A joint venture led by Rio Tinto has thrown its hat in the ring...

A joint venture led by Rio Tinto has thrown its hat in the ring to snare CZR Resources’ crown jewel, joining Fenix Resources and Gold Valley in the Pilbara iron ore fight.The Robe River JV, which is 53 per cent controlled by Rio and the remainder by Japan’s Mitsui & Co and Nippon Steel, on Thursday lobbed a non-binding offer to acquire CZR’s 85 per cent stake in the Robe Mesa iron ore project for $75 million.Rio’s Mesa F deposit adjoins CZR’s Robe Mesa, stoking rumours for years that the Anglo-Australian mining giant would make a move to swallow up the minnow.The Robe River offer, announced on Friday, sees CZR retain its other early-stage gold and copper exploration projects and its 50 per cent interest in the Ashburton Link export logistics project.CZR said the Robe River offer is non-binding and subject to due diligence, approval from CZR’s majority shareholder Mark Creasy — who owns the other 15 per cent of Robe Mesa outright — and approval from the Foreign Investment Review Board.CZR’s board is continuing to recommend Fenix Resources’ all-scrip takeover offer, which now looks set to be worth less than $70m, but is breaking its exclusivity arrangement with Fenix to engage with the Robe River proposal.“The CZR board has determined in good faith after consultation with its external legal advisers that the Robe River JV proposal is a potential competing proposal . . . that could reasonably be expected to lead to a superior proposal,” the company stated on Friday.The announcement of Rio’s Robe Mesa offer comes a day after Yuzheng Xie said his Gold Valley was being stonewalled by CZR’s board.Gold Valley on Wednesday made a $73.3m cash offer to buy all of CZR. Mr Xie said the takeover target’s board was not engaging with Gold Valley’s proposal, which was “far superior” to the one tabled by John Welborn’s Fenix Resources.“All we got is a one line email back saying ‘we don’t want to engage’,” he told The West Australian on Thursday.“They should allow competition . . . let John’s (Welborn) Fenix and us have a beating up, let us duel it out.“We really encourage the CZR board to lift a standstill agreement we previously signed with them because now we can’t buy any (CZR) shares . . . their shareholders are the ones losing out.”Both the Gold Valley and the Robe River offers will likely face scrutiny from Australia’s FIRB.The Stefan Murphy-led CZR is scarred by a recent FIRB experience. CZR shook hands with Frank Yin’s Miracle Iron last January to sell its 85 per cent stake in Robe Mesa for $102m, but the deal was canned last month after FIRB kept delaying an approval decision with no explanation.Shares in CZR rose 6 per cent to 30¢ each in early Friday trade. They gained more than 14 per cent on Thursday after Gold Valley’s proposal came to light.