Guardian Metal Resources PLC Announces Pilot Mountain Pre-Feasibility Progress Update

Maiden S-K 1300 Technical Summary Report Delivers 16% Increase in Open Pit Constrained Indicated Mineral Resources vs 2018 Scoping Study; Drilling Ongoing

LONDON, UK / ACCESS Newswire / December 19, 2025 / Guardian Metal Resources plc ('Guardian Metal' or the 'Company') (LON:GMET)(OTCQB:GMTLF), a strategic exploration company focused on tungsten in Nevada, USA, is pleased to announce the submission to the SEC of a S-K 1300 Technical Summary Report ("TRS") and updated Mineral Resource Estimate ("Resource" or "MRE") on the 100%-owned Pilot Mountain tungsten Project ("Pilot Mountain" or the "Project") located in Nevada, USA. Importantly, in accordance with Regulation S-K 1300 17 CFR Part 229 Subpart 229.1300 ("S-K 1300"), the updated MRE is pit-constrained and therefore potentially suitable for open-pit mining, offering a potential pathway to development and positioning the Company, subject to permitting, financing and further technical work, to support the development of a domestically mined source of tungsten in the United States for the first time in more than a decade. The TRS will also underpin the technical disclosures required for the Company's planned listing on a U.S. securities exchange.

Tungsten is a key defence and industrial metal and has been designated as a strategic priority by the U.S. government. Guardian Metal's mission is to bring into production two of its tungsten projects, Pilot Mountain and Tempiute, as the cornerstone of U.S. tungsten supply, directly supporting national efforts to reshore mined production. Significantly, this would mark a major step in the U.S. effort to reduce reliance on foreign supply chains and reinforce economic and defence security, laying the groundwork for durable, long-term value creation.

The TRS, dated 15 December 2025, was prepared by the Qualified Person RESPEC Company LLC ("RESPEC ") of Rapid City, South Dakota, USA in accordance with the United States Securities and Exchange Commission ("SEC") requirements under S-K 1300 and will be publicly available via the SEC Electronic Data Gathering, Analysis and Retrieval (EDGAR) system in due course.

Oliver Friesen, CEO of Guardian Metal, commented:

"Supported by the U.S. Department of War's US$6.2 million Defense Production Act (DPA) Title III investment in Guardian Metal's wholly-owned subsidiary, Golden Metal Resources (USA) LLC, we are making strong progress toward completing the Pre-Feasibility Study ("PFS") and advancing towards our goal of delivering the first new mined source of tungsten on U.S. soil in more than a decade.

"The inaugural pit-constrained Mineral Resource for Desert Scheelite, prepared in accordance with S-K 1300, represents the culmination of over 12 months of diligent drilling completed by our in-country Nevada-based operations team. This Resource, which includes a 16% increase in pit constrained Indicated tonnage, establishes a solid foundation for future resource growth, and, more importantly, represents an important step in supporting a potential U.S. listing.¹

"Concurrently, drilling is ongoing at Desert Scheelite, targeting multiple areas that remain open for expansion. A second drill rig has been secured and is scheduled to mobilise early in the New Year, enabling an expanded drill programme at Desert Scheelite as well as several other underexplored tungsten zones across the Project including the Garnet Zone. Results from this work are expected to be incorporated into a future MRE update, which will underpin the progressing PFS.

"Now more than ever, the Company believes that the United States requires a secure domestically mined source of tungsten, and Guardian Metal is firmly focused on delivering that outcome."

Marc Leduc, P.Eng., Operations Manager of Guardian Metal, commented:

"Preparation of the Pre-Feasibility Study continues to advance well. All key technical and engineering studies required to support the PFS are currently underway, including mine planning, metallurgy, infrastructure studies, hydrogeological drilling, and environmental baseline studies to support mine permitting.

"The outcomes of these workstreams will be integrated into a comprehensive development plan, which will form the basis of the Project's Mine Plan of Operations and underpin the permitting pathway and subsequent mine development activities."

MAIDEN S-K 1300 MINERAL RESOURCE AND PFS PROGRESS

• The Company has successfully completed its first MRE prepared in accordance with S-K 1300 at Desert Scheelite, representing only one of the Project's four known at-surface tungsten-rich skarn zones. The PFS is advancing well with a highly qualified multi-disciplined specialist team.

• The establishment of the Project's first ever Resource, prepared in accordance with S-K 1300, represents a key milestone as the Company builds towards a potential listing on a U.S. securities exchange.¹

• The Resource was completed by RESPEC Company LLC - an experienced specialist mining engineering firm based in Rapid City, South Dakota and Reno, Nevada (Table 1).

