Geode Rock Formations

geode
What is a Geode Rock Formation?

Geodes are a great way to view and learn about the formation of rocks. They occur in sedimentary as well as some volcanic rocks too. These geological rock formations are most commonly limestone on the outside, while the inside is hollow and full of quartz crystals. If there is no air pocket in the formation it is called a nodule instead of a geode.

How Do Geodes Form?

A geode starts off as a bubble or a void left by an animal burrow, tree root, or something else. Water is trapped inside of the void, which contains silica precipitation that has other minerals or elements present in it such as calcite, iron or manganese. The basic crystals of a geode are made of quartz (silicon dioxide) and are colored based on the contents of the surrounding soil. Over thousands of years different layers of silica precipitation cool and create different layers of crystals. There is no way to tell what is on the inside of a geode without cracking it open. You can view the process of cracking open a geode below.

How to open a Geode

This video demonstration shows cracking open a Geode with a pipe cutter.

If you want to learn how to break open your own geode, check out this page at the Geode Gallery.

Where you can find Geodes

Geodes are found in areas where there had been:

  • Volcanic activity at one point.
  • Weathering had taken place that allowed the accumulation of minerals and organic substance.

Over at The Geode Guys, they have a list of some locations that are known to have geodes.

Where you can Purchase Geodes


Heath Scientific can provide you with a solid geode or crack it open for you.