21 September 2026

Guardian Metal Resources plc

('Guardian Metal' or the 'Company')

Tempiute Tungsten Project: Positive Drilling Results Drive Accelerated Underground Rehabilitation Decision

Broad Tungsten Intersections Include 92.0m @ 0.34% WO3

Guardian Metal Resources plc (NYSE.A: GMTL, LON: GMET, OTCQB: GMTLF), a strategic exploration and development company focused on tungsten in Nevada, USA, is pleased to provide an update from its Tempiute tungsten project ("Tempiute" or the "Project"). This update covers results from the Company's now completed Phase I regional exploration drilling, in addition to the initial results from the ongoing Phase II drilling campaign, which is focused on the historically producing South Thumb and Schofield Zones.

The Phase I exploration drilling program comprised 41 diamond drillholes across regional target zones and confirmed that multiple tungsten-rich zones exist beyond the historical mine footprint. Notably, many of these targets warrant follow-up drilling and are detailed further below.

The ongoing Phase II resource drilling program is planned to include approximately 46 diamond drillholes, of which 28 have been completed to date. The program is designed to test the continuity, thickness and grade of mineralization around and beyond the historical underground workings, and to generate the data needed to support the potential definition of an initial Mineral Resource estimate at Tempiute.

On the strength of the results for the first four Phase II holes reported herein, together with visual observations from a further 24 drillholes awaiting assay, the Company has decided to commence a rehabilitation program to safely access the underground historical workings. This will allow underground drill rigs to be mobilized, providing improved access to further delineate Phase II target areas and prepare the Project for the stages that follow including, subject to further drilling and evaluation, mine development and operations.

Oliver Friesen, CEO of Guardian Metal, commented: 

“These exciting drilling results represent an important step forward for Tempiute. We are seeing broad and high-grade tungsten mineralization around a mine that historically produced tungsten for many years. In addition, the regional drilling campaign has successfully proved that the mineralized system at Tempiute extends well beyond the historical workings.

“The 92.0 meter intersection at 0.34% WO₃ is particularly encouraging and reinforces our confidence in advancing the South Thumb and Schofield areas toward a planned initial Mineral Resource estimate.

“The results have also prompted a decision to begin rehabilitation of historical underground workings, which will give us more efficient access to the targets we most want to drill as well better positioning the Project for its expected next steps.

“Our objective is clear: demonstrate the scale of the mineralizing system at Tempiute, define an initial Mineral Resource estimate and evaluate the fastest responsible pathway to bringing Tempiute back into the U.S. tungsten supply chain.”

PHASE II DRILLING HIGHLIGHTS: BROAD TUNGSTEN MINERALIZATION SUPPORTS ACCELERATED UNDERGROUND REHABILITATION DECISION

• The planned 46-hole Phase II campaign is well progressed, with 28 holes completed to date (drilling ongoing with two surface drill rigs). Assay results from the first four holes, reported in this announcement, demonstrate strong tungsten grades over favorable widths, with assays pending for a further 24 holes. Notable downhole intersections (see Table 1) include:

• TP26-046: 27.9m @ 0.27% WO3 from 68.6m, including

-          10.5m @ 0.36% WO3 from 70.1m,

-          5.9m @ 0.31% WO3 from 85.9m, and,

92.0m @ 0.34% WO3 from 102.5m, including

-          12.7m @ 0.53% WO3 from 170.5m,

-          5.1m @ 0.49% WO3 from 188.4m.

• TP26-042: 20.2m @ 0.21% WO3 from 210.0m, including

-          6.9m @ 0.35% WO3 from 211.9m.

• TP26-044: 23.9m @ 0.22% WO3 from 175.1m (see Table 1 notes)

• TP26-045: 5.2m @ 0.28% WO3 from 253.4m

• The South Thumb and Schofield Zones are centered on the historical underground production workings last operated by Union Carbide Corporation ("UCC") before the Tempiute Mine closed in the 1980s. These zones are the principal focus of the Phase II drilling campaign, which has been designed to generate sufficient data to support the planned definition of a Mineral Resource estimate.

