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Diablo (ASX: DBO) starts maiden North Star drilling to test high-grade Utah silver-antimony system at depth

Jane Morgan Management

Key Facts:

• First-ever drilling at North Star – Diablo has kicked off maiden diamond drilling beneath surface mineralisation grading up to 3,043 g/t silver and 0.7% antimony.
• Plenty of room to scale the program – The initial campaign covers ~1,000m across five holes, with approvals already in place for up to 27 holes from 12 drill pads if results warrant follow-up.
• North Star is only the first target – Diablo is also advancing a >3km silver-antimony trend at South Star, a ~400m copper-in-soil anomaly at East Star, and drill targeting at nearby Horn Silver, giving it multiple exploration catalysts across its Utah portfolio.

2 September 2026 – Perth, WA | Diablo Resources (ASX: DBO) has started maiden diamond drilling at its North Star Prospect in Utah, marking the first direct subsurface test of a silver-antimony system where surface sampling has returned grades of up to 3,043 g/t silver and geophysics has defined multiple priority targets.

The approximately 1,000-metre program will comprise five diamond holes targeting silver-antimony-copper-gold mineralisation beneath high-grade surface results and coincident geophysical anomalies.

For Diablo, the drilling represents a shift at North Star from surface exploration and target definition into testing the scale, continuity and geometry of the mineralised system at depth. The program will also provide the first subsurface geological information needed to refine the company's exploration model and determine where subsequent drilling should be directed.

Previous surface sampling at North Star has returned results including 3,043 g/t silver with 1.37 g/t gold, 1,592 g/t silver with 0.7% antimony and 2,311 g/t silver with 0.4% antimony. The samples are selective point samples and are not considered representative of the average grade or width of the mineralised structures.

The initial holes will test targets generated by combining surface geochemistry, geological mapping and induced polarisation geophysics, including anomalies that coincide with mapped structures and high-grade mineralisation.

Existing approvals give Diablo scope to expand beyond the initial program, with up to 27 holes permitted from 12 drill pads. Any follow-up drilling will be determined by initial results and ongoing geological interpretation.

North Star is the first drill target within Diablo's wider Star Range exploration pipeline in Utah's Frisco Mining District. Exploration is continuing elsewhere across the project, including at South Star, where the prospective silver-antimony trend extends for more than 3,000 metres, and East Star, where an approximately 400-metre copper-in-soil anomaly has been defined.

The work also sits within Diablo's broader Utah critical minerals strategy. Star Range and the company's nearby Horn Silver Project are around 15 kilometres apart and host exploration targets prospective for silver, antimony, copper, gold and other metals. Silver, copper and antimony are included on the United States' final 2025 List of Critical Minerals, providing a strategic backdrop to the company's exploration focus.

CEO Lyle Thorne commented:

“Our U.S. exploration team is excited to have drilling underway at North Star. Star Range continues to demonstrate strong potential across multiple target zones, and this program will provide important subsurface data to guide the next phase of exploration.

With drilling underway at Star Range and ownership consolidated at Horn Silver, Diablo is well positioned to accelerate exploration across both projects. This activity comes against a strengthening market backdrop for silver and copper and aligns with recent U.S. critical-minerals policy initiatives aimed at strengthening domestic supply chains and supporting exploration, permitting and development of strategic mineral resources.

With multiple exploration programs now progressing across our Utah portfolio, we look forward to updating shareholders as drilling advances and results come to hand.”

Diablo will continue the initial North Star drilling program alongside geological logging, sampling and progressive assay submissions. Results will be incorporated into the North Star geological model to determine follow-up drilling priorities, while regional exploration and target ranking continue across South Star, East Star and other areas of Star Range.

At Horn Silver, the company is continuing to integrate recent reconnaissance results, refine priority drill targets and progress planning for maiden drilling, alongside the exercise of the option over the patented claims in accordance with the existing Option Agreement.

Contact details:

Jane Morgan

E:[email protected]‭

T: +61 405 555 618‬

Lyle Thorne
Chief Executive Officer
Diablo Resources Ltd
E: [email protected]
T: +61 (8) 6383 7837
W: diabloresources.com.au