Alamos Gold Intersects Additional High-Grade Mineralization Near Existing Infrastructure at Island Gold which is Expected to Drive Further Growth in Mineral Reserves and Resources

Press Release

TORONTO, Feb. 13, 2024– Alamos Gold Inc. (TSX:AGI; NYSE:AGI) (“Alamos” or the “Company”) today reported new results from underground exploration drilling at the Island Gold Mine. Underground exploration drilling continues to extend high-grade gold mineralization across the Island Gold Deposit within the main E1E and C-Zones, as well as several hanging wall and footwall structures in proximity to existing underground infrastructure. These results are expected to contribute to another increase in high-grade Mineral Reserves and Resources at Island Gold to be outlined in the 2023 year-end update to be released later this month.

Island Gold Main zone exploration highlights: high-grade mineralization extended outside of Mineral Reserves and Resources in the E1E and C-Zones. These zones are the main structures which host the majority of currently defined Mineral Reserves and Resources at Island Gold. New highlights include¹:

Island East (E1E-Zone)
- 34.48 g/t Au (34.48 g/t cut) over 2.82 m (840-632-49);
- 20.85 g/t Au (20.85 g/t cut) over 2.41 m (1040-619-20);
- 19.22 g/t Au (19.22 g/t cut) over 2.05 m (945-624-34); and
- 16.13 g/t Au (16.13 g/t cut) over 2.45 m (840-530-09).

Island West (C-Zone)
- 106.04 g/t Au (48.86 g/t cut) over 2.38 m (490-456-13); and
- 19.56 g/t Au (19.56 g/t cut) over 3.81 m (790-479-40).

Island Gold Hanging wall and Footwall exploration highlights: high-grade gold mineralization intersected within several recently defined hanging wall and footwall zones across the main Island Gold Deposit. These zones represent a significant opportunity to add near mine Mineral Reserves and Resources which would be low-cost to develop and produce given their proximity to existing infrastructure. This includes the NS1 Zone which was discovered early in 2023 and was being developed and mined by the end of the year. New highlights include¹:

Island West Hanging Wall Zones

B Zone

29.33 g/t Au (23.89 g/t cut) over 6.93 m (790-479-34);
40.36 g/t Au (40.36 g/t cut) over 3.91 m (790-479-40);
65.23 g/t Au (24.36 g/t cut) over 2.28 m (900-506-09);

NS1 Zone: currently defined over a North-South strike of approximately 70 m and vertical continuity of over 450 m, and remains open up and down dip

23.34 g/t Au (12.56 g/t cut) over 4.03 m (900-506-10);
17.30 g/t Au (8.61 g/t cut) over 3.41 m (900-506-11A);
12.33 g/t Au (12.33 g/t cut) over 3.96 m (900-506-07); and
10.46 g/t Au (10.46 g/t cut) over 4.17 m (900-506-08).

Island East Footwall Zones

E1D1 Zone

67.08 g/t Au (13.21 g/t cut) over 2.56 m (1040-619-22);
50.10 g/t Au (12.67 g/t cut) over 2.35 m (1040-619-31); and
14.78 g/t Au (14.39 g/t cut) over 2.17 m (1040-619-20).

E1D Zone

228.50 g/t Au (70.63 g/t cut) over 2.79 m (945-624-31A); and
52.31 g/t Au (15.13 g/t cut) over 2.06 m (945-624-32).

Other Hanging Wall and Footwall intersections: drilling continues to intersect high-grade mineralization in proximity to existing underground infrastructure in yet to be defined zones. These are part of more than 2,000 intersections above 3 g/t Au outside of existing Mineral Reserves and Resources in the hanging wall and footwall, highlighting the opportunity for significant near-mine additions as ongoing drilling further defines these areas. New highlights include²:

Footwall