• In parallel with the ongoing surface drilling, the Company has engaged an underground mining contractor to rehabilitate strategically located historical workings and drill stations, with works expected to start in October 2026.

• Once rehabilitation is complete, underground drill rigs will be mobilized to support improved drilling access to the South Thumb and Schofield zones. The underground adit accesses are approximately 200 meters from these zones of historical production and are generally in fair to good condition.

• In parallel, Guardian is assessing the permitting requirements for mining a near-surface mineralized lode located on patented mining claims, with a view to identifying the shortest path to extracting new tungsten feed material from Tempiute.

PHASE I DRILLING HIGHLIGHTS: RESULTS HIGHLIGHT BROADER TEMPIUTE DISTRICT POTENTIAL

• A total of 20 diamond drillholes from the 41-hole Phase I regional exploration program intersected strong tungsten mineralization representing an encouraging hit rate for a regional exploration drilling campaign.

• The Phase I results demonstrate that tungsten-skarn mineralization is well defined across multiple areas outside the historically mined zones at Tempiute, pointing to a more extensive and robust mineralizing system associated with the two main causative intrusive bodies. Multiple targets require further follow-up.

• Regional exploration drillhole results (see Table 2) include downhole intersections of:*

• TP25-021: 32.4m @ 0.26% WO3 from 293.7m including

-          1.7m @ 2.00% WO3 from 306.9m

• TP25-028: 18.5m @ 0.18% WO3 from 24.5m including

-          4.0m @ 0.32% WO3 from 27.1m and

-          3.4m @ 0.38% WO3 from 39.6m

• TP26-031: 14.0m @ 0.35% WO3 from 59.5m including

-          5.8m @ 0.63% WO3 from 67.7m

• TP25-015: 11.2m @ 0.17% WO3 from 94.5m including

-          2.3m @ 0.64% WO3 from 98.6m

• TP25-014A: 10.2m @ 0.13% WO3 from 132.3m

• TP25-020A: 8.8m @ 0.35% WO3 from 183.6m

*Cut-off for the purposes of the regional exploration results (Phase I) was set at >2m @ 0.10% WO3

Note: True thicknesses of all intercepts reported herein are not yet known.

Figure 1: Project geology along with location of Phase I and Phase II drillholes.

Figure 2: Location of the Phase II drill holes together with the planned drill hole traces within the South Thumb and Schofield target zones.

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Figure 3: Orthogonal three-dimensional model of the planned resource targets at the Schofield and South Thumb zones displaying completed and planned drillholes and the existing underground mine network.

ASSAY RESULTS

Analytical results from the Phase I regional exploration drilling and ongoing Phase II Mineral Resource campaign are summarized below.

Table 1: Phase II - Mineral Resource Drilling Significant Downhole Intersections

Table 2: Phase I - Regional Exploration Drilling Significant Downhole Intersections

Table 3: Phase II – Collar Locations

Table 4: Phase I – Collar Locations

Next Project Steps

Phase II drilling continues across the South Thumb and Schofield zones, with 28 of the planned 46 holes already completed and assays from a substantial number of holes still pending. The program is designed to provide the geological and analytical information required to support an initial Mineral Resource estimate.

In parallel, underground mine rehabilitation is expected to commence in October 2026. Re-establishing access to the historical mine which will enable shorter and more targeted underground drilling and represents an important step toward rebuilding operational access to the Tempiute mineralized system.

Guardian is also evaluating opportunities to accelerate the pathway toward extracting newly mined tungsten material from Tempiute. This work includes assessing access to the near-surface mineralized lode located on patented mining claims, and the permitting requirements for mining it, with a goal of returning Tempiute to an active role in the U.S. tungsten supply chain.

Note: Tempiute is an exploration-stage property, and no Mineral Resource or Mineral Reserve has been estimated for the Project. The exploration results reported in this announcement are not sufficient to support such an estimate, and there can be no assurance that an initial Mineral Resource estimate will be defined at Tempiute. Any extraction of material from Tempiute on an accelerated basis may not be supported by a Mineral Reserve estimate or a feasibility study demonstrating economic viability, and would be subject to significant technical, permitting, financing and other risks, including those described in the Company's filings with the U.S. Securities and Exchange Commission.

