Mineral Resource update delivers high-grade, shallow Shelf Zone,
outside of critical habitat
| • | Drill and geophysical data define a highly promising “Shelf Zone” within the South Basin. |
| o | Li-B mineralisation is notably shallower than elsewhere in the basin. |
| o | Lithium grades are significantly higher compared to the resource average. |
| o | Mineralised sedimentary layers are relatively flat lying with favourable geotechnical characteristics. |
| o | Lies completely outside of Critical Habitat. |
| o | Largely within the pit shell currently being permitted by the BLM. |
| • | Given the significance of this zone, the Resource estimate is being updated and will be further updated within the next three months as pending drill results are received and finalized. Drilling was completed in January 2024 and results for 12 holes are pending. |
| • | For the first time, the April 2024 Resource is subdivided into three separate streams: |
| o | Stream 1 – high-boron lithium mineralisation (low clay content) |
153Mt Resource containing 1.33Mt LCE and 11.26Mt BAE.
| o | Stream 2 – low-boron lithium mineralisation (low clay content) |
142Mt Resource containing 1.20Mt LCE and 1.16Mt BAE.
| o | Stream 3 – low-boron lithium mineralisation (high clay content) |
56Mt Resource containing 0.72Mt LCE and 0.39Mt BAE.
| • | Streams 1 and 2 are both suitable for vat leach processing based on extensive testwork – although only Stream 1 is included in the 2020 DFS mine plan and economic analysis. |
| • | Stream 3 is high in clay and is not amenable to Rhyolite Ridge vat leaching. This material will be stockpiled and is subject to a research partnership with Eco Pro. |
| • | The 2022-2023 drilling was solely focused on the southern and southeastern extension of the deposit and has added approximately 32Mt of Stream 1 and Stream 2 mineralisation, the majority of which is in Measured and Indicated resource categories. |
| • | 71% increase in the overall Measured Resource (75Mt) compared to 2023 (44Mt). |
| • | Allows mining to commence outside of Critical Habitat and further underpins Ioneer’s commitment to minimise and manage mine related activity within Critical Habitat, consistent with the Mine Plan of Operation currently under NEPA review. |
| • | Updated mineral resource and ore reserve estimate to be completed over the next three months. |
Tuesday 30 April 2024 – Ioneer Ltd (“Ioneer” or the “Company”) (ASX: INR, NASDAQ: IONR), is pleased to announce an updated Mineral Resource estimate for the South Basin at the Rhyolite Ridge Lithium-Boron Project located in Nevada, USA. The effective date for the updated Mineral Resource estimate is April 19, 2024.
Ioneer Ltd. (ASX: INR, NASDAQ: IONR) Suite 16.01, 213 Miller Street, North Sydney, NSW 2060 T: +61 2 9922 5800 W: Ioneer.com ABN: 76 098 564 606
Independent Mining Consultants, Inc (IMC) estimated the April 2024 Mineral Resource. The previous Resource estimate was completed in March 2023, and an Ore Reserve estimate in April 2020, for the Rhyolite Ridge Definitive Feasibility Study (‘DFS’).
For the first time, the Mineral Resource is being reported as three separate streams:
| • | Stream 1 – high-boron lithium mineralisation (low clay content) 153Mt Resource containing 1.33Mt LCE and 11.26Mt BAE.
|
| • | Stream 2 – low-boron lithium mineralisation (low clay content) 142Mt Resource containing 1.20Mt LCE and 1.16Mt BAE.
|
| • | Stream 3 – low-boron lithium mineralisation (high clay content) 56Mt Resource containing 0.72Mt LCE and 0.39Mt BAE. |
Streams 1, 2 and 3 all contain high levels of lithium. Stream 1 is differentiated by having high boron content (>5000ppm) and low clay content. Stream 2 is differentiated by having low boron content (<5000ppm) and low clay content. Stream 3 is differentiated by having low boron content and high clay content and is solely restricted to one stratigraphic unit within the deposit (M5 unit).
Streams 1 and 2 are both suitable for vat leach processing. Only Stream 1 is included in the 2020 DFS mine plan and economic analysis. Due to the high clay content of Stream 3, it cannot be processed through the same vat leach flowsheet and requires an alternative processing path. This material is subject to a research partnership with Eco Pro.
The total Resource decreased slightly compared to 2023 due to 1) an adjustment in density assumptions based on new, superior density data and 2) the updated geological/structural model which captured a break in continuity of the units where faulting has uplifted a block in the central part of the basin.
The total number and spacing of drill holes has resulted in a material increase in the portion of the Resource classified as Measured and Indicated, the two highest confidence categories. The Measured Resource for all three streams has increased from 44Mt to 75Mt, an increase of 71%.
