The Yandicoogina Braid deposit, discovered in 2014 and located 15km from the Yandicoogina mine, was the key driver behind the Pilbara upgrade.

The deposit holds Brockman ore, which is found at a number of Rio operations, along with lower grade Brockman process ore and Channel Iron Deposit ore types.

Yandicoogina Braid was classified as inferred and pegged at 488 million tonnes Brockman ore at 61.7% iron, along with 238Mt at 57.7% Brockman process ore.

A further 62Mt at 56.9% fell under the Channel iron category.

The new deposit helped the Hamersley Iron Brockman resource increase 681Mt to 2.99 billion tonnes at 62%, with Brockman process ore rising 324Mt to 1.13Bt at 57%.

Elsewhere in the Pilbara, metallurgical assessments of drill core added 677Mt of inferred Channel iron mineralisation at 53.1% iron at the Jimmawurrada deposit.

Ore reserves at the Koodaideri deposit increased from 49Mt to 467Mt.

Outside iron ore, marketable coal reserves at the Hail Creek mine in Queensland rose 25Mt to 85Mt.

Reserves at the Diavik diamond joint venture in Canada also improved, supporting production until 2023.

The total reserve at Diavik now stands at 18.1Mt at 2.9 carats per tonne for 53.3 million carats.