Category: Developing Talents

Duration: 30 minutes (plus a few minutes to inspect at the next activity).  You can also do Borax Snowflakes to make this a full-length activity on crystals.
  • Half an empty styrofoam egg carton for each girl (you can also use 6 dixie cups instead)
  • Six rough rocks for each girl (must fit in the egg carton cups)
  • 1/4 cup each of these per about every five girls you have:
    • Salt
    • Sugar
    • Washing Soda (Arm & Hammer brand found in laundry aisle)
    • Borax (laundry aisle)
    • Alum (spice aisle)
    • Epsom Salts (bath aisle)
  • Food coloring
  • 6 large cups or jars that can handle boiling water
  • 6 spoons
  • 6 pens of permanent markers that can write on styrofoam
  • At least one tablespoon measure
  • Towel or three
  • Boiling water (or close to it – we microwaved a big bowl of water in the church kitchen)
  • (Optional) magnifying glasses
  • (Optional) A copy of this picture: types of mineral crystals

Preparation: None I can think of!

1. Before starting, share some facts from this page about crystals and crystal structure.
2. Boil 4 cups of water. While it is boiling, have the girls put their rocks in each egg cup of their container. Have them label on the lid of their carton with the names of each of the six crystals you will be creating.
3. Measure 1/4 cup of each ingredient for one jar each (so one jar will have salt, one will have sugar, etc.). Make sure to label or otherwise designate each jar so they don’t get mixed up. Add LOTS of food coloring to each jar. Feel free to add the whole dropper!
4. Pour about 1/2 cup of water (no need to be exact) into each jar and have the girls stir for at least two minutes. (The towels are there if you are worried about your jars cracking – put the towel underneath as an insulator.) Some of the solutions will completely dissolve, while others will not,  and that’s okay.
5. Test one liquid on a piece of spare styrofoam to make sure your water isn’t so hot that it will melt the foam. Use the tablespoon to carefully measure two tablespoons of liquid onto the correct rock in the carton. Be careful not to mix them but only let them fall into one egg cup!
6. Carefully set the cartons (lid OPEN) in a place where they can remain undisturbed for at least two weeks. You may have to wait a month if you choose a dark place, or you live in a humid climate.
7. After all the liquid has dried, use the magnifiers to observe and identify each crystal structure.

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