Alamos Gold Intersects Higher-Grade Mineralization within a New Zone Near Existing Infrastructure at Young-Davidson

Press Release

TORONTO, May 14, 2024 — Alamos Gold Inc. (TSX:AGI; NYSE:AGI) (“Alamos” or the “Company”) today reported new results from its underground exploration program at the Young-Davidson mine. Underground exploration drilling from the mid-mine intersected a new style of higher-grade gold mineralization in zones within the hanging wall of the Young-Davidson deposit.

These zones are located between 10 and up to 200 metres (“m”) south of existing infrastructure and Mineral Reserves and Resources, highlighting the upside potential with grades intersected well above the current Mineral Reserve grade of 2.31 grams per tonne of gold (“g/t Au”).

• Young-Davidson Hanging Wall Zones: high grade gold mineralization intersected within the hanging wall, in proximity to existing infrastructure and south of existing Mineral Reserves and Resources. This represents a new style of mineralization at Young-Davidson, hosted in hanging wall stratigraphy including a folded sequence of Timiskaming assemblage conglomerates and sediments. Gold mineralization is associated with 3-20% pyrite and occurs both as wide, low- to moderate-grade mineralization, and also within narrower, high-grade structures (Figures 1 and 2). New highlights include¹:
  • 9620-Level Drilling¹
    • 7.41 g/t Au over 22.00 m, including 15.84 g/t Au over 6.00 m (YMEX24-9620-143);
    • 19.94 g/t Au over 4.55 m (YMEX24-9620-147);
    • 21.86 g/t Au over 4.00 m (YMEX24-9620-147);
    • 5.24 g/t Au over 9.00 m (YMEX24-9620-147);
    • 9.07 g/t Au over 5.00 m (YMEX24-9620-137);
    • 4.70 g/t Au over 10.00 m (YMEX24-9620-143);
    • 17.55 g/t Au over 2.00 m (YMEX24-9620-142); and
    • 4.13 g/t Au over 8.31 m (YMEX24-9620-141).
  • 9500-Level Drilling^1,2
    • 10.73 g/t Au over 15.55 m (YM23-9500-107A).

¹ All reported composite intervals are core length and gold grades are reported as uncut. Based on initial review of core angles, true width is interpreted to be less than 50% of core length for some composites. Additional drilling and interpretation is ongoing to further define the geometry and extent of the mineralized zones.

² YM23-9500-107A was drilled as a BQ-diameter definition drillhole, which was extended into the hanging wall. This hole was assayed using whole core at the Young Davidson on-site assay lab (see QA/QC section of Press Release).

“Young-Davidson is a consistent, long-life operation with a long-track record of Mineral Reserve replacement having maintained at least a 13-year Mineral Reserve life since 2011. With the deposit open at depth and to the west, we expect this track record to continue well into the future as we extend gold mineralization within the Young-Davidson syenite. The new zones being discovered in the hanging wall highlight the significant exploration potential outside of the syenite. This is a new style of higher-grade mineralization, near our existing underground infrastructure, which has the potential to provide meaningful production upside,” said John A. McCluskey, President and Chief Executive Officer.

New highlight intercepts can be found in Tables 1 and 2, and in Figures 1 and 2 at the end of this news release.

2024 Exploration Drilling Program – Young Davidson

A total of $12 million has been budgeted for exploration at Young-Davidson in 2024, up from $8 million spent in 2023. This includes 21,600 m of underground exploration drilling, and 1,070 m of underground exploration development to extend drill platforms on multiple levels.

The majority of the ongoing underground exploration drilling program will focus on extending mineralization within the Young-Davidson syenite, which hosts the majority of Mineral Reserves and Resources. As part of the 2024 program, drilling was also planned to test gold mineralization in the hanging wall of the deposit where higher grades have been previously intersected.

As of May 1, 2024, two exploration drills completed 9,610 m in 26 holes from the 9220 West exploration drift, 9025 East footwall drift, 9305 East transfer, and the 9620 Hanging wall drift. Drilling from 9025, 9305, and 9220 west is targeting syenite-hosted mineralization. The 9620-level drilling is focused on testing for gold mineralization in the hanging wall sediments and mafic-ultramafic lithologies. Drilling from the 9025-level has also been successful at expanding gold mineralization within the syenite outside of current Mineral Reserves and Resources in the lower mine, in proximity to existing underground infrastructure.

Hanging Wall Gold Mineralization

An objective of the 2024 underground exploration drilling program is to test for gold mineralization in the hanging wall from a drill bay established on the 9620-level. This program is following up on gold mineralization that was intersected in surface drill holes completed between 2008 to 2010. These holes were collared south of Young-Davidson in the hanging wall, and drilled to the north, through the hanging wall. The surface holes were drilled to target the syenite-hosted mineralization, and as a result limited sampling was completed in the hanging wall lithologies at that time.

In addition, an underground definition drill hole completed from the 9500-level in the fourth quarter of 2023 intersected 10.73 g/t Au over 15.55 m (YM23-9500-107A) in a conglomerate, 93 m from the syenite-hosted Mineral Reserves and Resources. This definition hole had been extended into the hanging wall to test the potential for gold mineralization.

