.N The heavyweight mining index .AXMM gained 1%, with top miners BHP Group Ltd BHP.AX and Rio Tinto Ltd RIO.AX rising 1.7% and 1.6%, respectively. By Ayushman Ojha July 12 (Reuters) - Australian shares extended gains on Wednesday, on the back of mining and energy stocks, while investors awaited crucial U.S. inflation data that could provide clues on the Federal Reserve's rate hike policy going ahead. Investors are looking for further clues on whether price pressures are abating and if the Federal Reserve is nearing the end of its cycle of interest rate hikes.