89 responses

  1. Julia
    March 24, 2013

    SUPER COOL! We tried to make these once with Epsom salt, but you are inspiring me to try again. I love the colors!

    Reply

    • Tara Ziegmont
      March 24, 2013

      I’ve never tried epsom salts. I think I have a gallon of them. How do they turn out?

      Reply

      • Haylee Rohn
        October 8, 2019

        I don’t know

        Reply

    • Michael
      February 18, 2017

      I use Borax (Sodium Tetraborate) and they turn out very nice!

      Reply

      • Judy
        June 3, 2017

        What ingredients did you used and what amts. Thank you. I have been having trouble find the right alum.

        Reply

  2. Jackie Higgins
    March 24, 2013

    These look great and I loved the slideshow that allowed me to see the crystals close up. Now I want to make these! My dad is a retired science teacher and loves doing this kind of stuff with all the grandkids so maybe I’ll just send him over to read your article 😉

    Reply

  3. Julia
    March 24, 2013

    They are supposed to crystallize like yours did, but we didn’t get any crystals to form. Probably our solution wasn’t concentrated enough. We might try it again.

    Reply

  4. Gina
    March 28, 2013

    As a Homeschooler with 3 science nuts in the house this is just fabulous. We will be doing this project soon. Thanks for the tutorial.

    Reply

    • Tara Ziegmont
      March 28, 2013

      Fun! Depending on their ages, you might consider letting each of your science nuts prepare her own eggs and solution. Every single batch of these crystals turn out differently, so it would be fun to see how each kid’s eggs look. It would be a great time to talk about variables in an experiment – the ones you can control (amount of alum, amount of water, length of time you let the crystals grow) and the ones you can’t (imperfections in the different bowls, invisible differences in the arrangement of the alum crystals {when they dust the wet glue}, visible differences in the amount of glue used, and so on), as well as the constants across all of the bowls (temperature variations in the room, amount of light exposure, type of egg used).

      Reply

  5. Beth
    March 29, 2013

    This is SO cool! What a fun clever idea!

    I am featuring this on TGIF this week here: http://www.123homeschool4me.com/2013/03/tgif-linky-party-69.html – Feel free to grab an I was featured button if you like. Thanks again for linking up and sharing your creativity with the rest of us.

    I hope to see you linked up again soon! Have a WONDERFUL Easter,
    Beth =)

    Reply

  6. Ticia
    March 29, 2013

    I love how yours turned out, what a great job. I saw that pin too, and I want to do this.

    Thanks for linking up to Science Sunday!

    Reply

  7. Tracy
    March 29, 2013

    These look fabulous, and AAAAARRRRGGGGGHHH!!! we just had our Science Fair last night, and these would have been FANTASTIC! And so much fun and so cute. I’ve totally bookmarked this page for next year. Thanks for the great, explicit details. Adorable AND educational!

    Reply

  8. Mom to 2 Posh Lil Divas
    March 30, 2013

    So cool! The finished geodes look amazing – so colorful. Thanks for sharing these on the Sunday Showcase. I have wanted to make some for years and never get around to it. You have inspired me. Featured this on this week’s Sunday Showcase.

    Reply

    • Tara Ziegmont
      April 5, 2013

      Thank you!

      Reply

  9. Hannah
    April 5, 2013

    Impressive! I pinned this for summer break when our playscool willhave school aged children!

    Reply

  10. boopila
    May 1, 2013

    This is so cool. My mom’s birthday is coming up and I’ve been racking my brain for some personalized gift ideas that my kids will actually enjoy. Because G-ma is a decor-holic, and macaroni posters are the opposite of tasteful or chic (cute as they may be), I’ve decided this would be the perfect project. Not to mention we’ll be able to use eggs from her own hens. Yay science! Props to Auntie Gomo who sent us this link.

    Reply

  11. Jeffery
    May 2, 2013

    I simply wished to take a couple of moments and let
    you know that I enjoyed reading the post. I
    truthfully don’t think many people know exactly how much effort that goes into putting together a good web page. I know that this is sort of random however it bothers me occasionally. Anyhow excellent post.

    Reply

  12. Mike
    May 31, 2013

    Wow this is awesome , I tried this before but it didn’t turn out this good. I might give it another go sometime. 🙂

    Reply

  13. Antoinette
    November 18, 2013

    This is great! I can’t wait until my kids are old enough to appreciate this.

