Egg Geodes

Have you ever grown your own crystal geodes? Try this egg experiment and grow your very own borax crystals in a shell! Experiment with different borax concentrations and see how big your egg geodes can grow. 

  1. Ages: 9 - 16

  2. 2+ hours

  3. Messy

  4. Grownup needed


Materials you'll need

Step-by-step tutorial

  • Step 1

    Gather your materials!

    Photo reference of how to complete step 1

  • Warning

    Borax (sodium tetraborate) is a naturally-occurring mineral salt commonly used as a laundry booster or cleaner. As with any other cleaning product, it should be kept away from children not under direct supervision of an adult. Do not allow children to ingest Borax. If consumed, contact a poison control center immediately. Wash hands after play, as prolonged skin exposure may cause irritation.

  • Step 2

    Start by preparing your borax solution. Add 4 tablespoons of borax and 1 cup of water to a jar. Microwave the solution in 30-second intervals, stirring after each internal. After about 2 1/2 minutes (or 5 intervals) the borax should be completely dissolved. You can always microwave the solution for a few more seconds or add a tablespoon of water, if the borax is not yet dissolved.  

    Photo reference of how to complete step 2

  • Warning

    The jar and solution will be very hot. Be careful when taking it out of the microwave!

  • Step 3

    While your crystal solution is cooling down, start preparing the eggshells. We cracked the top portion of the egg open and removed the egg to make little egg cups for our geodes. 

    Photo reference of how to complete step 3

  • Tip

    You'll want to rinse out the inside of the egg to get rid of all the egg white.

  • Step 4

    Brush some glue on the inside the eggshell, and then sprinkle borax inside the shell. Pour out any excess borax. Next, wait for the glue to dry. The borax coating inside the egg will act as starting "seeds" for crystallizing the borax solution.

    Photo reference of how to complete step 4

  • Step 5

    Fill a cup with crystal solution and add a few drops of food coloring. You'll need enough crystal solution in the glass to fully submerge the eggshell. If you have enough crystal solution, you can make multiple colors of crystal solution.

    Photo reference of how to complete step 5

  • Step 6

    Once the eggshell is dry and the water is room temperature, gently lower it into the crystal solution. Let it sit overnight or until your crystals have reached the size you want. If you want more crystals, you can mix up a new batch of the borax solution and drop the egg into the new solution.

    Photo reference of how to complete step 6

  • Final result!

    Once you are satisfied with the size of the crystals, carefully take out the shell and place on a paper towel to dry. When your egg geode is dry, you can put it on display to amaze your friends and family!

    Photo reference of how to complete step 7

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