That may be true if you throw up a ball, but it is disputable in this case. Just like with oil running out, precious metals are slowly too.
That is true in the long run, or probably even in the medium run, but in the short run, there has been a lot of fear-based speculative buying in the commodities market. Recall what happened to oil a couple of years ago. Commodity markets are naturally highly volatile in the short term, and there's no reason to expect that to change. The problem for a market for any good where the price is rising very rapidly in the short term is that it requires a constant stream of new investors to enter the market at higher and higher prices; eventually you run out of buyers who can afford to play.