How to open your geode: 
There are several ways you can open your geode, including our favorite which is to throw it down a hill until you see the gems! 
 
Here is the most common method to opening geodes of this size: 
1) Take a rock or masonry flat chisel (or the back side of a hammer) and hold it at top center of your geode, then strike with a hand-held sledge hammer or other heavy object to score the geode. 
 
2) Rotate your geode a bit, then strike again to create a line around the circumference of the stone.

3)Repeat, as necessary, until the rock splits open. Patience is key; if the geode is hollow, it will probably take a few minutes of gentle scoring to open it, but if the geode is solid, it'll take longer