Bubble, bubble, this rock is neither toil nor trouble—place it in a bath of vinegar and watch the bubblicious crystals grow. In one to two weeks, you'll have a miniature crystal formation, like the ones that form in caves all over the world. Let it dry, and your delicate geological experiment will harden into something beautiful and a bit more permanent.
Bubble Rock is a natural mineral, gray limestone, found in Utah. The crystals created with this experiment are similar to the geological formations seen within caves throughout the world. Bubble Rock is a carbonate rock that, when immersed in a weak acid like vinegar, undergoes a chemical reaction. This reaction causes some of the stone to dissolve and recrystallize, growing crystals on top of the specimen.