Rhyolite Ridge Drilling Update and Maiden Ore Reserve...Resource estimate at 1,050ppm lithium and...

ioneer Ltd. (ASX: INR) Suite 203, 161 Walker Street, North Sydney, NSW 2060 T: +61 2 9922 5800 W: ioneer.com ABN: 76 098 564 606

Rhyolite Ridge Drilling Update and Maiden Ore Reserve

Highlights

• Drilling at Rhyolite Ridge, Nevada has intercepted shallow, high-grade lithium and boron that may improve cash flow in the first few years of mining by:

o Increasing boron grades mined o Lowering the strip ratio

• Maiden Ore Reserve containing the equivalent of 160,000 tonnes of lithium carbonate and 1.1 million tonnes of boric acid

Friday, 21 December 2018 – Emerging lithium-boron supplier, ioneer Ltd (ioneer or the Company) (ASX: INR) today announced preliminary drilling results and a maiden Ore Reserve for its 100%-owned Rhyolite Ridge Lithium-Boron Project (Rhyolite Ridge or the Project) in Nevada, USA.

A drilling program comprising approximately 46 holes is being undertaken to upgrade the current lithium-boron (Searlesite) Mineral Resource at Rhyolite Ridge to the Measured category and extend high-grade, shallow mineralisation to the south of the proposed starter pit.

Initial assays have been received from the first nine holes showing:

• Higher boron grades (circa 30%) than currently modelled for the area planned to be mined during the first few years; and

• Extension to the south of shallow, high-grade lithium-boron mineralisation.

The Company released its Rhyolite Ridge Pre-Feasibility Study (PFS) on 23 October 2018. The PFS included a two-stage mine development – a starter pit covering the first seven years and an expanded pit covering a mine life of over 30 years.

A maiden Ore Reserve has been estimated for the first stage of mine development:

• 15.8 million tonnes at 1,900ppm lithium (equivalent to 1.0% lithium carbonate) and 12,200ppm boron (equivalent to 7.0% boric acid).

• Containing the equivalent of 160,000 tonnes of lithium carbonate and 1.1 million tonnes of boric acid.

The Indicated Mineral Resource comprises 950,000 tonnes of lithium carbonate and 7.5 million tonnes of boric acid (inclusive of the Ore Reserve).

Managing Director of ioneer, Mr Bernard Rowe, commented:

“These drilling results extend and further confirm high-grade shallow mineralisation at the Rhyolite Ridge Lithium-Boron Project. The strong boron grades within and to the south of the proposed starter pit are likely to provide stronger cash flow in the early years of the Project.

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“With the aim of upgrading the current Mineral Resource and extending the shallow lithium-boron mineralisation further to the south, the three rigs currently on site will continue drilling into 2019.

“This work is a fundamental part of the Rhyolite Ridge Definitive Feasibility Study (DFS), which Fluor Corporation has recently commenced.

“The recently completed PFS demonstrated the Project’s scale, long life and potential to become the lowest cost lithium producer in the world as well as the largest lithium producer in the United States with annual production of 20,200 tonnes of lithium carbonate.”

The highly experienced Fluor team has commenced work on the DFS which is scheduled for completion in Q3 2019. The Rhyolite Ridge Mineral Resources and Ore Reserves are planned to be updated during 2019 as part of the DFS process.

Drilling

The 2018-19 drilling program was designed to upgrade and extend the high-grade portion (Searlesite lithium-boron zone) of the current Indicated and Inferred Mineral Resource of 121.4 million tonnes at 1,740ppm lithium (Li) and 1.26% boron (B).

The current Mineral Resource:

• underlies an area approximately 1.2km by 2.3km (2.6km2); • starts from surface; and • remains open to the south, east and north.

With the gently dipping Searlesite lithium-boron zone averaging 20m in thickness, extensions to the current resource are likely to add significant near-surface tonnes to the south.

Thirty core holes in the 2018-19 drilling program have been completed to date and assay results from nine holes have been received.

The boron grades in the first three years of the PFS mine plan average 1.03% boron (equivalent to 5.9% boric acid). Recent drilling results are likely to materially increase the boric acid grade in the first few years of the starter pit. Each 1% increase in the boric acid grade would provide a revenue increase of approximately US$6/tonne of ore processed (at a boric acid sale price of US$700/tonne). At the PFS base case processing rate of 2.6 million tonnes per annum, each 1% increase in the boric acid grade equates to an additional US$15.6 million of revenue per annum.

The highest lithium grades in the current resource are scheduled to be mined in the early years of the PFS mine plan. The recent drilling has confirmed these strong lithium grades and intercepted near-surface extensions to the south.

Drill hole SBH-58 was drilled to the south of the current Mineral Resource and intercepted 21.3m at 1.08% lithium carbonate and 8.0% boric acid.

Further extending shallow lithium-boron mineralisation to the south has the potential to reduce the strip ratio in the early years of mining. The mining rate in the early years of the project may also be reduced by deferring the need to pre-strip overburden in advance of mining deeper ore.

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The table below summarises the assays received to date for the lithium-boron (Searlesite) mineralisation.

Hole Number

Dip/ Azimuth (o)

From (m)

Intercept (m)

ETW (m)

VD (m)

Li (ppm)

Li2CO3 (%)

B (%)

H3BO3 (%)

Infill holes within Starter Pit SBH-43 -45/0 68.6 10.7 10.6 48.5 2,206 1.17 1.31 7.5 SBH-44* -45/270 97.5 19.8 14.1 68.9 2,014 1.07 1.36 7.8 SBH-45* -45/180 112.8 42.7 30.2 79.8 2,036 1.08 1.65 9.4 SBH-48* -60/180 77.7 30.5 26.8 67.3 2,214 1.18 1.47 8.4 SBH-56* -60/270 108.2 24.4 24.4 93.7 2,264 1.20 1.55 8.9 SBH-57* -60/225 106.7 33.5 33.5 92.4 2,109 1.12 1.60 9.1 Infill holes outside of Starter Pit SBH-55* -45/0 268.2 32.0 22.7 189.6 1,754 0.93 1.82 10.4 SBH-59* -45/45 262.1 22.9 19.9 185.3 1,771 0.94 1.99 11.4 Step-out holes outside of current Resource SBH-58 -45/180 149.4 21.3 18.5 105.6 2,035 1.08 1.39 8.0

* Further assays for these holes are pending.

