Mr. Louis Castro reports

OROSUR MINING INC ANNOUNCES OPERATIONAL UPDATE

Orosur Mining Inc. has provided an update on the progress of exploration activities across its project portfolio.

• Minera Monte Aquila reviewing its position in relation to Anza;
• Mapping and sampling at El Pantano enhance prospectivity;
• Regional sampling results from Ariquemes provide vectors for next phase.

Anza -- Colombia

The Anza project is an advanced-stage exploration project in the mid-Cauca belt of northern Colombia that plays host to most of that country's major gold deposits.

Anza comprises a number of contiguous granted exploration titles and applications totalling roughly 200 square kilometres.

Since late 2018, Anza has been the subject of an exploration agreement with venture option with Colombian company Minera Monte Aguila (MMA). MMA is itself a 50/50 joint venture (JV) between Newmont Corp. and Agnico Eagle Mines Ltd., and is the Colombian vehicle by which these two companies jointly exercise their rights and obligations with respect to the exploration agreement over the project.

The first phase of the exploration agreement was completed in September, 2022, with MMA spending in excess of $10-million (U.S.) on the project and in so doing earning an equity interest of 51 per cent. MMA subsequently informed the company of its intention to progress to phase 2. This included the payment to the company of a $2-million (U.S.) option fee (received in February, 2023) and formation of a new mining company required to crystallize the various ownership stakes.

As at Dec. 31, 2022, MMA had already incurred about $3.65-million (U.S.) in excess qualifying expenditures for phase 1. This excess may be carried forward and credited toward MMA's investment obligation of $4-million (U.S.) for the first year of phase 2.

MMA has advised the company that it has reduced exploration expenditures on the project and effectively placed it in care and maintenance. The company expects that MMA will continue to focus on protecting the asset and maintaining positive relationships with local community groups while it explores options regarding its involvement in the project.

The company will keep shareholders informed as MMA reaches a decision regarding its involvement in the project. The company has great faith in the prospectivity of the Anza project and stands ready and able to reassume operatorship of Anza if that is deemed a viable option.

El Pantano -- Argentina

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

The El Pantano project covers nine contiguous licences totalling over 600 square km in the prolific Deseado massif region, roughly 45 km from Anglo Gold's Cerro Vanguardia mining camp.

The El Pantano project is subject to an exploration and joint venture agreement with private Argentine company Deseado Dorado SAS and its shareholders, the details of which were announced on Feb. 15, 2022.

As announced on March 2, 2023, low-level reconnaissance fieldwork has been continuing at El Pantano for the current field season since late 2022 and will continue until roughly mid-May, 2023, before ceasing for the winter recess.

These work programs are focused on geological mapping, soil and rock chip sampling, and ground magnetic surveys. As a largely untouched, grassroots project, these programs were designed to collect the necessary underlying base data to confirm the prospectivity of the project, develop the exploration model and begin the process of defining targets for the next phase of work after the winter recess.

Thus far, the results of these programs have exceeded the company's expectations and El Pantano has the potential to develop into a large-scale gold exploration project.

As noted in March, 2023, company geologists and a specialist structural geology consultant were invited to visit Newmont's Cerro Negro gold project, as it was felt by various visitors that El Pantano bore many similarities to Cerro Negro, both in geology and geographic scale. This visit provided substantial guidance to the company's exploration team to allow more efficient targeting over El Pantano's large area.

Most of the gold/silver deposits of the Deseado massif region are of the low-sulphidation epithermal style. In particular, there is a close correlation to major crustal-scale fractures related to the breakup of the Pangea supercontinent and opening of the Atlantic Ocean in the mid- to upper Jurassic. This is often manifested locally as major southeast-northwest rift systems with pervasive silicification and veining, over tens of kilometres, precisely the features that are present at El Pantano and which attracted the company to the project.

From an exploration perspective, a key feature is the mechanism by which gold is precipitated from solution to form low-sulphidation gold deposits, which is by boiling. Hot, gold-bearing fluid rising from depth boils as the binding pressure of the surrounding host rocks falls below a certain point, occasionally producing large, and very high-grade gold deposits, as seen at Cerro Negro, that are constrained to a particular vertical level of the epithermal system (the boiling zone).

