Meridian Discovers 2nd VMS Layer at Santa Helena

Meridian Expands Upside Potential at Santa Helena With the Discovery of a Second Layer of Gold-Silver and Zinc-Lead VMS Mineralisation

Highlights:

§ Santa Helena expansion programme discovers a second Au-Ag & Zn-Pb system of VMS mineralisation;

§ New VMS layer of Au-Ag & Zn-Pb mineralisation intercepted below and east of Santa Helena Central resource

• CD-869 returns 7.2m @ 1.4g/t Au, 0.1% Cu, 24.3g/t Ag, 2.3% Zn, 0.9% Pb;
• First appearance of visible gold hosted within the Santa Helena area mineralisation;
• CD-869 interpreted as the down-dip extension of Santa Helena North IP anomaly;
• Mineralisation remains open;

§ Exploration drill programmes for further multiple stacked horizons hosted within the Santa Helena VMS system continue;

• Programme to test for both open pit and underground extensions to CD-869.

LONDON, United Kingdom, June 17, 2026 / Newsfile / Meridian Mining plc (LSE: MNO) (TSX: MNO) (FSE: N2E0) (Tradegate: N2E0) (OTCQX: MRRDF) ("Meridian" or the "Company") is pleased to report that its ongoing drill programme targeting the Santa Helena VMS system has intercepted a new VMS layer of strong precious and base metal mineralisation. CD-869 returned a 7m-wide zone of gold-silver and zinc-lead dominated mineralisation including an interval containing visible gold. This new layer of Au-Ag & Zn-Pb mineralisation is located below and east of the Santa Helena Central resource. The zone is interpreted to represent the down-dip projection of the Santa Helena North chargeability anomaly.

CD-869 returned 7.2m @ 1.4g/t Au, 0.1% Cu, 24.3g/t Ag, 2.3% Zn, 0.9% Pb from 177.6m, highlighting the prospectivity of the down-dip and down-plunge extensions of Santa Helena North's surface geophysical and geochemical anomalies. The Au-Ag and Zn-Pb mineralisation remains open and follow-up drilling continues.

Mr. Gilbert Clark, CEO, comments: "CD-869's discovery of a second layer of strong precious and base metal mineralisation at Santa Helena presents an exciting opportunity for Meridian's shareholders. The potential of further resource growth is enhanced as is the future installation of a second hub[1] along the Cabaçal Belt. CD-869 and the recently reported CD-852 at Álamo[2] both intercepted gold-rich mineralisation. CD-869's visible gold is an attribute rarely seen at Santa Helena, and this may signal an additional structural gold overprint or gold-enriched VMS mineralisation like that seen at Cabaçal[3]. Following the London IPO, our well-funded exploration programmes are delivering, with a high frequency of exceptionally encouraging results. This reflects the high prospectivity of what we see as South America's most prospective VMS belt."

Santa Helena Near-Mine Exploration

Ongoing exploratory drilling in the Santa Helena area continues to enhance the potential for defining stacked VMS horizons within the Cabaçal Project. Drill hole CD-869 has returned an interval of more than 7m of gold-silver and base metal mineralisation, north of and below the Santa Helena Central resource area ("Figure 1").

Figure 1: Location of CD-869, collared in eastern margin of Santa Helena Central resource area and drilled to the north of and below the resource envelope.

CD-869 was collared on the eastern margin of the Santa Helena Central resource area, and drilled northwards to test the down-dip projection of the Santa Helena North ("SHN") chargeability response (Figure 1). This SHN anomaly extends for approximately 1km and remains open to the west. Initial confirmation of mineralisation within this anomaly came from CD-607, which intersected VMS pathfinders and trace mineralisation[4]. In the current campaign, CD-859, drilled 390m WNW of CD-607, returned gold and base metal VMS horizons, including one sample grading 5.0g/t Au, 3.2g/t Ag, 1.0% Zn, 0.3% Pb over 0.8m from a depth of 63.2m. SHN's chargeability and surface geochemical anomalies are interpreted as the uppermost surficial expression of a VMS exhalative horizon. The horizon is considered prospective for thickened down-dip or down-plunge extensions. Broad spaced drilling commenced this year to improve geological understanding and assess the potential for resource extensions. Additional potential also exists for structurally controlled gold with overprinting mineralisation associated with later deformational events in the Cabaçal Belt.

The shallow-dipping stratigraphy provides access to a broad extent of prospective greenstone contact at explorable depths, and CD-869 was drilled approximately 270m to the south of the southern edge of the SHN chargeability anomaly.

