El Cedro sampling opens new horizons.

·    Soil sampling completed at El Cedro south - prospectivity enhanced

·    Aeromag over El Cedro and APTA now completed

·    Pepas rig moved from Pepas West to new target

London, April 28th, 2026. 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 exploration project at Anzá in Colombia ("Anzá").

Anzá - Colombia

The Anzá Project in Colombia comprises a number of granted exploration titles and applications totalling roughly 330km², within the Mid-Cauca gold belt, west of the city of Medellin.

These titles and applications are owned by two Colombian companies, Minera Anzá, and Minera Monte Aguila, both wholly owned subsidiaries of the Company. The latter of these was acquired by Orosur in November 2024 from the Company's previous JV partners, Newmont Mining and Agnico Eagle Mines.  Orosur thus owns 100% of the Anzá Project.

Since acquiring 100% control, the Company has focussed its attention on three prospects:

·    Pepas - a shallow, high-grade body of gold mineralisation for which the Company has calculated a Mineral Resource Estimate ("MRE"), announced on February 10^th 2026.

·    APTA - a high-grade body of gold mineralisation that has to date seen over 38,000m of historical drilling, and at which drilling is currently underway. 

·    El Cedro - a cluster of gold porphyry intrusions in the south of the Project area that are currently subject to mapping and sampling programs, with a view to potentially being drilled later in H1 2026.

Figure 1. Anzá Project

El Cedro

The El Cedro prospect lies to the south of the same integrated licence that hosts both Pepas and APTA and is roughly 4km south of the APTA base camp.

Work on the area began some years before Orosur's tenure, when Anglo American undertook reconnaissance mapping and sampling, identifying a highly prospective gold/copper porphyry system. This work was largely focussed on a small soil program in the centre of what was known of the northern porphyry, plus mapping in flanking creeks and drainages which identified several veins systems with rock chips returning over 10 g/t Au.

Little work was then undertaken until late 2021, when the Company's previous JV partner, MMA, re-entered the area to carry out mapping, sampling and ground geophysics that largely confirmed Anglo American's previous work and mapped several large dioritic intrusions and associated epithermal systems.

Post resumption of control of the Project, the Company began a large-scale soil geochemical survey in May 2025, planned to cover most of what was thought to be the extent of the porphyry system as it was known at the time.  Soil samples were taken at roughly 25m intervals, along ridges and spurs for ease of access and to ensure soils were residual.  Results from this work were announced on October 30^th, 2025, which included the identification of a second intrusive body immediately south of the known northern body.

Figure 2. Regional Tectonic Setting

Identification of this second body led to the commencement of an additional soil and mapping program to the same specifications.

Assay results from this new program demonstrate this southern intrusive system to be largely similar to the northern body, demonstrating high grade gold in soils, at times over 1g/t Au, over total area of roughly 2km x 3km.

Mapping suggests both intrusive systems to be geologically similar and therefore likely to be related events (albeit based on limited outcrop) but with slightly different geomorphological settings and soil profiles.

Both sit within the same N-S structural corridor with the highest-grade soil and rock chip samples being in fault systems between the two intrusions and on the flanks of each, suggesting the presence of porphyry associated epithermal systems.

Figure 3. El Cedro soil samples, combined north and south centres (over previous mag)

A detailed drone mounted magnetic survey has just been completed over the southern portions of the Anzá project area, including El Cedro and APTA. It is anticipated that several weeks may be required to finalise processing of these data, which can then be used in conjunction with the recent sampling data at El Cedro and drilling currently underway at APTA, to develop new drill targets in the region.

It is anticipated that drilling can commence at El Cedro in the near term once targeting and access permitting has been completed.

Pepas

As announced on April 14^th, 2026, a new zone of gold mineralisation ("Pepas West") has been discovered some 100m west of the Pepas deposit, which geologically, bears a close resemblance to Pepas.

Excluding two previous holes from early 2025, in this recent campaign, nine holes have now been drilled into this new zone (PEP082 to PEP090).  Results from holes PEP082 and PEP083 have already been announced, with samples from the remaining holes either in the laboratory or being prepared for shipment.

In the meantime, the decision has been taken to temporarily move the Pepas rig to a new target several hundred metres to the south, which will also allow time for data from this recent drilling at Pepas West to be compiled and examined.

Mineralisation identified in this new western zone closely resembles Pepas, suggesting the possibility that both are derived from the same original source, but then broken up by post mineralisation faulting.  The Company believes it is important to understand the structural setting that has led to the emplacement of Pepas West and the implications of this for both extension and repetitions.

Orosur CEO Brad George commented:

"With the possibility of three rigs operating soon on three prospects, Anzá is now inexorably growing in scope, scale and complexity.  The picture is emerging of a substantial mineralised province, the surface of which is only now starting to be scratched."

For further information, visit www.orosur.ca, follow on X @orosurm or please contact:

Orosur Mining Inc

Louis Castro, Chairman,

Brad George, CEO

[email protected]

Tel: +1 (778) 373-0100

SP Angel Corporate Finance LLP - Nomad & Joint Broker

Caroline Rowe / Jen Clarke / Devik Mehta

Tel: +44 (0) 20 3470 0470

Turner Pope Investments (TPI) Ltd - Joint Broker
Andy Thacker/Guy McDougall
Tel: +44 (0)20 3657 0050

Flagstaff Communications and Investor Communications

Tim Thompson
Mark Edwards
Fergus Mellon

[email protected]

Tel: +44 (0)207 129 1474

The information contained within this announcement is deemed by the Company to constitute inside information as stipulated under the Market Abuse Regulations (EU) No. 596/2014 ('MAR') which has been incorporated into UK law by the European Union (Withdrawal) Act 2018. Upon the publication of this announcement via Regulatory Information Service ('RIS'), this inside information is now considered to be in the public domain.

Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.

About Orosur Mining Inc.

Orosur Mining Inc. (TSXV: OMI; AIM: OMI) is a minerals explorer and developer currently operating in Colombia and Argentina.

Qualified Persons Statement

The information in this news release was compiled, reviewed, verified and approved by Mr. Brad George, BSc Hons (Geology and Geophysics), MBA, Member of the Australian Institute of Geoscientists (MAIG), CEO of Orosur Mining Inc. and a qualified person as defined by National Instrument 43-101.

Orosur Mining Inc. staff follow standard operating and quality assurance procedures to ensure that sampling techniques and sample results meet international reporting standards.

Forward Looking Statements

All statements, other than statements of historical fact, contained in this news release constitute "forward looking statements" within the meaning of applicable securities laws, including but not limited to the "safe harbour" provisions of the United States Private Securities Litigation Reform Act of 1995 and are based on expectations estimates and projections as of the date of this news release.

Forward-looking statements include, without limitation, the continuing focus on the Pepas prospect, the exploration plans in Colombia and the funding of those plans, and other events or conditions that may occur in the future. There can be no assurance that such statements will prove to be accurate. Actual results and future events could differ materially from those anticipated in such forward-looking statements. Such statements are subject to significant risks and uncertainties including, but not limited to, those described in the Section "Risks Factors" of the Company's MD&A for the year ended May 31, 2025. The Company's continuance as a going concern is dependent upon its ability to obtain adequate financing. This material uncertainty may cast significant doubt upon the Company's ability to realize its assets and discharge its liabilities in the normal course of business and accordingly the appropriateness of the use of accounting principles applicable to a going concern. The Company disclaims any intention or obligation to update or revise any forward-looking statements whether as a result of new information, future events and such forward-looking statements, except to the extent required by applicable law.