(via TheNewswire)

Vancouver, BC, Canada – Tuesday, July 28, 2026 – TheNewswire - Great Plains Metals Corp. ("GPS" or "the Company", TSX-V: GPS, Frankfurt Exchange: 8VC) is very pleased to announce that the assay results confirm the discovery of a “pencil porphyry” at the Goodrich copper-gold project in New South Wales, Australia.

Laboratory assays from drill hole GGDD004 have successfully verified a continuous, 128-meter intercept of porphyry-style mineralization. This broad intersection validates the Company’s porphyry exploration thesis: the historical, shallow Goodrich mine workings represent the upper tip of a multiphase, intact porphyry system.

Key Drill Highlights:

• Discovery Hole Intercept: Drill hole GGDD004 intersected 128 meters of mineralization with 0.34% copper and 0.17 g/t gold from 81.45m downhole.  

• Mineralized Magmatic Cupola: A prominent high-grade zone right at the porphyry contact returned 3.55 meters @ 2.80% Cu and 0.18 g/t Au from 81.45m.  

• Continuous Disseminated Chalcopyrite: Multiple sub-intervals dissected by post mineral dykes confirm continuous mineralization , including 26 meters @ 0.52% Cu and 0.24 g/t Au from 102m, and 5 meters @ 0.66% Cu and 0.49 g/t Au from 158m.  

• Near-Surface Depth: Importantly, the 128-meter mineralized intercept begins near-surface at just 81.45 meters depth.  

Technical Evaluation & Drill Hole Comparative Data

The initial Phase One diamond drilling program was designed to test porphyry-style mineralization below the former Goodrich mine. Drill hole GGDD004 intersected significant disseminated copper and gold mineralization hosted in a monzonite porphyry stock (Figure 1).   Drill hole GGDD003 intersected altered monzonite porphyry representing the inner propylitic halo of the Goodrich porphyry (Figure 4).

Table 1: GGDD004 Assay Results

Figure 1.  GGDD004 Drill Intersection.

Technical Analysis of Drill Hole GGDD004

The mineralized unidirectional solidification textures (USTs) zone intersected at 81.4 meters (Figure 2) represents the cupola contact of a mineralized monzonite porphyry stock (i.e. the top of the system) and comprises magmatic bands of milky quartz, coarse chalcopyrite and pyrite aggregates and minor magnetite. Below the UST zone, hydrothermal alteration consists of pervasive white mica-chlorite and pale albite which appears to overprint an earlier K-spar-biotite assemblage to varying degrees. The entire 128 meters of monzonite porphyry has disseminated chalcopyrite and pyrite with traces of molybdenite in rare quartz veins (Figure 3). After 209 meters the hole transitions into an inner propylitic zone with increasing epidote, chlorite and pyrite. Several relatively narrow intercepts of post-mineral trachyte dykes are present throughout the hole.

Click Image To View Full Size

Figure 2. GGDD004 82.30 – 82.50m Brecciated quartz – magnetite UST textures.  Massive broken chalcopyrite with trace bornite.

Click Image To View Full Size

Figure 3. GGDD004 116.85 – 162.0m Grey mottled crowded porphyry with pervasive chlorite – illite -albite alteration & strong disseminated chalcopyrite locally up t o 5% x vol.  Contains miarolitic cavities and a lmost no fractures & no quartz veining.

Table 2: GGDD003 Assay Results

Click Image To View Full Size

Figure 4.  GGDD003 Drill Intersection

Technical Analysis of Drill Hole GGDD003

Drill hole GGDD003 intersected altered chlorite-white mica-epidote monzonite porphyry considered to represent the inner propylitic halo of the Goodrich porphyry.  Two intervals displaying UST textures were observed at 31.8 meters (Figure 5 and 6) and 76.8 meters depth (Figure 7), both of which were associated with copper mineralization (similar to those in GGDD004 but less well-developed).  A significant fault was intersected at 82m after which only weak mineralization and alteration were encountered.  

Click Image To View Full Size

Figure 5. GGDD003 31.85 – 32.15m Quartz-magnetite UST (brecciated) with molybdenite & chalcopyrite. Blebby disseminated chalcopyrite in chlorite-sericite-actinolite-K spar altered crowed porphyry.

Click Image To View Full Size

Figure 6. GGDD003 32.1 – 32.6m Quartz – magnetite UST s.  Blebby chalcopyrite , chlorite-sericite-albite ± K spar altered crowded porphyry.

Click Image To View Full Size

Figure 7. GGDD003 76.83 – 77.34m quartz-magnetite-chalcopyrite UST ; broken & brecciated.  Strong chalcopyrite in matrix and thin fractures.

The location of drill holes GGDD003 and GGDD004 at the Goodrich mine are shown below (Figure 8).

Click Image To View Full Size

Figure 8.   The location of drill holes GGDD003 and GGDD004 at the Goodrich mine.

The other two diamond drill holes: GGDD005 and MRDD001 did not encounter significant mineralization.  Hole GGDD005 was designed to test a magnetic high target 100 meters southeast of the Goodrich mine.  It was terminated at 161.2 meters and drilled weakly magnetic unmineralized monzonite/granodiorite.  Hole MRDD001 was collared next to the small historical workings at Mt Rose and was terminated at 140.1 meters after encountering weak pervasive chlorite-epidote altered monzonite with minor disseminated pyrite.

