REG - Rio Tinto - Lithium Mineral Resources and Ore Reserves
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RNS Number : 2449K Rio Tinto PLC 04 December 2025
Notice to
ASX/LSE
Initial reporting of lithium Mineral Resources and Ore Reserves
4 December 2025
Rio Tinto today announces initial reporting of Mineral Resources and Ore
Reserves 1 (#_ftn1) for seven lithium assets acquired as part of the purchase
of Arcadium Lithium, namely:
· Four lithium brines deposits: the Fenix and Olaroz operations,
and the Sal de Vida and Cauchari projects in Argentina
· Three hard rock spodumene deposits: the Whabouchi and Galaxy
projects in Northern Quebec, and the Mt Cattlin operation in Western Australia
Mineral Resources are reported inclusive of Ore Reserves for lithium brines
deposits 2 (#_ftn2) , and in addition to Ore Reserves (exclusive) for hard
rock spodumene deposits.
Fenix
Fenix is a lithium brines operation located in the Salar del Hombre Muerto in
northwest Argentina. It is 100% owned by Rio Tinto and is currently in
operation producing lithium carbonate.
Mineral Resources and Ore Reserves for the Fenix operation 3 (#_ftn3) are
presented in Table A and Table B. Mineral Resources inclusive of Ore Reserves
total 11.7 Mt Lithium Carbonate Equivalent (LCE) consisting of 2.7 Mt LCE of
Measured Mineral Resources, 4.3 Mt LCE of Indicated Mineral Resources and 4.7
Mt LCE of Inferred Mineral Resources. Ore Reserves total 5.4 Mt LCE consisting
of 1.2 Mt LCE Proven Ore Reserves and 4.1 Mt LCE Probable Ore Reserves(3).
Olaroz
Olaroz is a lithium brines operation located in the Olaroz-Cauchari Salar,
Jujuy, Argentina. It includes properties operated by Rio Tinto through its
local subsidiary Sales de Jujuy, which is a joint venture between Rio Tinto
(66.5%), Toyota Tsusho Corporation (25%) and Jujuy Energía y Minería
Sociedad del Estado (JEMSE, 8.5%). In addition, Rio Tinto has 100% ownership
of six properties to the north and west of the joint venture area which
contain a portion of the reported Mineral Resources. All Ore Reserves are
located within the Sales de Jujuy joint venture properties.
Mineral Resources and Ore Reserves for the Olaroz operation(3) are presented
in Table A and Table B. Mineral Resources inclusive of Ore Reserves total 19.7
Mt LCE consisting of 8.5 Mt LCE of Measured Mineral Resources, 8.4 Mt LCE of
Indicated Mineral Resources and 2.8 Mt LCE of Inferred Mineral Resources. Ore
Reserves total 2.7 Mt LCE consisting of 0.6 Mt LCE of Proven Ore Reserves and
2.2 Mt LCE Probable Ore Reserves.
Sal de Vida
Sal de Vida is a lithium brines project located in the Salar del Hombre
Muerto, Catamarca, Argentina. It is 100% owned by Rio Tinto.
Mineral Resources and Ore Reserves for the Sal de Vida project(3) are
presented in Table A and Table B. Mineral Resources inclusive of Ore Reserves
total 7.2 Mt LCE consisting of 3.5 Mt LCE of Measured Mineral Resources,
3.0 Mt LCE of Indicated Mineral Resources and 0.7 Mt LCE of Inferred Mineral
Resources. Ore Reserves total 2.5 Mt LCE consisting of 0.4 Mt LCE of Proven
Ore Reserves and 2.0 Mt LCE Probable Ore Reserves.
Cauchari
Cauchari is a lithium brines project located in the Olaroz-Cauchari Salar,
Jujuy, Argentina. It is 100% owned by Rio Tinto.
Mineral Resources and Ore Reserves for the Cauchari project(3) are presented
in Table A and Table B. Mineral Resources inclusive of Ore Reserves total 6.0
Mt LCE consisting of 1.9 Mt LCE of Measured Mineral Resources, 2.6 Mt LCE of
Indicated Mineral Resources and 1.5 Mt LCE of Inferred Mineral Resources. Ore
Reserves total 1.1 Mt LCE consisting of 0.2 Mt LCE of Proven Ore Reserves and
0.9 Mt LCE Probable Ore Reserves.
Whabouchi
The Whabouchi project in northern Quebec, Canada, is a hard rock
lithium-bearing spodumene deposit and is being developed by Nemaska Lithium, a
joint venture between Investissement Québec (50%) and Rio Tinto (50%).
