Australia- and US-listed Ioneer has secured a key legal victory after a US federal court upheld approvals for its flagship Rhyolite Ridge lithium-boron project in Nevada.

The US District Court for the District of Nevada dismissed all challenges in the case Center for Biological Diversity v. Stone-Manning, confirming that the Bureau of Land Management and the US Fish and Wildlife Service had complied with key environmental and land-use legislation in approving the project.

The ruling found that the agencies met requirements under the Endangered Species Act, National Environmental Policy Act and Federal Land Policy and Management Act.

Ioneer said the decision was a milestone for the project, which is expected to produce both lithium and boron – two critical minerals used in batteries, permanent magnets, semiconductors and energy systems. The company added that the project would support US efforts to strengthen domestic supply chains and reduce reliance on foreign sources.

MD Bernard Rowe said the outcome reflected the extensive review and permitting process undertaken over several years.

“Today’s outcome is a credit to all involved parties in the thorough assessment and approval process. We look forward to bringing our long-term, low-cost and stable supply of lithium and boron online,” he said.

Ioneer noted that it had worked for more than six years with federal, state and tribal stakeholders, as well as the local Fish Lake Valley community, to advance the project responsibly.

The company is now focused on completing its strategic partnering process and moving towards construction. Rhyolite Ridge is expected to generate hundreds of jobs and provide a domestic source of critical minerals for US industries, including electric vehicles and defence applications.

The project is one of the few known lithium–boron deposits globally and is considered a cornerstone development within Nevada’s emerging “Lithium Loop”.

Ioneer secured a $996-million loan from the US Department of Energy in January last year and received its final federal permit in October 2024, concluding a permitting process that began in 2020. The company has also signed offtake agreements with major industry players, including Ford Motor Company, Prime Planet Energy & Solutions, and EcoPro Innovation.