    Reply

  14. Haley
    December 16, 2013

    I tried this project with my little ones and the crystals did not form so we tried it agian and it still would not work I do not recommend this😞

    Reply

    • Tara Ziegmont
      December 17, 2013

      I’m sorry that you weren’t happy with your results. Where did you get your alum powder? As I said in the post, if you don’t get a very specific type of alum powder, the crystals will not form. You might try Epson salts. They will also form crystals and may be less temperamental. I haven’t tried them yet.

      Reply

  15. Kari
    January 8, 2014

    I did this in elementary school with sugar and salt in plastic cups.

    Reply

  16. tina
    January 9, 2014

    I pinned this & shared on FB. Im on my phone – hopefully it worked….

    Thanks!

    Reply

  17. ken
    January 17, 2014

    My kids love these crystal experiments! They recently made their own video on Alum crystals: https://www.youtube.com/watch?v=pfy9mjNs7yk&list=TLsEBie84rHA0Jhdrj5dmhmFT9H74qlRE6

    Reply

  18. Robin Romack
    January 22, 2014

    I am sooo not good at science though i like it. I talked my high school daughter into this for her science fair after she did something else last year. The plan to compare the crystals of 4 solutions. sugar, alum, vinegar/salt, and borax BUT i am sadly somewhere between 5 and 50 on the understanding scale. we tried heating and stirring and first just poured them in the eggshells, reread and then reheated solution and poured it around the the whole shell. It is the second day and growth looks pretty minimal–she switched projects at the last minute to this and claims every suggestion of mine gets her a horrid grade. (In 4th grade we had to do a building from our town and being a Landscape Arch I insisted on this old hotel which we made to scale with lights and researching history etc–she got a check minus sooo alot rides on this) Anyway. Do you take them out of the water to grow, take them out of bowl and leave solution in egg, take the solution out of bowl and reheat/refill, set the whole darn thing on the heater, leave all in bowls and put on heater??? I feel like an idiot and failure right now as she pointed out it’s one third of her grade and somewhere (none I saw) someone called this project hard.

    Reply

    • Tara Ziegmont
      January 22, 2014

      My first guess is that your solutions weren’t super saturated. Did you heat it and stir in as much of the solid as would dissolve (leaving some in the bottom of the pan or bowl)? Then you just strain out the excess solid and have a super saturated solution.

      Where did you get the alum? It’s possible that you used the wrong kind of alum, but the sugar and borax should definitely have worked if you had the solution super saturated.

      You put the eggshell right into the bowl of saturated solution and leave it there for a few days until the solution has cooled and the crystals have formed. The solution has to cool or else the crystals won’t form. If you keep it hot, you’ll never get crystals. Also, the faster the solution cools (like if it’s in a cold draft or something), the smaller the crystals will be. So keep it in a warmish spot – but not a hot spot like on a heater or on the stovetop.

      Reply

      • Robin Romack
        January 22, 2014

        Thanks for the quick reply!

        Reply

    • Tara Ziegmont
      January 22, 2014

      oh, and! Don’t forget to glue some of the undissolved crystals into the eggshell. Those are the seeds on which the crystals will form. Crystals can form without them, but they speed up the process.

      Reply

  19. Emily Sorensen
    February 5, 2014

    I make Christmas ornaments by making a saturated borax solution and hanging shaped pipe cleaner on a sting in it overnight or so. The cooling borax adheres to the pipe cleaner and beings to form crystals much like sugar would when making rock candy.

    DO NOT ATTEMPT TO EAT.

    Reply

  20. Jamie
    March 12, 2014

    Great step by step. I homeschool my 2 boys, and we just started a new unit in science about rocks,and rock formation. Next weeks lesson is all about crystals! How fun for us to have this awesome project to go along with it!!

    Reply

  21. Alwyn Lefae
    April 22, 2014

    Such a cool little experiment! I will deffinitley have to try this in dorm this weekend when I go to town!!! My only question is: Does it absolutely have to be alum? Because I’m not sure I can get alum in town (you’d think so, but it’s a small town, and who uses alum anymore?!). I will deffinitley look, but if someone else used some other crystal-making solution that would be easier for a student to get on a tight budget, that would be amazing~

    Reply

    • Tara Ziegmont
      April 22, 2014

      You can make crystals with epsom salts or sugar pretty easily.

