Alamos Gold Inc. Reports New Results from Underground and Surface Drilling At the Island Gold Mine

Alamos Gold Inc. reported new results from underground and surface drilling at the Island Gold Mine. Exploration drilling continues to extend high-grade gold mineralization across the Island Gold Deposit, as well as within several hanging wall and footwall structures, and delineation drilling continues to support the conversion of high-grade Mineral Resources to high-grade Mineral Reserves. Additionally, the regional exploration program continues to intersect high-grade gold mineralization at the past-producing Cline-Pick mines, located seven kilometres from the Magino Mill.

Regional drilling within the past producing Cline-Pick Mines continues to extend high-grade gold mineralization beyond the extent of previous mining. The targets are open in multiple directions, including at depth, with the deepest holes drilled to date down to a vertical depth of only 540 metres (?m?). By comparison, the deepest holes within the main Island Gold structure have intersected high-grade mineralization beyond depths of 1,600 m. The past-producing Cline-Pick and Edwards mines are within seven kilometres of the Magino mill by existing road and are being targeted as potential sources of additional higher-grade mill feed within a larger expansion.

New highlights include: Cline-Pick Mines:178.07 g/t Au over 3.54 m (25IGX128) including; 219.00 g/t Au over 0.70 m; 301.00 g/t Au over 0.68 m; 295.00 g/t Au over 0.62 m; and 112.50 g/t Au over 0.50 m.15.28 g/t Au over 5.52 m (25IGX128) including;25.20 g/t Au over 0.66 m;19.15 g/t Au over 0.35 m; and40.30 g/t Au over 0.59 m.12.75 g/t Au over 8.79 m (25IGX112), including; 93.75 g/t Au over 1.01 m; and 23.57 g/t Au over 2.34 m (25IGX124) including;115.00 g/t Au over 0.45 m. 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 include: Island West (C-Zone)64.70 g/t Au (63.19 g/t cut) over 2.13 m (900-506-23);12.95 g/t Au over 4.10 m (1025-492-06); and13.79 g/t Au over 3.01 m (900-506-19).Island East (E1E-Zone)31.53 g/t Au (12.05 g/t cut) over 7.55 m (1190-607-04);9.84 g/t Au (8.64 g/t cut) over 21.41 m (1190-607-18);16.22 g/t Au over 4.49 m (1190-607-13); and 11.71 g/t Au over 5.75 m (1190-607-12).

Island Gold Hanging Wall and Footwall exploration highlights: high-grade gold mineralization intersected within new and recently defined hanging wall and footwall zones across the main Island Gold Deposit. These zones represent significant opportunities to continue to grow near mine Mineral Reserves and Resources which are low-cost to develop, given their proximity to existing infrastructure. New highlights include: Island West Hanging Wall and Footwall Zones: NS2 Zone: growing parallel structure, 160 m east of NS1 Zone13.81 g/t Au (5.31 g/t cut) over 6.01 m (900-506-44);17.23 g/t Au (9.69 g/t cut) over 3.69 m (900-506-22);20.92 g/t Au (8.77 g/t cut) over 2.94 m (900-506-35);20.66 g/t Au (18.79 g/t cut) over 2.87 m (900-506-24); and9.06 g/t Au (6.33 g/t cut) over 5.89 m (900-506-18A).

NS3 Zone: growing parallel structure, 90 m west of NS1 Zone58.92 g/t Au (9.93 g/t cut) over 8.00 m (790-460-36);53.98 g/t Au (4.28 g/t cut) over 2.88 m (850-470-07); and39.98 g/t Au (12.88 g/t cut) over 2.31 m (850-475-25). NS4 Zone: growing parallel structure, 180 m west of NS1 Zone24.91 g/t Au (4.45 g/t cut) over 2.46 m (850-472-51); and22.21 g/t Au (7.33 g/t cut) over 2.46 m (900-506-22). Island East Footwall Zones: NTH4 Zone132.73 g/t Au (34.86 g/t cut) over 2.08 m (1160-625-26); and8.99 g/t Au over 6.08 m (1160-625-25).

Island Gold East delineation and definition drilling highlights: the primary focus of the 2025 drill program was the conversion of a portion of the large Mineral Resource base to Reserves. Surface and underground delineation drilling has been successful over the past year in driving significant Mineral Reserve growth that will be incorporated into the Expansion Study to be released this week. New highlights include:E1E-Zone54.85 g/t Au (39.73 g/t cut) over 17.99 m (MH42-03);56.05 g/t Au (35.02 g/t cut) over 7.05 m (MH41-01); 60.00 g/t Au (57.81 g/t cut) over 4.08 m (MH41-03); 87.63 g/t Au (46.48 g/t cut) over 2.43 m (945-624-87);48.31 g/t Au (47.68 g/t cut) over 2.11 m (1160-625-15);5.27 g/t Au over 14.72 m (945-624-75);5.88 g/t Au over 13.09 m (945-624-78);4.11 g/t Au over 17.50 m (1190-607-08);13.55 g/t Au over 5.29 m (MH42-02); and18.71 g/t Au (14.89 g/t cut) over 3.44 m (1190-607-09).

C-Zone21.41 g/t Au (14.77 g/t cut) over 5.56 m (890-461-54);43.26 g/t Au over 2.17 m (490-450-06); and10.83 g/t Au over 3.07 m (1025-503-16). A total of $24 million was spent on exploration at the Island Gold District in 2025, up from $20 million spent in 2024. Following up on a successful 2024 program, a total of 46,889 m of underground drilling was completed in 180 holes in 2025 with a focus on defining new Mineral Reserves and Resources in proximity to existing production horizons and infrastructure.

Additionally, 14,609 m of surface exploration drilling was completed in 15 holes targeting the area between the Island Gold and Magino deposits, as well as the down-plunge extension of the Island Gold deposit, below a depth of 1,500 m. Over the past five years, the discovery cost of the high-grade Mineral Resource additions has averaged an attractive $13 per ounce. A primary focus of the 2025 drill program was the conversion of a portion of the large Mineral Resource base to Mineral Reserves to be included in the Island Gold District Expansion Study. As part of that focus a total of 33,964 m of underground delineation drilling was completed in 117 holes, and 12,269 m of surface delineation drilling was completed in 12 holes.

Additionally, 22,390 m of surface delineation drilling was completed in 51 holes at Magino. A total of 11,060 m drilling was also completed in 36 holes as part of regional exploration program at the Island Gold District. The program focused on stepping out from high-grade mineralization intersected at the Cline-Pick deposit located approximately seven kilometres northeast of the Island Gold mine, with 29 holes totalling 9,911 m completed in 2025.

Initial drilling was completed at the past-producing Edwards Mine, which was successful in expanding high-grade mineralization and will continue to be advanced as part of the 2026 program.