Orosur Mining - Pepas Advancing

• Assays from five more holes at Pepas and Pepas North. Best results include:

  • PEP033 - 21.3m @ 5.88 g/t Au from surface

  • PEP034 - 59m @ 10.15 g/t Au

  • PEP035 - 11.4m @ 2.71 g/t Au from surface

  • First two holes at Pepas North intersect halo.

  • Preliminary technical studies commencing at Pepas.

  • Highly anomalous soil geochemistry at El Cedro

LONDON, UK / ACCESS Newswire / May 28, 2025 / Orosur Mining Inc. ("Orosur" or the "Company") (TSXV:OMI) (AIM:OMI), is pleased to announce an update on the progress of exploration activities at the Company's flagship Anzá Project ("Project") in Colombia.

Colombia - ANZÁ Project

The Anzá Project is now 100% owned by the Company following completion of a Share Purchase Agreement ("SPA"), announced 28^th November 2024, whereby the Company purchased all of the shares of its previous JV partner; Minera Monte Aguila ("MMA").

The Project, which is located 50km west of Medellin, is easily accessible and boasts excellent infrastructure including water, power and communications as well as a large exploration camp.

The Project sits within the prolific mid-Cauca belt, Colombia's primary gold belt, and is located along strike between several world class gold/copper deposits including Buritica, Quebradona and Guayabales/Marmato (Figure 1).

From September 2018 to November 2024, the Anzá Project was under the control of its previous JV partner MMA, itself a 50/50 venture between the world's two largest gold miners, Agnico Eagle Mines and Newmont Mining.

Figure 1. Mid-Cauca Belt

Prospects

The Company is currently focussed on three prospects within the Anzá Project - Pepas, APTA and El Cedro. All three prospects are within the same granted exploration title that is broken into two, non-contiguous pieces (Figure 2).

Drilling is currently being undertaken at the Pepas prospect in the northern extent of the Anzá Project (pre-acquisition) over 10km north of the central base camp at APTA. In parallel, mapping and sampling is being undertaken over the El Cedro porphyry system in the south of the project area.

Figure 2. Main prospects, licences pre-MMA acquisition

Pepas and North Pepas Prospects

Pepas was discovered by MMA in late 2021 by BLEG sampling and geological mapping, followed by 11 diamond drill holes in 2022 (PEP001 to PEP011). After completion of the transaction to buy MMA, the Company restarted drilling at Pepas in late-November 2024. Drilling commenced with hole PEP012, which was positioned to confirm previous high-grade results in holes PEP001, PEP005 and PEP007 drilled in 2022.

North Pepas is an area several hundred metres north of Pepas where anomalous rock chip and soil geochemistry has indicated a zone of interest.

Figure 3. Plan of holes

Drilling at Pepas, post transaction, has largely concentrated on a small central core, where a body of high-grade gold mineralisation is being defined from surface.

Hole PEP033 was drilled at the southern extent of Pepas, to gradually extend mineralisation in this direction. A thick intersection of high-grade mineralisation (21.3m @ 5.88 g/t Au) was identified from surface, suggesting potential for extension of Pepas toward the south that will require follow-up.

Hole PEP034 was drilled internal to the existing Pepas mineralised body, but orthogonal to previous drilling, and sub parallel to the Tesorito South fault, to test continuity of mineralisation from section to section and to assist in future resource modelling. A thick intersection of extremely high-grade mineralisation (59m @ 10.15g/t Au) was identified, adding substantially to the geological understanding of the Pepas body.

Hole PEP035 was drilled in the centre of Pepas, but toward the west, outside the previous mineralised envelope, to test the depth extension of previous surface mapping. The positive response from this hole (11.4m @ 2.71g/t Au) has opened up the potential for additional extensions in this direction.

Pepas North was identified as an area of potential several hundred metres to the north of Pepas, by virtue of a number of highly anomalous rock chip and channel samples.

However, these samples, while highly anomalous, contained little geological or orientation contextual information, and thus initial drilling here was unguided.

Two holes PEP036B and PEP037 were drilled as a scissor pair underneath previously defined geochemical anomalies.

Both holes intersected thick sequences of highly altered and silicified tuffs, with moderate gold mineralisation similar in nature to the lower grade halo zones identified around Pepas to the south. This is potentially suggestive that these holes may be marginal to a more mineralised system. Both also intersected numerous structurally complex zones, with some indication of having been drilled sub-parallel to the controlling strike.

A third hole, PEP038 has been collared orthogonal to these first two holes to provide additional structural and lithological information. Once complete, the rig will move back to Pepas, to allow time for full multi-element geochemical analysis to be completed on these three holes that, in conjunction with airborne magnetics and surface sampling, may be of assistance in vectoring and targeting of later exploration and drilling activities.