      Reply

  22. FRUSTRATED
    April 26, 2014

    We have so many different ways to get these crystals to grow in the last couple weeks & all we ever get is SLUDGE in the bottom of the cup. We have THOUGHOUGLY MEMORIZED these directions & still no crystal geodes! Just eggs with crystals glued to them sitting in sludge! We are using the correct POTASSIUM ALUMINUM SULFATE…WE DROVE TO A LABORATORY SUPPLY STORE & BOUGHT 16 oz of “LABORATORY GRADE” FOR OVER $20!! . Ridiculous, but the only thing we found in stores didn’t contain the potassium like some commenters had warned was necessary. It was in irregular, small crystals vs “powdered” form but that should not make a difference once dissolved. You’d also think the crystal form would also be a good base for the crystals to adhere to in more of a geode appearance. Our experiment involved testing how/if environmental temp (fridge, room & warm) differences affected the crystal formation…problem is ABSOLUTELY NO NEW CRYSTALS FORMED! The glued on ones remained in place but the dissolved, saturated, filtered through coffee filters alum…we tried so many things over the course of the past couple weeks… just precipitates out to the bottom in a fine grained sludge. We tried forming “true seed crystals” to glue to egg shells…we can’t even get THOSE, again just powder residue. We used distilled water so we had no contamination from our well water. You use metal spoons so our thought that ions from the steel somehow got introduced during the stirring of the heated solution and changed our chemical isn’t probable… We’re done pouring any more time or $ into further trips to the laboratory store. This supposedly fool-proof project DID NOT work for us. So much for trying to do a project with “common household things”… Back to the drawing board. The science fair is a week away & we will be switching to rock salt (which we can obtain more easily in larger supply) & trying other methods described out there. 6th grade son are EXTREMELY FRUSTRATED & parents are too because we have to keep trying to coach him to try again & change what might have gone wrong… to heck with scientific process when it doesn’t ever do what it’s suppose so the kid runs out of time & QUITS!!! We should have never wasted our time with this project!

    Reply

    • Tara Ziegmont
      April 28, 2014

      I’m really sorry this happened to you. I don’t have experience with any alum except that sold from Talas, and it has worked every time I’ve ever tried the experiment. You might want to try epsom salts or sugar. They usually give good results, too.

      Reply

    • Peter
      January 15, 2017

      I saw a workshop recently with 20 primary school children where this worked fine for all of them. They had it done within an hour, put it in a fridge and had crystals a couple of hours later. Sometimes it’s best not to be too careful. For instance, using distilled water might be your problem – just use tap water, it should work fine. (As an aside, when brewing beer, tap water is needed because it contains minerals that the yeast enzymes need, distilled water is no good.)

      Also, just add borax (or epsom salts) till no more dissolves – that is, some settles on the bottom and won’t dissolve – then just pour off the solution at the top (it will be saturated). Just get your experiment to work and then decide if you want to try again to get better results.

      You can see from Tara’s description that she has done the experiment multiple times in order to optimise the results, but when you first try it it’s best to start out “quick and dirty” then optimise.

      Reply

      • Peter
        January 15, 2017

        Oops, I meant to include alum as one of the possible chemicals to use for crystal growth. Also, I always find videos often make procedures “crytsal clear” (excuse the pun). Emmymade has a good crystal growing video, plus lots of other ideas, https://www.youtube.com/channel/UCQjEdAaQ0zzbrsD-biel8eg

        Reply

  23. Tiffany LeClair
    July 15, 2014

    I have done this every year for the past four years with my fourth grade and it has worked perfectly every time. I order my alum from Carolina biological, and have never had a problem. When we had tried grocery store or spice quality alum it didn’t work, just as you have already pointed out.

    Reply

  24. Sharon Abel
    January 13, 2015

    Tara I have a 5 year old grandson that we are always doing things together…when he spends the night we always work on ‘Projects’…lol..this is one we’ll be trying soon…Am sorry for all the negitive responses from some of the people. I won’t comment on the ones that got me a little ticked, this is suppose to be a fun thing to do with the kids…am thinking up ways to incorporate this into other fun projects with the little ones! Keep up the fun ideas!

    Reply

  25. Natali
    March 15, 2015

    Importantly, all very easy to do with children. Will definitely try.

    Reply

  26. SherriSue
    May 8, 2015

    I have a couple questions;
    Can you remove the crystals from the shells after they have completely dried?
    Can you use different small plastic containers instead of egg shapes?

