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 specialty minerals manufacturer Amcol International (NYSE: ACO) sank 13% Friday after its quarterly results disappointed Wall Street.

So what: Despite a double-digit rise in revenue, Amcol's second-quarter profit fell 16% to $0.43 per share, versus the average analyst estimate of $0.56 per share. "Our gross margins deteriorated in each of our three major business segments," said CEO Ryan McKendrick, "and led to our disappointing earnings in the second quarter."

Now what: Investors should expect more short-term turbulence. For the rest of the year, management said it expects upgrades at its chrome sand operations to lead to losses of between $0.08 and $0.12 per share. And it sees continued margin pressure at its oil-field services segment. Of course, with the stock down about 20% over the past two weeks, and now sporting a dividend yield of 2%, much of Amcol's risks might already be priced in.

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

Fool contributor Brian Pacampara owns no position in any of the companies mentioned. Try any of our Foolish newsletter services free for 30 days.

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