Diablo Resources (ASX: DBO) is accelerating exploration activity across its Utah critical minerals assets, advancing work at the Star Range project and its recently acquired Horn Silver project.

At Star Range, earthworks have been completed at the North Star prospect in preparation for an upcoming diamond drilling program. The initial campaign will comprise five diamond drill holes for approximately 1,000 metres of drilling. The holes are designed to evaluate the subsurface scale, continuity and geometry of the mineralised breccia-vein system at depth, where surface sampling has returned high-grade silver of up to 3,043 grams per tonne (g/t) and antimony of up to 0.7%. Antimony is designated a critical mineral by the United States Government, reflecting its use in products such as flame retardants, lead-acid batteries and ammunition, alongside concerns over concentrated global supply chains.

At the historic Horn Silver project, reconnaissance work has commenced across the unpatented claims, with field teams undertaking geological mapping, regional sampling and validation of historical workings.

The company has acquired an 80% interest in 101 unpatented lode claims and holds an exclusive option to acquire 101 patented claims that together form the Horn Silver tenure package.

Chief Executive Officer Lyle Thorne said this enables the company to advance early-stage fieldwork within the unpatented claims while progressing the option exercise on the patented claims, which remains on schedule for completion in September.

Horn Silver hosts multiple historical workings, including the Horn Silver mine, where approximately 17 million ounces of silver were extracted at an average grade of 604 g/t between the late 1800s and the 1950s. The mine, located in Beaver County, was among Utah's notable historic silver producers, and the state remains an established mining jurisdiction today, hosting large-scale operations such as the Bingham Canyon copper mine.

"The completion of earthworks at Star Range and the progress made at Horn Silver mark important steps in advancing our district-scale critical minerals strategy in Utah," Mr Thorne said.

"We now have drill-ready access at Star Range and a clear pathway to define our maiden drill program at Horn Silver as initial reconnaissance and data integration continue.

"With both projects moving forward in parallel, the company is well positioned to begin testing high-priority targets across two highly prospective mineralised system in coming months."

The initial exploration phase at Horn Silver is designed to refine structural interpretations, confirm the distribution of mineralised zones and support systematic target ranking. Early observations continue to reinforce the presence of widespread polymetallic mineralisation across multiple structural corridors, consistent with a district-scale carbonate-replacement system, a deposit style well documented as a source of silver, lead and zinc mineralisation.

In parallel, the company is continuing to review extensive historical datasets to rank near-mine extensions and regional prospect targets for the planned upcoming maiden drill program. Upcoming milestones for readers to track include the start of the Star Range drilling campaign and its initial assay results, completion of the Horn Silver patented claim option in September, and the definition of the maiden drill program as the historical data review advances.

Prior to the market open, DBO shares were steady at 1.8 cents, with a market capitalisation of $9.091 million.