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: Amcol International (NYSE: ACO) shares plunged 10.1% in intraday trading today, after the minerals manufacturer reported lackluster quarterly results.

So what: You can't really blame investors for feeling jarred. This is the first time Amcol has missed analysts' estimates in six quarters. Worse yet, it missed profit estimates by a whopping $0.17 per share, even though it reported better-than-expected revenue. Higher costs have plagued the company, pinching its profit margins.

Now what: Amcol shares had been rising since last October, so today's pullback might seem like a good opportunity to buy in. However, the company's P/E of 18 sounds a little exotic for a minerals manufacturer. Before buying in, investors should wait and see whether today's developments are a one-time deal or a sign of things to come.

Interested in more info on Amcol International? Add it to your watchlist.

Alyce Lomax does not own shares of any of the companies mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.