Investors face a dilemma when they earn quick gains in resource stocks. Freeport-McMoRan (FCX) is on such a hot streak that one analyst pegs the stock at a $20 valuation. The stock traded at $10 for most of this year, but rising copper prices lifted the stock.FCX’s stock price depends directly on copper prices. It looks, though that the stock price is getting ahead of fundamentals. At overbought levels, stock holders may lock in profits with FCX. Look for a correction to the $12 - $14 range, although a move to $18 is possible.If FCX dips, load up. In 2017, confirmation the U.S. will raise infrastructure spending will lift copper prices to the $3.00 range, setting up a $20 - $30 valuation for Freeport. Related:Cliffs Natural Resources (CLF), an iron ore producer, is nearly double on the stock market. Like FCX, the stock is up on speculation U.S. infrastructure spend will rise. Markets are ignoring a perpetual slowdown in construction activity in China.Vale SA, BHP and Rio Tinto are both up for the same reasons.