    Reply

    • Tara Ziegmont
      May 8, 2015

      I’ve never tried to remove the crystals. You’d have to try it and see. They may break when you try.

      You could use any shape plastic container. For that matter, you could use almost any surface to grow the crystals on. The important thing is starting with the seed crystals, and the big ones will grow from there.

      Reply

  27. billiejo
    May 14, 2015

    I’ve tried this over and over and verified the correct alum. We can’t seem to get any crystals. I am trying with the borax this week. I’m wanting this to be successful because this will be an activity at our Harry Potter Hogwarts on the Bayou camp. The students are make g the sorcerer stone. How do you get your plastic eggs from not floating to the top of the solution?

    Reply

    • Tara Ziegmont
      May 15, 2015

      I didn’t have to do anything. They just sunk. They weren’t whole, of course, just halves.

      Reply

  28. Nancy
    June 15, 2015

    My first attempt failed. I now have the correct alum and am ready to try again. Are you suppose to submerge the eggs while the solution is still hot/warm? I let mine cool the first time and that may have been one of the issues.

    Reply

    • Tara Ziegmont
      June 16, 2015

      Yes, submerge the eggs while the solution is still warm. That way the crystals can form as it cools down.

      Reply

  29. Mercy
    September 1, 2015

    million dollar question

    You mentioned they’re quite sturdy once dry. Sturdy enough to drill a tiny hole in it? Or would it crack, explode, shatter, die…. You get the gist 🙂

    Reply

    • Tara Ziegmont
      September 3, 2015

      I think it depends on how tiny the hole is. They might stand up to a really tiny drill bit.

      Reply

  30. Dianah Rutledge
    January 1, 2016

    I want to try this. I have a question. How long do the crystals last?

    Reply

    • Tara Ziegmont
      January 6, 2016

      They will last pretty much forever. We got tired of ours and threw them out, but they really are hard and durable.

      Reply

  31. Ana Luisa
    January 19, 2016

    They are beautiful

    Reply

  32. Ana Luisa
    January 19, 2016

    I will tell my sis so she can help me do it ; )

    Reply

  33. Maria Julia
    January 20, 2016

    Hi I’m Ana Luisas sister

    Reply

  34. Maria Julia
    January 20, 2016

    🙂

    Reply

    • Ana Luisa
      January 20, 2016

      😉

      Reply

    • Ana Luisa
      January 20, 2016

      ;):)

      Reply

  35. Katherine
    March 30, 2016

    Did this with my first grader for the school science fair. He loved it, it turned out great, and the crystals were awesome. It was a hit with the kids, parents, and teachers. We cited your website on his poster and I’ve had a number of parents tell me they have visited it to make geodes at their house. THANK YOU!

    Reply

    • Katherine
      March 30, 2016

      FYI, I ordered Jacquard alum through Amazon.

      Reply

    • Tara Ziegmont
      April 3, 2016

      Wow, that’s awesome! Thank you so much for the recommendation!

      Reply

  36. Florence
    April 3, 2017

    I love your blog! (chemistry teacher)

    Reply

    • Tara Ziegmont
      April 5, 2017

      Thanks 🙂

      Reply

  37. Takeshi
    April 18, 2017

    when you drop the egg shells in, does the liquid need to be hot? cold? or it doesn’t matter.

    Reply

    • Tara Ziegmont
      April 18, 2017

      It does matter. The liquid should be hot. The crystals will form as it cools.

      Reply

  38. Nicole
    May 9, 2017

    As I am reading all the post, I realize that the alum I bought from the spice isle will not be successful for this project! We just did the first step tonight-glue and alum. I do not have enough time to order the alum online. Is the next best thing borax? We have to complete the project for Thursday! Any advice?

    Reply

    • Tara Ziegmont
      May 10, 2017

      I’ve never done borax crystals, but I have had good results with Epsom salts crystals. Overnight is a very tight squeeze though; I don’t know if the crystals will have time to form.

      Reply

  39. gail
    April 6, 2018

    What’s the best way to preserve crystals? I’ve read that clear nail polish isn’t a great idea.
    Thanks

    Reply

    • Tara Ziegmont
      April 6, 2018

      You don’t need to do anything to them. They’re quite sturdy and will last pretty much forever if you don’t knock them around.

      Reply

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