I got the inspiration to try this experiment from the Explainer who posted about cracking marbles a few days ago. So, I and another Science Guide (DHDC Explainers) went a head and cracked up a marble to see the difference between two similar marbles. All I can say is BEAUTIFUL!!! The cracks do look way better in person and add a nice shininess to the marble. This is a great way to discuss how item expand when warmed and contract when cold and the effects that happen when items under go an extreme temperature change. Below should be some pictures that compare the two marbles after the cracking.
Douglas L. Holeman