Notice to ASX/LSE                                                                                                                       

Mineral Resources and Ore Reserves updates

19 February 2026

Rio Tinto has today announced to the Australian Securities Exchange (ASX) changes in Mineral Resources and Ore Reserves to support its 2025 annual reporting[1], including: 

·      Increased Proved and Probable Ore Reserves and decreased Mineral Resources at the Rio Tinto Copper (RTC) Oyu Tolgoi Oyut open pit deposit in Mongolia.

·      A significant conversion of Mineral Resources to Ore Reserves at the Rio Tinto Copper Kennecott Bingham Canyon open pit deposit in Utah, USA, resulting in a material reduction in reported Mineral Resources.

·      An increase in reported Mineral Resources and Ore Reserves at the Rio Tinto Copper Kennecott Bingham Canyon underground deposit in Utah, USA.

·      Increased Ore Reserves and improved confidence with an associated decrease in Mineral Resources at the Rio Tinto Aluminium (RTA) Pacific Operations Amrun deposit in Queensland, Australia.

·      Increased Mineral Resources and revised classification for the Ore Reserves at Rio Tinto Borates (RTB) Boron deposit.

Supporting information for the changes in Mineral Resources and Ore Reserves is set out in the Table 1 Release and its appendices. This release provides a summary of those changes. Mineral Resources and Ore Reserves are quoted in this release on a 100 percent basis. Mineral Resources are reported in addition to Ore Reserves. 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.  

These changes will be included in Rio Tinto's 2025 Annual Report, to be released to the market on 19 February 2026 (London time), which will set out in full Rio Tinto's Mineral Resources and Ore Reserves position as at 31 December 2025, and Rio Tinto's interests.  

Rio Tinto Copper - Oyu Tolgoi

Mineral Resources and Ore Reserves for the Oyu Tolgoi deposits[2] are presented in Table A and Table B. Proved Ore Reserves have increased by 17 million tonnes (Mt) and Probable Ore Reserves have increased by 63 Mt, for an overall increase in Ore Reserves of 80 Mt (8%). Within the Oyut open pit Proven Ore Reserves have increased by 17 Mt (7%) and Probable Ore Reserves have increased by 61 Mt (17%), for an overall increase of 79 Mt (14%).

There is no material change to Mineral Resources at the Property level. Within the Oyut open pit Measured and Indicated Mineral Resources have increased by 65 Mt (60%), while Inferred Mineral Resources have decreased by 125 Mt (39%) for an overall decrease of 60 Mt (14%).

The material change in both Oyut open pit Ore Reserves and Mineral Resources is largely driven by the Oyut block model update and resulting conversion of Inferred Mineral Resources into Indicated Mineral Resources and subsequently Ore Reserves through increased drilling density and geological confidence, with mining production depletions being the other minor contributing factor.  There has been no material change to other modifying factors, including mine design, governmental, tenure, environmental, cultural heritage or community factors and the methodology for determining Mineral Resources remains unchanged. Note the material variance is solely at the Oyut open pit level, and at Property level there no material change to Mineral Resources or Ore Reserves.

Rio Tinto Copper - Kennecott Bingham Canyon open pit

Mineral Resources and Ore Reserves for the Kennecott Bingham Canyon open pit deposit[3] are presented in Table C and Table D. Measured and Indicated Mineral Resources tonnes have decreased by 63 Mt and Inferred Mineral Resources have increased by 7 Mt for an overall decrease of 56 Mt (74%) as a result of the conversion to Ore Reserves.

Rio Tinto Copper - Kennecott Bingham Canyon underground

Mineral Resources and Ore Reserves for the Kennecott Bingham Canyon underground deposit[4] are presented in Table E and Table F. These Mineral Resources have increased by 32 Mt (122%) and Ore Reserves have increased by 4.0 Mt (85%). These updated Mineral Resources and Ore Reserves reflect increased confidence in the Mineral Resources due to the completion of orebody knowledge drilling, a lower cut-off grade that considers current mining costs, and ongoing experience mining the orebody.

