Company: RTNTF
Filing Date: 2025-02-20
Form Type: 20-F
Source: 0001628280-25-006642
Chunk: 524

Company: RIO TINTO LTD
Filing Date: 2025-02-20
Form: 20-F
Chunk 524
---
 to granodiorite composition into host volcanics. Primary mineralisation has undergone secondary supergene leaching and enrichment with associated local formation of copper oxide mineralisation, predominately brochantite. Supergene enrichment generated laterally-continuous and sub- horizontal high-grade sulphide mineralisation zones across the deposit, predominately chalcocite and covellite. The primary hypogene mineralisation, present in the deepest parts of the deposits is chalcopyrite with bornite. Mineral Resources The table on pages 294 - 295 sets out the amount and grade of Escondida’s Measured, Indicated and Inferred Mineral Resources for the year ended 31 December 2024. Mineral Resources for Escondida are reported as in situ estimates. Compared to the year ended 31 December 2023, there is an increase of 7% in Measured and Indicated Resources and a decrease of 6% in Inferred Mineral Resources resulting in an overall decrease of 3% as at December 31 2024. These changes were mainly due to mine factors and inclusion of additional drilling results to the estimate. The Mineral Resources estimate for Escondida is based on the following assumptions: – Exclusive of Mineral Reserves – Mineral Resources are reported exclusive of Mineral Reserves. – Moisture – All Mineral Resources tonnages are estimated and reported on a dry basis. – Mineral Resources are estimated using ordinary kriging. – Escondida point of reference for the Mineral Resources is mine gate. – Escondida Mineral Resources cut-off criteria used are Oxide ≥ 0.20% soluble Cu; Mixed ≥ 0.30% Cu; Sulphide ≥ 0.25% Cu for mineralisation assigned to be processed via leaching or ≥ 0.30% Cu for mineralisation assigned to be processed via the concentrator. – Escondida metallurgical recoveries are Oxide 54%; Mixed 41%; Sulphide 42% for material processed by leaching or 85% for material processed via the concentrator. – The pit optimisation used to determine the Mineral Resources that have reasonable prospects of economic extraction based on a copper price of US$4.29/lb. For more information regarding the material assumptions for the Mineral Resources estimates for Escondida, see Section 11 of the Escondida Technical Report Summary filed as exhibit 96.2 to this Form 20-F for the year ended 31 December 2022 (“2022 Form 20- F ”).