Mr. Peeyush Varshney reports

UPDATE ON GPS DRILLING PROGRAMS

Great Plains Metals Corp. has provided an update on the drill programs at the Goodrich porphyry copper-gold project in the Lachlan fold belt.

Highlights:

• Goodrich drilling summary;
• Alteration mineralization highlights: drill hole GGDD004;
• Geological context;
• Review of historical drill core at Goodrich;
• Stage 2 earn-in commenced to reach 70-per-cent ownership.

Goodrich drilling summary

The company announced on May 4, 2026, the completion of an extensive shallow air-core program of 2,065 metres around the former Goodrich mine and historic Mount Rose workings.

All holes reached bedrock defining several coincident bedrock gold-copper-molybdenum anomalies for follow-up investigation.

Following the air-core program, four diamond drill holes were completed for a total of 1,020 metres (three at Goodrich and one at Mount Rose).

The second hole collared adjacent to the Goodrich open cut, GGDD004, was particularly notable as it intersected a chalcopyrite-bearing cupola, with unidirectional solidification textures (USTs) at 81 metres and visible varying amounts of disseminated chalcopyrite (a copper mineral) in white-mica-albite altered monzonite porphyry to a depth of 218 metres. These are classic signatures of a porphyry copper-gold system.

Follow-up drilling is being actively planned to delineate the extent and potential of the mineralization discovered in the phase 1 drilling.

Alteration and mineralization highlights: drill hole GGDD004

Detailed core logging from drill hole GGDD004 has defined a classic, well-zoned porphyry copper system with distinct downhole alteration and mineralization profiles:

• Zero to 8.0 metres (regolith zone): near-surface oxidized zone characterized by intense limonitic weathering and pervasive clay-group alteration;
• 8.0 to 81.8 metres (inner propylitic halo): grey-white granodiorite wallrock crosscut by multigeneration, salmon-pink albite vein selvedges and thin quartz-carbonate-epidote veins; notably, a dense quartz-carbonate vein cluster at 66.5 metres hosts trace bornite mineralization;
• 81.8 to 240.0 metres (mineralized porphyry): located immediately beneath a prominent UST chalcopyrite-quartz layer; this extensive interval consists of a crowded monzonite porphyry hosting widespread disseminated chalcopyrite; mineralization is directly associated with strongly developed, overlapping assemblages of pink-orange albite and white-grey phyllic (white mica) alteration;
• 240.0 to 297.5 metres (inner propylitic zone): patchy sulphide mineralization transitioning structurally into peripheral, late-stage chloritic-, epidotic- and carbonate-dominant assemblages near the base of the hole.

The primary monzonite porphyry body is punctuated by an intermediate granodiorite intrusive phase and localized postmineral trachytic dykes, highlighting a complex, multiphase magmatic system.

Geological context

Porphyry copper-gold mineralization has been recognized in the Yeoval-Goodrich district since the 1970s. Despite this, there has been only limited exploration with shallow drilling campaigns targeting geochemical and geophysical anomalies. The geological setting of the disseminated porphyry copper-gold mineralization is not well understood and the recent recognition of monzonitic cupola textures at the former Goodrich mine highlight the potential for pencil porphyry targets. It is not known at this stage whether the copper and gold mineralization intersected in GGDD004 is a southern extension of the high-grade ore previously mined at Goodrich or another mineralized porphyry stock as such deposits often occur as clusters. A phase 2 drilling program is scheduled to commence in August.

The company expects to receive all the assay results this month and will provide an update in due course.

Review of historical drill core at Goodrich

A review of drill core from exploration undertaken by Malachite Resources at Goodrich 25 years ago was conducted at the New South Wales Mines Department storage facility at Londonderry. Recent logging of this core showed that significant altered and potentially mineralized intervals were surprisingly not assayed, and a total of 324 samples have been submitted for assay.

Stage 2 earn-in commenced to reach 70-per-cent ownership

The company announced on June 15, 2026, that it has completed the expenditure and drilling requirements to achieve a 51-per-cent interest in the Goodrich project and elected to progress to Stage 2 of the earn-in and joint venture agreement with Australian Securities Exchange-listed Godolphin Resources Ltd.

Under the terms of Stage 2, Great Plains Metals must incur a further $1-million (Australian) in exploration expenditure over the next 12 months and complete a minimum of 500 metres of reverse circulation and/or diamond drilling to increase its interest to 70 per cent.

Great Plains Metals has now commenced Stage 2 of the project and is actively preparing the work program and drill targets and expects to be drilling next month.

The company completed a private placement in the amount of $4.18-million in February, 2026, to ensure it was financed to progress the project through this next phase.

Everton project update

Five diamond drill holes were completed for a total of 678 metres at the Everton porphyry molybdenum-copper porphyry prospect in northern Victoria. Assays have been received for the first two holes and molybdenum and copper values typically ranged from 100 parts per million to 2,000 parts per million. The drilling did intercept the target UST-bearing cupola rocks; however, the mineralization is considerably weaker than what was previously mined. The company does not plan to carry out any further exploration work at Everton.

Peeyush Varshney, chief executive officer, commented: "These detailed logging results from drill hole GGDD004 at our Goodrich project are a highly encouraging step forward for our technical team and the pencil porphyry exploration program. Intersecting visible chalcopyrite and strong alteration zonation confirms that we are uncovering a potential significant porphyry copper-gold system.

"What makes this campaign even more compelling is our recent review of available historical drill core. Finding significant altered intervals that were never assayed will both increase our understanding of the porphyry copper-gold system and assist our technical team in generating additional Stage 2 drill targets.

"We look forward to receiving the formal laboratory assays, which will provide the definitive quantitative data needed to accurately evaluate the grade distribution and guide our next phase of targeted drilling."

About Great Plains Metals Corp

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

The flagship Goodrich project (New South Wales)

Located in the heart of New South Wales's premier copper-gold jurisdiction -- near the Yeoval township and roughly 70 kilometres northwest of Orange -- the project spans an extensive 290 square kilometres across exploration licences EL9243 and EL8538. The Goodrich project is situated within the world-class Lachlan fold belt and the highly endowed Macquarie Arc.

Proven mineral footprint

Historically the largest mine in the Yeoval district, Goodrich operated intermittently between 1868 and 1912. Production from its historic 46-metre open pit and 90-metre underground shafts yielded an estimated approximately 300 tonnes of copper, 159 kilometres of gold and 62 kilograms of silver, notably supporting a local smelter facility during its peak operational phases. Modern geological modelling 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

Great Plains Metals holds a 37.1-per-cent equity stake in Eversley Resources, giving the company low-cost exposure to the massive Eversley North Gawler Craton project in South Australia. Spanning an extensive 2,584 square kilometres within the prolific Olympic Dam IOCG (iron oxide copper-gold) province, the project targets shallow, high-intensity 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 metres, the project represents immediate, high-value asset diversification.

Qualified person

The scientific and technical data contained in this news release have been reviewed and approved by Douglas Kirwin, who serves as the qualified person under the definition of National Instrument 43-101.

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