Orosur Mining Inc - Pepas Advancing · Assays from five more holes at Pepas and Pepas North. Best results include:

Orosur Mining Inc - Pepas Advancing

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

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

o PEP034 - 59m @ 10.15 g/t Au

o 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, May 28 th 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 ("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 modell ing. 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 f or 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 compl eted 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:

Hole Number From (m) To (m) Interval

(m) Au (g/t)

Pepas

PEP033 0 21.3 21.3 5.88

including 0 7.25 7.25 12.74

including 15.6 17.5 1.9 11.19

PEP034 0 8 8 0.87

36 95 59 10.15

including 47.1 71.15 24.05 14.47

including 82.1 89.8 7.7 14.21

PEP035 0 11.4 11.4 2.71

including 5.2 10.1 4.9 4.37

Pepas North

PEP036B 0 40.45 40.45 0.62

including 8.4 22.2 13.8 1.24

including 8.4 12.4 4 2.36

PEP037 0 3 3 0.65

97.4 111.7 14.3 0.32

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 8 8% 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 int rusions 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.

Hole Number From (m) To (m) Interval (m) Au (g/t)

PEP012 0 66.75 66.75 5.64

PEP013 0 77.30 77.30 7.68

PEP014 0 75.1 75.1 5.58

PEP015 23.5 63.7 40.2 3.75

PEP016 61.6 105.3 43.7 3.13

PEP017 56.1 96.3 40.2 2.06

PEP018 0 54.1 54.1 6.01

PEP019 0 44.3 44.3 1.63

PEP020 0 54.65 54.65 1.94

PEP021 0 107.05 107.05 6.22

PEP022 0 76.3 76.3 7.24

PEP023 0 15 15 1.7

PEP024 9.24 15.6 6.35 1.99

PEP025 0 10.1 10.1 1.45

16.5 79 62.5 5.4