How to Polish a Geode

What You'll Need
Tumbler designed for geodes or agate
Small file
Soft rag
Polishing powder
Tin oxide

Geodes are beautiful, especially when polished to a high gloss, but learning how to polish a geode like this can be a challenge at first. A geode is a special kind of rock that is made from some kind of geological deposition, either sedimentary or volcanic. The rocks look shiny and are used as decoration pieces. Their outside is generally rich in limestone, while inside they may have special materials such as quartz. There are also complete crystal geodes which are valued more highly than the quartz ones.

Step 1: Decide How to Polish

If the geode has many pieces that seem breakable, it might be best to polish by hand.  

Step 2: Remove Obvious Imperfections

Use the low grade to gently file away any imperfects in the stone.  

Step 3: Polish with a Tumbler

If you want to use the tumbler, read the instructions to find the proper amount of water and grit for recommended use. Place the geode inside and let it go for the tumbler’s recommended amount of time usually a few days. If you are concerned, it is fine to stop the process and inspect the stone. Remember that overpolishing can lose detail on the geode.

Step 4: Add the Finishing Touches

After removing the geode from the tumbler clean it thoroughly to remove any grit. Then, gently go over the geode using the polish. Don’t clump or overuse the polish. Be careful to use less polish around a place where it is likely to fill the space and be difficult to remove.