Activity Overview
Grow your own rock crystals and geodes with this spellbinding science experiment. Geodes are pockets of crystals that form in sedimentary and igneous rocks. They start as hollow spaces in rock that is porous enough for water to seep through. The water carries dissolved minerals, which are deposited in the open space, forming a lining of crystals within the interior of the rock.
This experiment is sure to keep young scientific minds engaged. Some adult supervision and patience is required, as the whole process takes 3-4 days to complete.
In this experiment. you will use the lining if eggshells to simulate a geode-like environment for crystals to grow. You will create a supersaturated solution which is a solution that is forced to hold more atoms in water than it normally should. Crystals form when a supersaturated solution comes in contact with a seed molecule which causes the the other atoms to naturally fall out of the solution and attach to the seed. In this experiment, the seeds are the alum powder that you sprinkles onto the glue to line your eggshell.
Materials Needed
- 3 whole fresh eggs
- 3/4 cup of alum powder ( found in the spice aisle)
- Steak knife
- 2 cups of warm water
- paintbrush
- school glue
- food coloring
- small saucepan
How to Do It
- Have an adults carefully use a steak knife to cut the fresh eggs in haldf lengthwise.
- Rinse out the eggshell halves and allow to dry completely.
- Use your paintbrush to apply a thin layer of school glue to the insides of the eggshells.
- Generously sprinkle the alum powder onto the wet glue to create a lining on the inside of your eggshells.
- Set the eggshells out to dry overnight.
- Place your water and 3/4 cup of alum powder into a small saucepan with 2 cups of water.
- Dissolve the powder into the water by bringing the mixture to a boil under adult supervision. Allow the solution to cool completely.
- Add a couple of squirts of food coloring to the solution and stir well.
- Carefully submerge your eggshells into the solution.
- Allow the eggshells to remain in the alum solution for three days. Do not touch the eggshells or the solution during this time period.
- At the end of the 3 days, gently remove the eggshells from the solution and set aside on a paper plate to dry thoroughly.
- Observe and report your findings.