Notes: Estimated true widths (ETW) are based on dips measured in core and geological interpretation. Vertical depth (VD) is depth from surface to top of lithium-boron mineralisation. Intersections have been calculated by applying a 0.5% B cut-off. Lithium content expressed in ppm or % Li can be converted into Lithium Carbonate (Li2CO3) by multiplying by 5.32 (e.g. – 2,000ppm Li is equivalent to 1.06% LCE). Boron can be converted into boric acid (H3BO3) by multiplying by 5.72 (e.g. 1.81% boron is equivalent to 10.36% boric acid).

Drilling has generally intercepted the lithium-boron zone within 100m of surface. Only SBH-55 and SBH-59 intercepted the lithium-boron mineralisation deeper, due to being located down-dip to the east and outside of the starter pit.

The plan below shows the outline of the current Mineral Resource and the location of the hole collars for the current drilling program.

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Plan of South Basin Mineral Resource area showing drill hole locations

Notes: South Basin Resource area showing drill hole and trench locations. The approximate outline of the Indicated Resource is shown in red. The Resource remains open to the north, south and east. UTM Zone 11 (NAD83).

Indicated Resource Outline

SBH-58 high-grade Li-B 100m south of Resource

Starter Pit Outline

SBH-45 Shallow high-grade Li-B

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Ore Reserves

RPMGlobal USA Inc. (RPM) was engaged by ioneer to undertake the mining study for the PFS and to estimate the Ore Reserve.

A conservative approach was taken to the reporting of Ore Reserves at the PFS stage of the Project. To expedite the Project’s development, the operation and associated facilities have been constrained to a maximum surface disturbance of 640 acres or one square mile. This allows the project to be considered for permitting under an Environmental Assessment (EA). Subsequently, a detailed schedule has been prepared for mining an initial portion of the deposit, referred to as the starter pit. This constrained starter pit is scheduled to be mined over approximately seven years; however, the mine life is likely to exceed 30 years when removing this constraint and with the necessary permitting approvals. A mining schedule for the current Indicated Resource outside of the starter pit has not yet been prepared at a sufficient level of detail to enable conversion to an Ore Reserve. Thus, the initial Ore Reserves have been estimated only within the area targeted for the starter pit.

The PFS was completed and released in October 2018, however the supporting documentation for the Ore Reserve estimate was only recently finalised. Key production parameters in the PFS are to:

• Process ore at a rate of 2.6 million tonnes per annum over a 30-year period; and • Produce 20,200 tonnes of lithium carbonate and 173,000 tonnes of boric acid per

annum.

The initial Ore Reserve is estimated to total 15.8 million tonnes at 1,900ppm lithium (equivalent to 1.0% lithium carbonate) and 12,200ppm boron (equivalent to 7.0% boric acid).

Notes:

1. Tonnages are metric tonnes as contained within the pit design. 2. Figures reported are rounded which may result in small tabulation errors. 3. Based on ownership at the latest applicable date (100%). 4. Marginal cut-off grade defined by a combination of block profitability and boron grade

>5,000 ppm. 5. Conversion factors - lithium (ppm) was converted into Li2CO3 (%) by multiplying by 5.32

and boron (ppm) was converted into H3BO3 (%) by multiplying by 5.72.

The material moved in the starter quarry totals 107.4 million tonnes, comprised of:

• 15.8 million tonnes of ore; and

• 91.6 million tonnes of sub-grade rock (waste and lithium-only mineralisation stockpiled).

This provides a strip ratio for the starter quarry of 5.8:1.

Classification Tonnage Li B Li B Li2CO3 H3BO3 Li2CO3 Boric Acid

Mt ppm ppm kt kt % % kt kt

Proved - - - - - - - -

Probable 15.8 1,900 12,200 31 193 1.0 7.0 160 1,102

Total 15.8 1,900 12,200 31 193 1.0 7.0 160 1,102

ContainedContained

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Summary of Ore Reserve Estimate Parameters and Reporting Criteria

The Ore Reserve is based on the Indicated Resources in the October 2018 Mineral Resource estimate at 1,050ppm lithium and 0.5% boron cut-off, released by ioneer on 23 October 2018. No value was allocated to Inferred Resources which were treated as waste rock.

The host rock for the lithium-boron (searlesite) zone contains low amounts of clay with typically less than 20% carbonate minerals and more than 40% of the sodium borosilicate mineral searlesite. Metallurgical testwork has led to the PFS being predicated on processing the lithium-boron (searlesite) ore and stockpiling the lithium-only mineralisation. For the purposes of the PFS, the process plant feed is mineralisation above a cut-off grade of 0.5% boron.

Study Status

• The outcomes of the Rhyolite Ridge PFS form the basis of the Modifying Factors applied for the Ore Reserve estimate.

Cut-off Parameters

• An economic cut-off and a processing cut-off grade were applied. A cut-off was applied to the boron grade to discern the difference between high clay lithium-bearing minerals and material suitable for processing (predominantly searlesite).

• A combination of a net block profit value and a cut-off grade of 0.5% boron was applied to define the process plant feed. Material that was found to have a positive margin and was above the cut-off is defined as ore.

Mining Factors

• Open cut mine with 5m bench heights. • Selective mining unit (SMU) of 6.25m (east-west) by 6.25m (north-south) by 5m

(height) resulted in a global loss of 4% and global dilution of 9%. • The geometry and gradational nature of the deposit resulted in the mineralisation

diluting the “ore zone” being at similar or slightly less grade than the ore.

Metallurgical Factors

• Overall recoveries of 81.8% for lithium and 83.5% for boron

Environment

• A Plan of Operations is to be submitted for the Project to be considered for permitting under an Environmental Assessment approval process.

Costs, Revenue Factors and Economics

• Project operating costs (net of boric acid credit) forecast to average US$1,796/tonne of lithium carbonate, which would make Rhyolite Ridge the world’s lowest cost producer of lithium.

• Project initial capital expenditure of US$600 million.

• Sale prices of US$10,000/tonne for lithium carbonate and US$700/tonne for boric acid have been used for PFS mine planning.

