How to Make a Homemade Geode

I’ve been so excited about this science project! Sam chose to do his science fair on the topic of crystallization. Did you know that you can make your own geode in 24 hours?  It’s so cool!

You need egg shells and glue…

and something that you get in the spice aisle at the grocery store called Alum.  I guess it’s used for pickling?

It takes one full container of the stuff to make the experiment complete.  Be warned:  don’t buy the stuff in bulk for a class.  The bulk stuff, called Alum, is actually Aluminum Sulfate which will NOT work.  The stuff in the spice racks is Potassium Aluminum Sulfate.  Hot water and food coloring make the final result really attractive.

After 12 hours in the solution it comes out all gel like, but then they dry out for your very own geode!

Check out all the steps and the how & why at Steve Spangler Science.  Even though this is for Sam’s science fair, we plan to make many of these this summer. Too fun!

12 thoughts on “How to Make a Homemade Geode”

  1. This is something I will enjoy doing with my granddaughters. I saw a very large one in a museum just Monday.

  2. What a cool project! One question though. Would it work to use anything other than an eggshell for the base? My daughter is allergic to eggs, so I’m wondering what else might be used? Is the eggshell a crucial ingredient?

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