CD-869 intersected an interval with a higher abundance of banded sulphides, returning:

• 7.2m @ 1.4g/t Au, 0.1% Cu, 24.3g/t Ag, 2.3% Zn, 0.9% Pb from 177.6m,

o Including 6.2m @ 1.6g/t Au, 0.1% Cu, 26.6g/t Ag, 2.6% Zn, 1.0% Pb from 178.1m.

The CD-869 position lies more than 330m down-dip from the shallower CD-859 gold intersection, underscoring the broad extent of prospective contact available for testing, and the potential for mineral zones to thicken. CD-869 was also collared approximately 390m west-north-west of the recently reported CD-852 Álamo gold intersection. In this early phase of the Santa Helena near-mine exploration programme, the results continue to indicate the potential of the surrounding areas to yield new positions prospective for resource extensions. CD-869 shows consistently elevated gold and silver grades ("Table 1"; "Table 2").

Table 1: CD-869 sulphide zone, visible gold observed in sample CBDS129223. Intervals and assays are rounded to one decimal place. Total composite for copper of 0.063% is rounded up to 0.1% for reporting.

Peak grades in the CD-869 intersection included 4.8% Zn (CBDS129216), 3.8 g/t Au (CBDS129224), 41.5 g/t Ag (CBDS129218), 1.6% Pb (CBDS129216). Peak Cu was 0.2% (CBDS129216). The metal distribution suggests that this sulphide zone may represent a more distal cooler domain of a broader VMS system, with ongoing drilling along strike designed to test for variations in Cu:Zn ratios. The mineralised zone is positioned within and immediately above a zone of sodium depletion, indicative of hydrothermal leaching. The footwall also shows increased magnesium, consistent with chloritic alteration.

Additional drilling is in progress. CD-857 tested approximately 80m down-dip from CD-869, and CD-867 was drilled ~117m obliquely up-dip. Both holes returned multiple intersections of lower grade mineralisation. The stratigraphic succession is locally disrupted by mafic intrusions, and the extent to which these intrusions offset or displace the dip projection of CD-869 is currently under review. Given the mound-like morphology of VMS systems and linear character of the known deposits in the belt, there remains ample space to project the emerging CD-869 and CD-852 mineralised zones.

Santa Helena Drill Results

The last of the drill results from the Santa Helena Central drill programme, gathering additional data in proximity to historical grade control and mine development, have been received ("Figure 2"; "Table 3"). Highlights include:

• CD-866: 15.4m @ 0.7g/t Au, 0.6% Cu, 29.1g/t Ag & 5.1% Zn from 31.3m;

o Including 8.6m @ 0.8g/t Au, 1.0% Cu, 42.7g/t Ag & 8.6% Zn from 38.1m;

• CD-861: 12.0m @ 0.8g/t Au, 0.6% Cu, 36.7g/t Ag & 4.9% Zn from 29.7m;

o Including 3.4m @ 1.0g/t Au, 1.3% Cu, 68.7g/t Ag & 7.7% Zn from 30.1m;

• CD-862: 11.1m @ 0.2g/t Au, 0.2% Cu, 15.2g/t Ag & 2.1% Zn from 48.0m; and

o 13.6m @ 0.3g/t Au, 0.2% Cu, 16.2g/t Ag & 2.3% Zn from 61.9m.

Large extents of the Santa Helena and neighbouring Álamo system remain untested. With the recognition of the CD-852 gold zone, the CD-869 gold-base metal zone, and the currently unconstrained strike projection of the resource area, the Company will await further drilling and metallurgical results before initiating the next resource assessment to properly optimise the development strategy.

Figure 2: Santa Helena Central resource drilling.

Espigão Exploration Programme

The Company has also commenced field evaluation of Espigão Cu-Au targets to plan logistics and access for a first phase of reconnaissance drilling to be executed in the coming months. The Company has obtained permission from the state environmental agency, SEDAM, to carry out the drilling programme in the Espigão project.

On behalf of the Board of Directors of Meridian Mining plc

Gilbert Clark - CEO and Director

Meridian Mining plc

8th Floor, 4 More London Riverside

London SE1 2AU

United Kingdom

Ph: +44 (0) 203 930 3145 (GMT)

Table 2: Assay Results - Álamo

[1] Meridian Mining News Release of November 3, 2025.

[2] Meridian Mining News Release of May 14, 2025.

[3] Cabaçal Gold-Copper Project NI 43-101 Technical Report and Pre-feasibility Study, March 10, 2025

[4] Meridian Mining News Release of July 9, 2025.