Drill intersections for these most recent five holes are as follows:

Table 1. Latest drill Intercepts, Pepas and Pepas North

Geological Modelling and Economic Studies

Encouraged by the exceptional results at the Pepas prospect, the Company has begun the process of geological modelling and preliminary economic assessment at Pepas.

While exploration continues across several prospects at Anzá, the Company feels that the nature of the gold mineralisation thus far defined at Pepas, could, if proven, underpin a range of development options. The Company does not at this stage plan to move Pepas to a Mineral Resource Estimate ("MRE"), or to commence formal feasibility studies, but will focus on very preliminary technical studies to better understand the optionality of Pepas and to map out work programs to further explore and advance these options.

Several studies have been completed or are underway.

The Company has commissioned external consultants to carry out 3D modelling of the body of mineralisation as it currently stands at Pepas. The purpose of this work is to compare and contrast with the modelling work done by Company geologists, to determine if an MRE can be developed and if so, to formulate a drilling plan to facilitate this.

Some months ago, several samples of Pepas core were sent to a metallurgical laboratory in Canada for preliminary metallurgical testing. These sample were not representative of the entire body of mineralisation, and the testing program was very rudimentary, designed only to test for the existence of potentially deleterious elements and to carry out a basic recovery test that could be used to guide later testing. Results from this work were positive, with no deleterious element issues being identified and 88% Au recovery being achieved by simple cyanide leaching at a coarse grind of 120 microns. More substantial metallurgical studies would be required in future if the project advances.

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 ago before Orosur's tenure, when Anglo American undertook reconnaissance mapping and sampling, identifying a highly prospective gold/copper porphyry system.

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.

Figure 4. El Cedro Sampling - historical and planned - over airborne magnetics

Several weeks ago, the Company commenced a large soil sampling program, planned to cover most of what was thought to be the extent of the porphyry system.

Large soil samples were to be taken at roughly 25m intervals, along ridges and spurs for ease of access and to ensure soils were residual. Samples were sent to both Medellin and Canada for assay.

The program was expected to require approximately two months to complete, but heavy rains and associated landslides have recently prevented access to the site, with thus far only 28% of the program being completed, largely on the eastern margin of the prospect. Local government crews are working to repair the roads, but it is expected that access for OMI teams may not be re-established for some weeks.

However, early assay results have been returned and show highly anomalous results over large areas along the eastern flank, with substantial areas of over 0.3 g/t Au in soils, and some samples in excess of 1 g/t Au and 0.5% Cu.

Figure 5. El Cedro soil sample assays and progress

Soil samples have been taken at the interface between the B and C soil horizons, as clays in the C horizon act as collectors for mobile metal ions. A wider area needs to be sampled to more accurately define the background levels, however these early results are considered by OMI to be highly encouraging.

Holes Drilled post MMA transaction

26 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

Orosur CEO Brad George commented:

"Pepas is moving nicely, both in terms of expanding the footprint, but also commencing examination of potential development options. In addition, while rains are hampering us at El Cedro, the initial results of high-grade soil anomalies over such a large area are very encouraging."

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

Orosur Mining Inc
Louis Castro, Executive Chairman,
Brad George, CEO
This email address is being protected from spambots. You need JavaScript enabled to view it.
Tel: +1 (778) 373-0100

SP Angel Corporate Finance LLP - Nomad & Joint Broker
Jeff Keating / Jen Clarke / Devik Mehta
Tel: +44 (0) 20 3470 0470

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

Flagstaff Communications and Investor Communications
Tim Thompson
Mark Edwards
Fergus Mellon
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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 - Pepas prospect 2022/2024 Programme*

* 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, Argentina and Nigeria.

About the Anzá Project

Anzá is a gold exploration project, comprising three exploration licences, several small exploitation permits and a large number of licence applications, totalling 399km2, in the prolific Mid-Cauca belt of Colombia.

The Anzá Project is currently wholly owned by Orosur via its subsidiaries, Minera Anzá S.A. and Minera Monte Aquila S.A.S.

The project is located 50km west of Medellin and is easily accessible by all-weather roads and boasts excellent infrastructure including water, power, communications and large exploration camp.

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.

All drill core is HQ.

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, 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 for holes PEP-001 to PEP-011 were sent to the Medellin preparation facility of ALS Colombia Ltd, and then to the ISO 9001 certified ALS Chemex laboratory in Lima, Peru.

Samples from PEP-012 onwards are sent to Medellin laboratory of Actlabs for preparation and assay.

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, 2024. The Company's continuance as a going concern is dependent upon its ability to obtain adequate financing, to reach profitable levels of operations and to reach a satisfactory closure of the Creditor´s Agreement in Uruguay. These material uncertainties 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.

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