El Pantano Project Developing

·    Drilling identifies major epithermal gold/silver system.

·    NI 43-101 Technical Report completed and filed.

·    JV obligations met, project now owned 100%.

·    Next phase of work being planned.

London, July 22^nd 2026. Orosur Mining Inc. ("Orosur" or the "Company") (TSXV/AIM:OMI), is pleased to announce an update on the Company's exploration project at El Pantano in Argentina ("El Pantano" or the "Project").

El Pantano - Argentina

The El Pantano project is an early-stage gold/silver exploration project in Santa Cruz province, southern Argentina.

The Project comprises approximately 560km² of contiguous granted licences in the prolific Deseado Massif of Santa Cruz Province, roughly 45km from Anglo Gold's Cerro Vanguardia mining camp and 100km SE of Newmont Mining's giant Cerro Negro mine.

Figure 1. Project Location

Figure 2. Licence Package

El Pantano was subject to an Exploration & Joint Venture agreement ("JV Agreement") with private Argentinean company Deseado Dorado S.A.S and its shareholders ("Deseado"), the details of which were announced on February 15^th, 2022.

The JV Agreement required exploration expenditure of US$3m over 5 years from February 14^th, 2022, in two phases to earn 100% ownership of the Project. The Company completed the first phase of the JV Agreement, having invested US$1m over three years as announced on February 17^th, 2025. With the recently completed drilling program, the Company has now completed the Phase 2 commitments of US$2m ahead of the required deadline and, as such, has exercised its option to retain 100% ownership of the Project.

As part of the Phase 2 obligations, the Company has granted to the original vendors a 2% NSR royalty on future production, 1% of which the Company may purchase for US$1m at its discretion.

Exploration Work

While displaying positive surface geology, the Project had seen little historical modern exploration, apart from some superficial geochemical and geophysical work in the SE quadrant by a previous company. No drilling had ever been undertaken within the Project area.

Since inception of the JV Agreement, the Company had conducted large scale reconnaissance mapping, sampling, geochemical and geophysical programs across the project area. Results of these work programs supported the Company's thesis that the Project had the potential to host a major epithermal mineral system. 

As a result, the Company then committed in late 2025, to the first drill program ever undertaken within the Project area.

Commencing in November 2025, 24 diamond drill holes, for a total of 5533m were completed across the Project area, targeted to address a number of geological areas:

·    Test sources of geochemical anomalism

·    Assess a variety of Induced Polarisation responses

·    Intersect, if possible, mineralised structures indicative of the low sulphidation epithermal model being postulated at El Pantano

·    Gain understanding of the vertical variations in the system, especially in relation to the potential for fluid boiling.

In a general sense, the broad objective of the program is to determine if a mineral system is present at El Pantano, and if so, develop exploration plans for further work.

Figure 3.  El Pantano geology and geochemistry

Drill holes were spread across the eastern and western extremes of the main rift related epithermal system, with several sections being completed to facilitate an assessment of lateral and vertical variations in geochemistry and structures.

Full results and discussion of the Project and all work undertaken is included in the Canadian National Instrument 43-101-Standard of Disclosure for Mineral Projects compliant technical report ("Technical Report"), dated 13 July 2026 with effective date 15 May 2026, which has been filed on SEDAR, and available to view on the Company's website at www.orosur.ca.

Figure 4. Drill hole locations

Discussion of Drilling Results

The rift related, low sulphidation epithermal model being employed at El Pantano, sees gold and silver mineralization being derived from deep, underlying intrusives, and then concentrated in quartz veins at a higher level in structures developed as part of the macro scale Jurassic rifting. At the vertical scale, development of economic mineralization is often driven by fluid boiling as gold bearing fluids rise up and binding pressures are relaxed.

A key objective then of the drilling campaign, was to intersect such structures, and to gain some information of the vertical zonation and potential proximity and vectors toward mineralisation.

El Pantano West: Structurally Controlled Gold-Bearing Vein Corridors

El Pantano West target area is interpreted to represent a structurally controlled low-sulphidation epithermal domain hosted mainly by Jurassic volcanic rocks of the Bajo Pobre Formation. Drilling, geological logging and structural measurements from core indicate a hierarchy of principal vein corridors, subsidiary vein structures and faults. These structures are interpreted to form part of an integrated hydrothermal system rather than isolated mineralized occurrences.

Initial scout drilling at El Pantano West returned multiple gold-bearing intervals associated with interpreted vein corridors. Examples include DH_ELP003, which returned 18.0 m at 0.46 g/t Au, including 4.9 m at 0.79 g/t Au; DH_ELP018, which returned several gold-bearing intervals including 27.12 m at 0.20 g/t Au and narrower higher-grade sub-intervals; and DH_ELP023, which intersected multiple broad anomalous gold-bearing intervals, including 27.0 m at 0.14 g/t Au, 23.6 m at 0.13 g/t Au and 20.7 m at 0.12 g/t Au.

These early results are interpreted as evidence of a structurally controlled gold-bearing hydrothermal system developed across multiple vein corridors.

