Diablo Resources (ASX:DBO) has strengthened its U.S. critical minerals portfolio after shareholders approved the company's acquisition of an 80% interest in the Horn Silver Project in Utah, marking a major milestone during the June quarter.

The acquisition significantly expands Diablo's presence in one of the United States' historic mining districts and complements its nearby Star Range Project, located approximately 15 kilometres away. The Horn Silver project covers roughly 13.2 square kilometres across 201 claims, including 101 patented claims, which the company said provides potential advantages for future access and permitting.

Diablo stated that the project hosts multiple exploration opportunities, including interpreted extensions beneath the historic mine, induced polarisation anomalies, shallow gold-silver mineralisation, and regional copper-silver skarn targets. Rock sampling at Horn Silver returned assays of up to 1,310g/t silver and 0.2% antimony, supporting the view that the area hosts a large, underexplored silver-antimony-copper system. Antimony is included on the U.S. Government Critical Minerals List, and both antimony and silver carry strategic relevance across industrial, energy, and defense supply chains.

With shareholder approval secured, Diablo is now positioned to complete the acquisition and begin advancing exploration across the project.

Exploration also continued to yield encouraging results at the company's Star Range Project during the quarter. Rock and soil sampling returned assays of up to 534g/t silver, 0.19% antimony, 1% copper, and 1.04g/t gold, extending known mineralised trends and identifying new target areas.

At the South Star prospect, soil sampling outlined a silver-antimony anomaly extending for more than one kilometre and remaining open to the northeast. When combined with historical data, the prospective trend now extends for more than 2.5 kilometres.

The company also identified a new gold-anomalous corridor at the Utah TLA lease, where mapping and sampling outlined an approximately 300-metre zone of altered rocks with assays up to 1.04g/t gold.

Preparations for Diablo's maiden drilling program at the North Star Prospect advanced during the quarter, with permitting applications lodged and logistics progressing. Subsequent to quarter end, the company received final regulatory approval to begin drilling. The initial campaign will comprise approximately 1,000 metres across five diamond drill holes, while existing approvals provide flexibility for up to 27 drill holes from 12 drill pads. The program will be the first test of the prospect's mineralised system at depth.

Diablo also completed the second tranche of its $3.5 million capital raising after the quarter, providing funding to advance exploration across both the Horn Silver and Star Range projects. The company said the funds will support drilling at Horn Silver, the maiden North Star drilling campaign, regional exploration, and ongoing target generation across its growing Utah portfolio.

DBO is currently trading at $0.13 per share.