Locksley Resources taps top engineers to fast-track US antimony push

Old workings at Locksley Resources’ historic Desert antimony mine in California.

The ASX-listed critical minerals player Locksley Resources (ASX: LKY) has kicked off an expression of interest (EOI) process to recruit tier-one engineering firms in the US for scoping-stage engineering and pilot-plant designs at its Desert antimony mine in California.

The formal tender follows on from direct engagement earlier this year between its senior management team and leading US engineering groups, with early conversations now crystallising into a formal selection process.

According to the company, the response has been strong, with potential partners recognising both the quality of the project and how neatly it lines up with US federal priorities around rebuilding critical mineral capacity.

Management says proven local experience in San Bernardino County – home to Locksley’s antimony project - is non-negotiable, since smooth permitting, regulatory know-how and stakeholder relationships can often be the difference between shaving months off the schedule and losing them altogether.

In parallel with the EOI, the company has continued to push forward with its metallurgical optimisation work, enabling real-time data to flow directly into design decisions. Ongoing tests are being focused on refining processing flowsheets, improving recoveries and locking down mass balance assumptions.

Lockley says the practical approach has been designed to maintain momentum and de-risk the project early, while positioning the Desert antimony mine for rapid progression into more advanced studies. Once the work is wrapped up, the results will be fed directly into a broader pre-feasibility push planned for 2026.

With the completion of our recent capital raise, we are fast-tracking our 2026 initiatives. We are now engaging with leading U.S. engineering firms. The strong response to our expression of interest highlights confidence in our development strategy. It confirms that we have access to the technical capability and local US experience required to advance the project efficiently.

Locksley Resources Managing Director and CEO Kerrie Matthews

At the heart of Locksley’s push is Washington’s need for its own critical minerals backbone. Antimony, which is used in semiconductors, batteries and defence alloys, has shot up the priority list after China, which controls almost 80 per cent of global supply, slammed the door on exports in 2024. Prices promptly rocketed 300 per cent to more than US$55,000 (A$83,000) a tonne, exposing just how fragile Western supply chains had become.

To help the US cut the cord entirely, the company is rolling out a bold mine-to-market strategy built around its Desert project, twinning its fast-tracked resource development plan with new processing technologies being designed in partnership with Houston-based Rice University and Hazen Research.

And on the ground, momentum is starting to bite. Locksley has now paid the all-important reclamation bond, securing the final nod from the US Bureau of Land Management for an aggressive new drilling blitz. With approvals locked in, the gates have swung open for a 16-hole, 2,300-metre assault across the Main and North target zones.

The Desert antimony prospect is shaping up as one of the highest-grade antimony occurrences ever recorded on US soil. Although the operation hasn’t seen a tool since 1937, it appears to have plenty up its sleeve. Last year’s surface sampling lit up like a pinball machine, with eye-watering grades up to 46 per cent antimony and more than a kilogram of silver per tonne.

Adding to the prospect’s credentials, a high-resolution LiDAR survey recently traced 236 metres of historic underground development, revealing four mining levels stretched along a 130-metre strike. The scan captured the geometry of multiple old tunnels and adits, highlighting three quartz-carbonate-stibnite veins likely targeted a century ago. Locksley says the resulting 3D model has given it an unprecedented window into the subsurface and a geological roadmap for the drill program.

Moving forward, Locksley says it will assess EOI submissions, issue a formal request for proposal by mid-March and begin awarding separate engineering work packages by the end of the first quarter. Processing-related scopes will take priority, with mine engineering timed to align with upcoming exploration results at Desert Antimony.

For punters, the message seems clear. Locksley is not waiting for sentiment to shift, but instead building the technical and commercial foundations now, betting that when domestic antimony supply becomes a national imperative, projects with momentum will be the ones closest to the front of the queue.

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