Mineral Resources and Ore Reserves for the Whabouchi project are presented in
Table C and Table D. Mineral Resources exclusive of Ore Reserves total 26.9 Mt
at 1.45% Li(2)O, consisting of 18.7 Mt at 1.51% Li(2)O of Indicated Mineral
Resources and 8.3 Mt at 1.31% Li(2)O of Inferred Mineral Resources 4 (#_ftn4)
. Ore Reserves total 26.5 Mt at 1.32% Li(2)O consisting of 10.5 Mt at 1.40%
Li(2)O of Proved Ore Reserves and 16.0 Mt at 1.27% Li(2)O of Probable Ore
Reserves 5 (#_ftn5) .
Galaxy
The Galaxy project is a hard rock lithium-bearing spodumene deposit located in
the northeastern part of the Superior Province in northern Quebec, Canada. It
is 100% owned by Rio Tinto.
Mineral Resources and Ore Reserves for the Galaxy project are presented in
Table C and Table D. Mineral Resources exclusive of Ore Reserves total 74.0 Mt
at 1.25% Li(2)O consisting of 18.1 Mt at 1.12% Li(2)O of Indicated Mineral
Resources and 55.9 Mt at 1.29% Li(2)O of Inferred Mineral Resources 6
(#_ftn6) . Ore Reserves comprise 37.3 Mt at 1.27% Li(2)O of Probable Ore
Reserves 7 (#_ftn7) .
Mt Cattlin
The Mt Cattlin operation is a lithium-bearing spodumene deposit in Western
Australia. It is 100% owned by Rio Tinto. Mt Cattlin was placed on care and
maintenance on 1 July 2025 due to market conditions. The potential
for underground mining
(https://www.google.com/search?safe=active&rlz=1C1GCEA_enAU1114AU1114&cs=0&sca_esv=366d6a2a4988c533&sxsrf=AE3TifOVIYDw0JGXJhuE1zTA5haRo1PJWQ%3A1756695070742&q=underground+mining&sa=X&ved=2ahUKEwj_zJaNx7aPAxUzjGMGHS4jM9wQxccNegQIBRAB&mstk=AUtExfDsi2L0VytKbrjKGwPf-tJRhxYEwLt1EcqlCWUsjeaK-H8EIlWvWqZiqSR7fY0mP6rdZN2fWInj5D0QoejuPoY9YFVEXasDXNzhQlrb8F82Ms0K457ZrgqDYeSlIIj1C38y-uJl0EtvU12foncZlIUqQqlMzdO3vMJRVw5Kteil89c&csui=3)
to extend the mine's life is the subject of current studies.
Mineral Resources and Ore Reserves for Mt Cattlin are presented in Table C and
Table D. Mineral Resources exclusive of Ore Reserves total 11.3 Mt at 1.35%
Li(2)O, consisting of 0.1 Mt at 1.11% Li(2)O of Measured Resources, 6.4 Mt at
1.42% Li(2)O of Indicated Mineral Resources and 4.8 Mt at 1.27% Li(2)O of
Inferred Mineral Resources 8 (#_ftn8) . Ore Reserves total 2.3 Mt at 1.10%
Li(2)O consisting of 0.1 Mt at 0.80% Li(2)O of Proved Ore Reserves and 2.2 Mt
at 1.11% Li(2)O of Probable Ore Reserves 9 (#_ftn9) .
