Did you know that snow, frost and diamonds all have something in common? They are all made up of crystals that form through the process of crystallization when liquids cool and harden. There are many different types of crystals.

Snowflakes are made up of tiny ice crystals that form on microscopic dust particles high in the atmosphere

Gemstones like diamonds and rubies are mineral crystals that form when liquid rock, known as magma, slowly cools. Sometimes, hollow air bubbles form in the cooling magma and create a pocket for crystals to form. These become hollow rocks, called geodes, that are lined with mineral crystals.

Mineral crystals can also form when water evaporates from a liquid that contains dissolved minerals.

Today, we will create our own crystals at home using water and any kind of mineral salts, or even sugar. We get the best results from using borax, which is made of the mineral, sodium borate.

This activity is ideal for elementary-aged learners with adult assistance and will take 24 hours to complete.

Materials:

• Borax (see alternative options listed below)
• Heat-resistant glass jar
• Food coloring
• Pipe cleaner, cut in half
• String
• Pencil
• Water

Procedure:

1. Plan out what color crystals you want to make ahead of time from your food coloring options. The color of the pipe cleaner will also show through the crystals so have some fun deciding on a color combination that you like.
2. Create a shape out of your pipe cleaner that will fit in and out of the jar without touching the sides. Keep in mind that the crystals will make the shape even bigger at the end so be sure you have plenty of space to get your shape out.
3. Tie one end of the string to the pencil and attach the other end to your pipe cleaner so it hangs in the middle of the jar and does not touch the sides or bottom.

4. Pour water into the jar so that the pipe cleaner is completely covered.

5. Remove the pipe cleaner and pour the water into a pot to boil.
6. Once the water is boiling carefully pour it back into the jar.
7. Add borax one tablespoon at a time and stir until it is dissolved. Keep adding borax until no more will dissolve into the water, about 4-5 tablespoons per cup of water. It’s ok if there are some particles at the bottom of the jar.
8. Add food coloring. The more food coloring you add, the more colorful your crystals will be. If you prefer white crystals then you can skip this step.
9. Return the pipe cleaner to the jar and make sure that it is suspended in the middle.

10. Place the jar in a safe place and leave it overnight. Make sure the jar is somewhere where it will not be accidentally bumped or moved.
11. After 24 hours, carefully lift your pipe cleaner out and admire the sparkly, colorful crystals you created!

Crystallization explained

The amount of solute that can be dissolved into a liquid depends on the temperature of the liquid. In this case, borax was our solute. When we heated up the water, the water molecules moved further away from each other, which allowed more borax to be dissolved into the water. When no more borax would dissolve into the water, we created a saturated solution.

As the water cooled, the molecules moved closer together and made the solution supersaturated, meaning there was more solute than the solution could hold. Crystals begin to form when a supersaturated solution containing a dissolved mineral begins to cool. As the crystals form, they will cling to bumps and other textured surfaces – like the pipe cleaner suspended in our solution. Once tiny bits of borax begin to settle on the pipe cleaner, other crystals attach to those making the layers of glittering crystals that you saw when you removed it the next day.

Different minerals crystallize in different ways. Experiment with making crystals using other minerals in your house like table salt, Epsom salt or sugar. Observe the similarities and differences between the different crystalline structures that form.

Safety note: Borax can be harmful if swallowed and the dust can irritate eyes and the throat if inhaled. For some people, it can also cause skin irritation. An adult should help younger children add the borax to the water. Make sure to wash your hands after handling the crystals. Adults should also monitor small children closely and ensure that they do not mistake the Borax crystals for candy.