How to grow geodes in eggshells

Imagine a rock. Any rock. Not much to look at, is it?

Now imagine cracking it open and finding a treasure trove of crystals.

This isn't a fairy story. It's a real-life rock you can find in nature. And those crystals are old – thousands of years old, in fact.

This type of rock is called a geode – and it's proof that you should never judge a book by its cover. A geode may look as plain as a potato, but it's actually a natural treasure chest!

Geodes are formed when water seeps into rocks and hardens into crystals. But did you know that you can also grow your own geode in an eggshell? Here's how.

1. Gather your materials

First, you'll be working with hot water, which can cause burns, and epsom salt, which can be dangerous if swallowed. Make sure there's an adult around to supervise things before you start.

To grow your own geode, you need four things:

A raw egg
Epsom salt
Water
Glue

If you want your geode to be colourful (the shell, the crystals or both), you could also use some food colouring. You should also put down some newspaper or a plastic sheet to avoid staining the table.

2. Get your eggs ready

First, make a large hole in the eggshell and pour away the yolk and white. Try to keep the shell as intact as possible. You want to be able to pour liquid inside, but still have a nice enclosure for your crystals.

Before you add anything to the shell, you need to wash and dry it.

If you want a colourful geode, you can now dye your shell with food colouring. You could do this to the inside, outside or both.

Once that's done, place your eggshell in an egg carton or bowl. Coat the inside of the shell with glue and sprinkle the glue with Epsom salt.

Now it's time to boil the kettle. Carefully pour the hot water into a heatproof jug and stir in more Epsom salt. Keep adding the salt until it stops dissolving. If you want your crystals to pop with colour, you can add food colouring to the mixture.

This is your geode juice. Let it cool and then pour it into a container with the egg.