Historical Drill Core Review at Londonderry

Per the Company’s news release dated 14 July 2026, a review was being conducted of historical core archived at the New South Wales Mines Department facility in Londonderry . Detailed logging identified that extensive, highly altered intervals from historical drill holes DDHG4 (Baker Ltd. 1980) and GRDD01 (Malachite Resources 1999) were never submitted for assay.

A total of 324 samples was compiled and delivered to Intertek Laboratories in nearby Orange. Assays are expected within the next few weeks and will be integrated into the regional porphyry cluster model. The Company will provide further updates in due course.

Phase Two Drilling

The Company announced previously the completion of Stage 1 of the Earn-in and Joint Venture Agreement, achieving a 51% interest and the commencement of Stage 2 which upon completion will result in GPS owning a 70% interest.  The Company will now form a subsidiary company (“GPS Goodrich”) in New South Wales, Australia which will then hold the tenements that comprise the Goodrich Project.  GPS Goodrich will then undertake the process for the transfer of land access agreements and the approval of work programs.  Upon completion, which is anticipated in Q4 2026, the Phase Two drill program will commence.

Peeyush Varshney, CEO, commented:

“The results from Drill Hole GGDD004 confirming the discovery of a “pencil porphyry” at Goodrich is a very exciting milestone for GPS. Intersecting 128 meters of copper-gold mineralization starting from just 81 meters from the surface is significant and represents a new exploration opportunity consistent with other porphyry deposits in the Lachlan Fold Belt, a mineral province that has historically produced over 80 million ounces of gold and 13 million tonnes of copper .

The presence of multiple textbook UST cupola textures indicates potential for significant porphyry mineralization that the old-timers missed. Combined with our ongoing review of previous drilling and unassayed historical core, these definitive data points give our technical team the coordinates needed to expand this porphyry footprint when Phase Two diamond drilling commences."

About Great Plains Metals Corp

Great Plains Metals Corp is an emerging, Australia-focused exploration company targeting copper-gold porphyry and district-scale critical mineral discoveries. The Company’s fast-track discovery strategy centers on technically validating high-grade, drill-ready targets situated within premier geological jurisdictions.

• The Flagship Goodrich Project (NSW): Located in the heart of New South Wales' premier copper-gold jurisdiction – near the Yeoval township and roughly 70 km northwest of Orange – the project spans an extensive 290 km² across exploration licenses EL9243 and EL8538.  The Goodrich Project is situated within the world-class Lachlan Fold Belt  

• Proven Mineral Footprint: Historically the largest mine in the Yeoval district, Goodrich operated intermittently between 1868 and 1912. Production from its historic 46 meter open pit and 90 meter underground shafts yielded an estimated ~300 tonnes of copper, 159 kg of gold, and 62 kg of silver, notably supporting a local smelter facility during its peak operational phases. Modern geological modeling suggests this historical mining merely exposed the upper tip of a significantly larger, robust porphyry core system below the old mine.  

• Strategic District-Scale Upside: GPS holds a 37.1% equity stake in Eversley Resources, giving the Company low-cost exposure to the Eversley North Gawler Craton Project in South Australia. Spanning an extensive 2,584 km² within the prolific Olympic Dam IOCG province, the project targets shallow, high-intensity Iron Oxide Copper-Gold (IOCG) systems alongside a near-surface Ionic Clay Rare Earth Element (REE) prospect. With a Native Title Mining Agreement for Exploration secured and target depths uniquely shallow at under 150 meters, the project represents immediate, high-value asset diversification.  

Corporate Information & Contacts

• Contact: Peeyush Varshney, CEO 

• Email/Investor Relations: hello@greatplainsmetals.com 

• Phone: (604) 684-2181 

• Official Website: greatplainsmetals.com  

Social: linkedin.com/company/great-plains-metals-corp | X: @GPSMetals

• Qualified Person (QP): The scientific and technical data contained in this news release has been reviewed and approved by Douglas Kirwin, who serves as the qualified person (QP) under the definition of National Instrument 43-101.  

Cautionary Note Regarding Forward-Looking Statements

This news release contains certain statements that may be deemed “forward-looking statements.” Forward-looking statements are statements that are not historical facts and are generally, but not always, identified by the words “expects”, “plans”, “anticipates”, “believes”, “intends”, “estimates”, “projects”, “potential” and similar expressions, or that events or conditions “will”, “would”, “may”, “could” or “should” occur. Although the Company believes the expectations expressed in such forward-looking statements are based on reasonable assumptions, such statements are not guarantees of future performance and actual results or realities may differ materially from those in forward looking statements. Forward looking statements are based on the beliefs, estimates and opinions of the Company’s management on the date the statements are made. Except as required by law, the Company undertakes no obligation to update these forward-looking statements in the event that management’s beliefs, estimates or opinions, or other factors, should change.

Neither the TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this press release.

Copyright (c) 2026 TheNewswire - All rights reserved.