Mining’s 2 021 and 2022 exploration work programs. First Mining’s exploration team
completed data review, field site investigations consisting of mapping and sampling, airborne geophysics,
and the application of 3D modelling for a modernized geoscience approach to targetin g. Through these
work phases the C ompany has identified an important exploration centre with expansion opportunities
and substantial future resource potential.
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Figure 2: Plan view of Horseshoe 2023 Drilling with 2022 SkyTEM Airborne Geophysics Magnetic Survey
Historical drilling was completed on the Horseshoe target area by previous operators, reportedly totalling
145 holes for approximately 24,000 m, with some being completed in the 1940s and more continuous
exploration occurring between 1970 and 2000, which in addition to diamond drilling also included
geophysics surveys, soil surveys, prospecting, mapping and trenching. Highlights from historical work
programs include exploration focus of altered and deformed granodiorite which returned an interval of
16.5 m of 3.96 g/t Au in hole HSI84-008 (1984 – St Joe Canada Inc), as well as 15.0 m at 2.61 g/t Au in hole
HI85-33 and 3 m at 10.97 g/t Au in hole HI85-36. Gold mineralization encountered in the historical drilling
was hosted within highly silicified zones of increased quartz veining and strongly altered granodiorite
consistent with the expansions and logging descriptions of Firs t Mining. In combination with the 2023
drilling, results are indicative of a mineralization envelope that is host to significant gold potential and
which will form an important focus for additional follow-up exploration.
Figure 3 shows the downhole assay results from the 2023 Horseshoe drilling which indicate the expansion
of the gold mineralization beyond the original modelled zones.
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Figure 1: Oblique Section View of Horseshoe 2023 Drilling agains t First Mining’s Original 3D Target
Model (Looking South)
Atlantis Target
Additional exploration of the BUGB Project during the winter program included an initial drill hole testing
the Atlantis target within the Birch Property , located approximately 4 km north of First Mining’s
Springpole Gold Project , where several significant high -grade gold settings have been identified in
previous exploration campaigns. Historical exploration includes the discovery of centres of high -grade
gold in q uartz veining that is hosted within intermediate volcanics, mafic volcanics, and banded iron
formation lithologies. Mineralization across the property has returned gold grades of up to 15.3 g/t Au in
rock grab samples at the Canamer target (see news release January 17, 2023), towards the southeast of
Atlantis during the 2022 field campaign, and historical drilling programs on the HGI target, located towards
the east-southeast of Atlantis, reported grades of up to 113.94 g/t Au over 2.95 m (hole TWBL-096) and
246 g/t Au over 1 m (Hole P255A-078).
Recent airborne geophysical surveys coupled with ongoing data compilation through out 2021 and 2022
have evolved a new series of underexplored targets for drill testing and groundwork follow -up. The
Atlantis target occurs as a series of plate model ed EM conductors identif ied in the 2 022 SkyTEM
geophysical campaign, coincident with a magnetic high trend interpreted to be folded iron formation
stratigraphy (Figure 4).
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Figure 4: Oblique Section View of Drill Hole BIR23-001 Testing Atlantis Target (Looking West)
This target was tested with one drill hole during the recent program in an effort to discover new gold
mineralization in analogous structural and stratigraphic settings to other known mineralized occurrences
on the property. Drill hole B IR23-001 was a technical success in that it intercepted significant quartz
veining, as well as multiple zones of pyrite and pyrrhotite sulphidized iron formation stratigraphy that will
provide additional vectoring within the target and property-wide area. Gold grades returned were below
detection limits, with additional characterization work and target vectoring in this target area still to be
completed.
