Incredible Egg Geode
Forgive the wordplay, but we love to do “eggs-periments.” Get it? We’ve made naked eggs, put eggs in a bottle, folded eggs, and we’ve even shown you how to determine whether an egg is hard-boiled or raw. We want to find something new and amazing to do with eggs, and the Incredible Egg Geode is “eggs-actly” what we are looking for.
- Food coloring
- Alum powder (look in the spice section of your local grocers)
- Paper towels
- You have an egg, now you need to get all the yolk and egg white out of it. WAIT! You can't just crack the egg like you're making breakfast. You need that egg in one piece. Use a pushpin to carefully poke a hole in each end of the egg.
- Put your mouth on one end of the egg and blow the yolk out through the other hole. Blow the yolk into a bowl or garbage disposal, depending on whether you're hungry 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 a pair of scissors. If there are any small pieces around the edges, go ahead and pull them off. They're of no use to you.
- Continuing to exercise caution (who knew science was so fragile?), wipe out the inside of the egg with a paper towel. Get the interior surface of the egg as clean and dry as possible without cracking it.
- Drop a small amount of glue into the egg and use a paintbrush to spread it around. Try to cover the entire interior surface, all the way up to the edges, of the egg with glue. Add more glue if needed.
- Quickly, before the glue dries, cover it with alum powder. How much? Cover it all! Our experiment tester suggested the word “generously”… so use quite a bit.
- So you covered the glue with alum powder, now what? Well, your options are to sit around until everything is completely dry or let it sit overnight. The first option gets really boring and you need your rest, so come back tomorrow and we'll pick the experiment up there.
- Is it tomorrow yet? Yes? Then let's do this!
- Bring two cups of water (that's 473 mL to everyone outside the U.S.) to the point where it is almost boiling. Pour the heated water into a beaker or glass and stir 30-40 drops of food coloring and 3/4 cup of alum powder into the heated water.
- Let the colored alum solution cool for around thirty minutes.
- Once the colored alum solution has cooled, place the egg, opening up, into the solution. Push the egg to the bottom of the beaker with a spoon and allow the egg to sit in the solution for 12-15 hours. That's a long time, right? Good thing you practiced patience by waiting for the glue to dry earlier.
- After the 12-15 hours have passed, check out your egg. It's grown crystals! Carefully remove the egg and place it on a paper towel or drying rack to finish the geode-creation process.
While a geological geode is a mass of minerals within a rock that can take thousands of years to form, your Incredible Egg Geode only takes a couple of days. See? All that waiting could have been much worse.
How Does It Work?
Your egg geode is formed through a process called sedimentation. The heated alum solution contains suspended particles of alum powder and as the solution cools, these particles of alum begin settling. When the alum particles settle towards the bottom of the beaker or glass, they begin crystallizing. With the alum-covered egg at the bottom, the alum particles from the solution begin attaching themselves to the egg. Covering your egg in alum powder beforehand gives the suspended alum particles a surface to which they can more readily attach themselves. The particles that settle onto the surface of the egg crystallize, and you will also see crystallization on the bottom and sides of the beaker or glass.
- Eggs-cellent Egg-speriment! Review by Karen
This is so much fun, Steve! Thanks for the appropriate timing. I did this with K-5th graders as well as a little more challenging version with 9-12 graders, and we all had a blast. Very easy, great video explanation.
(Posted on April 4, 2012)
- very egg-salent Review by chloe
I loved this experiment! it worked great and my parents spent very little money. I hope this works for the rest of you.
p.s. put two eggs in at a time
(Posted on April 9, 2013)
- Tease! Review by Joahna
Think this looks really fun and my nephew watched the video with me and we were totally committed to doing it! Then we tried to find Alum, figuring we'd need almost a cup per color we wanted to do. The only Alum we could find was a tiny container hidden at the grocery store, about 1/6 of a cup in a package and selling for $3.25 each. They had three of them. Idea abandoned...
(Posted on April 6, 2012)
- Awesome project for science fair!! Review by Donna
This experiment was so fun for my 4th grader and me to do. It was easy and we ended up with great results! Just make sure you use a LOT of alum on the glue inside of the egg, and make sure you let it dry completely. We will do this again next year for sure!!
(Posted on March 20, 2013)
- flop Review by 5th grade teacher
spent $80 dollars on Alum. tried it with 2 classes for a mothers day gift. 48 eggs. Not a single one turned out. No crystals just a bunch of colored egg shells.
(Posted on May 10, 2012)
- egg geode gone wrong Review by kerrie schulze
The first time I did this experiment, it went great. My geodes were beautiful. Thought I would try it again using some different colors. The only thing that happened was the egg shell turned color but no crystals at all. Not sure why. It is costly if you get the alum from the grocery store. I got online and ordered in bulk to do the experiment with my kids at school so it wasn't as costly. I'm trying the experiment again so hopefully it isn't the new alum that flopped rather than operator error.
(Posted on April 22, 2012)
- my kids love this! Review by Traci Mae
I am spoiled rotten (pardon the pun) but this website is so reliable and fun that I know I'll get great results. You're the first place I look for something out ot the box!
(Posted on April 4, 2012)
- Very cool experiment! Review by Erin
My class is doing this experiment this week. We did a trial experiment today. When we submerged the egg into the water/alum mixture, the eggshell floated up and stayed at the surface. Will this work or are we supposed to leave the spoon in to weigh the shell down?
(Posted on May 15, 2012)
- Is the eggshell necessary Review by Christy
Can someone tell me if the eggshell is a crucial part of the experiment, or if some other material can be used in it's place? I have a daughter who is allergic to eggs, so if there is another material that would allow the geodes to grow on it as well as the eggshell does, I would love to hear about it. Thank you!
(Posted on July 8, 2012)
- Amazing Review by Jessica Miles
My son did this experiment for his school science project. The eggs turned out better than we ever expected! Obviously, the more alum used, the more crystals were formed. We used McCormick Alum powder from the grocery store.
(Posted on November 21, 2012)