O3 Mining Inc. (TSX-V: OIII) (OTCQX: OIIIF) is pleased to announce that it has received partial assay results from its 24,505 metre drilling campaign completed between January and March 2024 on the Malartic H area within the Marban Alliance project, in Val-d’Or, Québec, Canada.

Highlights:

• 119.1 g/t Au over 2.5 metres in hole O3MA-24-652 at a vertical depth of 114.2 metres, including 297.0 g/t over 1.0 metre on Malartic H
• 80.6 g/t Au over 3.1 metres in hole O3MA-24-554A at a vertical depth of 33.6 metres, including 411.0 g/t over 0.6 metres on Malartic H
• 1.9 g/t Au over 40.6 metres in hole O3MA-24-647 at a vertical depth of 77.6 metres on Malartic H

O3 Mining’s President and Chief Executive Officer, Mr. José Vizquerra commented: “These high-grade intercepts from our 2024 infill drilling program at Malartic H represent the first set of assay results since our maiden mineral resource estimate in June 2023. Malartic H continues to show potential to grow both laterally and at depth and we remain hopeful that additional infill drilling could allow us to grow the deposit. These results continue to demonstrate the potential at Malartic H and the robustness of the Marban Alliance Project.”

The objective of the 2024 drilling campaign on the Malartic H deposit was the conversion to the indicated category of the inferred resource estimated in 2023 (see news release of O3 Mining dated June 20, 2023 and entitled “O3 Mining Delivers Maiden Mineral Resource Estimate for Malartic H“). This campaign totalled 121 drill holes of which assay results for 56 of them are reported today. We will continue reporting as new assay results become available.

Malartic H Deposit

The Malartic H deposit has a recognized strike length of 950 metres, 300 metres wide and down to a vertical depth of 500 metres. It is located within five kilometres of the proposed processing plant described in the pre-feasibility study published on Marban Alliance in 2022 and approximately one kilometre to the north of the Malartic Hygrade former mine, near the hinge of a regional Z-shaped fold. The mineralized system is partially open laterally and completely open at depth. Notably, the Malartic H deposit is positioned between the northwestern extensions of the Marbenite and Norbenite shears, which host most of the resources of the Marban Alliance Project. At Malartic H, the two shears are northwest-trending and dipping around 70 degrees to the northeast. The deposit is hosted by an alternance of mafic and ultramafic volcanic sequence of the Jacola formation. Similar to the Hygrade area, numerous intermediate to felsic dyke systems are injected in the volcanic sequence. The mineralization occurs as disseminated pyrite with local visible gold in quartz veins and veinlets and disseminated in the host rock. Zones are spatially correlated shears within mafic volcanic units or with the intermediate to felsic dykes. All zones are roughly subparallel.

Today’s news release also includes the last significant intercepts obtained from the fall 2023 drilling program at Norlartic Extension (see news release of O3 Mining dated February 22, 2024 and entitled “O3 Mining Intersects 9.6 g/t Au over 6.2 Metres at Norlartic Extension, Marban Alliance“).

The dyke swarm hosting the gold mineralization at Norlartic Extension is geologically identical to the one hosting the Norlartic and Kierens mineralization. They correspond to mafic and intermediate fine-grained dykes, which have been successfully traced along a two-kilometre trend and serve as a marker to the mineralized corridor.

Figure 1: Photo of visible gold at 46.7 metres in hole O3MA-24-554A at Malartic H

Table 1: Drill Hole Intercepts. Only intercepts with metal factor above 5.0 (g/t Au x metres) are reported, cut-off 0.3 g/t Au and above 200 metres from surface. See Table 2 below for full technical parameters.

Table 1 (continued):  Drill Hole Intercepts. Only intercepts with metal factor above 5.0 (g/t Au x metres) are reported, cut-off 0.3 g/t Au and above 200 metres from surface. See Table 2 below for full technical parameters.

Figure 2: Marban Alliance Project Map

Figure 3: Malartic H – Significant Intercepts Map

Figure 4: Norlartic Extension – Significant Intercepts Map

Table 2: Technical parameters of holes of the 2023-2024 campaign at Malartic H and Norlartic Extension that have received assay results

Qualified Person

The scientific and technical content of this news release has been prepared, reviewed, and approved by Mr. Louis Gariepy , P.Eng (OIQ #107538), VP Exploration of O3 Mining, who is a “qualified person” within the meaning of National Instrument 43-101 – Standards of Disclosure for Mineral Projects.

Quality Assurance/Quality Control

Intercepts occur within geological confines of major zones but have not been correlated to individual vein domains at this time. Half-core samples are shipped to Agat laboratory in Val-d’Or, Québec, and Mississauga, Ontario for assaying. The core is crushed to 75% passing -2 mm (10 mesh), a 250 g split of this material is pulverized to 85% passing 75 microns (200 mesh) and 50 g is analyzed by Fire Assay (FA) with an Atomic Absorption Spectrometry (AAS) finish. Samples assaying >10.0 g/t Au are re-analyzed with a gravimetric finish using a 50 g charge.

Commercial certified standard material and blanks are systematically inserted by O3 Mining’s geologists into the sample chain after every 18 core samples as part of the quality assurance and quality control (“QA/QC”) program. Third-party assays are submitted to other designated laboratories for 5% of mineralized samples. Drill program design, QA/QC, and interpretation of results are performed by qualified persons employing a QA/QC program consistent with NI 43-101 and industry best practices.

About O3 Mining Inc.

O3 Mining Inc. is a gold explorer and mine developer on the road to produce from its highly prospective gold camps in Québec, Canada. O3 Mining benefits from the support and expertise of a team of industry leaders as it grows towards becoming a gold producer with several multi-million-ounce deposits in Québec.

O3 Mining is well-capitalized and owns a 100% interest in all its properties (107,000 hectares) in Québec. O3 Mining trades on the TSX Venture Exchange (TSXV: OIII) and OTC Markets (OTCQX: OIIIF). The Corporation is focused on delivering superior returns to its shareholders and long-term benefits to its stakeholders.