• Importantly, the Resource incorporates data from 68 drillholes at Desert Scheelite completed by the Company. Since the MRE data cutoff of October 20, 2025, a further eight drillholes have been completed, with additional drilling planned to further test extensions of Desert Scheelite where the Resource remains open along strike (east and west) and down dip. These recently completed and future planned drillholes will be incorporated into a further updated MRE expected prior to completion of the PFS.

• The MRE update will include a recent intercept in drillhole PM25-065 which returned a 26.8m intersection (from 172.17m - 198.97m) with one of the strongest visual (under ultra-violet light) intersections of scheelite (CaWO₄) mineralisation noted by the Company on the Project to date.

• To support the planned 2026 MRE, the Company has secured a second exploration drill rig, scheduled to arrive on site early in 2026. This additional rig will enable the testing of several known at-surface tungsten zones across the Project that have not yet been adequately drill tested-including at Desert Scheelite and the Garnet Zone-and will also provide additional capacity for further engineering-related drilling.

• The PFS, supported by a US $6.2m DoW DPA III investment in Guardian Metal's wholly-owned subsidiary, Golden Metal Resources (USA) LLC², is progressing well and is being led by the Company's Operations Manager, Marc Leduc, P.Eng., a highly experienced mine builder. Mr. Leduc and the Company's technical team are joined by a group of highly experienced partners who are engaged to progress the various ongoing PFS workstreams including:

  • Samuel Engineering, Inc. (Denver, Colorado)*: Overall PFS lead, metallurgy, process engineering and plant design, financial modelling and final report preparation.

  • RESPEC Company LLC (Rapid City, South Dakota and Reno, Nevada): Resource modelling, geotechnical engineering and mine design.

  • KTW Environnemental (Boise, Idaho): Project permitting.

  • Life Cycle Geo LLC (Longmont, Colorado): Geochemical characterisation and baseline data collection.

  • Clear Creek Associates (Scottsdale, Arizona): Hydrogeology.

  • Qualus, LLC (Lake Mary, Florida): Power engineering.

  • Westland Engineering & Environmental Services, a Trinity Consultants Team (Reno, Nevada): Baseline data collection and permitting.

  • NewFields Mining Design & Technical Services, LLC (Denver, Colorado): Tailings and waste design.

  • Reliant Well Drilling and Pump Corp. (Tucson, Arizona): Hydrogeological drilling services.

• In total, more than 25 specialists from 8 independent firms with decades of U.S.-focused mine design, engineering, procurement and construction management experience are currently engaged by the Company's Pilot Mountain PFS team. Guardian Metal's owners team includes a group of geologists, geotechnicians and engineers with over 100 years' of combined exploration, mine building and operations experience.

• The PFS study is expected to be completed by the end of H1 2026, and mine permit applications will be submitted promptly thereafter. Further PFS progress updates will be provided and any preliminary results from any of the above ongoing workstreams will be released when allowable, including pending drilling results from both the Desert Scheelite and Garnet Zones. The Company's objective is to achieve initial commercial production before the end of 2028.

MINERAL RESOURCE DETAILS

The updated Mineral Resource Estimate applies a 0.06% tungsten trioxide (WO₃) cut-off grade, reflecting increased tungsten prices since the 2018 MRE and the planned open-pit mining approach. The MRE also incorporates the favourable tungsten recoveries demonstrated in historical metallurgical test work. An initial preliminary pit design has been developed and supports both the Indicated and Inferred Mineral Resources.

Importantly, the Desert Scheelite Deposit now comprises a high proportion of pit-constrained Indicated Mineral Resources, providing a strong foundation for the ongoing PFS. The now established MRE, prepared in accordance with S-K 1300, is expected to grow further as results from ongoing exploration drilling are incorporated into a future update.

Drilling completed by the Company during 2024 and 2025 successfully achieved its key objectives, including re-estimating the Mineral Resource under S-K 1300 based on additional drilling and updated technical work, upgrading overall resource confidence, generating material for detailed metallurgical test work (currently underway), and providing the data required to support mine planning and permitting activities, which are also now in progress.

When compared to the Mineral Resource estimate underpinning the 2018 Scoping Study, the updated resource sensitivity analysis shows that the tonnage of Indicated Resources within a projected open-pit design has increased by approximately 16%.

Table Error! No text of specified style in document. Desert Scheelite Mineral Resources

Notes:

1 The effective date of Desert Scheelite Mineral Resource statement is December 1, 2025.

2 Mineral Resource stated in metric tonnes.

3 Average grades of the tabulations are comprised of the weighted average of block-diluted grades within an optimised pit.

