Introduction: How to Make Crystal Egg Geodes

Picture of How to Make Crystal Egg Geodes
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:

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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:

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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:

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Squirt a little glue into each shell half

Step 4:

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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:

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

Step 6:

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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:

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

Step 8:

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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:

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

Step 10:

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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:

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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:

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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:

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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!


theresias (author)2016-05-16

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 ?

texasaggies (author)theresias2016-11-16

you suck thats why

texasaggies (author)texasaggies2016-11-16

just kidding same thing happened to me

craftknowitall (author)theresias2016-05-19

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!

FearLisa (author)2016-03-24

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?

EricaB34 (author)FearLisa2016-03-26

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

EricaB34 (author)FearLisa2016-03-26

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

FearLisa (author)EricaB342016-03-26

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.

FearLisa (author)FearLisa2016-03-24

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

craftknowitall (author)FearLisa2016-03-25

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.

FearLisa (author)craftknowitall2016-03-25

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.

heidisatwork (author)2014-03-01

after the crystals are grown, can you peel off the egg shell?

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.

Super_G (author)craftknowitall2016-03-22

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!

ninjakid11 (author)heidisatwork2014-05-26

heidisatwork, I think you can, but I just saw this now

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.

shawn.peabody.9 (author)2014-10-15

can you use food coloring instead of the dye pills?

Super_G (author)shawn.peabody.92016-03-22

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. :-)

lmaupin (author)2014-03-20

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!

theblckwlf (author)lmaupin2015-12-06

how did that work out? It's a clever idea.

lasoren14 (author)2015-07-11

Can you do this without food coloring? Like with paint?

sophx44 (author)2015-02-21

Hi we are doing this for a science project as well and I was wondering if we wanted to show the different mediums like borax for instance-- am I still soaking them completely and do I include the alum with the other mediums? Thanks!!

craftknowitall (author)sophx442015-02-21

You can if you use exactly the same amount of alum with each other medium. Use the metric system and use a scale to measure it. What is you hypothesis? What are you trying to discover? With that info I would know how to better answer you question. Hope to hear from you soon.

callie.keller.3 (author)2015-02-06

Im in the process of making these eggs but i was also wondering, do you think i can make them in clam or oyster shells? Thanks :)

Sounds like an experiment to me> Why don't you try and let me know the results. I can think of no good reason why it shouldn't work. Thanks for asking.

hayleybass (author)2015-02-03

About how long does this take? I'm doing geodes for a science project and only have a few months so i dont want anything longer than a month to grow. If you could answer back thanks

These crystals take a couple of hours. You can watch them grow. Thanks for asking. By the way what is your hypothesis?

shawz (author)2015-01-27

Can you NOT use alum and still make crystals?

craftknowitall (author)shawz2015-01-27

You can make crystals from sugar like found here: or from salt, basically the same as sugar. Thanks for asking

KwartzKitten (author)2015-01-26

These would make nice decorations or conversation starters. I wonder what would work besides eggshells?

craftknowitall (author)2014-10-16

You may not get as intense a color with food coloring. You should try it and see. Let me know how it went. Thanks for asking.

ninjakid11 (author)2014-05-26

interesting, but how is it supposed to come out, in the way you showed. And we do not have to break these, neat.

natarol (author)2014-02-28

exelente gracias por tu ayuda!!!!!

craftknowitall (author)natarol2014-02-28

Su bienvenida

hazelle (author)2014-02-10

i made this for a school priject and hope get first placed

craftknowitall (author)hazelle2014-02-11

I hope you do too. Good luck, and thanks for commenting!

DUSTERMUSTER (author)2012-07-12

I seen the finished product on Pinterest when I was first informed of the link. I have searched for this in books,online,etc. SOooooo very happy to find it, I think they are great. Congrs. on a great job.

Jason Bedard (author)2012-04-11

Congratulations on taking First Place in the egg challenge. Very cool project that I will for sure try.

Thanks, it really surprised me. Lots of fun though.

kkarwan (author)2012-04-07

you could also make a deep bowl and just poke the holes and put the alum into the holes to keep the egg whole because then you could crack the egg like a real geode, it'll look like a real egg and you can crack it to the candy inside

craftknowitall (author)kkarwan2012-04-11

Try it and let me know how it goes.

Reed_Sky_Born (author)2012-04-05

it looks so good

Thank you for looking.

Shadow13! (author)2012-04-06

Great instructable although your definition of super saturated is not quite correct. When a solution can hold no more medium at the current temperature then it has become fully saturated. A solution is super saturated when the solution is fully saturated at a higher temperature and then allowed to cool. This then allows the solution to hold more medium then if it had just been saturated. This is super saturated.

craftknowitall (author)Shadow13!2012-04-07

I stand corrected, Thank you for commenting and looking.

h8864 (author)2012-04-04

i found that alum crystals make a great antipersperant

craftknowitall (author)h88642012-04-04

Yes it does! Thanks for looking.

jessyratfink (author)2012-04-03

These are so neat looking! This would be so fun to do with kids - though they might need to learn patience. :D

The patience results from making sugar crystals at a 1 week wait. Thanks for looking and commenting.

About This Instructable




Bio: In a valiant attempt to keep myself from dying of boredom, I create.
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