Iron ore heir Julian Wright says he "did not fully comprehend" what he was being told when his father's partner, the late mining magnate Lang Hancock, informed him 35 years ago that his family owned "the best iron ore deposit in the whole of the Hamersley field".
Mr Wright was giving evidence as part of his legal action against his sister, billionaire Angela Bennett, and the estate of his late brother Michael, who he alleges withheld information from him about the potential value of the family's company before he sold his one-third share to them in 1987 for $6.8 million.
The company, which is now worth billions, was founded by the three siblings' father, Peter Wright, who along with Hancock pioneered the discovery of iron ore in WA's Pilbara region.
It was Julian Wright's third day in the witness box in WA's Supreme Court, and he was being cross-examined by Sydney barrister Kristina Stern SC, who is representing Ms Bennett and Michael Wright's estate.
Ms Stern pressed him about a letter he and his siblings received from Hancock in November 1985, in which he described one of their family's mining tenements, Giles Mini, as "the most valuable and possible saleable ore body in your half".
Hancock went on to say, "Current iron producers seem to be unanimous in their opinion that Giles is the best iron ore deposit in the whole of the Hamersley field".
'Not credible to say I had all this knowledge'
Julian Wright accepted Hancock was telling him his family owned a potentially very valuable ore deposit, but he maintained at the time he did not "fully comprehend" the significance of the letter.
"It's not credible to say I had all this knowledge," he told the court.
"I might be stupid, I might be naive, I might be a lot of things, but I did not have that knowledge or understanding."
He also denied a suggestion from Ms Stern that despite "being armed with this knowledge", he was still willing to enter into a sale agreement with his siblings.
"If I had realised the significance of these ore bodies, I would have used them as a bargaining chip," he said.
"I never said to Michael, 'You've got Giles Mini out there with its squillions of dollars and you can afford to pay more'."
Mr Wright told the court he had sold his share "not realising how valuable Giles Mini was".
I was 'ignorant' about royalty agreement
Earlier, Mr Wright testified he could not recall every conversation he had with his siblings in the lead-up to his decision to sell his share of the company.
He also said he had no recollection of signing a document relating to a 1962 royalty agreement with Hamersley Iron before his father's death, saying he "remained ignorant of what the agreement was about".
"It wouldn't be the first time I signed something because my father asked me to. I trusted him implicitly," he said.
The case, before Justice Rene Le Miere, is expected to run for another two weeks.
