Last month Gina Rinehart, Australia’s richest woman and matriarch of Perth’s Hancock mining dynasty delivered an unwelcome shock to her workers in Western Australia: accept a possible 10pc pay cut or face the risk of future redundancies. Ms Rinehart, whose family have accumulated vast wealth from iron ore mining, has seen her fortune dwindle since commodity prices began their inexorable slide last year. The Australian mining mogul has seen her estimated wealth collapse to around $11bn (£7bn) from a fortune that was thought to be worth around $30bn just three years ago. This colossal collapse in wealth is symptomatic of...