Table 2: Drill Intercept Results from the Horseshoe and Atlantis Targets
Hole ID From (m) To (m) Length (m) Au (g/t) Target
HOR23-001 22 25 3 2.01 Hoof
and 70.6 74 3.4 0.30 Horseshoe
and 159 194 35 0.57 Horseshoe
and 221 269.5 48.5 0.48 Horseshoe
including 256 256.5 0.5 4.29
HOR23-002 27 29 2 0.70 Horseshoe
and 68 72 4 0.49 Horseshoe
and 90 92 2 0.48 Horseshoe
and 105 107 2 1.35 Horseshoe
and 158 215 57 0.54 Horseshoe
including 193 203 10 0.90
including 211.06 215 3.94 1.05
HOR23-003 48.4 49.5 1.1 2.02 Hoof
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Hole ID From (m) To (m) Length (m) Au (g/t) Target
and 74 75 1 1.06 Hoof
and 82 83 1 1.41 Hoof
and 100 101 1 1.00 Hoof
and 134 140 6 1.38 Horseshoe
including 135 136 1 4.49
and 150 174 24 0.64 Horseshoe
including 153.8 154.4 0.6 5.43
including 173 174 1 4.86
and 183 197.5 14.5 0.45 Horseshoe
including 195.5 197.5 2 2.23
and 217 221 4 0.94 Horseshoe
and 234 236 2 0.76 Horseshoe
and 263 268.4 5.4 0.32 Horseshoe
and 355.85 357.25 1.4 0.57 Horseshoe
HOR23-004 80 81 1 0.96 Trigger
and 272 273.65 1.65 0.46 Trigger
HOR23-005 No significant assays Horseshoe
BIR23-001 No significant assays Atlantis
*Reported intervals are drilled core lengths, true widths are not yet established; assay values are uncut
Table 3: Drill Hole Locations, Horseshoe and Atlantis Targets
Hole ID Azimuth (°) Dip (°) Length (m) UTM E UTM N Target
HOR23-001 110 -60 331 539157 5691769 Horseshoe
HOR23-002 125 -70 310 539330 5691852 Horseshoe
HOR23-003 125 -80 395 539408 5691928 Horseshoe
HOR23-004 305 -56 275 539465 5692408 Horseshoe
HOR23-005 123 -55 278 539544 5692391 Horseshoe
BIR23-001 200 -51 329 548706 5698229 Atlantis
Note: Collar coordinates in UTM NAD 83 z15
First Mining’s exploration team is continuing to analyze data from the 2023 winter drilling campaign
around the Horseshoe and Atlantis targets , from which the learnings will further be incorporated into a
revised and updated geological model to support continued exploration opportunities.
“Our dedicated exploration and support teams are making tremendous progress at the Birch-Uchi Project
as we are continuing to push forward with mapping and sampling on a multitude of prospective areas
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which will uplift our database strength and support improved modelling and informed geological targeting
in the district surrounding Springpole.” stated James Maxwell, VP of Exploration for First Mining.
Birch-Uchi Greenstone Belt Project
First Mining’s BUGB Project hosts significant district -scale exploration leverage in forming part of a
consolidated >70,000 hectare mineral tenure. The property and broader greenstone belt hosts historic
production centres that demonstrate a strong gold endowment and an affinity for potential new
discovery. First Mining’s extensive BUGB property position is located within the Red Lake Mining District
and is situated approximately 80 km east of the Red Lake Mines Complex of Evolution Mining, and 75 km
northeast of Kinross Gold’s Dixie Project (formerly owned by Great Bear Resources Ltd). Geology of the
region is comprised of Archean Greenstone terranes that are endowed by significant gold mineralization
inclusive of orogenic and alkaline intrusion related deposit styles. Initial data compilation and validation
to date has indicated that the region demonstrates an underexplored and previously fragmented
exploration immaturity that is well levered to the Company’s strategy of consolidation and district
screening.
The Birch-Uchi Greenstone Belt hosts multiple gold mineralization styles throughout, which supports
having a strong multi-discipline geoscience foundation that can be applied in an integrated and iterative
targeting approach. Early targeting and vectoring elements highlight consolidated target opportuniti es
surrounding the Springpole Gold Project.
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 2023 drilling
program were sent to AGA T Laboratories in Thunder Bay and Mississauga, Ontario where they were
processed for gold analysis by 50 gram fire assay with an atomic absorption finish, and 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 Standards of Disclosure for Mineral Projects (“NI 43-101”).
Senior Management Change
Samir Patel, the Company’s General Counsel & Corporate Secretary, will be leaving his role at First Mining,
effective July 21, 2023, having notified the Company that he will be pursuing another opportunity in the
mining industry. Following Mr. Patel’s departure from the Company, Lisa Peterson, the Company’s CFO,
will assume corporate secretary duties on an interim basis.
“We would like to thank Samir for his service and dedication to First Mining. As one of the Company’s
longest standing employees, Samir has been a key part of the development of First Mining, and we wish
him well in his future endeavours,” stated Dan Wilton, CEO of First Mining.