Rio Tinto has finally pulled the covers off its rumoured big copper find in the remote Paterson province of the East Pilbara, revealing an encouraging discovery but one that is still in its infancy.

Releasing its 2018 full-year results yesterday, the mining giant also announced that drilling at its Winu project 130km north of Telfer had intercepted copper, gold and silver.

The company revealed it had drilled eight RC holes and 20 diamond holes between December 2017 and the end of last year for a total of 13,286m. Assay results revealed some wide intersections of vein-style mineralisation with grades above one per cent copper, 1g/t gold and up to 26.41g/t silver.

Rio said the mineralisation had been encountered beneath relatively shallow cover from 50-100m and remained open at depth and to the east, north and south.

However, it is yet to establish a resource estimate for the find.

Four holes covering 1409m have been completed since drilling resumed in mid-January with assay results pending.

Rio chief executive J-S Jacques described the Winu discovery as promising, although it was early days and more work needed to be done.

“But the initial results from the first phase of drilling are pretty encouraging, there is copper, there is gold, there is silver,” he said.

“And I’m really looking forward to the second phase and for sure we will keep you and the market updated.”

Speculation about the scale of Rio’s find in the East Pilbara went into overdrive late last year after it was revealed the company had set up an exploration camp at Winu, applied to upgrade roads to the location and planned to build an airstrip on site.

The activity has stoked hopes of belt-scale mineralisation across the Paterson province and prompted a scramble for land adjacent to Rio’s vast 11,000sqkm tenement package in the area.

Mr Jacques said the company had agreed to increase its investment at Winu, its adjacent tenements and joint venture licences to support drill work as part of the mining giant’s $US250 million global exploration spend this year, with a focus on copper.

Rio yesterday exceeded analysts’ expectations with full-year net earnings of $US13.64 billion ($19 billion) and $US7.1 billion ($9.9 billion) in returns to shareholders.

Underlying earnings of $US8.8 billion was up 2 per cent on the previous year, well above analysts’ expectations of $US8-8.4 billion.

The mining giant kept up its policy of big returns to shareholders, declaring a final dividend of $US1.80 a share and a special dividend of $US2.43 a share on the back of recent asset sales.

Rio shares closed up 56¢ at $95.12 yesterday near last week’s 10-year-plus high of $95.60.