Change to Argyle Diamonds Mineral Resources

02 March 2017

Included in Rio Tinto’s annual Mineral Resources and Ore Reserves tables, released to the market today as part of its 2016 Annual Report, are decreases in Mineral Resources at Rio Tinto’s 100 per cent-owned Argyle Diamond mine in the East Kimberley, Western Australia.

The updated Mineral Resources are 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. As such, the reported decreases relating to the Argyle Mine requires the additional supporting information set out in this release and its appendix.

Rio Tinto’s Ore Reserves and Mineral Resources are set out in full in its 2016 Annual report.

During 2016, estimated Argyle Mineral Resources exclusive of Ore Reserves decreased by 29Mt from 44Mt to 15Mt. Previously reported Mineral Resources included mineralisation that could support a potential extension of the currently planned mine life. As mine life extension options are under ongoing review, the reported Mineral Resources have now been restricted to those parts of the mineralisation which can be potentially developed, mined and processed during the existing mine-life defined by the current underground operation. It is for this reason that there has been a material reduction in reported Mineral Resources in 2016.

As the change to Argyle Mineral Resources does not impact reported Ore Reserves, this reduction has no bearing on the current mine plan which sees production continuing until 2021.