The quartz vein systems will then invariably continue upward to the surface, but have often been stripped of gold, thus producing minimal surface gold geochemical anomalism.

Following the Cerro Negro visit, Orosur's geologists recognized that much of the modern-day surface across El Pantano sits at a high level in the epithermal system, above any boiling zone, and therefore gold anomalism in soil geochemistry is likely not an effective indicator of mineralizing potential. Instead, greater attention should be paid to the higher-level pathfinder elements, in particular mercury (Hg) and Arsenic (As), as well as textural variations in quartz veins and surrounding silicification that provide guidance as to the level within the system.

Exploration programs were modified on this basis with positive results achieved.

Ground magnetic surveys have been continuing for several months using in-house crews and equipment. Magnetic surveys have proven a fast and effective method for defining the primary structural corridors in the prospect area and this work will continue for several more weeks. Some preliminary interpretations have been undertaken, in advance of more detailed work once the survey is complete, and demonstrate that the project is dominated by a very large, northwest-southwest rift system, exactly as predicted by the local mineral system model.

Mapping and ground magnetic surveys have identified a major northwest-southeast structural corridor over 20 km long and five km wide, with large areas of silicification, alteration and geochemical anomalism over large areas. Gold anomalism in soils is evident in the northwestern end of the main structure, suggesting this area is somewhat lower in the epithermal system, while the southeastern end shows significant Hg and As anomalism, suggesting a higher level.

A large section of the central part of the main structure covering more than 10 km is not suited to soil geochemistry due to being covered by river sediments and recently transported Cretaceous cover. Magnetic data, however, show the main structure continues uninterrupted under this thin cover.

Mapping to the north of the main structure has so far identified over 70 quartz veins over an area in excess of 20 square km, with textures indicative of cooler temperatures, fully consistent with the model of a very large low-sulphidation epithermal system. Mapping of this vein field continues with more being identified on a daily basis.

Future work

As noted, mapping, sampling and magnetic surveying will continue until roughly mid-May, 2023, before the winter closure, with final assay results and magnetic survey data then due in June.

Upon receipt of all data, a detailed process of compilation and interpretation will be undertaken to better understand the mineral system and to plan work programs for after the winter recess in September, 2023.

The required environmental permit process for drilling will also commence in May, 2023, such that drilling will then be able to be undertaken later in 2023 should appropriate targets be identified.

Ariquemes -- Brazil

The Ariquemes project is a large-scale tin (and associated metals) exploration project in Rondonia state, Brazil, entirely within the world-class Ariquemes tin field. The project comprises a large number of granted licences and applications that in total cover more than 3,000 square km, representing the largest landholding in this key mining district.

Ariquemes is a JV with Canadian-listed Meridian Mining U.K., whereby Orosur has the right to earn a 75-per-cent stake in the project by investing $4-million (U.S.) in exploration over a four-year period in two stages.

While the Ariquemes district is a major tin-producing region, most production is sourced from local co-operatives or artisanal producers and as such little or no modern exploration has ever been undertaken across the wider district.

The company was therefore required to start exploration work at the regional scale, collecting wide-spaced stream sediment samples across the entire 3,000 square km area as the first pass to identify key areas for follow-up.

To avoid issues with access to farming land, samples were taken using the 10 km by five km road network across much of the area. During the campaign, over 400 samples were taken, and then assayed for a wide variety of elements, including tin, niobium, titanium and a suite of rare earths.

Results from the reconnaissance program demonstrate widespread tin, niobium and rare earth anomalies across the wider area, with most tin interest focused on the southern portion and a lease package to the far east of the area.

In general, tin and niobium are often found and exploited together given they derive from the same source rocks, however the above data demonstrate a transition from tin dominance in the southern areas to niobium dominance in the north -- a fact that was anecdotally known by local miners. The two metals are roughly similar in pricing structure and as such the company will examine commercial opportunities in both.

