Rio Tinto $RIO (-0.16%) shares Winu valued at 2 billion US dollars following a buy-in deal with a Japanese heavyweight partner

Japanese mining giant Sumitomo Metal Mining $8053 (+0.46%) has paid A$615 to join Rio Tinto in its underdeveloped Winu copper-gold province in the Great Sandy Desert.

Winu, which famously began the rush for the land in the once desolate East Pilbara after its discovery in 2017, will now be split 70-30 between Rio Tinto and Sumitomo.

Rio Tinto has been looking for viable partners for Winu since January this year.

There were several local options on the table

- recently, The Australian had reported that South32 and IGO were both interested - but it was Rio Tinto's new Japanese partners who signed the AUD615 million deal earlier this week.

Sumitomo has already paid US$195 million, with US$204 million bundled into "deferred consideration" which will then be capitalized at certain milestones.

As part of the transaction, both parties entered into a letter of intent to work together to develop a broader strategic partnership.