Great Boulder (ASX:GBR) high grade drilling extends mineralisation beyond Side Well Resource

Great Boulder has reported further high grade drilling results from the Side Well Gold Project near Meekatharra in Western Australia, including drilling completed across Mulga Bill, Eaglehawk, Mulga Bill East, Flagpole and Golden Bracelet.

The company reported mineralisation outside the current resource in several areas, with RC drilling continuing at Eaglehawk, AC drilling continuing across the Eastern Corridor, and planning underway to start drilling at Peak Hill upon acquisition completion and receipt of final approvals.

The Side Well Gold Project Mineral Resource, reported in December 2025, stands at 16,042,000 tonnes at 2.0g/t Au for 1,021,000oz Au.

Highlights

• Drilling extended known mineralisation beyond the current resource in several areas.
• Drilling between Mulga Bill and Eaglehawk confirmed gold mineralisation within an approximate 100m gap.
• Mulga Bill East drilling defined mineralisation across an approximate 900m strike length.
• Diamond hole 25MBDD004 returned 0.45m @ 165g/t Au from 454.5m.
• RC drilling is continuing at Eaglehawk and AC drilling continues across the Eastern Corridor.
• Planning is underway to start drilling at Peak Hill upon acquisition completion and receipt of final approvals.

At Mulga Bill and Eaglehawk, 78 RC holes were completed, with drilling ongoing and several holes yet to be assayed, including drilling at Mulga Bill East, within the gap between Mulga Bill and Eaglehawk, and extensional drilling within both deposits.

The company said the Mulga Bill and Eaglehawk resources are separated by an approximate 100m gap, an area of limited previous drilling.

Recent RC drilling returned 4m @ 23.6g/t Au from 134m in 26EHRC002, 9m @ 14.1g/t Au from 91m in 26EHRC003 and 4m @ 3.53g/t Au from 144m in 26MBRC014.

The company said this drilling confirmed gold mineralisation in this area and indicates potential for continuous gold mineralisation joining the two deposits over a combined strike length of 2.5km.

At Mulga Bill East, drilling has defined gold mineralisation over an approximate 900m strike length, with the company noting part of this area was included in the 2023 MRE, but had not been updated in December 2025.

Recent drilling on the eastern side of Mulga Bill intersected west dipping high grade vein hosted mineralisation, including 21m @ 7.24g/t Au from 99m in 26MBRC021, 19m @ 2.64g/t Au from 92m in 26MBRC023 and 6m @ 8.04g/t Au from 156m in 26MBRC026, with the company saying recent drilling indicates continuity of veins across the gap between Mulga Bill and Mulga Bill East.

Diamond hole 25MBDD004 intersected 0.45m @ 165g/t Au from 454.5m at the northern end of Mulga Bill, with the company saying several other deep holes in this program are yet to be sampled and assayed, while a separate RC program completed 500m south of Mulga Bill returned 2m @ 17.5g/t Au from 206m in 26MBRC001.

At Golden Bracelet, 10 RC holes were drilled testing dip and strike continuations of mineralisation in the December 2025 MRE.

At Flagpole, 19 RC holes were drilled to infill and extend the maiden MRE announced in December 2025, with the company reporting this work extended Flagpole by approximately 150m to the north, while mineralisation remains open to the north, south and at depth.

Results included 7m @ 2.87g/t Au from 73m in 26FPRC012 and 4m @ 1.92g/t Au from 164m in 26FPRC001.

Great Boulder Managing Director Andrew Paterson said,

“These results show that we are exceptionally well on track to grow the Side Well resource from 1Moz.”

He also said drilling is continuing at Mulga Bill and Eaglehawk while the AC rig continues testing regional targets.

Drilling is ongoing, with multiple rigs exploring targets within the Eastern and Central corridors, while RC drilling continues at Eaglehawk and AC drilling continues across the Eastern Corridor.

The company said planning is underway to commence field work at Peak Hill as quickly as possible once the acquisition is completed.

It also said planning is underway for a 40,000m drilling campaign in the first 6 months, with Peak Hill drilling to begin following acquisition completion and receipt of final approvals.

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