Investors should be looking to take advantage of the dip in the price of copper, and this stock is an ideal way to do that.Having crossed $5 per pound in May, the price of copper has declined to around$4.12 per pound, and that fall has taken the share price of copper miner Freeport-McMoRan (FCX 1.05%) with it -- it's down almost 18% since copper crossed $5 per pound. That said, these kinds of dips often create buying opportunities in commodity stocks, which is the case now. Here are three reasons why.Freep ...