• PFS cash flows for the EA Period (first seven years) indicate that the Project has an IRR of 12% and a payback period of 5 years. As it is likely that the Project will

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continue to operate beyond the EA period, the Project is estimated to have an IRR of 28% for the forecast life-of-mine in the PFS.

The location of the EA starter pit is illustrated in the plan below.

The Rhyolite Ridge Mineral Resources and Ore Reserves are planned to be updated during 2019 as part of the DFS process.

Contacts

Bernard Rowe James D. Calaway Roger Howe Managing Director Chairman Investor Relations T: +61 419 447 280 T: +1 713 818 1457 T: +61 405 419 139 E: [email protected] E: [email protected] E: [email protected]

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About ioneer

The Company’s 100%-owned Rhyolite Ridge Lithium-Boron Project in Nevada, USA provides a substantial foundation for ioneer to become a responsible and profitable producer of the materials necessary for a sustainable future.

The Rhyolite Ridge Pre-Feasibility Study demonstrated the Project’s scale, long life and potential to become the lowest cost lithium producer in the world as well as the largest lithium producer in the United States.

With forecast annual production of 20,200 tonnes lithium carbonate and 173,000 tonnes boric acid, Rhyolite Ridge will be a globally significant producer of both lithium and boron.

Lithium and boron are both used in a diverse range of everyday items and innovative technologies that are essential to modern life and emerging clean technologies such as electric vehicles.

Competent Persons Statement

The information in this report that relates to Exploration Results is based on information compiled by Bernard Rowe, a Competent Person who is a Member of the Australian Institute of Geoscientists. Bernard Rowe is a shareholder, employee and Managing Director of ioneer Ltd. Mr Rowe 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). Bernard Rowe consents to the inclusion in the report of the matters based on his information in the form and context in which it appears.

In respect of Mineral Resources referred to in this report and previously reported by the Company in accordance with JORC Code 2012, the Company confirms that it is not aware of any new information or data that materially affects the information included in the public report titled “Updated Rhyolite Ridge Mineral Resource Statement” dated 23 October 2018 and released on ASX. Further information regarding the Mineral Resource estimate can be found in that report. All material assumptions and technical parameters underpinning the estimates in the report continue to apply and have not materially changed.

The information in this report that relates to Ore Reserves is based on information compiled and reviewed by Mr Igor Bojanic, who is a Fellow of the Australasian Institute of Mining and Metallurgy, and is an employee of RPM Advisory Services Pty Limited. Mr Igor Bojanic has sufficient experience, which is relevant to the style of mineralisation and type of deposit under consideration and to the activity which, he has undertaken to qualify as a Competent Person, as defined in JORC Code 2012.

In respect of production targets referred to in this report and previously disclosed, the Company confirms that it is not aware of any new information or data that materially affects the information included in the public report titled “Outstanding Results from Rhyolite Ridge Pre-Feasibility” dated 23 October 2018. Further information regarding the production estimates can be found in that report. All material assumptions and technical parameters underpinning the estimates in the report continue to apply and have not materially changed.

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Appendix 1 – Location of Drill Holes

Hole Number

Northing Easting Elevation

(m) Length

(m) Dip (°)

Azimuth (°)

SBH-43 4,184,601 424,159 1,859 210 -45 0

SBH-44 4,184,601 424,159 1,859 146 -45 270

SBH-45 4,184,601 424,159 1,859 165 -45 180

SBH-48 4,184,582 424,316 1,875 121 -60 180

SBH-55 4,184,203 424,527 1,896 329 -45 0

SBH-56 4,184,203 424,527 1,896 155 -60 270

SBH-57 4,184,203 424,527 1,896 159 -60 225

SBH-58 4,184,203 424,527 1,896 303 -45 180

SBH-59 4,184,203 424,527 1,896 305 -45 45

Note: Coordinates are in UTM Zone 11 (NAD27).

Project Location

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Appendix 2 – Mineral Resource Estimates

October 2018 Mineral Resource Estimate (1,050ppm Li Cut-off)

Total Resource including Lithium-Only Mineralisation and Lithium-Boron (Searlesite) Mineralisation

October 2018 Mineral Resource Estimate (1,050ppm Li & 0.5% B Cut-off Cut-off)

Lithium-Boron (Searlesite) Mineralisation

Note: Mineral Resources quoted in this report are inclusive of Ore Reserves.

Group Classification Tonnage Li B Li2CO3 H3BO3 K2SO4 Li2CO3 Boric Acid Potassium

Mt ppm ppm % % % kt kt kt

Indicated 149.6 1,890 7,250 1.0 4.1 1.6 1,510 6,180 2,430

Inferred 49.4 1,860 4,300 1.0 2.4 1.6 490 1,200 770

Total 199.1 1,880 6,520 1.0 3.7 1.6 2,000 7,380 3,210

Indicated 192.4 1,370 2,880 0.7 1.6 1.6 1,410 3,060 3,020

Inferred 83.9 1,480 1,080 0.8 0.6 1.5 660 490 1,230

Total 276.3 1,410 2,340 0.7 1.3 1.5 2070 3,550 4,250

Indicated 342.0 1,600 4,800 0.9 2.7 1.6 2,910 9,240 5,450

Inferred 133.4 1,600 2,300 0.9 1.3 1.5 1,150 1,690 2,000

Grand Total 475.4 1,610 4,100 0.9 2.3 1.6 4,060 10,930 7,460

Contained

Upper Zone

Lower Zone

Upper &

Lower Zone

Group Classification Tonnage Li B Li2CO3 H3BO3 K2SO4 Li2CO3 Boric Acid Potassium

Mt ppm ppm % % % kt kt kt

Indicated 71.9 1,840 14,110 1.0 8.1 2.0 700 5,800 1,420

Inferred 14.7 1,970 12,150 1.0 6.9 2.0 150 1,020 300

Total 86.6 1,860 13,780 1.0 7.9 2.0 860 6,830 1,720

Indicated 32.2 1,430 9,750 0.8 5.4 1.7 240 1,730 530

Inferred 2.6 1,620 6,690 0.9 3.3 1.8 20 90 50

Total 34.8 1,440 9,520 0.8 5.2 1.7 270 1,820 580

Indicated 104.1 1,700 12,800 0.9 7.2 1.9 950 7,540 1,950

Inferred 17.3 1,900 11,300 1.0 6.4 2.0 180 1,110 340

Grand Total 121.4 1,740 12,600 0.9 7.1 1.9 1,130 8,650 2,300

Contained

Upper Zone

Lower Zone

Upper &

Lower Zone

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Appendix 3

Rhyolite Ridge Lithium-Boron Project, Nevada, USA

JORC Code, 2012 Edition – Table 1

Section 1 Sampling Techniques and Data

Criteria JORC Code explanation Commentary

Sampling techniques • Nature and quality of sampling (eg cut channels, random chips, or specific specialised industry standard measurement tools appropriate to the minerals under investigation, such as down hole gamma sondes, or handheld XRF instruments, etc). These examples should not be taken as limiting the broad meaning of sampling.

