Home >> Science & Nature >> Rocks & Minerals

How to Classify a Geode

Geodes are spherical or oval rock formations prized by rock collectors for their stunning appearance. Geodes have crystalline formations inside them and, when cut open, they make for beautiful display pieces. Some geodes will be completely hollow inside, while others will be filled solid with crystal. Classifying a geode is based on its appearance rather than weight, smell or any other factor. The most important aspects to look at are shape and the color of the crystals.

Instructions

- 1
  Use a wet-saw to cut your geode in half. This will allow you to examine the geode's crystalline structure, which will help you classify it.
- 2
  Look at the inside of the geode on either half and see whether it has a hollow space or if it is entirely filled. If it is filled up, it is called a nodule geode. If hollow, it is simply a geode.
- 3
  Examine the geode's shape. If it is long and thin, it is a cathedral geode. If it has two chambers, or hollow spaces, on each half, it is a double-chambered geode. If the geode is cube shape, it is a cubic geode. If it is shaped like a barrel, it is a barrel geode.
- 4
  Examine the colors of the geode's crystals. If they are a deep, dark purple color, it is an amethyst geode. If the crystals are write or pinkish red, it is a quartz geode. If it is completely black inside the geode, it is a black calcite, which is a very rare geode.

Rocks & Minerals