Bucking the trend, shares in domestic carrier Regional Express REX.AX jumped 3.7%, after the company said its unit would buy aviation operator Cobham's fly-in fly-out business National Jet Express. July 15 (Reuters) - Australian shares snapped a three-session rally on Friday, as weakness in commodity prices weighed on mining and metal stocks, with mining major Rio Tinto RIO.AX tumbling after flagging a hit to its second-half earnings on inflation woes. Leading the decline, local miners .AXMM tanked as much as 3.9% to hit their lowest since September 2021, as iron ore prices slipped on demand fears in China.