Name of the Project
Rhyolite Ridge lithium/boron project.

Location
Nevada, US.

Project Owner/s
Emerging miner ioneer.

Project Description
Rhyolite Ridge ore reserves more than quadrupled from 60-million tonnes in 2020 to 247-million tonnes in June 2025, delivering a mine life of 95 years. The project will produce at least three saleable chemical products – lithium carbonate, lithium hydroxide monohydrate and boric acid.

The ore reserve contains a total of 1.92-million tonnes of lithium carbonate equivalent (LCE) and 7.68-million tonnes of boric acid equivalent, underpinning plans for a large, long-life, low-cost expandable operation, producing lithium carbonate, boric acid and then battery-grade lithium hydroxide.

The mine plan comprises almost entirely reserve material, with nearly 50% of that being proven ore reserves.

Rhyolite Ridge ore will be processed by vat acid leaching, impurity removal, evaporation, and crystallisation, following a flowsheet developed for this project using known and commercially proven equipment and technology.

By prioritising high boron ore in the first 25 years of production, the project is poised to produce an average of 19 200 t/y of LCE and 116 400 t/y of boric acid.

The resource remains open in three directions, allowing for a potential extension to the life-of-mine.

Potential Job Creation
About 400 to 500 jobs are expected to be created during construction and 250 to 300 jobs during operations.

Net Present Value/Internal Rate of Return
The project has compelling economics with an after-tax net present value of $1.37-billion, and an unlevered, after-tax internal rate of return of 14.5%.

Capital Expenditure
Total capital expenditure to complete the project is estimated at $1.67-billion, including a 10% contingency.

Planned Start/End Date
First production is expected within 36 months of a final investment decision.

Latest Developments
ioneer has formally started a strategic partnering process to identify a new equity partner for the Rhyolite Ridge project.

The announcement follows recent technical milestones, including a significant ore reserve upgrade and updated project economics.

ioneer has appointed Goldman Sachs & Co as financial adviser to assist with the process, which is expected to take at least four months.

“The Rhyolite Ridge project is unique in the global lithium and boron sectors,” ioneer said in a statement on June 26, citing its capacity to produce high-purity lithium and boron chemicals on site, its dual revenue stream from lithium (75%) and boron (25%), and strong project fundamentals.

The company has said that the project is shovel-ready, with a Class 2 capital cost estimate and about 70% of engineering complete. It also has all major permits in place and a conditional $996-million loan from the US Department of Energy’s Loan Programs Office.

Offtake agreements for lithium and boron have already been secured with “blue-chip partners", ioneer noted in the press statement.

The strategic partnering initiative follows the withdrawal of Sibanye-Stillwater from a planned joint venture (JV) earlier this year. In February,  Johannesburg- and New York-listed Sibanye-Stillwater announced it would not proceed with the 50:50 JV, citing the project’s failure to meet its investment hurdle rates at prudent pricing assumptions. 

Sibanye’s withdrawal prompted ioneer to re-evaluate its project financing strategy and seek a new strategic partner to support construction and long-term development.

Key Contracts, Suppliers and Consultants
Fluor (definitive feasibility study).

Contact Details for Project Information
ioneer, tel +61 2 9922 5800 or email ir@ioneer.com.