• Include reference to measures taken to ensure sample representivity and the appropriate calibration of any measurement tools or systems used.

• Aspects of the determination of mineralisation that are Material to the Public Report. In cases where ‘industry standard’ work has been done this would be relatively simple (eg ‘reverse circulation drilling was used to obtain 1 m samples from which 3 kg was pulverised to produce a 30 g charge for fire assay’). In other cases more explanation may be required, such as where there is coarse gold that has inherent sampling problems. Unusual commodities or mineralisation types (eg submarine nodules) may warrant disclosure of detailed information.

Drilling was conducted by ioneer in the second half of 2018.

All holes being reported are diamond core holes drilled using PQ core size diameter and a standard tube. The core was sampled as quarter core at 1.52m intervals using a standard electric core saw.

The entire sample was crushed then split and a sub-sample pulverised to produce a sample for multi-element analysis by ICP-MS.

Drilling techniques • Drill type (eg core, reverse circulation, open-hole hammer, rotary air blast, auger, Bangka, sonic, etc) and details (eg core diameter, triple or standard tube, depth of diamond tails, face-sampling bit or other type, whether core is oriented and if so, by what method, etc).

Diamond core was conducted using PQ core diameter with standard tube.

Drill sample recovery • Method of recording and assessing core and chip sample recoveries and results assessed.

• Measures taken to maximise sample recovery and ensure

Core recovery was estimated to be >90%.

Holes were logged by an experienced geologist soon after they were drilled and logs were completed with lithology and recovery recorded.

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representative nature of the samples.

• Whether a relationship exists between sample recovery and grade and whether sample bias may have occurred due to preferential loss/gain of fine/coarse material.

Overall recoveries were high ensuring samples were representative. No sample bias has occurred as no preferential loss of fine or coarse material has occurred.

There is no observed relationship between sample recovery and grade.

Logging • Whether core and chip samples have been geologically and geotechnically logged to a level of detail to support appropriate Mineral Resource estimation, mining studies and metallurgical studies.

• Whether logging is qualitative or quantitative in nature. Core (or costean, channel, etc) photography.

• The total length and percentage of the relevant intersections logged.

All holes have been geologically and geotechnically logged over their entire length to a level of detail sufficient for a Mineral Resource estimation.

The logging is qualitative in nature.

All core was photographed.

Sub-sampling techniques and sample preparation

• If core, whether cut or sawn and whether quarter, half or all core taken.

• If non-core, whether riffled, tube sampled, rotary split, etc and whether sampled wet or dry.

• For all sample types, the nature, quality and appropriateness of the sample preparation technique.

• Quality control procedures adopted for all sub-sampling stages to maximise representivity of samples.

• Measures taken to ensure that the sampling is representative of the in situ material collected, including for instance results for field duplicate/second-half sampling.

• Whether sample sizes are appropriate to the grain size of the material being sampled.

Samples comprise wet sawn quarter-core.

The nature, type and quality of the sample preparation technique is considered appropriate.

Samples are considered representative of the in-situ rock.

Quality control measures included the routine insertion of standards and duplicates. Results were reported to be satisfactory.

The sample sizes are considered to be appropriate.

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Quality of assay data and laboratory tests

• The nature, quality and appropriateness of the assaying and laboratory procedures used and whether the technique is considered partial or total.

• For geophysical tools, spectrometers, handheld XRF instruments, etc, the parameters used in determining the analysis including instrument make and model, reading times, calibrations factors applied and their derivation, etc.

• Nature of quality control procedures adopted (eg standards, blanks, duplicates, external laboratory checks) and whether acceptable levels of accuracy (ie lack of bias) and precision have been established.

Samples were analysed by ALS Chemex in Reno, Nevada using 4-acid digestion and ICP mass spectrometry.

The methods and procedures are appropriate for the type of mineralisation and the techniques are considered to be total.

Standards for Li, B, Sr and As and blanks were routinely inserted into the sample batches.

Acceptable levels of accuracy were reportedly obtained.

Verification of sampling and assaying

• The verification of significant intersections by either independent or alternative company personnel.

• The use of twinned holes.

• Documentation of primary data, data entry procedures, data verification, data storage (physical and electronic) protocols.

• Discuss any adjustment to assay data.

Significant intersections have been independently verified by at least two company personnel.

Data is stored in digital format in a database.

There has been no adjustment to assay data.

Location of data points • Accuracy and quality of surveys used to locate drill holes (collar and down-hole surveys), trenches, mine workings and other locations used in Mineral Resource estimation.

• Specification of the grid system used.

• Quality and adequacy of topographic control.

Collars are marked on the ground with a permanent concrete marker and measured by DGPS. Locations are accurate to within 1m.

The area of drilling and hole coordinates are shown in UTM Zone 11, NAD83 grid system.

Data spacing and distribution

• Data spacing for reporting of Exploration Results.

• Whether the data spacing and distribution is sufficient to establish the degree of geological and grade continuity appropriate for the Mineral Resource and Ore Reserve estimation procedure(s) and classifications applied.

Most drill holes being reported were infill between earlier drill holes. Drill holes spacing was a nominal 100m.

The spacing is considered sufficient to establish geological and grade continuity appropriate for a Mineral Resource estimation.

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• Whether sample compositing has been applied. Samples were composited to 1.525m prior to estimation.

Orientation of data in relation to geological structure

• Whether the orientation of sampling achieves unbiased sampling of possible structures and the extent to which this is known, considering the deposit type.

• If the relationship between the drilling orientation and the orientation of key mineralised structures is considered to have introduced a sampling bias, this should be assessed and reported if material.