Rio Tinto Aluminium Pacific Operations - Amrun

Mineral Resources and Ore Reserves for the RTA Pacific Operations, including the Amrun deposit[5], are presented in Table G and Table H. The updated Ore Reserves at Amrun reflects a material increase in Ore Reserves, and a material change in Ore Reserve classification. Proved Ore Reserves have increased by 258 Mt (55%), while Probable Ore Reserves have decreased by 161 Mt (31%), for a net increase of 123 Mt (13%), offset by 25 Mt depletion, to a total of 1,076 Mt.  The increase in Ore Reserves has resulted from a routine review of economic assumptions over the life of the mine, and updated orebody knowledge. The change in Ore Reserves classification reflects a higher level of confidence in the modifying factors resulting from increased confidence in the underlying Mineral Resources due to updated orebody knowledge. There has been no material change to other modifying factors, including governmental, tenure, environmental, cultural heritage or community factors. Mineral Resources exclusive of Ore Reserves have decreased by 94 Mt (13%) at Amrun due to the conversion of Mineral Resources to Ore Reserves, updated orebody knowledge and increased resource confidence.

Rio Tinto Borates - Boron

Mineral Resources and Ore Reserves for the RTB Boron Operations[6] are presented in Table I and Table J.  Mineral Resources have increased by 9.3 Mt saleable boric oxide (B₂O₃), reflecting an increase in the level of studies to process mineralised stockpiles. This provides reasonable prospects for eventual economic extraction of the additional material.

Total Ore Reserves (combined Proved and Probable) remain consistent with 2024, with mining depletion of 0.5 Mt B₂O₃ the only change. However, there has been a change in the classification methodology whereby a higher level of geotechnical study is now required for Proved Ore Reserves. Applying this change has converted 1.7 Mt B₂O₃ of Ore Reserves previously classified as Proved Ore Reserves to Probable Ore Reserves. There is no change to level of geotechnical information supporting the Ore Reserves, nor are there changes to any other modifying factors, including governmental, tenure, environmental, cultural heritage or community factors. The result of this change is that Proved Ore Reserves have decreased by 2.2 Mt B₂O₃ and Probable Ore Reserves have increased by 1.7 Mt B₂O₃.

1 These Mineral Resources and Ore Reserves were 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 19 February 2026 titled "Ore Reserve and Mineral Resource updates: supporting information and Table 1 checklists" (Table 1 Release). 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 The Competent Person for the information in the Table 1 Release that relates to Oyu Tolgoi Mineral Resources is Ms Joanna Marshall MAusIMM.  The Competent Person for the information in the Table 1 Release that relates to Oyu Tolgoi Ore Reserves is Mr Nathan Robinson MAusIMM. 

3 The Competent Persons for the information in the Table 1 Release that relates to Kennecott Bingham Canyon open pit Mineral Resources is Mr Gerry Austin MAusIMM and Mr Pancho Rodriguez MAusIMM.  The Competent Person for the information in the Table 1 Release that relates to Kennecott Bingham Canyon open pit Ore Reserves is Mr Eric Hoffmann MAusIMM.

⁴ The Competent Person for the information in the Table 1 Release that relates to Kennecott Bingham Canyon underground Mineral Resources is Mr Ryan Hayes MAusIMM.  The Competent Person for the information in the Table 1 Release that relates to Kennecott Bingham Canyon underground Ore Reserves is Mr Charles McArthur MAusIMM.

⁵ The Competent Person for the information in the Table 1 Release that relates to RTA Pacific Operations Mineral Resources is Mr Angus C. McIntyre MAusIMM.  The Competent Person for the information in the Table 1 Release that relates to RTA Pacific Operations Ore Reserves is Mr William Saba MAusIMM.

⁶ The Competent Person for the information in the Table 1 Release that relates to RTB Boron Mineral Resources and Ore Reserves is Mr Brandon Griffiths who is a Registered Member of the Society for Mining, Metallurgy, and Exploration.