Gina Rinehart defrauded her children, lawyer alleges

A lawyer for Mrs Rinehart's children, Christopher Withers SC, said there was clear evidence mining licences were unlawfully transferred to the company and a subsidiary against her father's wishes after he died in 1992.

"We don't use the word fraud lightly," he told the Supreme Court trial on Monday.

Mr Withers accused Mrs Rinehart of devising a multi-step scheme to move Hope Downs and East Angeles tenements, including the "Roy Hill diversion", to avoid accruing capital gains tax or stamp duty liability.

"We say the evidence that fraud was perpetuated by Gina on her children is overwhelming," he said, referring to a long-running family feud that is also in arbitration in the Federal Court.

He said Lang Hancock wanted his grandchildren to benefit from the assets via trusts, including John Hancock and Bianca Rinehart, who made an unexpected appearance at court.

Under a 1988 agreement penned by Lang Hancock, his grandchildren were to be the principal benefactors of his efforts to develop an iron ore mine at Hope Downs and 49 per cent shareholders in Hancock Prospecting.

"Lang was simply not prepared to give Gina everything she wanted, which was everything," Mr Withers said.

Mr Withers said Mrs Rinehart "deliberately destroyed" the arrangement after Lang Hancock died through a series of transactions that increased her shareholding at the expense of her children.

"The events after Lang died constitute an egregious fraud orchestrated by Gina and carried out by people who did whatever Gina wanted without questioning," he said.

He said the actions were "covered up" with a "false narrative to her children and the public generally that (Hancock Prospecting's) and her personal success was simply a product of hard work rather than dishonesty".

"The truth is Lang discovered the mining areas in the Pilbara. He was the driving force behind the decision to start a mine," he said.

Mr Withers said Mrs Rinehart lied to her children about her actions and threatened John Hancock and his lawyers when they attempted to investigate the matter.

The court also heard about the multiple disputes Mrs Rinehart allegedly had with her father in the 1980s, including after he married his housekeeper Rose Porteous and she allegedly contacted the immigration department in a bid to have her stepmother deported to the Philippines.

"(Lang Hancock) removed her as a director of (Hancock Prospecting) because she was saying very unfortunate things ... for example calling (Mrs Porteous) an oriental concubine," Mr Withers said.

"She (also) repeatedly called Rose a prostitute."

Mrs Rinehart also allegedly had a "major rift" with her father after she took her mother's will to the US to hold up probate amid fears her father would leave Mrs Porteous mining assets in his will.

The claims were made in a high-stakes legal stoush in Perth in which Mrs Rinehart's company and her children are defending the claims of Wright Prospecting and DFD Rhodes, with Bianca Rinehart in court on Monday listening to her barrister.

Wright Prospecting is suing for a share of some Hope Downs tenements and royalties amid a claim that it never relinquished the assets and Hancock Prospecting has breached a series of partnership agreements.

The family company of the late prospector Don Rhodes, DFD Rhodes, says it is entitled to 1.25 per cent royalty share of the Hope Downs production following 1960s deal.

Mr Withers made repeated calls for Mrs Rinehart to front the court, saying she is one of the few people still alive who could provide evidence about many of the issues raised in the trial.

The Hope Downs mining complex near Newman is one of Australia's largest and most successful iron ore projects, comprising four open-pit mines.