Name of the Project
Rhyolite Ridge lithium/boron project.

Location
Nevada, US.

Project Owner/s
Emerging miner ioneer.

Project Description
A definitive feasibility study (DFS), completed in April 2020, has placed Rhyolite Ridge as the most attractive project for the production of lithium carbonate, lithium hydroxide and boric acid globally.

The lithium and boron mineral resource is estimated at 146.5-million metric tonnes, including an ore reserve of 60-million metric tonnes – an increase in the reserve from the previous estimate of 280% over the 26-year life-of-mine (LoM).

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

The resource remains open in three directions, allowing for a potential extension to the LoM.

The project will mine 2.5-million metric tons a year of ore over the LoM to produce about 20 600 t/y of lithium carbonate, or about 22 000 t/y of lithium hydroxide and 174 400 t/y of boric acid, on average.

Potential Job Creation
Not stated.

Net Present Value/Internal Rate of Return
The project has an after-tax net present value, at an 8% real discount rate, of $1.265-billion, and an unlevered internal rate of return of 20.8%, with a payback of 5.2 years from the start of first production.

Capital Expenditure
The DFS estimates that the total capital expenditure to complete the project will be $785-million, including an 8% contingency.

This represents an increase of $186-million from the prefeasibility study.

The US Department of Energy has said it will lend ioneer up to $700-million to develop the mine.

Planned Start/End Date
ioneer expects to start production in 2025 to support urgent requirements for battery materials in the US.

Latest Developments
Emerging miner ioneer has announced a 45% increase in the project's mineral resource estimate. The updated estimate, incorporating new data from 12 drill holes completed in 2024, now stands at 510-million tonnes containing 3.97-million tonnes of lithium carbonate equivalent and 14.66-million tonnes of boric acid equivalent.

The revised estimate falls entirely within the fully permitted project area, which received US government approval in October 2024 and is supported by a $996-million loan from the US Department of Energy’s Loan Programs Office.
Notably, 81% of the mineral resource is now classified as measured and indicated, strengthening the project's economic outlook ahead of an anticipated ore reserve estimate release in April 2025.

“No other lithium project offers this level of flexibility and economic advantage. In today’s low lithium price environment, the company can prioritize high-boron ore (Stream 1) over low-boron ore (Stream 2) to optimise the proportion of total revenue derived from boron,” ioneer MD Bernard Rowe has stated. 

Boron is expected to contribute 30% to 40% of the project’s revenue, with lithium accounting for the remaining 60% to 70%.

The announcement follows a setback for the project, as Sibanye-Stillwater withdrew from its planned joint venture (JV) with Ioneer in February 2025. The JSE- and New York-listed miner had been set to acquire a 50% stake in the JV, with Ioneer retaining operational management responsibilities. However, after a management review and due diligence, Sibanye’s board determined that Rhyolite Ridge did not meet its investment hurdle rates at prudent pricing assumptions and opted not to proceed with the project.

Key Contracts, Suppliers and Consultants
Fluor (DFS).

Contact Details for Project Information
ioneer, tel +61 2 9922 5800.
Sibanye-Stillwater, tel +27 11 278 9600 or email ir@sibanyestillwater.com.