Gina Rinehart, Australia's richest person, just added more money to her wealth. On Friday, she and another female billionaire were awarded $200 million after they won a lawsuit against Rio Tinto (ASX: RIO).

Justice David Hammerschlag of the Western Australia Supreme Court ruled in favour of the companies owned by Ms Rinehart and Angela Bennett over royalties to iron ore in the Pilbara mines run by Rio.

The royalties date back more than 20 years based on an agreement between the fathers of the two women billionaires - who were business partners - in 1970 covering the Channar mine and Eastern range mine, which became highly profitable mines.

Ms Rinehart's father, Lang Hancock, is credited with the discovery of the large iron ore deposits in the two mines. But Rio insisted it was not obliged to pay the descendants of Hancock and Peter Wright, Ms Bennett's father, because they did not control the land continuously, having lost control from 1974 to 1979.

The judge ruled in favour of the two women, who ironically battled it out between themselves also over ownership of other mine businesses their fathers started.

The award, to be split between Ms Rinehart and Ms Bennett and her brother Michael Wright, may be just loose change to both women mining magnates. Ms Rinehart's fortune is estimated at $18 billion. She also used to be the world's richest woman until the title was recaptured by a Walmart heiress.

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