How to Make a Geode

by The Earth (as told to Amy)

1. Create a cavity deep within an existing rock. You can do this 2 different ways: either by trapping a pocket of gas (or water) in cooling lava, or – if you’re so inclined- bury something inside a rock that will decay (wood, coral or dissolvable minerals) and leave you with the cavity you require. Think of it as a mini-cave, and a cave as sometimes a giant geode.