11 December 2025
Locksley Resources Limited (ASX: LKY / OTCQX: LKYRF / ADR: LKYLY) has commenced a key phase of its U.S. mine-to-market critical minerals strategy, issuing an Expression of Interest (EOI) to Tier 1 U.S. engineering firms for the Scoping Engineering Design of the Desert Antimony Mine pilot plant.
The EOI marks a significant milestone in Locksley’s accelerated development pathway, which aims to establish a fully integrated domestic supply chain for antimony, a critical mineral essential to defence systems, semiconductors, and advanced metal alloys.
Strong Interest from Leading U.S. Engineering Firms
Beginning with direct engagement in October 2025, the Company’s Chief Operating Officer met with senior U.S. engineering executives to align on study objectives, execution frameworks and the availability of local capability. This has now advanced to the formal issuance of an EOI to a shortlist of Tier 1 engineering groups.
The response has been “highly encouraging,” with firms recognising the Project’s strong alignment with U.S. federal initiatives aimed at rebuilding domestic critical mineral supply chains. Respondents also acknowledged Locksley’s disciplined approach to early technical de-risking and best-practice project development.
A key objective of the EOI is to identify partners with demonstrated experience operating in San Bernardino County — including permitting pathways, regulatory engagement and stakeholder management — viewed as essential for timely project advancement.
Integrated Metallurgical and Engineering Workstreams
Locksley continues to undertake metallurgical optimisation in parallel with the EOI, refining processing flowsheets, improving recoveries and validating mass balance assumptions. These results will directly inform the engineering basis for the Scoping Study, enabling concurrent progression of technical workstreams.
This integrated approach is designed to maintain project momentum and support robust technical definition.
Locksley Managing Director & CEO Kerrie Matthews said:
"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 as an Expression of Interest. The strong response to our Expression of Interest highlights confidence in our development strategy and confirms that we have access to the technical capability and local U.S. experience required to advance the Project efficiently.
Our ongoing metallurgical optimisation work will feed directly into the scoping study, allowing engineering design, economic evaluation and project planning to progress without delay. This integrated execution strategy ensures the Desert Antimony Project continues to advance at speed toward the next stage of development."
Next Steps
Locksley outlined the key upcoming milestones:
• Evaluation of EOI submissions, including technical and local operating capabilities
• Issuance of a formal Request for Proposal (RFP) for the PFS and site investigation scopes by mid-Q1 2026
• Award of professional services contracts in separable packages, with processing-related scopes targeted for completion by end-Q1 2026, and mine engineering scopes aligned with exploration outcomes at the Desert Antimony Mine Project.
The Company also confirmed it is well funded for its 2026 work programs, with more than $20 million in cash.
About us:
About the Desert Antimony Project and Mojave Project
The Desert Antimony Mine, last operated in 1937, is one of the highest-grade known antimony occurrences in the United States, situated within Locksley’s broader Mojave Project in California.
The Mojave Project comprises over 491 claims across key prospect areas, including the North/Northeast Blocks and the El Campo Prospect, directly adjacent to or along strike from MP Materials’ Mountain Pass Mine — North America’s only producing rare earth mine.
Locksley’s integrated mine-to-market strategy focuses on rebuilding domestic critical mineral capability, supported by partnerships with leading U.S. research institutions and industry collaborators.
Contact details:
Jane Morgan
Investor & Media Relations
T: +61 (0) 405 555 618
[email protected]