There are a few reasons why Australian investors shouldn’t be perturbed by Thursday’s wobble in the share prices of BHP and Rio Tinto, after a sharp jump in shipments from the brand spanking new Simandou iron ore mine in the African nation of Guinea.First, a little breather is hardly something to worry about in the context of a stonking year. BHP shares dipped 3 per cent on Thursday, but have still climbed 37 per cent since the start of the calendar year to hit yet another record high on Wednesday. Rio shares have also been trading at record levels, up more than 31 per cent this calendar year.Subscribe to gift this articleGift 5 articles to anyone you choose each month when you subscribe.Subscribe nowAlready a subscriber? Fetching latest articles