who let down the tyres, page-2

Copper up, gold up, BHP & RIO up... could it be something to do with the Aussie and US dollar? The last results were down a bit because the Aussie dollar had gone up (and US dollar down). Now, the local currency is even higher and the US is even weaker. So maybe the OX gets less profit even if the prices of copper, zinc and gold are higher in US? Not sure about how this works but I think it is the only explanation, isn't it? Can any of the educated investors explain if this is possible?