As announced on 27 February 2019[1], Rio Tinto has discovered copper-gold mineralisation at the Winu project in the Yeneena Basin of the Paterson Province in Western Australia. A significant programme of work has continued at the Winu camp in recent months with 180 people now on site and this release provides additional data on the intercepts for the eleven diamond drill holes reflecting drilling to the end of 2018. In addition, some assay data has changed as a result of quality control and assurance activities.

Significant intercepts for the eleven diamond drill holes not previously available in full, as well as all previously reported results, are set out in Table 1 and Table 2 in the PDF attached. Results continue to indicate relatively wide intersections of vein style copper mineralisation associated with gold and silver beneath relatively shallow cover which ranges from 50 to 100 metres. The mineralisation remains open at depth and to the east, north, and south.

Some changes have been made to the assays due to ongoing quality control and assurance procedures, and changes in analytical techniques. A comparison of original and revised intercepts for the affected drill holes are provided in Table 3 and Table 4. This outlines the completed drilling results to the end of 2018.

The next phase of reverse circulation (RC) and diamond drilling is underway to further define the mineralisation extents and continuity, and results will be reported in a subsequent release in Quarter 3, 2019. There are currently eight diamond rigs, three RC rigs, and a waterbore rig drilling at Winu.

Other activity at Winu includes cultural heritage surveys and the commencement of construction of a gravel airstrip for emergency response purposes, given the exploration camp is located approximately 200 kilometres by gravel and sand track from the Great Northern Highway and a seven hour drive from Port Hedland.

While results continue to be encouraging, the exploration project is still at an early stage and drilling to date does not allow sufficient understanding of the mineralised body to assess the potential size or quality of the mineralisation nor to enable estimation of a Mineral Resource. The assessment and interpretation of existing data is ongoing and is being used to help guide drilling in 2019.

• [Editor:tianyawei]