Sampling Returns Positive Tungsten Assay Results

Great Western Mining Corporation PLC (AIM: GWMO / Euronext Growth: 8GW / OTCQB: GWMOF), a strategic minerals exploration and development company, is pleased to announce assay results from a machine-cut channel sampling programme at its Defender-Pine Crow ("DPC" or the "Project") in Mineral County, Nevada, USA.

HIGHLIGHTS

• Four new machine-cut channels completed in April 2026 at Defender-Pine Crow returned significant tungsten mineralisation (Figure 1, Table 1):

o Channel C intercepted 27 m (89 ft) @ 0.15% WO3, including 11 m (30 ft) @ 0.25% WO3.

o Channel D intercepted 5 m (16 ft) @ 0.12% WO3.

o Channel E intercepted 3 m (10 ft) @ 0.34% WO3.

o Channel F intercepted 18 m (59 ft) @ 0.15% WO3, including 6 m (20 ft) @ 0.22% WO3.

• Very low concentrations of potential penalty elements (including Molybdenum ('Mo')) encountered during WO3 processing (Table 1).
• Silver (Ag) mineralisation found in Channel F across 2 intervals of 2m @ 17.6 g/t Ag and 2m @ 10.1 g/t Ag in the transition between Dunlap Formation limestones and garnet skarn.
• Additional infill rock chip samples between Defender Mine and the Company's M2 copper resource supports the hypothesis that there is a 2-3 km corridor of tungsten mineralisation (highlight chip samples are presented in Table 2).
• Channel and rock chip sampling results will inform the Company's fully permitted maiden drilling programme, expected to commence in the coming weeks.

Great Western CEO Ed Loye commented: "Following our initial channelling in December 2025, additional machine-cut channelling in April 2026 has confirmed broad and significant tungsten mineralisation at the historic Dough God and Pine Crow Mines. A further channel at the historic Widowmaker Mine, supported by new in-situ rock chip samples, extends the tungsten trend a further 1 km west from Pine Crow and strengthens our interpretation of a significant at-surface, multi-kilometre tungsten corridor. Silver mineralisation over intervals at Widowmaker is a welcome credit. Notably, elements that could impair tungsten processing such as molybdenum were immaterial in the results. The channel and rock chip sampling results provide important guidance for our maiden drilling campaign beginning in a few weeks' time."

DETAILS

Background

A 3 km skarn trend extends from Defender Mine through Pine Crow and the historic Widowmaker Mine to the Company's JORC-compliant M2 skarn copper resource, with each occurring approximately 1 km apart. All the skarns occur at the contact zones of Cretaceous granitic intrusions with limestones of the Jurassic Dunlap Formation. Detailed geological mapping and in-situ rock chip sampling conducted in April 2026 has complemented the initial sampling reported in June 2025. Recent gravity geophysical surveying alongside geological mapping is refining the geological model ahead of the Company's fully permitted 7000 ft maiden RC drilling programme, due to commence in the coming weeks.

Channel sampling

In April 2026, four channels were machine-cut to assess mineralisation by collecting samples at 1 m intervals. Channels C and D were cut across existing exposures at the historic Dough God Mine, while Channels E and F were cut across old surface workings at Pine Crow Mine and Widowmaker Mine respectively. Channel start and end co-ordinates were surveyed by Differential Global Positioning System ('DGPS') and the channels measured by chain survey. All samples were submitted to American Assay Laboratories, Sparks, Nevada.

The samples were analysed by ICP-OES and ICP-MS after both four acid-digest (4AD) and sodium peroxide fusion digestion (methods IM-4AB52 and IO-NF43). Quality control samples (duplicates, blanks and certified reference materials) were inserted by the Company and results reviewed prior to release.

The results are summarised in Table 1.

Whilst Channels C-E demonstrated tungsten mineralisation, Channel F also demonstrated silver mineralisation alongside tungsten mineralisation, intersecting 2 m (7 ft) at 17.6 g/t Ag, and another 2 m (7 ft) at 10.1 g/t Ag within the transition zones between Dunlap Formation limestones and metasomatic garnet skarn. Importantly, elements that could act as processing penalties for WO₃ such molybdenum, were recorded at very low concentrations (Table 1).

These results, together with new in-situ rock chip samples collected during geological field mapping in April 2026 (Table 2) and a complete set of assayed soils, including those collected in Spring 2025, will refine drill targeting and support further exploration across this emerging tungsten corridor.

Figure 1: Map showing the location of the 6 machine-cut channels at DPC, including the 4 channels from April 2026.

Table 1: Highlight channel sample assay intervals. Samples are plotted spatially in Figure 1.

Table note: *Samples assayed at American Assay Labs, Reno, USA. Ag assayed by IM-4AB52. W assayed by IM-NF43 and converted to WO3 by stoichiometric calculation.

Table 2: Highlight rock-chip (from in-situ outcrop) assays from April 2026. Samples are plotted spatially in Figure 1.

Table note: Coordinates in EPSG 26911. Assayed by American Assay Labs, Reno, with W assayed using IM-NF43 and converted to WO3 by stoichiometric calculation.

Figure 2: Machine cut Channel C (diamond saw) at Dough God Mine, April 2026 (left) and machine cut Channel E across the adit entrance at Pine Crow Mine, April 2026 (right).

Figure 3: Scheelite (tungsten ore mineral) in skarn outcrop at Widowmaker Mine fluoresces as bands of blue-white specks (akin to stars in galaxy bands) under short-wave ultraviolet light. Marking out 1-metre intervals for machine cutting at Widowmaker Mine April 2026.

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 an increasing strategic emphasis on tungsten as a critical mineral, 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.