The current drilling appears to have tested only selected portions of the interpreted structural system. Of particular interest is the central-western part of the El Pantano West section, where several interpreted principal structures appear to converge and where multiple gold-bearing intervals have been encountered. This structural convergence may represent a more focused fluid pathway or potential feeder zone that warrants additional drill testing at depth and along strike.

The exploration potential at El Pantano West is not interpreted to be limited to depth alone. Near-surface copper anomalism and multiple gold-bearing intercepts suggest that the hydrothermal footprint may extend laterally beyond the current drilling. This supports the potential for additional prospective structures along the broader corridor, subject to further exploration and drill confirmation.

Figure 5. El Pantano West Interpreted geological section showing drill traces, principal and secondary vein corridors, interpreted faults, host volcanic units and selected gold intercepts. The section illustrates the structural control on gold-bearing intervals and the presence of multiple interpreted vein corridors within the western low-sulphidation epithermal domain.

Figure 6. El Pantano West . Detailed drill section for DH_ELP023 showing multiple broad anomalous gold-bearing intervals spatially associated with interpreted principal and secondary vein structures. The section supports the interpretation of a broader structurally controlled hydrothermal corridor rather than isolated mineralized intervals.

El Pantano East: Silica Cap and Advanced Argillic Alteration Target

In the eastern part of the project, El Pantano East displays a different but complementary expression of the same broader hydrothermal system. Geological, geochemical and geophysical data indicate the presence of silica cap development, argillic to advanced argillic alteration, strong pathfinder geochemistry and conductive geophysical responses. The eastern domain is interpreted to represent a higher-level or more preserved part of the hydrothermal system, where volatile-rich pathfinder elements such as arsenic are more strongly expressed at or near surface.

Drilling sections from El Pantano East show broad arsenic-rich pathfinder intervals beneath the interpreted silica cap and argillic alteration zone, including DH_ELP015 with 125.5 m at 232 ppm As and DH_ELP014 with 60.85 m at 174 ppm As. These arsenic intervals are interpreted as pathfinder geochemical responses. However, in the context of epithermal systems, the presence of broad arsenic anomalism, silica cap development, argillic alteration and interpreted feeder structures supports the concept of a preserved high-level hydrothermal environment that warrants follow-up testing for deeper or laterally offset precious metal targets.

Figure 7. El Pantano East Interpreted conceptual geological section showing silica cap development, argillic alteration, interpreted feeder structures, secondary veins and selected arsenic-rich pathfinder intervals. The section illustrates the higher-level hydrothermal character of the eastern domain and provides vectors for follow-up testing of deeper or laterally offset precious metal targets.

Table 1. Drill results

Summary

The west-to-east zonation at El Pantano is a key outcome of the Technical Report and provides an important framework for future exploration. The western target areas show a stronger association of gold, copper and base metal responses, interpreted as representing relatively deeper or more eroded levels of the hydrothermal system. In contrast, the eastern target areas are characterized by silica cap development, argillic to advanced argillic alteration and stronger volatile pathfinder element expression, interpreted as potentially higher-level or more preserved portions of the system.

The western and eastern domains are interpreted to form part of a vertically and laterally zoned epithermal system controlled by a regional NW-SE structural corridor. This integrated model provides multiple exploration vectors, including structurally controlled gold-bearing vein corridors in the west, possible feeder structures at depth, newly identified regional soil anomalies south of the principal structure, and preserved pathfinder-rich alteration zones in the east.

The Company views these results as supportive of its thesis that the Project hosts a significant epithermal mineral system, and thus worthy of further exploration.

Suggested work programs are outlined in the Technical Report.  The Company will consider these suggestions and will develop exploration plans over the winter recess.

Orosur CEO Brad George commented:

"Starting exploration from scratch is never easy, but the work carried out by our team support our initial view of the extraordinary prospectivity of El Pantano.  We now own the project 100%, and so have many options available to us".

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.

Drill Hole Details, El Pantano Project 2025 onward

*  Coordinates WGS84, UTM Zone 18

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.

Drill core is split in half over widths that vary between 0.3m and 2m, depending upon the geological domain. One half is kept on site in the Minera Anzá core storage facility in the case of the Anza Project, or on site in temporary racks in the case of the El Pantano Project, with the other sent for assay.

Industry standard QAQC protocols are put in place with approximately 10% of total submitted samples being blanks, repeats or Certified Reference Materials (CRMs).

Samples from the EL Pantano project are sent to the preparation facility and fire assay laboratory of Alex Stewart Laboratories in Perito Moreno to be assayed for gold.  Pulps are then sent to the larger Alex Stewart facility in Mendoza for multi-element analysis.

30 gram nominal weight samples are then subject to fire assay and AAS analysis for gold with gravimetric re-finish for overlimit assays of >5 g/t.  ICP-MS Ultra-Trace level multi-element four-acid digest analyses may also undertaken for such elements as silver, copper, lead and zinc, etc.

Gold intersections are reported using a lower cut-off of 0.3g/t Au over 3m.

Intersections are quoted as downhole thicknesses.  True thicknesses are unknown.

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.