Saturday Science: Crayon Rocks

While spending time outdoors this summer, have you noticed different types of rocks? Chances are that answer is, “Yes!” There are three kinds of rocks: sedimentary, metamorphic and igneous. In this week’s Saturday Science experiment, courtesy of Momma Owl’s Lab, learn how to create colorful crayon rocks and discover how each type of rock forms.

Materials:

• 4 different colored crayons (multiple of each color) 
• Pencil sharpener
• 4 containers
• 3 6"x6" pieces of aluminum foil
• Popsicle stick 
• Mug
• Boiling water (Have a parent help you with this!)

Process:

1. Unwrap the crayons and sharpen them. 
2. Place each color of crayon shavings in a separate container. 

Create sedimentary rocks:

1. Lay one of the aluminum foil squares flat on the table or work station.
2. Add a few shavings of each color to the foil one at a time so that the colors form layers. 
3. Fold the foil tightly around the shavings. 
4. Compress the foil and shavings with your hands (or feet). 
5. Keep compressing. It takes awhile for the shavings to stick together. 
6. Carefully unfold the foil and remove your sedimentary rock!

Create metamorphic rocks: 

1. Lay another aluminum foil square flat on the table or work station. 
2. Layer the crayon shavings by color in the center of the square.
3. Fold up the foil around the shavings to create a boat. 
4. Have an adult pour boiling water into mug.  
5. Place the boat into the mug and let it float for 20 seconds. 
6. Remove the boat and fold the foil in half so that the shavings are compressed. (Be careful! The foil might be hot.) 
7. Let it cool and solidify. 
8. Open the foil and remove your metamorphic rock!

Create an igneous rock:

1. Lay another aluminum foil square flat on the table or work station. 
2. Layer the crayon shavings by color in the center of the square.
3. Fold up the foil around the shavings to create a boat. 
4. Have an adult pour boiling water into mug.  
5. Place the boat into the mug and let it float for 1-2 minutes. Shavings should be completely melted.  
6. Take the popsicle stick and stir the shavings until they are all mixed together.
7. Remove the boat. 
8. Let the crayon cool and solidify.
9. Take a look at your igneous rock!

Summary:

You just created sedimentary, metamorphic and igneous rocks! Can you tell the difference between each one?

Sedimentary rocks are formed from sediments, or tiny rock particles, that were layered and then compressed together. This is similar to when you compressed the crayon shavings together between the foil. Sedimentary rocks have distinct layers of sediment and often have visible rock particles in them. If you’re looking at rocks from Indiana, you’re looking at sedimentary rocks, like limestone, sandstone and shale.

Metamorphic rocks are formed when existing rocks are exposed to heat and/or pressure. You recreated this process by using heat (the boiling water) to melt your crayon shavings and then adding pressure (when you folded the foil in half). Distinct bands or blocks of crystals can be found in metamorphic rocks.

Igneous rocks are formed when magma, or molten rock, cools and solidifies. You made magma by completely melting your crayon shavings and as that magma cooled and solidified, it became an igneous rock.  

There might be three types of rock, but it is important to note that no rock is “set in stone.” Given the right conditions, each can be changed from one into another.