Drill holes were angled at between -45 and -60 degrees. Drilling intersected mineralisation at approximately 50 to 90 degrees for most holes being reported. The orientation is considered appropriate and provides unbiased sampling of the mineralisation. Estimated true widths are quoted for all holes being reported.

Sample security • The measures taken to ensure sample security. Samples were securely stored on-site and then collected from site by ALS and transported to the laboratory by truck.

Audits or reviews • The results of any audits or reviews of sampling techniques and data. RPM reviewed core and sampling procedures during the 2016 site visit and found that all procedures and practices conform to industry standards.

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Section 2 Reporting of Exploration Results

(Criteria listed in the preceding section also apply to this section.)


Mineral tenement and land tenure status

• Type, reference name/number, location and ownership including agreements or material issues with third parties such as joint ventures, partnerships, overriding royalties, native title interests, historical sites, wilderness or national park and environmental settings.

• The security of the tenure held at the time of reporting along with any known impediments to obtaining a license to operate in the area.

The Rhyolite Ridge Project tenements (unpatented mining claims) are owned by ioneer Minerals Minerals Corporation, a company wholly owned by ioneer Ltd.

The unpatented mining claims are located on US federal land administered by the Bureau of Land Management (BLM).

There are no known private royalties over the claims.

There are no known impediments to exploration or mining in the area.

Exploration done by other parties

• Acknowledgment and appraisal of exploration by other parties. At least two campaigns of modern lithium-boron exploration are known at the project. In the 1980's US Borax surface sampled and drilled a basin of lithium and boron-rich sediments over a 2km by 1km area. The area was known as the North Borate Hill project. In total, US Borax completed 57 holes totalling about 15,000m. The work was primarily focussed on boron mineralisation and the lithium mineralisation was largely ignored. In addition to the exploration completed at North Borate Hill, US Borax also drilled 12 holes at South Borate Hill where they described higher lithium values. In 2010-2011 American Lithium Minerals Inc and Japan Oil, Gas and Metals National Corporation (JOGMEC) conducted further lithium exploration in the south basin area. The exploration included at least 465 surface and trench samples and 36 drill holes. The Company has access to the American Lithium data including all drill holes and drill core

Geology • Deposit type, geological setting and style of mineralisation. Lithium, boron and potassium mineralisation is hosted within Tertiary-age carbonate-rich lacustrine sediments, deposited in a basinal environment in the Basin and Range terrain of Nevada, USA.

Drill hole information • A summary of all information material to the under-standing of the exploration results including a tabulation of the following information for all Material drill holes:

All information material to the drill holes being reported is included in the report.

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• easting and northing of the drill hole collar

• elevation or RL (Reduced Level – elevation above sea level in metres) of the drill hole collar

• dip and azimuth of the hole

• down hole length and interception depth

• If the exclusion of this information is justified on the basis that the information is not Material and this exclusion does not detract from the understanding of the report, the Competent Person should clearly explain why this is the case.

Data aggregation methods

• In reporting Exploration Results, weighting averaging techniques, maximum and/or minimum grade truncations (e.g. cutting of high grades) and cut-off grades are usually Material and should be stated.

• Where aggregate intercepts incorporate short lengths of high grade results and longer lengths of low grade results, the procedure used for such aggregation should be stated and some typical examples of such aggregations should be shown in detail.

• The assumptions used for any reporting of metal equivalent values should be clearly stated.

Grades were calculated by simple weighted averaging.

A lower cut-off of 1,000ppm lithium and 5,000ppm boron has been applied with no internal dilution.

No upper cutting was applied as the style and grade of mineralisation does not require it (no high-grade spikes).

No metal equivalent values are being reported.

Relationship between mineralisation widths and intercept lengths

• These relationships are particularly important in the reporting of Exploration Results.

• If the geometry of the mineralisation with respect to the drill hole angle is known, its nature should be reported.

• If it is not known and only the down hole lengths are reported, there should be a clear statement to this effect (e.g. ‘down hole length, true width not known’).

Drilling intersected mineralisation at approximately 50 to 90 degrees for most holes being reported.

Diagrams • Appropriate maps and sections (with scales) and tabulations of intercepts should be included for any significant discovery being

A summary map is included in the report showing the general location of the drilling and other relevant information. The map includes a scale and location

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reported. These should include, but not be limited to a plan view of drill hole collar locations and appropriate sectional views.

information.

Balanced Reporting • Accuracy and quality of surveys used to locate drill holes (collar and down-hole surveys), trenches, mine workings and other locations used in Mineral Resource estimation.

• Where comprehensive reporting of all Exploration Results is not practicable, representative reporting of both low and high grades and/or widths should be practiced to avoid misleading reporting of Exploration Results.

The report is believed to include all representative and relevant information and is believed to be comprehensive.

Other substantive exploration data

• Other exploration data, if meaningful and material, should be reported including (but not limited to): geological observations; geophysical survey results; geochemical survey results; bulk samples - size and method of treatment; metallurgical test results; bulk density, groundwater, geotechnical and rock characteristics; potential deleterious or contaminating substances.

All material information has been reported in the current and previous reports released by the Company.

The Company completed a Pre-Feasibility Study on the Rhyolite Ridge Project in October 2018 and released a summary of the report on 23 October 2018.

Further work • The nature and scale of planned further work (e.g. tests for lateral

extensions or depth extensions or large- scale step-out drilling).

• Diagrams clearly highlighting the areas of possible extensions, including the main geological interpretations and future drilling areas, provided this information is not commercially sensitive.

Drilling is ongoing and further results are anticipated over the next 2-3 months. The Company is currently undertaking a Definitive Feasibility Study on the project. The DFS will include an updated Mineral Resource and Reserve Statement.

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Section 4 Estimation and Reporting of Ore Reserves

Mineral Resources referred to in this report were released by the Company in the public report titled “Updated Rhyolite Ridge Mineral Resource Statement” dated 23 October 2018. Further information regarding the Mineral Resource estimate can be found in that report, including Sections 1 to 3 of Table 1 of the JORC Code.


Mineral Resource estimate for conversion to Ore Reserves

Description of the Mineral Resource estimate used as a basis for the conversion to an Ore Reserve.

Clear statement as to whether the Mineral Resources are reported additional to, or inclusive of, the Ore Reserves.

