Rinehart children's closing court bid for mining riches

The complex battle that started in July pits Ms Rinehart's company Hancock Prospecting against the heirs of mining pioneer Peter Wright and engineer Don Rhodes over the massive Hope Downs mining complex amid allegations of decades-old contract breaches.

Mrs Rinehart's eldest children, John Hancock and Bianca Rinehart, are also involved in the case and claim their grandfather Lang Hancock left them a hefty share in the Pilbara mining resources he discovered in the 1950s that are now mined in partnership with Rio Tinto.

The pair sat in the Supreme Court public gallery in Perth on Monday as their lawyer Christopher Withers SC summarised their case for Justice Jennifer Smith.

"The partnership was not in the business of building a mine and conducting mining operations," he said referring to Lang Hancock and Peter Wright's business partnership.

"After Peter (Wright) died it wasn't even permitted to be involved in mine management."

Wright Prospecting has demanded a share of unmined and mined Hope Downs tenements and royalties, amid a claim that Hancock Prospecting breached 1980s partnership agreements.

Mr Withers said the men's partnership never had legally enforceable rights over the tenements that became the Hope Downs mining complex, or confidential and valuable information about them.

Wright Prospecting also gave up its 1987 contractual right to royalties and letters from the WA government about the same time show that neither the partnership nor Hancock Prospecting had any rights to the assets.

"(Wright Prospecting's) case must be dismissed," he said.

Mr Withers also made reference to Lang Hancock's plan to develop a mine and export iron ore to Romania, saying Ms Rinehart was against the "bad idea" and that she had "castigated" her father over it.

'We never expected our company would be involved in reckless and possibly ruinous business deals involving outlandish agreements being made with tin pot governments," he said Mrs Rinehart had stated at the time.

He reminded the court that Lang Hancock set up a trust to enrich his grandchildren via the tenements, saying Wright Prospecting and DFD Rhodes hadn't helped him during a "relentless campaign" to secure them.

"He intended for my clients and their siblings to be able to control the income that would be generated," he said.

"Not to Gina, his grandchildren."

Mr Withers also targeted Hancock Prospecting's claim that Lang Hancock breached his fiduciary duty over his handling of the assets.

"There is no way that Your Honour could find Lang acted dishonesty when he was keeping Gina apprised of all of his plans and their implementation," he said.

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

DFD Rhodes is claiming a 1.25 per cent royalty share of Hope Downs' production, over an alleged deal with Mr Hancock and Mr Wright that handed over tenements in the 1960s.

Hancock Prospecting maintains it undertook all the work, bore the financial risk involved in the development at Hope Downs and is the legitimate owner of the assets.

About two dozen lawyers have packed the Perth courtroom for the trial, which has also featured sensational claims against Gina Rinehart, which she denies.

These include that the billionaire allegedly devised an unlawful scheme to defraud her children and threatened to have her father's former housekeeper Rose Porteous, who he later married, deported, and called her a "prostitute".

Hancock Prospecting has said Lang Hancock wrongly removed the tenements from the company and that he had shown "no regard" for Wright Prospecting's interests.

Ms Rinehart developed mines from the tenements at Hope Downs, signing a deal in 2005 with Rio Tinto, which has a 50 per cent stake in the project.

Australian Associated Press