Company: RTNTF
Filing Date: 2025-02-20
Form Type: 20-F
Source: 0001628280-25-006642
Chunk: 531

Company: RIO TINTO LTD
Filing Date: 2025-02-20
Form: 20-F
Chunk 531
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 The mineral deposits at Oyu Tolgoi lie in a structural corridor where mineralisation has been discovered over a 26km strike length. Four deposits hosting Mineral Resources have been identified: Oyut, Hugo Dummett North, Hugo Dummett South, and Heruga. The Oyu Tolgoi copper-gold porphyry deposits are distributed along a 12km north- northeast striking corridor. From north to south, the deposits comprise Hugo North, Hugo South, Oyut, and Heruga. These deposits lie within the Gurvansayhan island-arc terrane, a fault bounded segment of the broader Silurian to Carboniferous Kazakh-Mongol arc, located towards the southern margin of the Central Asian Orogenic Belt. Mineralisation is associated with multiple, overlapping, intrusions of late Devonian quartz-monzodiorite intruding Devonian (or older) juvenile, probably intra- oceanic arc-related, basaltic lavas and lesser volcaniclastic rocks, unconformably overlain by late Devonian basaltic to dacitic pyroclastic and volcano sedimentary rocks. These quartz-monzodiorite intrusions range from early-mineral porphyritic dykes, to larger, linear, syn-, late- and post-mineral dykes and stocks. Mineral Resources The table on pages 294 - 295 sets out the amount and grade, of Oyu Tolgoi’s Measured, Indicated and Inferred Mineral Resources for the year ended 31 December 2024. The negligible <1% reduction in Mineral Resources compared to the year ended 31 December 2023 is primarily due to the 2024 mined (production) Inferred material from the Oyut open pit Mineral Resources. The Mineral Resources estimate 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. – The sample data preparation including data capping is appropriate for use in estimation of a Mineral Resource. – The pit optimisation used to determine the resources that have reasonable prospects of economic extraction. – It is assumed that standard open pit load and haul mining operations and underground block cave mining operations will be applicable for the mining of Mineral Resources. Processing will be through crushing, grinding and a froth flotation concentrator process. – Copper, gold and silver are payable elements and are