If you have kids, chances are at some point they’ve collected pockets full of small rock treasures that sometimes wind up in the washing machine.
As adults we don’t always understand why that tiny grey rock is so special.
But when it comes to sparkling geodes, everyone seems to agree. Geodes are amazing to look at.
You and your child can learn about how geodes form by making your own salt crystal egg geodes, a favorite when it comes to STEM activities because of the beautiful results.
Egg experiments like this one are always popular in the springtime.
If you are looking for other ideas, you’ll want to discover how to make a rubber egg. It even glows!
Your child may also enjoy doing the egg drop challenge.
Crystal Egg Geodes
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- 3-4 Raw Eggs
- Craft Glue
- Epsom Salt
- Food Coloring
- Small Containers
- Small Paint Brush
- Small Pot and Stove
- Small Screw Driver (optional)
To make your egg geode, carefully crack your egg at the narrow end.
We found that this was easier to do if we tapped the end with a small screw driver.
Slowly widen the hole in the egg until it is a little larger than a quarter.
Empty the contents of the egg into a bowl. You can use it later to bake some fabulous muffin recipes with the kids.
Rinse the egg shell out.
Then gently rub your finger around the inside to remove the egg’s membrane.
Once the membrane is removed, you can dye the egg shell if desired. Or, you can skip this step.
Either way, make sure the shells are dry before proceding to the next step.
To dye the shells, use a few drops of food coloring in white vinegar. Simply let them sit in the color for 3-5 minutes. Then remove the shells to let them dry.
Dying the shells allows you to create geodes with 2 different colors, one for the shell and a different color for the crystals inside.
Once you’ve dyed the shells, turn them upside down on a paper towel and let them dry completely before moving on to the next step.
How to Make Geodes
Once the shells are dry, use a paint brush to coat the entire inside of the shells with a thin layer of craft glue.
Then sprinkle Epsom salts onto the glue, shaking off any excess. This will act as a starter to help grow your crystals in your homemade geode.
Let the glue dry completely.
Once the glue is dry, boil 1 cup of water.
Remove the water from the heat source and stir ins 1/2 cup of Epsom salt. Stir it until it s completely dissolved.
Continue stirring in 1-2 tablespoons of salt at a time until it not longer dissolves. Your super-saturated solution should be thicker that water when you stir it.
Place each hollow egg in a small container. You could also use a Styrofoam egg carton for this part.
Use a small ladle to fill each egg with your super-saturated salt solution.
Add a drop or two of food coloring and stir it with a toothpick.
Place the egg shells somewhere where they won’t be disturbed for several days. We had to put ours on top of our refrigerator to keep the cat from messing with them.
Check your egg experiment daily, and use a toothpick to break any thin solid layers that may form on top. You want the water to be able to evaporate.
After a few days, the water will evaporate, leaving behind beautiful homemade geodes!
You may even want to display them in one of these geode holders.
How Geodes Form
Actual geodes are rocks with open spaces, or cavities, inside that are lined with crystals.
The crystals form through a process called sedimentation, where particles (solute) are suspended in fluid (solvent) and then come together, accumulating to form crystals as the fluid disappears over many, many years.
When creating your salt crystal geodes, the Epsom salt acts as the solute and the water as the solvent. The water is so saturated with Epsom salt that the salt particles fuse together, forming crystals as the water evaporates.
Love geodes? We fell in love with these beautiful geodes with mini air ferns.
These egg geodes are fun to make and display.
You may also enjoy:
- Egg Geodes Using Alum from STEAM Powered Family
- Plastic Egg Submarines
- Salt Painting
- Make a Rubber Band Boat
Updated from May 1, 2019.