Her two eldest children and her famous father's former business partners are fighting for multi-billion stakes in a lucrative iron ore project that's half owned by Rio Tinto.
The complex case that starts on Monday centres around a claim by Wright Prospecting, the family company of Lang Hancock's former business partner Peter Wright.
It will demand a half share in the Hope Downs mines and royalties when the long-running stoush begins in the Supreme Court, almost 13 years after it started.
DFD Rhodes, deceased prospector Don Rhodes' family company, is also involved, claiming a 1.25 per cent royalty share of Hope Downs' production.
Mrs Rinehart's son John Hancock and daughter Bianca Rinehart claim they are entitled to half of Hancock Prospecting's share in the massive Hope Downs operation, assets their mining pioneer grandfather allegedly left them.
The trial is expected to run until November, with any judgment potentially superseded by the looming outcome of Federal Court arbitration between Hancock Prospecting and Mrs Rinehart's children concerning the same issues.
Mrs Rinehart was dealt a blow last week when the Supreme Court rejected her bid to have thousands of pages of evidence that's likely be presented at the trial classified as confidential.
The documents that contain claims about Mrs Rinehart's alleged conduct could have resulted in the court being closed for much of the trial had the application succeeded.
Mrs Rinehart inherited her father's iron ore discovery in WA's Pilbara region and then forged a mining empire after he died in 1992.
She developed mines from the tenements Mr Hancock and Mr Wright discovered at Hope Downs in the 1950s with Rio Tinto, which has a 50 per cent stake in the project.
This was followed by Hancock Prospecting Pty Ltd's flagship project, the Roy Hill iron ore mine.
Her wealth, estimated to be about $36 billion, has been bitterly contested.
She spent years in courts fighting her stepmother Rose Porteous over the fortune after Mr Hancock died.
Mrs Rinehart's ongoing battle with her children over the family trust resulted in Mrs Rinehart being granted control in 2015.
The Hope Downs iron ore mining complex is made up of four open-pit mines near Newman.
It produces more than 45 million tonnes each year and is one of Australia's largest and most successful iron ore projects.
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