MINING magnate Gina Rinehart has taken a small stake in listed coal explorer Carabella Resources, sparking speculation she is planning a takeover bid to expand her interests in Queensland. Shares in Carabella shot up 5.5 per cent to $2.10 after 917,434 shares in the company...representing 0.74% of its total shares on issue was acquired by a company associated with Australia's richest person.