Eggshell Geodes

We did another egg-cellent experiment this week, when we made eggshell geodes.

Making eggshell geodes is super simple. It just takes a few simple household items and a couple days. There are a lot of easy variations so odds are that you probably have most of these items at home.

This is also a great way to decorate your house for Easter! These geodes are beautiful once they are done.

Ingredients and Instructions


  1. Begin by cracking the eggs. The easiest way is the crack the egg at the narrow end and pick out the bits of broken shell. The harder, but fancier way is to gently poke a hole in the top with a pair of sharp scissors and gently snip across so you get two half shells. You can also use plastic Easter eggs.
  2. Wash the eggshells in hot water, carefully removing the membrane. Make sure all of the membrane is removed or it will start to mold.
  3. Let the egg shell air dry for 12-24 hrs.
    • Pro Tip: it’s recommended that you take these extra steps: 1. Pour a glob of Elmer’s Glue into the eggshell. 2. Spread a coat of glue all over the inside and edges of the shell with a paintbrush. 3. Give the inside of the eggshell an ample dusting of alum powder. 4. Turning the eggshell upside down and tapping out the excess alum … And, 5. Letting the eggshell dry overnight before going on to the next steps.
  4. Place your eggshells in a muffin tin or egg carton. If you don’t mind crystals growing on the outside of the shell, place your shell in a heat safe container.
  5. Pour half a cup of boiling water into your heatproof container then add 1/4 cup of the solid you are using, such as salt, sugar, etc. Stir the mixture well, then continue to add more of your solid until the mixture is super-saturated, meaning no more of the solid will dissolve. Then add your food coloring.
  6. Pour your mixture carefully into your eggshells or into your heat safe container. FIll it up as high as you can without causing the eggshell to tip or overflow.
  7. Place your eggshells in a safe and dry space where they won’t be disturbed. If you disturb the substance, the crystals won’t form correctly.
  8. In 12-24 hrs you’ll see the crystals forming!


Growing egg geodes teaches kids about how crystals grow, and it also gives you a perfect opportunity to introduce them to scientific concepts such as solvents and solutes, chemical reactions, and geology.

Dissolving the crystals in hot water created what is called a “super-saturated solution.” This basically means that the salts took advantage of the energy of the hot water to help them dissolve until there was no more space between molecules in the solution. As the solution cooled, the water lost its energy and the crystals are forced from the solution to become a solid again. Since this happens slowly along with the evaporation, the crystals have time to grow larger than they were when the experiment started. Natural geodes in rock are form in much the same way as mineralized water seeps into air pockets in rock. This is also how rock candy crystals are formed.

Did you do this experiment? What ingredients did you use? Tell us below! Feel free to share images on our Facebook page too!

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