ioneer Ltd. provided an update on its Rhyolite Ridge Project, the only known lithium-boron ore deposit in North America. Once operational, Rhyolite Ridge, located in Esmeralda County, Nevada, is expected to become a globally significant, low-cost source of lithium and boron. comments will be considered and where appropriate, incorporated into a final EIS which will be released ahead of a Record of Decision (ROD).

Mineral Resource and Ore Reserve Estimates: Ioneer completed 53 drill holes targeting the southern extension of the lithium-boron deposit in order to collect and provide valuable geotechnical information for the Project's evaluation required under the National Environmental Policy Act (NEPA). The 53 holes were drilled outside of the current 360Mt Resource over an area of approximately 0.8 km compared to the 3 km footprint of the current Resource. The four holes (3 locations) that did not intersect mineralized sediments were the furthest south holes and intersected volcanic rocks that underlie and form the margins of the sedimentary basin (South Basin).

Concurrently, Ioneer collected samples for geochemical analysis and metallurgical testing and expects results in April and May ahead of updates to the mineral resource and ore reserve estimates. Detailed engineering design at Rhyolite Ridge is now approximately 70% complete, which places the Project well-ahead of other comparable US development projects. Ioneer anticipates minimal engineering spending ahead of its Final Investment Decision (FID) expected later this year.

The current Rhyolite Ridge Mineral Resource estimate, all of which is located within the expected permitted boundary, includes: 157Mt of high-boron lithium (clay-poor); 128Mt of low-boron lithium (clays-poor); 77Mt of clay-rich lithium. Only 64Mt (26 years) of the high-boron Resource was included in the economic analysis reported in the 2020 Definitive Feasibility Study (DFS). Current estimates reflect multiple opportunities to increase production over time and extend the life of the Project.

Ioneer intends to report on metallurgical leach test work of the low-boron material during April and May. The test work is aimed at determining the most efficient way to process this material and provide options for increasing annual lithium production.