Table A Rio Tinto - Fenix, Olaroz, Sal de Vida and Cauchari
Mineral Resources inclusive of Ore Reserves as at 30 June 2025
Likely Measured Mineral Resources Indicated Mineral Resources Total Measured and Indicated Mineral
mining
method((1))
as at 30 June 2025 as at 30 June 2025 Reso
urce
s as
at
30
June
2025
Total Brine Volume Average Lithium Grade Lithium Metal LCE Total Brine Volume Average Lithium Grade Lithium Metal LCE Total Brine Volume Average Lithium Grade Lithium Metal LCE
Lithium Brine((2) (3)) Mm(3) mg/l Mt Mt Mm(3) mg/l Mt Mt Mm(3) mg/l Mt Mt
Fenix (Argentina)((4)) B/E 810 630 0.5 2.7 1,040 780 0.8 4.3 1,840 710 1.3 7.0
Olaroz (Argentina)((4) (5)) B/E 2,580 610 1.6 8.5 3,450 460 1.6 8.4 6,030 520 3.2 16.8
Sal de Vida (Argentina)((4)) B/E 880 750 0.7 3.5 760 740 0.6 3.0 1,640 750 1.2 6.5
Cauchari (Argentina)((4)) B/E 660 530 0.4 1.9 1,080 450 0.5 2.6 1,740 480 0.8 4.5
Inferred Mineral Resources Total Mineral Resources Rio Tinto
interest
as at 30 June 2025 as at 30 June 2025
Total Brine Volume Average Lithium Grade Lithium Metal LCE Total Brine Volume Average Lithium Grade Lithium Metal LCE
Lithium Brine((2) (3)) Mm(3) mg/l Mt Mt Mm(3) mg/l Mt Mt %
Fenix (Argentina)((4)) 1,210 730 0.9 4.7 3,050 720 2.2 11.7 100.0
Olaroz (Argentina)((4) (5)) 1,490 360 0.5 2.8 7,520 490 3.7 19.7 73.5
Sal de Vida (Argentina)((4)) 220 560 0.1 0.7 1,860 720 1.3 7.2 100.0
Cauchari (Argentina)((4)) 590 470 0.3 1.5 2,330 480 1.1 6.0 100.0
Notes:
1. Type of Mine: B/E = brine extraction.
2. Lithium Brine Mineral Resources Ore Reserves are reported as in
situ and inclusive of the Ore Reserves.
3. Lithium brine Resources lithium metal and LCE tonnages are in situ
values assuming 100% recovery as per standard brine reporting practices. To
obtain the equivalent tonnage for LCE, the estimated mass of lithium was
multiplied by a factor that is based on the atomic weights of each element in
lithium carbonate to obtain the final compound weight. The factor used was
5.323 to obtain LCE mass from lithium mass.
4. The estimates are based on: (1) specific yield values for
hydrogeological units in the brine aquifer; (2) applicable lithium cut-off
grade of 300 mg/l for Olaroz, Sal de Vida and Cauchari; (3) including only
tenements controlled by Rio Tinto as of the effective date.
5. Olaroz Rio Tinto interest represents its fractional ownership in
SDJ (66.5%), and 100% ownership in Olaroz Lithium, La Frontera, and Minera
Andes on a mass-weighted basis.
Table B Rio Tinto - Fenix, Olaroz, Sal de Vida and Cauchari
Ore Reserves as at 30 June 2025
Type of mine((1)) Proved Ore Reserves Probable Ore Reserves Total Ore Reserves
as at 30 June 2025 as at 30 June 2025 as at 30 June 2025
Anticipated Total Brine Volume Average Lithium Grade Lithium metal LCE Anticipated Total Brine Volume Average Lithium Grade Lithium metal LCE Anticipated Total Brine Volume Average Lithium Grade Lithium metal LCE
Lithium Brine((2) (3)) Mm(3) Mg/L Mt Mt Mm(3) Mg/L Mt Mt Mm(3) Mg/L Mt Mt
Fenix (Argentina)((4)) B/E 320 730 0.2 1.2 1,260 620 0.8 4.1 1,570 640 1.0 5.4
Olaroz (Argentina)((4) (5)) B/E 150 650 0.1 0.6 640 650 0.4 2.2 800 650 0.5 2.7
Sal de Vida (Argentina)((4)) B/E 100 800 0.1 0.4 510 740 0.4 2.0 620 760 0.5 2.5
Cauchari (Argentina)((4)) B/E 80 570 0.04 0.2 350 490 0.2 0.9 420 500 0.2 1.1
Average Process Efficiency Rio Tinto interest Rio Tinto share recoverable metal Rio Tinto share recoverable metal
Lithium LCE
Lithium Brine((2) (3)) % % Mt Mt
Fenix (Argentina)((4)) 76.6 100.0 0.8 4.1
Olaroz (Argentina)((4) (5)) 60 66.5 0.2 1.1
Sal de Vida (Argentina)((4)) 70 100.0 0.3 1.7
Cauchari (Argentina)((4)) 60 100.0 0.1 0.7
Notes:
1. Type of Mine: B/E = brine extraction.
2. Anticipated total brine volume is the cumulative brine volume
simulated from the entire wellfield over the life of mine whilst the extracted
grade is averaged for the entire pumping period for the simulated wellfield.
