Incredible Egg Geode – Science Experiment

Turn your eggs into beautiful alum-crystal geodes instead of frying or scrambling them.

Incredible Egg Geodes

Instead of frying or scrambling your eggs, learn how to make incredible egg geodes! Learn how to turn everyday eggs into beautiful alum-crystal geodes and enjoy beautiful geode crystals that you can display in your classroom, in your room and in your home. 

Egg Geodes Science Fair Project 

At Steve Spangler Science, we love to do “eggs-periments,” so if you’re looking for fun and easy experiments using eggs, we’re the place to be! We’ve made naked eggs, put eggs in a bottle, folded eggs, —  we’ve even shown you how to determine if an egg is either raw or hard-boiled. We are continually on the lookout for new and amazing things that you can do with eggs.

Our Incredible Egg Geode Science Fair Project is “eggs-actly” what we want to share! All you need are some easy-peasy instructions and a few eggs that you’ll most likely already have in your refrigerator. Our eggshell geodes make a fun chemistry experiment on how to make egg crystals at home or in your classroom. 

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Experiment Materials

  • Egg (Wash each one you use!)
  • Small paintbrush
  • White glue
  • Food coloring
  • Alum powder (in the cooking section of your local grocer)
  • Water
  • Sharp scissors
  • Paper towels
  • Bowl
  • Wide-mouth glass
  • Spoon
  • Pushpin

Experiment Videos



NOTE: Carefully wash each egg before you handle it or put your mouth on the shell.

You have an egg, now you need to get all the yolk and egg white out of it but you need the shell to stay pretty much in one piece.

Use a pushpin to carefully poke a hole in each rounded end of the shell.


Put your mouth on one end of the egg and blow the yolk and the egg white through the other hole. This may take a while and isn’t too easy so don’t rush. Blow into a bowl or garbage disposal, depending on whether you plan to enjoy scrambled eggs or not.


Now that you don’t have an egg so much as an eggshell, carefully cut the shell in half, down the egg’s length, with scissors.


Carefully wash the inside of the shell halves with warm water and wipe them dry with a paper towel. Get the interior surface of the egg as clean and dry as possible without cracking it. Peel off and throw away small pieces of shell from around its edge.


Generously drip some glue into the shell halves. A little on the outside is OK, too.


Use the paintbrush to spread the glue all over the inside of the shell. Completely cover the interior surface with glue all the way up to, and including, the edges. Use more glue if needed.


Generously sprinkle lots of alum powder on the wet glue.


Turn the shell-half over and gently tap out any excess alum. Place it on a paper towel or paper plate to dry overnight.


The next day, bring two cups of water (473 ml) almost to a boil and pour it into a bowl.

NOTE: If you plan to make more than one color of geode, use one cup  (237 ml) of water and adjust the food coloring and alum amounts accordingly. See the “Take It Further” section below.


Dissolve 30-40 drops of food coloring into the water. Use any color or color combination you wish. Stir it well.


Dissolve ¾-cup alum powder into the water.


Stir it well and make sure it dissolves completely. Let the mixture cool for 30 minutes.


When it’s cool, place the shells into the solution alum-side up. Gently push the shells to the bottom of the solution with the spoon and allow them to sit there for 12-15 hours.


After 12-15 hours, alum crystals have grown! Carefully remove the shells and place them on a paper towel to dry and finish the geode-creation process. Perhaps you can leave them in the bowl longer and see if they grow bigger.

How Does It Work

Your eggshell geode is formed through a process called “sedimentation.” This experiment is a representation about how geodes are formed. While a geological geode is a mass of minerals within a rock that can take thousands — even millions — of years to form, your egg geode only takes a couple of days. 

The heated alum solution contains suspended particles of alum powder in it; as the solution cools, these particles of alum begin falling to the bottom. When the alum particles settle on the bottom, they begin to crystallize. Coating the shell with alum powder beforehand gives the suspended alum particles a surface to which they can more readily attach themselves. The particles that settle onto the interior surface of the shell crystallize quickly but you will also see evidence of crystallization on other parts of the shell, as well as on the bottom and sides of the bowl.

Take It Further

You not only can learn how to make egg geodes in this experiment, you can make a few changes to modify this egg geode science fair project. Change out several variables, such as how much water you use or your amount of food coloring. 

You can test using a cup of water (or maybe less) per eggshell to make your egg geodes. The amounts of food color and alum you use may also be adjusted proportionately. That way, you might be able to make several colors of egg geodes at the same time. There may be other materials to test that will also grow egg crystals (like borax, Epsom salt, salt or sugar). Be sure to share your results of this egg geode science fair project.

Earth Science, Chemistry Experiments and More 

Did you have fun learning how to make egg crystals? Take your geode crystal learning even farther and explore other earth science and chemistry experiments by diving into other experiments that observe the reactions of the world around us. Each Steve Spangler Science experiment has that amazing WOW factor that we’re known for. Check out our experiments, have fun and get busy learning!

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