Rio Tinto plc (LON:RIO) has announced initial reporting of Mineral Resources and Ore Reserves[1] 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], 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] 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 Reserves3.
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 operation3 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 project3 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 project3 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% Li2O, consisting of 18.7 Mt at 1.51% Li2O of Indicated Mineral Resources and 8.3 Mt at 1.31% Li2O of Inferred Mineral Resources[4]. Ore Reserves total 26.5 Mt at 1.32% Li2O consisting of 10.5 Mt at 1.40% Li2O of Proved Ore Reserves and 16.0 Mt at 1.27% Li2O of Probable Ore Reserves[5].
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% Li2O consisting of 18.1 Mt at 1.12% Li2O of Indicated Mineral Resources and 55.9 Mt at 1.29% Li2O of Inferred Mineral Resources[6]. Ore Reserves comprise 37.3 Mt at 1.27% Li2O of Probable Ore Reserves[7].
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 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% Li2O, consisting of 0.1 Mt at 1.11% Li2O of Measured Resources, 6.4 Mt at 1.42% Li2O of Indicated Mineral Resources and 4.8 Mt at 1.27% Li2O of Inferred Mineral Resources[8]. Ore Reserves total 2.3 Mt at 1.10% Li2O consisting of 0.1 Mt at 0.80% Li2O of Proved Ore Reserves and 2.2 Mt at 1.11% Li2O of Probable Ore Reserves[9].
[1] 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] 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] 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] 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] 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] 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] 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] 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] 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.