The Mineral Resources have been estimated in accordance with the JORC Code (2012). The Competent Person for the Mineral Resource estimate is Mr. Robert Dennis who is a full time employee of RPM Advisory Services Pty Ltd (RPM) and is a Member of the Australasian Institute of Geoscientists with sufficient relevant experience to qualify as a Competent Person.

The Mineral Resources are inclusive of these Ore Reserves and not additional to.

Site visits Comment on any site visits undertaken by the Competent Person and the outcome of those visits.

If no site visits have been undertaken indicate why this is the case.

A site visit of the project location was undertaken by Mr. Aaron Poole (Mining Engineer) on May 8 2018 and by Mr. Igor Bojanic (Mining Engineer and Competent Person for the Ore Reserve estimate) on August 31 2018. The field visit involved meetings with Paradigm Minerals (ioneer) personnel in Reno, Nevada followed by a field visit to the Project Area.

Both Messrs Poole and Bojanic were full time employees of RPM at the time.

No material physical change is known to have occurred at the site since the visit.

Study status The type and level of study undertaken to enable Mineral Resources to be converted to Ore Reserves.

The Code requires that a study to at least Pre-Feasibility Study level has been undertaken to convert Mineral Resources to Ore Reserves. Such studies will have been carried out and will have determined a mine plan that is technically achievable and economically viable, and that material Modifying Factors have been considered.

A pre-feasibility study (PFS) has been completed in conjunction with Amec Foster Wheeler (AFW) by and on behalf of Paradigm Minerals USA Corporation, a wholly-owned subsidiary of ioneer. The PFS planning process was supported by a number of 3rd party specialist consultants including RPM. RPM completed the mining portion of the PFS. The outcomes of the PFS form the basis of the Modifying Factors applied for the Ore Reserve estimate. In RPM’s opinion the A3500 scenario plan of operations is likely to be technical achievable and economically viable. The mine plan aims to account for all material considerations including Modifying Factors.

Cut-off parameters The basis of the cut-off grade(s) or quality parameters applied.

The application of cut-offs involved two stages. An economic cut-off was applied based on the base case economic assumptions. The “processing profitability” was estimated for each block with the geological model. Only those blocks with a positive margin were considered economically viable to process through the plant.

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In addition, a processing cut-off grade was applied to determine which rock has the appropriate properties to be processed. A cut-off was applied to the boron grade to discern the difference between high clay Li-bearing minerals and material suitable for processing (predominantly searlesite). High clay Li-Bearing minerals are considered problematic and not suitable for the planned process but will be stockpiled for possible later processing within a modified plant.

Mining factors or assumptions

The method and assumptions used as reported in the Pre-Feasibility or Feasibility Study to convert the Mineral Resource to an Ore Reserve (i.e. either by application of appropriate factors by optimisation or by preliminary or detailed design).

The choice, nature and appropriateness of the selected mining method(s) and other mining parameters including associated design issues such as pre-strip, access, etc.

The assumptions made regarding geotechnical parameters (e.g. pit slopes, stope sizes, etc.), grade control and pre-production drilling.

The major assumptions made and Mineral Resource model used for pit and stope optimisation (if appropriate).

The mining dilution factors used.

The mining recovery factors used.

Any minimum mining widths used.

The manner in which Inferred Mineral Resources are utilised in mining studies and the sensitivity of the outcome to their inclusion.

The infrastructure requirements of the selected mining methods.

The mining method is open cut extraction with rock deemed ore being selectively mined on 5m bench heights. The mining method will be typical of stratigraphic deposits with moderate dip, and will utilise dozers to support removal of overburden. Grade control will be actively undertaken to further control ore loss and dilution.

The approach to determining the modifying factors accounted for the mining method, bench height and the target selectivity.

RPM completed a loss and dilution analysis on the Resource model examining the outcomes based on a range of possible SMU sizes. The analysis indicated that an SMU of 6.25m (EW) by 6.25m (NS) by 5m (height) was the best compromise to reflect the selective mining approach and resulted in a global loss of 4% and global dilution of 9%.

TGI were engaged by Ioneer to estimate the geotechnical pit slope design requirements for the open pit quarry. The overall slope in the alluvials and fresh rock was estimated at 26 degrees and 42 degrees, respectively.

The Inferred Resources were considered to be waste rock for the purposes of the PFS.

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Metallurgical factors or assumptions

The metallurgical process proposed and the appropriateness of that process to the style of mineralisation.

Whether the metallurgical process is well-tested technology or novel in nature.

The nature, amount and representativeness of metallurgical test work undertaken, the nature of the metallurgical domaining applied and the corresponding metallurgical recovery factors applied.

Any assumptions or allowances made for deleterious elements.

The existence of any bulk sample or pilot scale test work and the degree to which such samples are considered representative of the orebody as a whole.

For minerals that are defined by a specification, has the ore reserve estimation been based on the appropriate mineralogy to meet the specifications?

The metallurgical process design as set out by AFW essentially involves three stages. The first stage involves crushing and leaching, where ROM ore is crushed and leached to produce a pregnant leach solution (PLS) with boric acid grades approaching saturation point.

The second stage involves evaporation/crystallization and boric acid generation. The lithium remains soluble throughout evaporation and crystallization and reports to the lithium processing area (which is the third stage) as a high-grade lithium brine.

In the final stage the high-grade lithium brine is processed to produce lithium carbonate.

For the first three years the process plant will produce technical-grade lithium carbonate. The plant will then be upgraded to produce battery-grade lithium carbonate. The staged approach is planned to reduce operational risk.

The lithium product recovery is estimated by AFW at 81.8% The boron product recovery is estimated at 83.5%.

No bulk sampling has been completed to date. The test work is based on composite drill core and outcrop that aim for samples representative of the plant feed rock.

Test work has been undertaken to support the estimation of product recoveries, however RPM has relied on the third party experts.

Environment The status of studies of potential environmental impacts of the mining and processing operation. Details of waste rock characterisation and the consideration of potential sites, status of design options considered and, where applicable, the status of approvals for process residue storage and waste dumps should be reported.

EM Strategies, Inc. (EMS) has been engaged by ioneer to provide information on environmental considerations, permitting, and social and community impacts.