4 The Desert Scheelite Mineral Resource cut‑off grade of 0.06% WO₃ was selected by the authors. Operating assumptions were applied to establish a theoretical pit limit, including a WO₃ price of $65,500/t, an average recovery of 80% WO₃, a processing rate of 4,000 tonnes/day, $2.75/t mining cost for open pit, $15.64/t processing cost, $3.00/t processed for G&A, and an 83% payability. Blocks outside the pit limit are not considered to be economic at this time.

5 The accessory metals Ag, Cu, and Zn shown in this table are the quantities contained within the mineral resources using the cut-off grade established for the primary commodity (WO₃). No independent cut-off grade has been applied to these accessory metals. Reported quantities of accessory metals are therefore considered by-products of the primary metal resource and their value is contingent upon the ability to economically extract the by-products along with the primary commodity.

6 The estimate of mineral resources may be materially affected by geology, environmental, permitting, legal, title, taxation, sociopolitical, marketing, or other relevant issues.

7 Rounding as required by reporting guidelines may result in apparent discrepancies between tonnes, grade, and contained metal content.

8 Mineral Resources are not Mineral Reserves and do not have demonstrated economic viability. An Inferred Mineral Resource has a lower level of confidence than an Indicated Mineral Resource and must not be converted to a Mineral Reserve. RESPEC reasonably expects that continued exploration and delineation will upgrade the majority of Inferred Mineral Resources to Indicated Mineral Resources.

FURTHER PFS UPDATES

Ongoing work includes open-pit mine design and optimisation, detailed metallurgical test work, hydrogeological drilling to support future mine permitting, geochemical characterisation of waste rock, tailings design, and geotechnical investigations to support the planned open pit and associated mine infrastructure. Studies assessing options for all required mine and mill infrastructure are also underway.

The PFS is being coordinated by Guardian Metal's in-house team in collaboration with Samuel Engineering, Inc. and the various engineering contractors outlined above. Resource drilling at Desert Scheelite is ongoing and will ramp up into Q1 2026 upon the delivery of an additional drilling rig, with drillholes also planned at some of the other Project target areas. An updated MRE is expected prior to the completion of the PFS which is targeted for completion by end of H1 2026.

References

1 Company announcement, Intention to list in the US, dated 8 September 2025
(https://polaris.brighterir.com/public/guardian_metal_resources/news/rns/story/rdo0dpx)

2 Company announcement, U.S. Department of Defense Awards $6.2M to Golden Metal Resources for the Pilot Mountain Project, dated 23 July 2025
(https://polaris.brighterir.com/public/guardian_metal_resources/news/rns/story/wvm0n3w)

QUALIFIED PERSON

RESPEC is the author of the TRS and the Qualified Person under item 1302 of Regulation S-K, has reviewed and approved the inclusions of its summary of the TRS in this announcement.

This announcement includes a summary of the main elements of the PFS which is included in a Technical Report Summary which has been prepared in accordance with S-K 1300, as adopted by the SEC. The effective date of the MRE in the TRS is 1 December 2025.

COMPETENT PERSON STATEMENT

The technical information contained in this disclosure has been read and approved by Mr Nick 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. 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, such as general economic, market and business conditions, competition for qualified staff, the regulatory process and actions, technical issues, new legislation, uncertainties resulting from potential delays or changes in plans, uncertainties resulting from working in a new political jurisdiction, uncertainties regarding the results of exploration, uncertainties regarding the timing and granting of prospecting rights, uncertainties regarding the timing and granting of regulatory and other third party consents and approvals, uncertainties regarding the Company's or any third party's ability to execute and implement future plans, and the occurrence of unexpected events.

Actual results achieved may vary from the information provided herein as a result of numerous known and unknown risks and uncertainties and other factors.

Nothing in this announcement is intended to constitute an offer of securities for sale or a solicitation of any offer to acquire securities in any jurisdiction.

For further information visit www.Guardianmetalresources.comor contact the following:

About Guardian Metal Resources

Guardian Metal Resources PLC (LON: GMET, OTCQX: 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 co-flagship 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 U.S.

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. The Company has announced plans to pursue a U.S. listing in the first half of 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 is well positioned to play a leading role in re-establishing a secure, domestically mined U.S. supply chain for this vital defense metal.

This information is provided by RNS, the news service of the London Stock Exchange. RNS is approved by the Financial Conduct Authority to act as a Primary Information Provider in the United Kingdom. Terms and conditions relating to the use and distribution of this information may apply. For further information, please contact rns@lseg.com or visit www.rns.com.

SOURCE: Guardian Metal Resources PLC