Following up on this intersection from the 9500-level definition drill hole (YM23-9500-107A), as well as underground mapping on the 9620-level, and the previous 2008-2010 surface drillhole intersections, underground exploration drilling commenced in the first quarter of 2024 from the 9620-level drill bay.

To date, 13 holes totalling 4,591 m have been completed from the 9620-level. New highlights include:

• 9620-Level
  • 7.41 g/t Au over 22.00 m, including 15.84 g/t Au over 6.00 m (YMEX24-9620-143);
  • 19.94 g/t Au over 4.55 m (YMEX24-9620-147);
  • 1.02 g/t Au over 101.00 m (YMEX24-9620-136);
  • 21.86 g/t Au over 4.00 m (YMEX24-9620-147);
  • 5.24 g/t Au over 9.00 m (YMEX24-9620-147);
  • 9.07 g/t Au over 5.00 m (YMEX24-9620-137);
  • 4.70 g/t Au over 10.00 m (YMEX24-9620-143);
  • 17.55 g/t Au over 2.00 m (YMEX24-9620-142);
  • 4.13 g/t Au over 8.31 m (YMEX24-9620-141); and
  • 1.75 g/t Au over 18.00 m (YMEX24-9620-144).

• 9500-Level
  • 10.73 g/t Au over 15.55 m (YM23-9500-107A).

Drilling is now underway from a drilling pad established to the east of the initial drilling on the 9620-level to continue to test for gold mineralization in the hanging wall, with the objective of better defining the extent, geometry, and continuity of the high-grade mineralization. In addition, a core relogging and sampling program is expected to commence in the second quarter of 2024, with a focus on evaluating the historic surface drilling in the hanging wall that had undergone limited sampling.

Qualified Persons

Scott R.G. Parsons, P.Geo., FAusIMM, Alamos Gold’s Vice President, Exploration, has reviewed and approved the scientific and technical information contained in this news release. Scott R.G. Parsons is a “Qualified Person” as defined by Canadian Securities Administrators’ National Instrument 43-101 – Standards of Disclosure for Mineral Projects.

Exploration programs at the Young Davidson Mine are directed and supervised by Niels Hendrikx, P.Geo., Geological Superintendent at the Young Davidson Mine. Niels Hendrikx is a “Qualified Person” as defined by Canadian Securities Administrators’ National Instrument 43-101 – Standards of Disclosure for Mineral Projects.

Quality Assurance and Quality Control

Alamos Gold maintains an internal Quality Assurance / Quality Control (QA/QC) program at the Young Davidson Mine to ensure sampling and analysis of all exploration work is conducted in accordance with best practices.

Access to the Young Davidson Mine is controlled by security personnel. Drill core is logged and sampled at core logging facilities within the mine site under the supervision of a Qualified Geologist. A geologist marks the individual samples for analysis, and sample intervals, sample numbers, standards and blanks are entered into the database.

Mine exploration core (NQ-diameter) is cut in half using an electric core saw equipped with a diamond tipped blade. One half of the core is placed into a plastic sample bag and sealed with zip ties in preparation for shipment. The other half of the core is returned to the core box and retained for future reference. The samples are placed in large heavy-duty nylon reinforced Fabrene bags, which are identified and sealed before being placed on pallets. The core samples are picked up at the mine site and mine samples are delivered to ALS laboratories, located in Timmins, Ontario.

Gold is analyzed by a 30 gram fire assay with an Atomic Absorption (AA) finish. Mine exploration samples greater than 8.0 g/t Au are re-analyzed using gravimetric finish methods. ALS is a certified laboratory and has an internal quality control (“QC”) program that includes insertion of reagent blanks, reference materials, and pulp duplicates.

The Corporation inserts QC samples (blanks and reference materials) at regular intervals to monitor laboratory performance.

Underground definition drill core (BQ-diameter) is assayed using whole core samples at the Young-Davidson Mine on-site laboratory. The laboratory has been operating since 2012 and has undergone regular external audits, most recently in 2022. The Young-Davidson laboratory maintains a rigorous assay quality control program including reagent blanks, insertion of reference materials, and pulp duplicates. Blanks and reference materials are inserted with underground definition drill core samples on a routine basis. Gold is analyzed by a 30 gram fire assay with an Atomic Absorption (AA) finish. Samples with fire assay grades greater than 8.0 g/t Au are re-analyzed using gravimetric finish methods. In addition, sample pulps are routinely submitted for check assays to an accredited commercial laboratory.

The Young-Davidson Mine QA/QC procedures described in detail in the January 25, 2017 Technical Report filed on SEDAR+ (www.sedarplus.ca).

About Alamos
Alamos is a Canadian-based intermediate gold producer with diversified production from three operating mines in North America. This includes the Young-Davidson and Island Gold mines in northern Ontario, Canada and the Mulatos mine in Sonora State, Mexico. Additionally, the Company has a strong portfolio of growth projects, including the Phase 3+ Expansion at Island Gold, and the Lynn Lake project in Manitoba, Canada. Alamos employs more than 1,900 people and is committed to the highest standards of sustainable development. The Company’s shares are traded on the TSX and NYSE under the symbol “AGI”.

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