A Plan of Operations (POO) (under 43 Code of Federal Regulations [CFR] 3809) and a Nevada Reclamation Permit (NRP) Application (under Nevada Administrative Code [NAC] 519A) (Plan Application) to the Bureau of Land Management (BLM) Tonopah Field Office and the Nevada Division of Environmental Protection (NDEP) Bureau of Mining Regulation and Reclamation (BMRR) is to be submitted in the very near future.

Based on information provided to RPM, EMS believes there are no known ongoing environmental issues with any of the regulatory agencies. Baseline studies are underway and indicate that there are limited biological and cultural issues; air quality impacts appear to be within State of Nevada standards; traffic and noise issues are present, but at low levels; and socioeconomic impacts are positive. A rare plant was previously identified in the project area. ioneer is working with the BLM on the management for that

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plant.

Sub-grade rock characterization results indicate the Sub-grade rock and ore are generally non-reactive, not acid generating, and do not leach metals.

RPM has been informed that the 1 square mile permit is likely to the approved. As such considers there to be no legal impediment for mining of the initial phase of development. If this permit is not approved this will delay commencement of mining.

Infrastructure The existence of appropriate infrastructure: availability of land for plant development, power, water, transportation (particularly for bulk commodities), labour, accommodation; or the ease with which the infrastructure can be provided, or accessed.

The site infrastructure requirements were determined by AFW. There is sufficient area available on the within the tenement for the placement of infrastructure to support the initial development plan within 1 square mile.

The proposed site infrastructure is typical of this type of proposed open cut development with a process, plant, administration buildings, workshops, service roads, etc.

The site is accessible from both the east and west using an existing county road. The east access is off Highway 95 south of Tonopah, while the west access is off Highway 6 via Highway 264 or 773.

No mining camp is required as labour will be accommodated in townships within the area.

Fresh water to the plant site is proposed to be supplied by a 2.5 km long pipeline from the fresh water wells located at the pit perimeter. The line will supply the domestic and fire water needs of the site, as well as provide process makeup water.

If the available water is insufficient, water rights will need to be obtained from the Nevada Division of Water Resources (NDWR). Water and water rights will come from the Fish Lake Valley Basin, which is a designated basin. The basin is over-appropriated and essentially all the water rights are for irrigation. The likelihood of obtaining new water rights is low and the purchase or leasing of existing rights will likely be necessary. ioneer is pursuing sourcing options.

The mine has the capability of importing or exporting power to the local utility, Nevada Energy (NVE). The interconnection point between the mine and NVE will be at NVE’s Silver Peak substation located 28 km away. The demarcation point between NVE and the mine will be at the 55 kV bus within the Silver Peak substation.

Costs The derivation of, or assumptions made, regarding The estimation of capital and operating costs were completed to a PFS level of engineering using

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projected capital costs in the study.

The methodology used to estimate operating costs.

Allowances made for the content of deleterious elements.

The derivation of assumptions made of metal or commodity price(s), for the principal minerals and co- products.

The source of exchange rates used in the study.

Derivation of transportation charges.

The basis for forecasting or source of treatment and refining charges, penalties for failure to meet specification, etc.

The allowances made for royalties payable, both Government and private.

industry standard first-principles costing.

Plant and infrastructure costs were estimated by AFW. RPM obtained capital and operating costs direct from mining equipment suppliers as well as a mining contractor estimate.

AFW estimate that the proposed project configuration, is estimated to cost US$599M.

AFW estimates the process operating cost to be ~US$38/t feed during the start-up period before reducing to ~US$32/t feed on average for the remainder of the operating life.

The Project can potentially produce 21,000 t of lithium carbonate and 176,000 t of boric acid over a >30-year period. AFW state that at the capital estimate of US$599M equates to a capital intensity of US$18,042 per tonne per annum LCE (lithium carbonate and boric acid).

Revenue factors The derivation of, or assumptions made regarding revenue factors including head grade, metal or commodity price(s) exchange rates, transportation and treatment charges, penalties, net smelter returns, etc.

The derivation of assumptions made of metal or commodity price(s), for the principal metals, minerals and co-products.

The Client completed comprehensive marketing studies into the sale of lithium and boron products to support the PFS. This formed the basis of the revenue factor estimates used for mine planning.

Forecast estimates of lithium have been reviewed by ioneer from six different sources. From the results, a long term price of US$10,000/t CIF has been estimated for the PFS mine planning. This was considered by ioneer as a conservative approach to mine planning as the average benchmarking pricing as applied in the financial model is over 25% higher.

Forecast estimates of boric acid pricing have been reviewed by ioneer from a number of different sources. From the results, a price of US$700/t CIF has been estimated for the PFS mine planning.

Freight costs are estimated at US$154/t for Li2CO3 and US$160/t for Boric Acid. Hence, the average mine gate price for mine planning was estimated at US$9,846/t for Li2CO3 price and US$540/tonne for Boric Acid.

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Market assessment The demand, supply and stock situation for the particular commodity, consumption trends and factors likely to affect supply and demand into the future.

A customer and competitor analysis along with the identification of likely market windows for the product.

Price and volume forecasts and the basis for these forecasts.

For industrial minerals the customer specification, testing and acceptance requirements prior to a supply contract.

Lithium

Consumption of lithium has grown from 66,200t LCE in 2010 to 211,000t LCE in 2017 with a cumulative annual growth rate (CAGR) of 7.3%. This growth has been led by the rechargeable battery market, which accounted for around 97,300t LCE or 46% of total lithium consumption in 2017 which is a CAGR of 19.3% since 2000. Demand for Li-ion batteries has increased significantly because of rapid expansion in the portable consumer electronics sector through to 2014 and a growing market for batteries for automotive electrification since.

The ioneer marketing study suggests longer-term, continued strong demand and consumption growth will place a strain on supply by the mid-2020s, with the market forecast to enter a supply-deficit during 2024. Stocks could alleviate some of this pressure, but significant volumes of additional refined lithium supply will be required beyond 2024, with the supply deficit growing to ~100,000t LCE in 2027 in the base-case scenario, although additional capacity is expected to be brought on-line in the mid-2020s to alleviate this squeeze.

Boron

The ioneer marketing study concluded that the fundamental drivers of the global borate market remain strong, underpinned by an improving global economy and strong economic outlook in the largest borates markets, China, India and the US. China is undergoing some structural changes to its economy that will have a far-reaching effect on the demand for raw materials, including borates.

