Eggshell Geode Crystals

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This project comes to us from Melissa Howard who is a Mom, Blogger, and photographer. This project nicely demonstrates how real-life geodes are formed in igneous and sedimentary rock. It also demonstrates super-saturated solutions and shows a nice variety of crystal shapes and formations.


  • clean eggshells
  • water
  • a variety of soluble solids: table salt, rock salt, sugar, baking soda, Epsom salts, sea salt, borax, or cream of tartar
  • small heat proof containers (coffee cups work well)
  • spoons
  • food coloring
  • egg cartons and wax paper or mini-muffin tins


    1. Crack the eggs for this project as close to the narrow end as possible. This preserves more egg to use as a container for the solution.
    2. Clean the eggshells using hot water. The hot water cooks the lining and allows you to pull the skin (egg membrane) out of the inside of the egg using your fingers. Make sure to remove all the egg membrane, if any membrane stays inside the shell it is possible that your eggshell will grow mold and your crystals will turn black.
    3. Use an egg carton lined with waxed paper or mini-muffin tins to hold the eggs upright.
    4. Use a saucepan to heat the water to boiling. .
    5. Pour half a cup to a cup of water into your heatproof container. If you poured half a cup of water into the container, add about a ¼ cup of solid to the water. Stir it until it dissolves. Likewise if you used a cup of water, add about ½ a cup of solid to the water. You wanted to add about half again the volume of the water as a solid to the mixture. When the initial amount of solid is dissolved continue adding small amounts of the solid until the water is super-saturated. Super-saturated simply means the water has absorbed all it is able to absorb and any solid you add will not dissolve.
    6. Add food coloring.
    7. Carefully pour your solution into the eggshell, filling it as full as possible without over-flowing it or causing it to tip.

    Find a safe place to put your shells while the water evaporates. Crystals will form inside the eggshells as the water evaporates.

      Dissolving the crystals in hot water created what is called a “super-saturated solution.” This basically means that the salts took advantage of the energy of the hot water to help them dissolve until there was no more space between molecules in the solution. As the solution cooled, the water lost its energy and the crystals are forced from the solution to become a solid again. Since this happens slowly along with the evaporation, the crystals have time to grow larger than they were when the experiment started. Natural geodes in rock are form in much the same way as mineralized water seeps into air pockets in rock. This is also how rock candy crystals are formed.

      You can visit Melissa’s great blog and see more pictures HERE.


      25 Responses to “Eggshell Geode Crystals”
      1. Alexis says:

        Heyy This Is So Kewl

      2. chelsea@wilder14:@) says:

        this is very kool me and my friend tessa are doing this as a science experiment…………hope it works well

      3. Tessa#Bynorth#101 says:

        me and my friend chelsea are doin this for a science experiment and cant wait to do it seems really interesting and awesome

      4. roulette-casino-money says:

        This is unbelievable

      5. KJ22 says:


      6. nicole says:

        science bob rocks xx

      7. RedVaporeon says:

        I think this the most awesome experiment ever!

      8. aadipeacock101 says:

        Why did I have to use eggshells?
        Is it a chemical reaction?
        Do eggshells resist all that acid?
        Please answer me back!

      9. ScienceBob says:

        Eggshells provide a nice porous surface for crystals to grow on and a place to hold the crystal solution while it is growing. You could pour the solution in a bowl and place some small rocks on the bottom. Let me know how it turns out.

      10. eislynn1 says:

        this is agood idea looks cool too

      11. ladygaga says:

        Hi i have to do a science fair project and i was wondering does this actually work?? PLEASE RESPOND!!!!!!!!!!

      12. scastill says:


      13. britzy bones says:

        What a cool experiment I am so going to use it for my science fair project!
        thanks for shairing this on sciencebob u rock!!!

      14. mano says:

        Sweet. The only drawback is it takes 3 weeks to do,i heard. PLEASE SAY IT ISN’T TRUE!!!!!

      15. shivadiva200 says:

        my kids loved it

      16. peanutbutterjealytime says:

        this is so cool this would be a great idea to do with your fourth grade science class ;) wink wink

      17. cyrax says:

        scienceBoB is beter on t.v because it is longer and it dusint stop when it is getting to the go part of the show.

      18. cutiepie9168 says:

        what are the independent, dependent and constant variables.

      19. Kmom says:

        I like this for a science fair project.. Just wondering what should we put as the hypothesis ? Thanks for answering.

      20. VickyandYaya says:

        Sciencebob will there be new experiments????? We have been looking @ your comments from TWO YEARS AGO!!!!!!!!!!!!!!!!!!!!!!!!!

      21. shavon123 says:

        love it very cool

      22. ScienceBob says:

        We’re gearing up for lots more experiments and videos by the early summer. Stay tuned!

      23. Dragon123. says:

        Do you think this experiment would work with ostrich eggs?


      Check out what others are saying about this post...
      1. […] Eggshell Geode Crystals via Science Bob's Science Experiment Blog by ScienceBob on 3/27/10 […]

      2. […] shapes and formations. YOU WILL NEED: clean eggshells water a variety of soluble solids: […] Science Bob’s Science Experiment Blog If you like this content, please follow the above link to the original […]

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