Rare earths on the other hand are not always correlated and there are several areas of interest in the centre of the exploration that will be examined further.

Future plans

Stream sediment sampling is largely a qualitive method due to the inherent uncertainty in how minerals are concentrated in drainage systems. However, it is an efficient method to cover large areas quickly.

Areas of substantial metal anomalism that have been subsequently identified will now be followed up by more direct, quantitative exploration methods in the coming months. These will include detailed mapping, soil and rock chip sampling, and auger drilling of metal-bearing drainages.

For efficiency, this work will be done by the company's exploration teams during the winter recess in Argentina.

Orosur chief executive officer Brad George commented:

"We respect MMA's decision to reassess Anza and fully understand the complex dynamics and priorities of companies of that size, especially in light of recent mergers. Orosur however sees a tremendous potential at Anza and would welcome the opportunity to get back into the driver's seat if that option is viable. In the meantime, our other projects are growing in stature and positioning us well as a diversified explorer."

About Orosur Mining Inc.

Orosur Mining is a minerals explorer and developer focused on identifying and advancing projects in South America. The company operates in Colombia, Argentina and Brazil. It has discontinued operations in Uruguay.

Qualified persons statement

The information in this news release was compiled, reviewed and verified by Brad George, BSc honours (geology and geophysics), MBA, member of the Australian Institute of Geoscientists (MAIG), chief executive officer of Orosur Mining, and a qualified person as defined by National Instrument 43-101.

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

Anza

Drill core is split in half over widths that vary between 0.3 metre and two m, depending upon the geological domain. One-half is kept on site in the Minera Anza core storage facility, with the other sent for assay.

Industry standard quality assurance/quality control protocols are put in place with approximately 20 per cent of total submitted samples being blanks, repeats or certified reference materials (CRMs).

Samples are sent to the Medellin preparation facility of ALS Colombia Ltd., and then to the International Organization for Standardization 9001-certified ALS Chemex laboratory in Lima, Peru.

Thirty-gram nominal weight samples are then subject to fire assay and atomic absorption spectrometry analysis for gold with gravimetric refinish for overlimit assays of over 10 grams per tonne. Inductively coupled plasma -- mass spectrometry ultratrace-level multielement four-acid digest analyses are also undertaken for such elements as silver, copper, lead and zinc.

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

El Pantano

Initial soil sample lines at El Pantano varied from 500 m to one km spacing with infill lines located at 120 m spacing in areas of anomalism. Samples were taken at 20 m intervals along these lines.

Samples were taken at depths of 30 centimetres to 60 cm below the surface, corresponding to the local equivalent of the B horizon. This layer of silt-clay is thought to contain the highest accumulation of metals commonly used in mineral prospecting.

Shallow material such as ashes and rock fragments was removed from the area before collecting samples. Manual tools were used to reach the silt-clay level, with sample weights varying from 1.5 to 2.0 kilograms. Samples were then sent to an ALS Chemex preparation facility in Santa Cruz province for preparation and thence to the ISO-9001 certified ALS Chemex laboratory in Lima, Peru, for assay by inductively coupled plasma -- atomic emission spectroscopy (ICP-AES) and inductively coupled plasma -- mass spectrometry (ICP-MS).

Ariquemes

Stream sediment samples were taken at specific locations where drainages intersected local roads, on roughly a 10 km by five km spacing. Samples of approximately 20 litres were gathered at a depth of around 70 cm to one m. To avoid anthropogenic contamination, the sampling points were located at a distance from the roads. The collection process was carried out using a post-hole digger, and samples were then packaged in plastic bags, sealed and labelled accordingly. Collected samples underwent a concentration process by panning to produce a concentrate of heavy minerals.

Samples were then sent to the SGS laboratory in Belo Horizonte, Minas Gerais state, for assay by inductively coupled plasma -- optical emission spectroscopy (ICP-OES) and inductively coupled plasma -- mass spectrometry (ICP-MS).

We seek Safe Harbor.