Break Your Own Unopened Crystal Geode "Surprise" Rock - Fun Gift
Photo shows an example of what might be inside.
There are a few ways to break a geode; the trick is to be patient. To make sure the geode breaks into large pieces, don't just hit it as hard as you can with a hammer. This could make it shatter into lots of small pieces and not 2 halves. You should always wear safety goggles when opening geodes.
To open a geode using a hammer and chisel, use a flat faced chisel to score a ring around the geode's circumference, like an equator line. Then place the chisel on the line and gently tap with the hammer until you see a crack. Follow the crack around the geode, tapping carefully, until it opens. If you don't have a chisel, using a hammer will also work but you may not get neat halves.
Always wear safety goggles and if you don't have goggles you could place the geode in a bag or cover with a cloth before opening to stop fragments flying everywhere.