The global demand for borates is projected to grow at a CAGR of 4-5 percent over the next five years and will be driven primarily by high growth rates in borosilicate glass, frits, insulation and agriculture end uses. All of these suit boric acid supply. Almost all the growth is in the refined borates segment with the minerals segment projected to be stagnant.

The supply-demand situation suggests that the non-sodium borate (mainly boric acid) is projected to be oversupplied over the next four years but demand should exceed supply by 2023. However, when we assume an 85 percent level of name plate capacity as marketable supply, the market should see supply tighten and prices stabilise during 2020.

Economic The inputs to the economic analysis to produce the net present value (NPV) in the study, the source and confidence of these economic inputs including estimated inflation, discount rate, etc.

A financial analysis was completed by ioneer and AFW commensurate with a PFS. The results for the EA Period (first seven years) indicate that the Project has an IRR of 12% and a payback period of 5 years. On that basis the Project meets the economic criteria set by the JORC Code for the reporting of Ore Reserves.

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NPV ranges and sensitivity to variations in the significant assumptions and inputs.

As it is likely that the Project will continue to operate beyond the EA period, LOM financial model results indicate an IRR of 28%.

Social The status of agreements with key stakeholders and matters leading to social licence to operate.

Social and community impacts have been and are being considered and evaluated for the various plan amendments performed for the project in accordance with National Environmental Policy Act (NEPA) and other federal laws. At this time, no known social or community issues will have a material impact on the project’s ability to extract mineral resources. Identified socioeconomic issues (employment, payroll, services and supply purchases, and state and local tax payments) are anticipated to be positive.

Other To the extent relevant, the impact of the following on the project and/or on the estimation and classification of the Ore Reserves:

Any identified material naturally occurring risks.

The status of material legal agreements and marketing arrangements.

The status of governmental agreements and approvals critical to the viability of the project, such as mineral tenement status, and government and statutory approvals. There must be reasonable grounds to expect that all necessary Government approvals will be received within the timeframes anticipated in the Pre-Feasibility or Feasibility study. Highlight and discuss the materiality of any unresolved matter that is dependent on a third party on which extraction of the reserve is contingent.

There are no material naturally occurring risks beyond geotechnical and hydrogeological risks that can be mitigated in the normal course of study. An operating risk could be if insufficient groundwater is identified on site requiring water to be purchased from local land and water right holders.

ioneer owns 100% interest in the claims over the Resource. There is a success payment of US$3M payable to the former claim owners upon ioneer publicly announcing a decision to commence development of a mine. There are no other encumbrances and no royalties.

Though there are no marketing arrangements in place for the products as the Project is only in at a PFS stage, the ioneer marketing study found that demand for the products is reasonable.

The BLM and the BMRR have implemented a process for the Plan Application that commences prior to the submittal and continues through the review and approval process for the Plan Application. A number of meetings have been held between ioneer and the BLM. Baseline data for the project are being collected and the reports have yet to be submitted and reviewed/accepted by the BLM.

A conservative approach was undertaken to the reporting of Ore Reserves. The Ore Reserves have been estimated only within the area targeted for short term approval, that is, the EA Pit. The pit limit optimisation indicated that there is potentially up to 90 Mt of plant feed able to be economically extracted. Further technical studies including mine planning are required to convert the expanded pit quantities to Ore Reserves.

Classification The basis for the classification of the Ore Reserves into varying confidence categories.

Whether the result appropriately reflects the Competent Person’s view of the deposit.

The proportion of Probable Ore Reserves that have

The Ore Reserves are based only on the Measured and Indicated Resources, which have been classified as Proved and Probable Ore Reserves, respectively. This Ore Reserve classification is considered appropriate given the nature of the deposit, the moderate grade variability, drilling density, structural complexity and technical analysis. That is, it was deemed appropriate to use Measured Mineral Resources as a basis for Proved Reserves and Indicated Mineral Resources as a basis for Probable Reserves.

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been derived from Measured Mineral Resources (if any).

No Inferred Mineral Resources were included in the Ore Reserve estimate.

Audits or reviews The results of any audits or reviews of Ore Reserve estimates.

The Ore Reserve estimate was audited by estimating values using mine planning software and then separately outside of the software using raw data. The mineable quantities were also estimated within the scheduling software which matched the Reserves.

Discussion of relative accuracy/ confidence

Where appropriate a statement of the relative accuracy and confidence level in the Ore Reserve estimate using an approach or procedure deemed appropriate by the Competent Person. For example, the application of statistical or geostatistical procedures to quantify the relative accuracy of the reserve within stated confidence limits, or, if such an approach is not deemed appropriate, a qualitative discussion of the factors which could affect the relative accuracy and confidence of the estimate.

The statement should specify whether it relates to global or local estimates, and, if local, state the relevant tonnages, which should be relevant to technical and economic evaluation. Documentation should include assumptions made and the procedures used.

Accuracy and confidence discussions should extend to specific discussions of any applied Modifying Factors that may have a material impact on Ore Reserve viability, or for which there are remaining areas of uncertainty at the current study stage.

It is recognised that this may not be possible or appropriate in all circumstances. These statements of relative accuracy and confidence of the estimate should be compared with production data, where available.

The Ore Reserve Statement is supported by a PFS managed by AMEC Foster Wheeler (AFW) and contributed to by a number of specialist consulting groups.

In RPM’s opinion, with the support of the PFS, the Ore Reserve estimate complies with the relative accuracy and confidence level required by the JORC Code.

A sensitivity analysis was completed by AFW over the ranges of ±30% for capital costs, operating costs, grade, and metal price (Li2CO3 and H3BO3). The project is most sensitive to changes in metal price and grade, followed by changes to operating costs and capital costs. The project’s NPV@7% is least sensitive to capital costs. For the EA Period, the Project has a negative NPV@7% for capital and operating cost increases of >20% or a fall in metal price of over 10%.

For the LOM operating period, the sensitivity analysis results at NPV@7% remained positive.

The results indicate that there is some short-term risk to the Project if economic conditions become unfavourable and also if the Project was not to operate for its full operating life. RPM understands it is ioneer’s intentions to operate the mine beyond the EA period.

Rhyolite Ridge Drilling Update and Maiden Ore Reserve...Resource estimate at 1,050ppm lithium and...

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