This image is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license. When we look at a rock, we often just focus on its size and appearance. Is it light or heavy? Dark or ...

MACK SLACK: Look at all you little rocks. Sitting there looking up at me, not knowing where you came from or what you're gonna be. Well, let me teach you the oldest story on the planet. The rock cycle ...