How To Make Crystal Geode Eggs

Have you ever wondered how to make your own crystal geode? Geodes might look like fancy, sparkling rocks, but they're also a golden opportunity to teach your kids some cool science.

Studies show that the earlier kids begin learning about science, the stronger their scientific thinking skills will be. That's why science, technology, engineering, art, and math (STEAM) projects are so great for young minds—it gets them thinking creatively about problem-solving while exploring the natural world.

Keep reading to learn more about how geodes form in the earth, how to make your own crystal geode eggs at home, plus clever ideas for what to do with them when the experiment is done.

What Are Crystal Geodes?

Geodes are small rock cavities lined with crystals or minerals that are usually found in limestone or shale. They form through sedimentation, a process in which particles (solute) are suspended in a fluid (solvent) and then accumulate. (In this STEAM activity, the Epsom salt is the solute, and the water is the solvent.) The salt particles fuse together because the water is so saturated, forming crystals as the water evaporates.

In nature, geodes get their color based on what minerals are present during formation. For example, iron makes red and purple, titanium makes blue, nickel and chromium make green, and manganese makes pink. In this geode egg experiment, kids will use food coloring to make their geodes shine bright with brilliant colors.

How To Make Crystal Geode Eggs

Follow these easy, simple instructions to make your own set of geodes. This experiment takes less than an hour to get started, but it will take a few days for the crystals to grow.

We use Epsom salt in this project to create the crystals. Other ingredients, such as sugar, table salt, cream of tartar, baking soda, borax, or alum powder can also be used as the solute for the experiment and will achieve similar results.

However, using Epsom salt or another nontoxic solute is recommended for safety and accessibility. Borax and alum powder are not safe for kids to consume—and could be dangerous if eaten. So, vigilant supervision and assistance are needed if you use either of these substances.

Try keeping a science journal handy to write down daily observations. This is a fantastic way to get kids thinking about science and begin learning how to solve problems using the scientific method. If your kids are too young to write, ask them to draw pictures of what they see and make a hypothesis about what will happen next. Or you can write down their observations, questions, and ideas for them.

What you'll need

• Eggs
• Bowls
• Hot water
  
• Egg dye
• Egg carton
• Craft glue
• Epsom salt
• Food coloring
• Toothpicks
• Blank paper and pencil or crayons (for jotting down observations)

Instructions

1. Crack eggs: Help kids crack an egg at the narrow end and carefully widen the opening to the size of a quarter. Empty egg into a bowl; repeat with more eggs. (Save the yolks and whites and make a scramble or frittata for lunch!)
2. Rinse eggshells: Set shells in a bowl of hot water to rinse. Then show kids how to gently rub their thumb on the inside to loosen and remove the membrane (there may be two layers). Turn the shells over on a towel to dry. If desired, dye them before the next step following the instructions on the box; let dry.
3. Glue eggs: Set the shells inside the egg carton. Brush the entire inside of the empty shell with a thin layer of glue and dust with Epsom salt (this will act as a starter crystal). Let dry completely (a few hours).
4. Boil water: Boil 1 cup of water and remove from heat (an adult's job). Slowly add 1/2 cup Epsom salt and stir until it's dissolved. Continue stirring in small amounts of salt (a tablespoon or two at a time but no more than 1/2 cup) until it no longer dissolves, then stop. You've made a super-saturated solution! It should be thick but not slushy.
5. Fill egg shells: Carefully pour the solution into your shells with a small ladle, filling to the top. Add a drop of food coloring to each egg and stir gently with a toothpick. Place your shells somewhere safe (such as in the egg carton) and at room temperature.
6. Observe: Check your eggs daily. If you find a thin, hard, jagged layer forming on the surface, gently break it up with a toothpick to allow the water to continue to evaporate. After a few days, all the water will evaporate, leaving colorful geode eggs behind!

What To Do With Crystal Geode Eggs

Geodes are super fun to make and keep for display. Here are a few fun ideas for what to do with your brand-new crystal geode egg collection:

• Hot glue magnets to the back and display them on the fridge.
• Place air plants in them and display them in a window.
• Arrange your geodes in a shoebox diorama with some fairy lights and use it as a night light.
• Wrap them up and give them as gifts.