Widely seen as a major future source of iron ore for China's voracious steel sector, Simandou has been the cause of repeated crises for Rio Tinto and a number of other mining companies, including Brazil's mining leader, Vale.
The thick and rich beds of high-grade ore located deep inside Guinea have also featured in political and corporate scuffles that saw the replacement of government ministers in Guinea, and a change of chief executive at Rio Tinto.
So much time and effort went into deals which swirled around Simandou that most players in the game took their eye off the prize which is the chance to develop a world-class iron ore project and associated rail and port systems.
That's changing as Chinese steel producers assume a prominent role in the future of a project which could become a significant rival to existing iron ore producers, including Rio Tinto.
Armed with deep financial reserves, and Chinese Government support, the steel companies have orchestrated an ownership shuffle which appears to clear the way for a start on construction and the creation of a business dedicated to supplying iron ore to China.
The changes at Simandou started late last year when the government of Guinea awarded two of four blocks covering the deposit (Blocks 1 and 2) to a syndicate of Chinese, Singaporean and French companies, the so-called SMB-Winning group which is already Guinea's biggest bauxite producer.
The other two blocks (3 and 4) were held by Rio Tinto with a 45% stake, Chinalco (China's biggest aluminium producer and a major shareholder in Rio Tinto) with 40% and the government of Guinea with 15%.
The ownership covering blocks 3 and 4 is reported to have changed with Chinalco selling its 40% stake to Baowu, a giant Chinese steel company which has grown from the merger of Baosteel with Wuhan Steel.
Chinalco, like all aluminium producers, is under financial pressure caused by low aluminium prices. Its exit from the Simandou consortium would not be a surprise, especially as it retains a minority interest through its 15% stake in Rio Tinto.
Baowu will be a very different shareholder than Chinalco in Simandou and is likely to be pressing for a quick development decision, not because it sees the project as particularly profitable but more for strategic considerations such as reducing exposure to iron ore from Australia at a time of strained diplomatic relations.
… whether Rio Tinto wants to participate in a new iron ore mine which is likely to deliver investment returns well below those generated at its Australian mines is a question which will have the full attention of the company's directors
A number of investment banks have recently ratcheted up their research of Simandou, including a report last month from UBS which focused largely on the SMB-Winning consortium which is moving ahead with its US$14 billion plan to start producing up to 80 million tonnes of high-grade ore a year with first shipments in 2026.
JP Morgan joined the Simandou watchers club on Monday with what it called a "deep dive" into the tenements in which Rio Tinto has its 45% stake, warning that the new ownership structure with Baowu joining "could force Rio Tinto to use-it, or lose-it", while also threatening the long term iron ore price.
The key finding of JP Morgan is that Simandou, after years on the sidelines or trapped in legal and political battles, is finally "moving forward".
SMB-Winning is building its project, despite formidable geographic challenges that include a 650km railway which will require 39 bridges, 1,000 culverts and 28km of tunnel before getting ore to a new, purpose-built, export port. The Rio Tinto/Baowu project will have similar challenges.
But whether Rio Tinto wants to participate in a new iron ore mine which is likely to deliver investment returns well below those generated at its Australian mines is a question which will have the full attention of the company's directors.
"Will Rio Tinto participate, or will it relinquish control?" was the question asked by JP Morgan, noting that Baowu will be "highly motivated" to develop Simandou.
Perhaps more significantly the bank suggested that Baowu might want to join forces with the SMB-Winning syndicate to cut development costs which currently look to be so high that the potential financial return might not clear Rio Tinto's required internal rate of return.
"We estimate Blocks 3 and 4 (Rio Tinto's 45% controlled area) could end up with a $150 per tonne capital intensity which generates a modest 11% IRR at our $60/t tonne long term iron ore price," JP Morgan said.
"This might not pass through Rio Tinto's capital allocation framework, or meet its ‘value over volume' strategy.
"However, Rio Tinto might also end up taking the view that it is going ahead anyway and it's better to participate and retain some control."