Heart Crystals

Our oldest daughter absolutely loves science and mathematics. She does still play with dolls; however, she would rather be building, exploring and experimenting. I set aside one big project for us to do together each week and this week happened to be these beautiful heart shaped crystals! It was so fun watching her learn and she had some fantastic questions during the whole project. Needless to say this project hit it out of the ballpark for her.

For my jars I used large mouth quart sized mason jars that I set aside specifically for crafting. They have large notches in the side so I can’t use them for canning. They also happen to be a pretty yellow color. You will want to pick a vessel that works for you; however you want to make sure it’s heat resistant. You don’t want to be pouring boiling water into a plastic cup and have it melt everywhere.

When shaping your hearts make sure you try to place them inside the jar before adding anything else to them. If you have to squeeze or shape the heart to get it in then it’s too big. The pipe cleaners are pliable now; however, when those beautiful crystals grow they will harden. Make sure to leave enough room to be able to pull them out!

Can you use cold water? In a short answer – no. This is where the science lesson comes into play. When water is cold the molecules move closer together eventually creating a solid state (ice). As the water heats up the molecules move farther apart. When they move apart and you stir in the borax the molecules from both substances mix together (this is why most substances dissolve better in hot water). As the water cools the molecules move closer together pushing the borax molecules to make those gorgeous crystals. Neat, right?


  • Mason Jar
  • Borax
  • Boiling water
  • Popsicle sticks
  • Pipe cleaners
  • String


  1. Shape pipe cleaners into hearts and measure that they will fit through your jar opening.
  2. Loop string through the pipe cleaner and hang off the popsicle stick.
  3. Add six tablespoons of borax to each Mason jar. (If using a different vessel you will need 3 tablespoons of borax per cup of boiling water).
  4. Pour two cups of boiling water into each Mason jar and stir until the borax is dissolved.
  5. Drop the hearts into the Mason jar making sure the entire pipe cleaner is below the water and borax solution.
  6. Let the jars sit untouched for 24 hours.
  7. Gently pull the crystals out of the jar. If your crystals are stuck to the bottom carefully wiggle them until they break free.
  8. Allow crystals to fully dry on a paper towel. The crystals might shed a bit during the transferring and drying process – do not worry.
  9. Hang your crystals in a window or somewhere bright and enjoy!

Make sure to always wash your hands, materials and workspaces after using borax. The borax can irritate your skin and can be toxic. This project is meant to be completed under the direct supervision of an adult.

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