Infill continues to deliver, 71.85m @ 6.13g/t Au

Orosur Mining Inc - infill drilling continues to deliver, 71.85m @ 6.13g/t Au.

• Assays from four more holes from the Pepas MRE infill program include:

o PEP050 - 34m @ 2.33g/t Au from surface

o PEP051 - 61.3m @ 3.36g/t Au

o PEP052 - 71.85m @ 6.13g/t Au

• El Cedro soil sampling 45% complete - first samples submitted for assay.
• Contracts being finalised for El Pantano (Argentina) drilling - planned to commence mid-October.

London, August 26th, 2025. Orosur Mining Inc. ("Orosur" or the "Company") (TSXV/AIM:OMI), is pleased to announce an update on the progress of exploration activities at the Company's flagship, 100% owned, Anzá Gold Project ("Project") in Colombia, and its El Pantano Gold/Silver Project ("El Pantano") in Argentina.

Anzá - Colombia

The first several holes of this program (announced 17th July 2025), vindicated this decision by returning exceptional widths and grades, especially hole PEP045 which returned 62.3m @ 12.76g/t Au.

The drill program has been designed in conjunction with external consultants to facilitate a MRE being calculated, with the multiple objectives of infilling previous drilling, expanding beyond current drilling to define the boundaries, and understanding the geological controls upon mineralisation and the variations in geology and grade across the deposit.

Holes will be drilled in an order that attempts to address these issues concurrently.

These four holes announced today are a continuation of this program and designed largely to infill to the required spacing to allow a MRE to be calculated to a high level of confidence. Drilling continues to return thick sequences of high-grade gold mineralisation, starting from surface or near surface.

Importantly, drilling is also providing guidance as to grade and mineralogical variation across the ore body that will allow our teams to define various metallurgical domains that will in turn form the basis of more advanced metallurgical studies that are planned to commence soon.

Table 1. Latest drill Intercepts, Pepas Prospect

Figure 2. Plan of holes

Figure 3. Section, PEP050

Figure 4. Section PEP051, PEP051 and PEP053

El Cedro - Anzá, Colombia

The El Cedro prospect is a large gold porphyry system, located toward the south of the Anzá project, on the same granted exploration licence as the Pepas and APTA deposits.

The Company has recommenced a large ridge and spur soil sampling program that had been previously suspended due to seasonal rain and access issues. This program is now roughly 45% complete, and it is expected that the remainder of the program should be completed by mid-October 2025.

The first batch of 40 samples from the restarted program have been submitted for assay this week, with results expected soon.

El Pantano - Argentina

The Project comprises approximately 550km2 of contiguous licences in the prolific Deseado Massif region, roughly 45km from Anglo Gold's Cerro Vanguardia mining camp.

The El Pantano Project is subject to an Exploration & Joint Venture ("JV") agreement ("Agreement") with private Argentinean company DESEADO DORADO S.A.S and its shareholders ("Deseado"), the details of which were announced on February 15th 2022. The Company has earned a 51% interest in the El Pantano Project and must spend an additional US$2m in the two years from Feb 14th, 2025, in order to earn 100% ownership.

The Company has been carrying out regional exploration at El Pantano for several years, including geological mapping, geochemical sampling, ground magnetics and induced polarisation geophysical surveys. These work programs have provided evidence suggestive of major rift-related low sulphidation epithermal system, of the type that has led to the development of major gold and silver deposits in the region.

Drill permits for El Pantano were obtained late in 2024, and the Company is now finalising drill contracts with a view to commencing drilling in mid-October 2025, the first drill program that has ever been undertaken anywhere on the property.

Between 10 and 14 diamond holes are planned for a total of approximately 3000m, targeting geological structures and geochemical/geophysical anomalies identified from previous work. Additional details will be provided once more precise timing is finalised.

The area is very remote and largely unpopulated and thus substantial effort has been required to plan and develop the necessary camp and access infrastructure for a drilling program of this size.

The Deseado Massif is a major gold producing area in Argentina and thus some necessary downstream infrastructure exists in the region. In particular, an international laboratory company has a fire assay facility in the regional town of Perito Moreno and thus a short assay turnaround time (for gold and silver) is anticipated.

Orosur CEO Brad George commented:

"Pepas remains on track and the high bar set by the early holes continues to be cleared on a regular basis. In the meantime, we are excited to be getting close to opening a second drilling front on our El Pantano project in Argentina. Early stage, but this is elephant country, and we like what we have seen thus far".

Colombia - ANZÁ Project ("Project")

Prospects

Figure 5. Main prospects, licences pre-MMA acquisition

Holes Drilled post MMA Transaction

38 holes have been drilled at Pepas since the MMA Transaction in November 2024.

Assay results are tabulated below.

Table 2. Results to date, post MMA Transaction