Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of rare-earth materials extractor Molycorp (NYSE: MCP) gained as much as 10.5% on above-average trading volume this morning.

So what: The price drivers today are plentiful: Financial Times reports that rare earth materials are being stockpiled in China, Piper Jaffray upgraded Molycorp to a buy, and a host of analysts piled on with positive assessments of the rare earth industry in general. Not surprisingly, rivals Avalon Rare Metals (AMEX: AVL) and Rare Element Resources (AMEX: REE) also jumped today.

Now what: OK, so Molycorp and friends have all fallen drastically from 52-week highs set in early May -- that perceived value is indeed one of the factors inspiring Piper to recommend the stock today. But you're still looking at a development-stage company with minuscule sales and no profits, working in an ill-understood market with most of the business happening half a world away at the whims of an artful Chinese administration. And for this, you're paying 70 times trailing sales.

Day traders may love this hypervolatile stock (and industry), but long-term investors and other proper Fools should stay away.

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