Drilling and sampling expands Pepas

• Channel sampling at North Pepas expands high grade anomalous zone, best surface sample of 27.23 g/t Au.
• Access to North Pepas complete - drilling to commence soon.
• Soil sampling at El Cedro underway

London, April 23rd, 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 Anzá Project ("The Project") in Colombia.

Colombia - ANZÁ Project

Figure 1. Mid-Cauca Belt

Prospects

Post the MMA acquisition in late November 2024, the Company more than doubled its land holding in the mid-Cauca belt to 400km2, by virtue of gaining ownership of a large number of licence applications held by MMA. This makes the Company one of the major land holders in one of the world's most exciting gold belts.

These applications have yet to be properly assessed by the Company as most financial and management resources have thus far been directed to drilling at Pepas.

Figure 2. Main prospects, licences pre-MMA acquisition

Pepas Prospect

After completion of the transaction to buy MMA, the Company restarted drilling at the Pepas prospect in late-November 2024.

Most drilling conducted to date by the Company has focussed on a central, high-grade core around the first discovery holes. This has been an intentional strategy based on several rationale:

• To understand the mineralisation and its litho-structural controls.
• To allow time for surface mapping and sampling to expand the anomalous zone and provide targets.
• To allow time for permits and physical access to be developed to other parts of the prospect.
• To examine the potential of moving a small part of Pepas to resource status which could be beneficial in the context of the Colombian permitting system and a pre-existing environmental exploitation permit over part of these licences.

Figure 3. Plan of holes

PEP028 was drilled at the northern extend of the central core, as a scissor hole to PEP015, (Figure 4) to define the position of the Tesorito South fault and thickness of transported cover in this location. This was necessary to assist in moving toward a resource if future results warrant. This hole confirmed previous drilling and recorded a thick sequence of medium grade mineralisation.

Figure 4. Section, PEP028 and PEP015

Holes PEP029 and PEP030 were drilled from the same pad, some distance from the central core and likely NW of the primary geological trend, testing a different geological horizon and several mildly anomalous outcrops. Both intersected thick sequences of lower grade mineralisation. Both of these holes and other work, suggest the potential for a large, reasonably consistent low-grade halo of roughly 0.3g/t Au around a higher-grade core.

Hole PEP031B was the redrill of PEP031 which became stuck in broken ground. This hole was drilled in the SE of the prospect, slightly off trend to test the downdip extension of a large moderate-grade silicified outcrop that was interpreted to be a later phase of mineralisation from the two phases that are thought to create the very high-grade mineralisation of earlier holes.

Hole PEP032 was drilled in the southern section of the prospect, at different angle to previous drilling. The hole was planned as infill for resource modelling purposes and returned a very thick intersection of moderate grade mineralisation from surface.

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

Table 1. Latest drill Intercepts, Pepas

North Pepas

Surface ridge and spur soil sampling undertaken previously by MMA, had identified a large, highly anomalous region to the north of the current Pepas mineralisation. The Company has been following up this work with more targeted and diagnostic channel sampling along tracks or other exposures, looking to sample and assay in-situ saprolite or fresh rock (where present). Such exposures are rare in the Pepas area due to soil cover and can be difficult to locate through thick vegetation.

Results from one large channel sample undertaken by the Company, some 200m north of the current extent of drilling were announced on 4th February 2025, returning 105m @ 1.15 g/t Au, with some individual samples exceeding 5 g/t Au.

Figure 5, Pepas soil and Channel samples

Ongoing mapping by field crews has identified another smaller exposure some 20m to the east, down slope in thick scrub. Channel sampling of this exposure has returned an average sample interval of 49m @ 2.59 g/t Au, including a 10m section of 6.93 g/t Au, with a number of samples exceeding 10g/t Au, and the highest 1m sample being 27.23 g/t Au (Figure 6).

Figure 6. North Pepas Channel Sampling

Crews continue to search for more such exposures, with current focus to the west and north.

North Pepas lies across a property boundary from the current drilling at Pepas, requiring both negotiation of land access with the property owner and then development of physical access to the area for drilling machinery. These have now been completed, and it is thus expected that drilling can commence at North Pepas in the next few weeks.

A drone based airborne magnetic survey was recently completed over the Pepas prospect. Preliminary data have been received but final data should be available this week. These data should be of assistance in understanding controls upon mineralisation at Pepas, and thus future drill targeting across the prospect. It is likely however that the first hole at North Pepas will be targeted to test depth extensions of the channel samples set out above.

El Cedro

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. Sampling was limited to creeks and drainages, and several small areas in the centre of the zone. However, wide areas of gold anomalism were identified in soils and channel samples, with assays above 5g/t Au identified across a large area, with associated copper and molybdenum anomalism (Figure 7).

Older airborne magnetic data suggests the presence of a large intrusive complex demonstrating a "ring" structure, often seen in such environments.

Several weeks ago, the Company commenced a large-scale ridge and spur soil sampling program covering most of what is thought to be the extent of the porphyry system, with a view to confirming and extending the previous work and if positive, to move toward drill targets in the medium term.

The sampling program is currently approximately 25% complete, with work expected to continue into May. In addition, teams have identified several abandoned artisanal tunnels across the prospect. Where safe to do so, some tunnels have been mapped and sampled, identifying a number of intrusive related epithermal vein systems.

Due to the requirement for more complex assay techniques not available in Colombia, samples are being first assayed for gold via fire assay in Medellin, before being sent to Canada for full multi-element analysis.

Results are thus expected to start becoming available within weeks.

Figure 7. El Cedro Sampling - historical and planned - over airborne magnetics

Holes Drilled post MMA transaction

21 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:

"The Anzá Project is progressing well, with Pepas continuing to be defined and new fronts being opened northward of Pepas, and to the south at El Cedro."