Lithium metal and LCE tonnages at each Reserve category are reported from a
point of reference of the wellhead and assume 100% recovery. To obtain the
equivalent tonnage for LCE, the estimated mass of lithium was multiplied by a
factor that is based on the atomic weights of each element in lithium
carbonate to obtain the final compound weight. The factor used was 5.323 to
obtain LCE mass from lithium mass.
3. Rio Tinto share recoverable metal Lithium and LCE values apply the
average process efficiency and the Rio Tinto % share.
4. Fenix, Olaroz, Sal de Vida and Cauchari Ore Reserves estimates are
based on lithium cut-off grade of 400 mg/l, 410 mg/l, 470 mg/l and 350 mg/l
respectively.
5. Olaroz Rio Tinto interest represents its fractional ownership in
SDJ (66.5%). Ore Reserves are not produced from Rio Tinto's other ownership
interests (Olaroz Lithium, La Frontera, or Minera Andes).
Table C Rio Tinto - Whabouchi, Galaxy and Mt Cattlin Mineral
Resources exclusive of Ore Reserves as at 30 June 2025
Likely mining method((1)) Measured Mineral Resources Indicated Mineral Resources Total Measured and Indicated Mineral
as at 30 June 2025 as at 30 June 2025 Resources as at 30 June 2025
Tonnage Grade Tonnage Grade Tonnage Grade
Lithium((2)) Mt % Li(2)O ppm Ta(2)O(5) Mt % Li(2)O ppm Ta(2)O(5) Mt % Li(2)O ppm Ta(2)O(5)
Whabouchi (Canada) O/P / UG - - 18.7 1.51 - 18.7 1.51 -
Galaxy (Canada) O/P - - - 18.1 1.12 - 18.1 1.12 -
Mt Cattlin (Australia) O/P / UG 0.12 1.11 176 6.4 1.42 185 6.5 1.41 185
Inferred Mineral Resources Total Mineral Resources Rio Tinto
interest
as at 30 June 2025 as at 30 June 2025
Tonnage Grade Tonnage Grade
Lithium((2)) Mt % Li(2)O ppm Ta(2)O(5) Mt % Li(2)O ppm Ta(2)O(5) %
Whabouchi (Canada) 8.3 1.31 - 26.9 1.45 - 50.0
Galaxy (Canada) 55.9 1.29 - 74.0 1.25 - 100.0
Mt Cattlin (Australia) 4.8 1.27 177 11.3 1.35 182 100.0
Notes:
1. Likely mining method: O/P = open pit/surface, U/G = underground.
2. Lithium Mineral Resources are stated as dry in situ tonnes.
Table D Rio Tinto - Whabouchi, Galaxy and Mt Cattlin Ore
Reserves as at 30 June 2025
Type of mine((1)) Proved Ore Reserves Probable Ore Reserves Total Ore Reserves Average process efficiency Rio Tinto interest Rio Tinto share recoverable
as at 30 June 2025 as at 30 June 2025 as at 30 June 2025
Tonnage Grade Tonnage Grade Tonnage Grade Spodumene Tantalite Li(2)O Ta(2)O(5)
Lithium((2)) Mt % Li(2)O ppm Ta(2)O(5) Mt % Li(2)O ppm Ta(2)O(5) Mt % Li(2)O ppm Ta(2)O(5) % % % Mt Mlbs
Whabouchi (Canada) O/P 10.5 1.40 - 16.0 1.27 - 26.5 1.32 - 85 - 50.0 0.15 -
Galaxy (Canada) O/P - - - 37.3 1.27 - 37.3 1.27 - 68.9 - 100.0 0.33 -
Mt Cattlin (Australia)
- Mt Cattlin Open pit O/P 0.1 0.80 158 1.6 1.31 151 1.7 1.29 150 67 20 100.0 0.015 0.11
- Mt Cattlin Stockpiles S/P - - - 0.6 0.54 67 0.6 0.54 67 25 20 100.0 0.001 0.02
Mt Cattlin Total 0.1 0.80 158 2.2 1.11 129 2.3 1.10 130 0.015 0.13
Notes:
1. Type of Mine: O/P = open pit/surface, S/P = stockpile.
2. Lithium Ore Reserves are stated as dry mill feed tonnes.
Contacts
Please direct all enquiries to media.enquiries@riotinto.com
Media Relations, Media Relations, Media Relations,
United Kingdom Australia Canada
Matthew Klar Matt Chambers Simon Letendre
M +44 7796 630 637 M +61 433 525 739 M +1 514 796 4973
David Outhwaite Alyesha Anderson Malika Cherry
M +61 434 868 118
M +44 7787 597 493
M +1 418 592 7293
Rachel Pupazzoni
Vanessa Damha
M +61 438 875 469
M +1 514 715 2152
Bruce Tobin
M +61 419 103 454
Media Relations,
US & Latin America
Jesse Riseborough
M +1 202 394 9480
Investor Relations, Investor Relations,
United Kingdom Australia
Rachel Arellano Tom Gallop
M: +44 7584 609 644
M +61 439 353 948
David Ovington
Eddie Gan-Och
M +44 7920 010 978
M +976 95 091 237
Laura Brooks
M +44 7826 942 797
Weiwei Hu
M +44 7825 907 230
Rio Tinto plc Rio Tinto Limited
6 St James's Square Level 43, 120 Collins Street
London SW1Y 4AD Melbourne 3000
United Kingdom Australia
T +44 20 7781 2000 T +61 3 9283 3333
Registered in England Registered in Australia
No. 719885 ABN 96 004 458 404
This announcement is authorised for release to the market by Andy Hodges, Rio
Tinto's Group Company Secretary.
riotinto.com
1 (#_ftnref1) These Mineral Resources and Ore Reserves have been reported in
accordance with the Australasian Code for Reporting of Exploration Results,
Mineral Resources and Ore Reserves, 2012 (JORC Code) and the ASX Listing Rules
in a release to the ASX dated 4 December 2025 titled "Initial reporting of
lithium Mineral Resources and Ore Reserves: Table 1s" (Table 1 Release).
Mineral Resources and Ore Reserves are quoted in this release on a 100 percent
basis. The figures used to calculate Mineral Resources and Ore Reserves are
often more precise than the rounded numbers shown in the tables, hence small
differences may result if the calculations are repeated using the tabulated
figures. Rio Tinto confirms that it is not aware of any new information or
data that materially affects the information included in the Table 1 Release,
that all material assumptions and technical parameters underpinning the
estimates in the Table 1 Release continue to apply and have not materially
changed, and that the form and context in which the Competent Persons'
findings are presented have not been materially modified.
2 (#_ftnref2) For lithium brines deposits Lithium Metal and LCE Ore Reserves
are reported at the well head and thus assume 100% recovery at that point. To
obtain the equivalent tonnage for LCE, the estimated mass of lithium is
multiplied by a factor that is based on the atomic weights of each element in
lithium carbonate to obtain the final compound weight. The factor used was
5.323 to obtain LCE mass from lithium mass.
3 (#_ftnref3) The Competent Person responsible for the information in the
Table 1 Release that relates to Fenix, Olaroz, Sal de Vida and Cauchari
Mineral Resources and Ore Reserves is Sean Kosinski, who is a Certified
Professional Geologist (CPG-12174) and a member of the American Institute of
Professional Geologists.
4 (#_ftnref4) The Competent Person responsible for the information in the
Table 1 Release that relates to Whabouchi Mineral Resources is Christian
Beaulieu, who is a Member of the l'Ordre des géologues du Québec (license
No. 101072).
5 (#_ftnref5) The Competent Person responsible for the information in the
Table 1 Release that relates to Whabouchi Ore Reserves is Jeffrey Cassoff who
is a Member of l'Ordre des Ingénieurs du Québec (license No. 5002252).
6 (#_ftnref6) The Competent Person responsible for the information in the
Table 1 Release that relates to Galaxy Mineral Resources is Luke Evans,
P.Eng., who is a Member of the l'Ordre des Ingénieurs du Québec (license No.
105567).
7 (#_ftnref7) The Competent Person responsible for the information in the
Table 1 Release that relates to Galaxy Ore Reserves is Normand Lecuyer,
P.Eng., who is a Member of l'Ordre des Ingénieurs du Québec (licence No.
34914).
8 (#_ftnref8) The Competent Person responsible for the information in the
Table 1 Release that relates to Mt Cattlin Mineral Resources is Jamie
Oppelaar, who is a Member of the Australasian Institute of Mining and
Metallurgy.
9 (#_ftnref9) The Competent Person responsible for the information in the
Table 1 Release that relates to Mt Cattlin Ore Reserves is based on
information compiled under the supervision of Ali Sami who is a Fellow of the
Australasian Institute of Mining and Metallurgy.
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