Reserves & Resources

A summary of the April 2024 Mineral Resource estimate is provided in the table below. Note that Mineral Resources are reported inclusive of the Ore Reserve.

April 2024 Mineral Resource Estimate for Rhyolite Ridge South Basin

notes

1. Kt = thousand tonnes; Li = lithium; B = boron; ppm = parts per million; Li₂CO₃ = lithium carbonate; H₃BO₃ = boric acid; mt = million tonnes.
2. Totals may differ due to rounding, Mineral Resources reported on a dry in-situ basis. Lithium is converted to Equivalent Contained Tonnes of Lithium Carbonate (Li₂CO₃) using a stochiometric conversion factor of 5.322, and boron is converted to Equivalent Contained Tonnes of Boric Acid (H₃BO₃) using a stochiometric conversion factor of 5.718. Equivalent stochiometric conversion factors are derived from the molecular weights of the individual elements which make up Lithium Carbonate (Li₂CO₃₎ and Boric Acid (H₃BO₃).
3. The statement of estimates of Mineral Resources has been compiled by Mr. Herbert E. Welhener, a Competent Person who is a Registered Member of the SME (Society for Mining, Metallurgy, and Exploration), and is a QP Member of MMSA (the Mining and Metallurgical Society of America). Mr Welhener is a full-time employee of Independent Mining Consultants, Inc. and is independent of Ioneer and its affiliates. Mr Welhener has sufficient experience that is relevant to the style of mineralisation and type of deposit under consideration and to the activity being undertaken to qualify as a Competent Person as defined in the 2012 Edition of the ‘Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves’ (JORC Code 2012).
4. All Mineral Resource figures reported in the table above represent estimates at April 19, 2024. Mineral Resource estimates are not precise calculations, being dependent on the interpretation of limited information on the location, shape and continuity of the occurrence and on the available sampling results. The totals contained in the above table have been rounded to reflect the relative uncertainty of the estimate.
5. Mineral Resources are reported in accordance with the Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves (The Joint Ore Reserves Committee Code – JORC 2012 Edition).
6. The Mineral Resource estimate is the result of determining the mineralized material that has a reasonable prospect of economic extraction. In making this determination, constraints were applied to the geological model based upon a pit optimization analysis that defined a conceptual pit shell limit. The conceptual pit shell was based upon a net value per tonne calculation including a 5,000ppm boron cut-off grade for high boron – high lithium (HiB-Li) mineralization (Stream 1) and 1,090ppm lithium cut-off grade for low boron (LoB-Li) mineralization below 5,000ppm boron broke in to two material types low clay and high clay material respectfully (Stream 2 and Stream 3). The pit shell was constrained by a conceptual Mineral Resource optimized pit shell for the purpose of establishing reasonable prospects of eventual economic extraction based on potential mining, metallurgical and processing grade parameters identified by mining, metallurgical and processing studies performed to date on the Project. Key inputs in developing the Mineral Resource pit shell included a 5,000ppm boron cut-off grade for HiB-Li mineralization, 1,090ppm lithium cut-off grade for LoB-Li low clay mineralization and 1,090 ppm lithium cut-off grade for LoB-Li high clay mineralization; mining cost of US$1.54 /tonne; plant feed processing and grade control costs which range between US$52.34/tonne and US$87.43/tonne of plant feed (based on the acid consumption per seam based on the mineral resource average grades); boron and lithium recovery for Stream 1 of 80.2% and 85.7%; Stream 2 and 3: M5 65% and 78%, B5 80% and 86%, S5 50% and 88%, L6 37% and 85%,  respectively; boric acid sales price of US$1,016.67/tonne; lithium carbonate sales price of US$17,868.50/tonne.

In December 2022, the United States Fish and Wildlife Service (USFWS) listed Tiehm’s buckwheat as an endangered species under the Endangered Species Act (ESA) and has designated critical habitat by way of applying a 500 m radius around several distinct plant populations that occur on the Project site. Ioneer is committed to the protection and conservation of the Tiehm’s buckwheat. The Project’s Mine Plan of Operations submitted to the BLM in July 2022 and currently under NEPA review has no direct impact on Tiehm’s buckwheat and includes measures to minimise and mitigate for indirect impacts within the designated critical habitat areas identified.

The mineral resource pit shell used to constrain the April 2024 mineral resource estimate was not adjusted to account for any impacts from avoidance of Tiehm’s buckwheat or minimisation of disturbance within the designated critical habitat. Environmental and permitting assumptions and factors have not been taken into consideration during modifying factors studies for the Project. The tonnes and grade within the avoidance polygons have not been removed from the Mineral Resources for the April 2024 estimate. Environmental and permitting assumptions and factors may be taken into consideration during future modifying factors studies for the Project. These permitting assumptions and factors may result in potential changes to the Mineral Resource footprint in the future.