How to Make Crystal Egg Geodes





Introduction: How to Make Crystal Egg Geodes

About: In a valiant attempt to keep myself from dying of boredom, I create.
I love crystals and especially geodes, so how could I pass up the chance to turn some empty egg shells into crystal filled geodes. I saw it here at  Well, I couldn’t resist, so I started gathering supplies and ran into one problem.  Where to get Alum in bulk?  A 1 oz. jar for $4 is just too much for my budget.  I finally found a 1 pound bag at a place called Allyson’s Pantry ( ) here in Utah ($6.00 for the bag). There are other places that have it on line.   I am excited to show you how to make Crystal Egg Geodes, so let’s get started.

Step 1:

1 empty (blown) egg shell
Pointed scissors
Paint brush
Alum (6+ Tbs. per color)
2 plastic or glass cups
Easter egg dyes (you choose what type, I paid $.99 for 6 pellets)
1 cup very hot water
2-3 cup size bowl
Rubber type gloves (to keep your hands from being dyed)
Paper towels

Step 2:

First take your empty egg shell and divide it in to, two pieces, lengthwise.  I took a pair of pointed scissors and started cutting down one side from the hole at one end to the hole at the other end.  The other side just broke in half when I pulled the two sides apart.  Don’t worry about straight edges.  Geodes don’t often have straight edges, so these won’t need straight edges either.  Make sure each egg shell half is clean and dry.

Step 3:

Squirt a little glue into each shell half

Step 4:

and use the paint brush to spread the glue all over the inside of the egg shell.  Sprinkle alum crystals (powder) all over the glue.  Let this dry for several hours.  The alum crystals in the glue provide the “seeds” for the crystals to grow on.  “Seeds” are a NEED in all crystal growing situations.

Step 5:

Lay each shell half in the bottom of its own plastic or glass cup, with the cut/seeded side up.

Step 6:

Put 1 cup water in the bowl.  This water needs to be hot.  Room temperature water can only hold so much dissolved medium (by medium I mean things like, alum, sugar, salt, Epsom salts, etc.).  At this point it is called “saturated”.  As you heat the water, it is better able to absorb more medium, so you keep adding heat to the water and you keep stirring in more medium until it just can’t hold any more, then the solutions is called “super saturated”.  A super saturated alum solution is what we are after.  So I heated the water for 1 minute in the microwave.

Step 7:

I added a color pellet, to the water and let it dissolve, making, in this case a nice orange color. 

Step 8:

I then slowly added 6 tablespoons of alum, stirring as I went, (it bubbled a little at first) the goal being to dissolve all the alum; this means no crystals in the bottom of the bowl. I learned that 6 heaping Tbs. was too much and 6 level Tbs. was too little, so do something in between. 

Step 9:

If you have stirred for what seems like FOREVER yet you still have crystals in the bottom of the bowl,

Step 10:

put the solution in the microwave for 30 more seconds and stir again.  That should do the trick.  Let the solutions sit at least 15 minutes but no more than 30 minutes.  You need your solution to be cool enough to handle, yet if you wait too long your crystals will start falling out of the solution into the bottom of the bowl and not into your egg shells.

Step 11:

Pour half of your solution over each egg half ( again it fuzzed a little, I think it was reaction between the Calcium carbonate in the shell and the alum, please don't make me balance an equation to figure this out),and set aside for 15 + hours.  Alum is great for this project because it is nontoxic, and it makes great crystals in very little time (compared to a week or more for salt or sugar crystals).

Step 12:

Using a spoon, remove each egg shell from the solution.  Pour off any extra solution and place the egg geode on some paper towels to dry. 

Step 13:

One thing I noticed was that the dye was mainly absorbed by the egg shell, not by the crystals.  Yet the crystals are transparent enough that they reflect the color.  Soooooo Cool!  Now to get some more Alum and this time use neon dyes! I love it and I hope you ENJOY!
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    50 Discussions

    Can I use plastic eggs for the project?

    i tried it, with regular school glue then covered it with alum powder (or tawas in Indonesia), but after i left it a day after, the glue and alum became fluid, not dried so i think it failed. what steps did i miss ? or i cant use some regular glue ?

    3 replies

    School glue is water soluble, so the water in the experiment will dissolve the glue. You need a stronger non "Washable" glue to make this work. I hope you find what you need, a white glue that is not "Washable". Good luck!

    I only had Elmer's washable glue to use for alum powder to adhere to eggshell. I checked around 12 hour mark and they will know crystals. Not even tiny ones. Is this because of the washable glue that was used? Did blue and alum powder get washed away after soaking in the solution? Can I use Gorilla Glue?

    6 replies

    I went to Kroger & bought the cheapest school glue I could find, so it was not Elmer'S brand but it worked. We also tried plastic eggs & real shells. I'm trying to download the pictures now from my phone

    the crystals will still grow with Elmers glue, my son is currently doing this as a science fair project. the glue has to be completely dried before putting in the alum solutions and also make sure that while the glue is wet you COVER it with alum. We did variables and it will not grow crystals if the alum powder is not on there. The solution takes about 3 days to see the crystals but they will begin growing up & out. we have now been growing them almost 2 weeks (His project is due Monday) & the solutions is almost gone. Try it again its really cool & experiment with colors, different dyes and mixing colors

    Thank you. The Elmer's glue you had, was it washable kind? I did find some nonwashable Elmer's glue online. Can you post a picture of your son's egg when done? I would love to see it.

    I painted eggshell with the washable glue and covered with alum powder and let dry over night. I left eggshell in alum solution since Thursday in hopes that the crystals would form . . . still no luck.

    Maybe my soution not saturated enough, maybe it was yhe washable glue. I will try again.

    Sorry, for typo. At 12 hour mark, I did not see any crystals. Not even tiny ones.

    Gorilla glue is activated by water. I just learned that, so I don't know. Sounds like an experiment to me. Hope you success. Thanks for asking.

    Thank you for your reply. I will try again with non-washable white glue. Good thing I was able to wash off the washable glue and alum powder from goose eggshells that I bought online. Will try again today. The kids and I cannot wait! This is a wonderful project, thanks for posting this. If I can actually make these crystal egg geodes . . . I will do this project with my Girl Scout troop. I am keeping my fingers crossed. Thanks, again.

    I think you would loose the color. The color seems to be in the shell not the crystals themselves. I just tried and every time I peeled a little shell away the crystal came with it. They really stick to the shell. Sorry.


    I think the shell is what gives it part of it's "rock" look. Play around with some paper mache and spruce it up a bit!

    I am sure you can, but I think you will loose the color and I don't know if the crystals will keep the shape of the egg. Should be a great experiment. Thanks for asking.

    I used food coloring and got an INTENSE coloring. it takes about 30 drops, so I suggest buying a large bottle and using a teaspoon. :-)

    I'm in the process of making one of these, but instead of using a real egg, I went out and bought a few of those giant (3 inches deep, 5 inches long) plastic easter eggs with a colored bottom and clear top. I'm hoping to get a giant 'geode' with a clear removable lid for keeping it safe and displaying it!