Quality Control and Assurance

All samples were submitted to MSA Labs (MSA) of Elko, Nevada which is an ISO9001 and ISO/IEC 17025 accredited laboratory. Samples were analyzed using method IMS-300 and IMS-230. Guardian Metal’s QA/QC program includes regular insertion of standards, duplicates and blanks into the sample stream with stringent review of all results.

Samples from Phase 1 were submitted to ALS Laboratories of Reno, Nevada. Samples were analyzed using methods ME-ICP61, W-XRF-15c and AG-OG46. Guardian Metal’s QA/QC program includes regular insertion of standards, duplicates and blanks into the sample stream with stringent review of all results.

COMPETENT AND QUALIFIED PERSON STATEMENT

The technical information contained in this disclosure has been read and approved by Mr Nicholas O'Reilly (MSc, DIC, MIMMM QMR, MAusIMM, FGS), who is a qualified geologist and acts as the Competent Person under the AIM Rules - Note for Mining and Oil & Gas Companies and as a “qualified person” as defined in Subpart 1300 of Regulation S-K of the U.S. Securities and Exchange Commission (“S-K 1300”). Mr O'Reilly is a Principal consultant working for Mining Analyst Consulting Ltd which has been retained by Guardian Metal Resources plc to provide technical support.

This announcement contains inside information for the purposes of Article 7 of EU Regulation 596/2014 (which forms part of domestic UK law pursuant to the European Union (Withdrawal) Act 2018).

Forward Looking Statements

This announcement contains forward-looking statements relating to expected or anticipated future events and anticipated results that are forward-looking in nature and, as a result, are subject to certain risks and uncertainties, including general economic, market and business conditions, competition for qualified staff, the regulatory process and actions, technical issues, new legislation, potential delays or changes in plans, uncertainties resulting from operating in a new political jurisdiction, uncertainties regarding the results of exploration, the timing and granting of prospecting rights, the timing and granting of regulatory and other third party consents and approvals, Guardian Metal’s or any third party's ability to execute and implement future plans, and the occurrence of unexpected events. 

Forward-looking statements in this announcement include statements regarding the Tempiute drilling program, the timing and content of further assay results, the potential definition of a Mineral Resource estimate at Tempiute, the planned rehabilitation of historical underground workings and its expected timing, the potential for an accelerated pathway to extracting material at Tempiute, and the Company’s plans to advance Pilot Mountain and Tempiute towards production. Forward-looking statements are subject to risks and uncertainties, including those described in the Company’s filings with the U.S. Securities and Exchange Commission. Guardian Metal undertakes no obligation to publicly update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, except as may be required by law.

This announcement does not purport to be full or complete. No reliance may or should be placed by any person for any purpose on the information contained in this announcement or its accuracy, fairness or completeness. The information in this announcement is subject to change.

For further information visit www.Guardianmetalresources.com or contact the following:

About Guardian Metal Resources 

Guardian Metal Resources PLC (NYSE.A: GMTL, LON:GMET, OTCQB:GMTLF) is a strategic mineral exploration company driving the revival of U.S. mined tungsten production and strengthening America's defense metal independence. The Company is advancing two tungsten projects, Pilot Mountain, one of the largest undeveloped tungsten deposits in the U.S. and Tempiute, formerly America's largest producing tungsten operation, both located in Nevada, one of the top-rated mining jurisdictions in the United States.

In July 2025, the U.S. Department of War (DoW) under Title III of the Defense Production Act of 1950, as amended, invested US$6.2M in Golden Metal Resources (USA) LLC, a wholly-owned subsidiary of Guardian Metal Resources PLC, to support the Pilot Mountain PFS.2 The Company completed a U.S. listing on the NYSE American on March 20, 2026. 

Tungsten is a strategic metal critical to the defense, energy transition, technology and industrial sectors. In the context of shifting geopolitical dynamics and tightening Chinese export restrictions, Guardian Metal is well positioned to play a leading role in re-establishing a secure, domestically mined U.S. supply chain for this vital defense metal.