16 September 2026

GREAT WESTERN MINING CORPORATION PLC

(“Great Western”, “GWM” or the “Company”)

Excellent Tungsten Recovery Rate from Bulk Sample

Metallurgical test results from Defender confirm amenability to standard processing

Great Western Mining Corporation PLC (AIM: GWMO / Euronext Growth: 8GW / OTCQB: GWMOF), a strategic minerals exploration and development company, is pleased to announce highly encouraging initial metallurgical results from bench-scale flotation test work on representative run-of-mine material from its Defender Tungsten Project (“Defender” or the “Project”) in Nevada, USA.

OVERVIEW

• Initial metallurgical test work at Defender has delivered high tungsten recovery and a substantial increase in tungsten grade.
• 92.98% of the tungsten was recovered from the pre-treated material into a rougher concentrate grading 7.21% WO₃, compared with a starting bulk sample grade of 0.35% WO₃.
• The results compare favourably with similar rougher test work undertaken by other regional skarn-hosted tungsten projects and support the potential to process Defender mineralisation using established flotation methods.
• Further test work will now focus on increasing the tungsten concentrate grade towards potential marketable product specifications.

Great Western CEO, Ed Loye, commented: “These preliminary results represent an excellent early milestone for Defender. Upgrading our 0.35% WO₃ bulk sample to a 7.21% WO₃ rougher concentrate while maintaining 93% recovery is a very encouraging result. This confirms that our metallurgical model is highly responsive right out of the gate.  Additionally, very low levels of deleterious elements such as molybdenum were recorded, which is important as these can hinder further purification steps.

“We have established a remarkably clean, low-volume rougher concentrate that serves as the perfect springboard for our next phase of metallurgical test work.”

DETAILS

As announced on 7 May 2026, Great Western commissioned Eriez Flotation Division (“Eriez”) in Pennsylvania, USA, to undertake initial metallurgical test work on material from Defender to assess the amenability of the mineralised material to flotation and establish an initial processing route for the recovery and concentration of tungsten.

A 750 kg representative bulk sample was collected from mineralised material across approximately 1 km of strike between the Defender Mine in the east, the Dough God Mine and the Pine Crow Mine in the west. The sample had a homogenised head grade of 0.35% WO₃ and was crushed to P80 150µm before undergoing sequential sulphide and scheelite flotation test work.

The sequential testing successfully demonstrated the bulk sample’s amenability to standard processing methods, achieving a high tungsten recovery rate alongside substantial grade upgrading during the preliminary rougher stages. The results compare favourably with similar rougher test work undertaken by other regional skarn-hosted tungsten projects.

The initial sulphide flotation stage, an essential pre-treatment step, successfully removed sulphide contaminants into a float stream representing just 3.97% of the total mass. The pre-float phase retained 99.46% of the tungsten within the main sink stream at a grade of 0.35% WO₃, resulting in minimal loss of the target mineral prior to the primary extraction stage.

Following sulphide removal, the tungsten-bearing stream was introduced to a flotation column using a specialised reagent suite optimised for skarn mineralogy. This primary recovery stage pulled just 4.55% of the total mass while recovering 92.98% of the remaining tungsten. The process upgraded the material to a clean, rougher concentrate grading 7.21% WO₃, compared with the original bulk sample head grade of 0.35% WO₃, and aligning with results from other regional skarn-hosted tungsten projects.

These preliminary results provide a strong technical foundation for the next stage of metallurgical work at Defender, supporting both the selection of the reagent suite and the effectiveness of the Eriez column configuration in suppressing silicate and calcium-rich waste rock. The high-recovery, clean, rougher concentrate generated from the representative bulk sample will now be used as feed material for the cleaner circuit optimisation tests, which will aim to further upgrade the material towards potential marketable product specifications.

As part of this follow-up work, Eriez will evaluate whether a mild regrind stage is required ahead of the cleaning cells to improve liberation of remaining trapped minerals without over-grinding the scheelite.

ENDS

For further information visit www.greatwesternmining.com or contact:

Notes

Great Western Mining Corporation PLC (AIM: GWMO / Euronext Growth: 8GW / OTCQB: GWMOF) is an exploration and development company focused on strategic minerals across several 100%-owned claim groups in Mineral County, Nevada, a highly prospective and mining-friendly jurisdiction. The Company has a strategic emphasis on tungsten, while continuing to advance its Huntoon Copper Project, which hosts a JORC-compliant resource of 4.3 Mt at 0.45% Cu with further porphyry upside. It also maintains exposure to gold and silver through exploration and tailings reprocessing opportunities, alongside evaluating farm-out and joint venture options to unlock wider portfolio value.

Forward Looking Statements

This announcement contains forward looking statements relating to the plans, activities and expectations of Great Western Mining Corporation PLC. Such statements include, but are not limited to, those concerning planned exploration programmes, anticipated timelines and potential mineral resource outcomes.

The results reported in this announcement are preliminary results based on initial flotation testing using Eriez's internal laboratory assessment and standards and are subject to additional QA/QC through third-party assay verification. These preliminary results should not be treated as definitive and may be subject to revision following completion of that verification process.

Forward looking statements are typically identified by words such as “plan”, “expect”, “anticipate”, “intend”, “may”, “could”, “potential” or similar expressions. These statements are based on current expectations and assumptions and involve risks and uncertainties that could cause actual results to differ materially.  Factors include geological risk, exploration and drilling results, permitting and regulatory approvals, funding availability, operational challenges, commodity price movements and general market conditions. No assurance can be given that any forward looking statements will prove to be accurate, and shareholders are cautioned not to place undue reliance on them.