The updated South Basin Mineral Resource Estimate comprises:
| • | Total Mineral Resource of 351 Mt |
| • | Contained lithium carbonate equivalent (LCE) of 3.25 Mt |
| • | Contained boric acid equivalent (BAE) of 12.82 Mt |
| • | Measured & Indicated Resource for Streams 1 & 2 of 214 Mt |
| • | Cut-off grades unchanged at 5,000ppm B (Stream 1) and 1,090ppm Li (Streams 2 & 3) |
| | | | | | | Contained |
Stream | Classification | Tonnage Ktonnes | Li ppm | B ppm | Li2CO3 Wt. % | H3BO3 Wt. % | Li2CO3 (kt) | H3BO3 (kt) |
1 | Measured | 43,178 | 1755 | 14657 | 0.93 | 8.38 | 403 | 3619 |
Indicated | 74,235 | 1599 | 12183 | 0.85 | 6.97 | 632 | 5171 |
Inferred | 35,608 | 1581 | 12144 | 0.84 | 6.94 | 300 | 2473 |
Total S1 | 153,021 | 1639 | 12872 | 0.87 | 7.36 | 1335 | 11262 |
2 | Measured | 17,160 | 1509 | 1566 | 0.80 | 0.90 | 138 | 154 |
Indicated | 79,264 | 1500 | 1560 | 0.80 | 0.89 | 633 | 707 |
Inferred | 46,096 | 1737 | 1139 | 0.92 | 0.65 | 426 | 300 |
Total S2 | 142,520 | 1578 | 1425 | 0.84 | 0.81 | 1197 | 1161 |
3 | Measured | 14,768 | 2454 | 1733 | 1.31 | 0.99 | 193 | 146 |
Indicated | 29,475 | 2420 | 1228 | 1.29 | 0.70 | 380 | 207 |
Inferred | 11,619 | 2388 | 605 | 1.27 | 0.35 | 148 | 40 |
Total S3 | 55,862 | 2422 | 1232 | 1.29 | 0.70 | 720 | 394 |
ALL | Grand Total | 351,403 | 1,739 | 6,379 | 0.93 | 3.65 | 3,251 | 12,817 |
Table 1. Summary of April 2024 Mineral Resource Estimate – Rhyolite Ridge South Basin
South Basin and The Shelf Zone
Rhyolite Ridge is a sediment-hosted lithium and boron deposit located in the Silver Peak Range of southwestern Nevada. Sedimentary layers containing lithium and boron were deposited into a lake bed approximately six million years ago. The lake formed within a closed structural basin measuring approximately 2 km by 6 km (South Basin). Over time, the lake filled with sediments and was eventually drained of water. The initially soft, sedimentary layers were turned into solid, competent rock over time. Today, the sedimentary rocks are up to 300m in thickness, can be subdivided into 11 separate units and are almost entirely concealed beneath a 20 m thick layer of unconsolidated alluvium (gravel).
Reprocessing and 3D modelling of detailed ground gravity and magnetic data coupled with drill hole information has resulted in a major advancement in the understanding of the architecture of the South Basin. In summary, at least four sub-basins have been identified within the South Basin. The sub-basins are separated by faults, flexures and fold axis that have either uplifted or down-dropped the sedimentary layers that host lithium and boron mineralisation. An uplifted block in the southeast portion of the South Basin that is herein referred to as “The Shelf Zone” was the primary focus of the most recent drilling. The Shelf Zone represents a highly prospective area due to 1) the shallow depth of the mineralized units, 2) the sediments sub-crop beneath unconsolidated gravel, 3) lithium grades are consistently higher than the Resource average, 4) sediments are relatively flat lying and 4) the entire area lies outside of Tiehm’s buckwheat critical habitat. The Shelf Zone measures approximately 1500 x 750 m and until recently, was largely undrilled. See Figure 1 below.
Within the area of The Shelf Zone, mineralised units lie within 30 metres of the surface and are covered by unconsolidated gravel. The mineralised units dip to the east at shallow angles which is likely to prove favourable for geotechnical stability of pit walls. Previously, these units were thought to dip to the west – toward the centre of the basin. The uplifted block that separates The Shelf from the deeper mineralised units to the west is well defined by gravity and magnetic data and has been confirmed with multiple drill hole intersections. Refer to cross-sections included in Appendix A.
Figure 1. Rhyolite Ridge South Basin showing contoured and coloured topography of the top of the B5 unit overlain on a coloured image of the 3D gravity model. “The Shelf” represents a broad area where the B5 is shallow, relatively flat and dips gently toward the east.
Figure 2. Rhyolite Ridge South Basin showing the areal extent of the B5 Resource coloured by resource category – Measured, Indicated and Inferred. The basin outline is shown as a black line.
