More rich folk... Gina Rinehart is pretty low key. And she owns a few percent of a certain mining minnow, Jupiter Mines!
From Wikipedia
Georgina "Gina" Hope Rinehart (born 1956) is the Chairman of Hancock Prospecting, and the daughter of mining magnate Lang Hancock. She has been described as "Australia's richest woman", with a net worth of more than AU$4bn. She is best-known for her part in an acrimonious fight with her father's widow, Rose Porteous, over the circumstances of his death.