Updated Density Measurements
The density analyses performed by Ioneer’s geotechnical consultants present during both the 2018 and 2022-2023 drilling programs followed a strict repeatable process in sample collection and analysis utilizing the Archimedes-principle (water displacement) method for density determination, with values reported in dry basis. This provided consistent representative data. Previous resource calculations were limited to data from the 2010 density data set. It was determined to exclude this data due to its small sample set and the inability to reproduce and validate data. The 2018 and 2022-2023 data aligned well and proved to be representative across the resource. This adjustment resulted in a reduction in the tonnage of the 2023 Resource Estimate which was approximately compensated for by the increased tonnage relating to the 2022-2023 drilling. The result was a minor net reduction in the total Resource tonnage.
Further detailed information is provided in:
| • | Appendix A - Mineral Resource Statement and Parameters |
| • | Appendix B – JORC Table 1 |
This ASX release has been authorised by Ioneer Managing Director, Bernard Rowe.
Chad Yeftich Ioneer USA Corporation | Daniel Francis FGS Global |
Investor Relations (USA) | Media Relations (USA) |
E: ir@Ioneer.com | E: daniel.francis@fgsglobal.com |
About Ioneer
Ioneer Ltd is the 100% owner of the Rhyolite Ridge Lithium-Boron Project located in Nevada, USA, the only known lithium-boron ore deposit in North America and one of only two known such deposits in the world. The Definitive Feasibility Study (DFS) completed in 2020 confirmed Rhyolite Ridge as a world-class lithium and boron project that is expected to become a globally significant, long-life, low-cost source of lithium and boron vital to a sustainable future.
In September 2021, Ioneer entered into an agreement with Sibanye-Stillwater where, following the satisfaction of conditions precedent, Sibanye-Stillwater will acquire a 50% interest in the Project, with Ioneer maintaining a 50% interest and retaining the operational management responsibility for the joint venture. In January 2023, Ioneer received a conditional commitment from the U.S. Department of Energy Loan Programs Office for up to $700 million of debt financing. Ioneer signed separate offtake agreements with Ford Motor Company and PPES (joint venture between Toyota and Panasonic) in 2022 and Korea’s EcoPro Innovation in 2021.
To learn more about Ioneer, visit www.Ioneer.com/investors.
Resource Estimate Advisors
Ioneer engaged the independent services of Independent Mining Consultants, Inc. (IMC) to compile and complete the updated South Basin Mineral Resource estimate, which has been verified and approved by their appointed Competent Person in compliance with JORC Code (2012).
Competent Persons Statement
The information in this report that relates to the April 2024 Mineral Resource estimate is based on information compiled by 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). Mr. Welhener consents to the inclusion in the report of the matters based on his information in the form and context in which it appears.
Important notice and disclaimer
Forward-looking statements
This announcement contains certain forward-looking statements and comments about future events, including Ioneer’s expectations about the Project and the performance of its businesses. Forward looking statements can generally be identified by the use of forward-looking words such as ‘expect’, ‘anticipate’, ‘likely’, ‘intend’, ‘should’, ‘could’, ‘may’, ‘predict’, ‘plan’, ‘propose’, ‘will’, ‘believe’, ‘forecast’, ‘estimate’, ‘target’ and other similar expressions within the meaning of securities laws of applicable jurisdictions. Indications of, and guidance on, the Conditional Commitment, financing plans, future earnings or financial position or performance are also forward-looking statements.
Forward-looking statements involve inherent risks and uncertainties, both general and specific, and there is a risk that such predictions, forecasts, projections and other forward-looking statements will not be achieved. Forward-looking statements are provided as a general guide only and should not be relied on as an indication or guarantee of future performance. Forward looking statements involve known and unknown risks, uncertainty and other factors which can cause Ioneer’s actual results to differ materially from the plans, objectives, expectations, estimates, and intentions expressed in such forward-looking statements and many of these factors are outside the control of Ioneer. Such risks include, among others, uncertainties related to the finalisation, execution, and funding of the DOE financing, including our ability to successfully negotiate definitive agreements and to satisfy any funding conditions, as well as other uncertainties and risk factors set out in filings made from time to time with the U.S. Securities and Exchange Commission and the Australian Securities Exchange. As such, undue reliance should not be placed on any forward-looking statement. Past performance is not necessarily a guide to future performance and no representation or warranty is made by any person as to the likelihood of achievement or reasonableness of any forward-looking statements, forecast financial information or other forecast. Nothing contained in this announcement, nor any information made available to you is, or shall be relied upon as, a promise, representation, warranty or guarantee as to the past, present or the future performance of Ioneer.
Except as required by law or the ASX Listing Rules, Ioneer assumes no obligation to provide any additional or updated information or to update any forward-looking statements, whether as a result of new information, future events or results, or otherwise.