How to Grow Crystals

Three Methods:Growing Crystals With AlumCreating Crystal OrnamentsMaking Crystal Rock Candy

Crystals are composed of atoms, molecules or ions arranged in highly ordered patterns with recognizable geometric structures. When you mix water with a crystal base, like alum, salt or sugar, you can watch crystals form in a matter of hours. Learn how to grow your own perfect crystal, create crystal ornaments and make colorful crystal rock candy.

Method 1
Growing Crystals With Alum

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    Fill a jar halfway with warm water. Make sure the jar is clean, since you don't want other substances interfering with your crystals. It's best to use a clear jar so you can see the formation process of the crystals.
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    Stir in some alum. Pour a few tablespoons of alum into the jar and use a spoon to stir the mixture until the alum dissolves. Pour more alum in and continue stirring. Keep doing this until no more alum will dissolve in the water. Let the mixture sit for a few hours. As the water begins to evaporate, crystals will form on the bottom of the jar.
    • Alum is a mineral used for pickling cucumbers and other vegetables, and can be found in the spice aisle of your grocery store.
    • You'll know you've reached the point where no more alum will dissolve when it begins to accumulate at the bottom of the jar.
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    Extract a seed crystal. Choose the biggest, best looking newly formed crystal to extract. Then pour the liquid from the jar into a clean jar (try not to fill the clean jar with undissolved alum) and use a tweezers to reach down into the jar and extract the crystal from the bottom.
    • If the crystals are still quite small, wait a few hours before extracting a seed crystal.
    • If you would prefer to keep growing the crystals in the first jar, let them sit for a week or so. At that point the bottom and sides of the jars should be lined with crystals.
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    Tie a string around the crystal and suspend it in the second jar. Use a thin nylon string or a piece of floss. Secure it around the crystal, then secure the other end around a pencil. Rest the pencil on the rim of the second jar and suspend the crystal in the solution.
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    Wait a week for the crystal to grow. When the crystal has grown to a shape and size that you like, remove it from the water. Untie the string and enjoy the crystal you have made.

Method 2
Creating Crystal Ornaments

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    Make a water and alum solution. Fill a jar halfway with water, then dissolve several spoonfuls of alum in the water. Continue adding alum until no more will dissolve.
    • You may also use salt or borax instead of alum.
    • If you would like to make ornaments in several different colors, divide the solution among more than one jar.
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    Stir food coloring into the jar. Add a few drops of red, blue, yellow, green, or any color of your choice to the solution in the jar. If you prepared several jars of solution, add different colored drops to each jar.
    • Mix different drops of food coloring to make a unique color. For example, combine 4 drops of yellow with one drop of blue to make a pale green color, or mix red and blue to make purple.
    • For festive holiday ornaments, dye the solutions colors that match your holiday decorations.
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    Bend pipe cleaners into ornament shapes. Shape them into trees, stars, snowflakes, pumpkins, or any other shape you'd like to make. Make the shapes clear and recognizable, keeping in mind that the pipe cleaners will be covered with crystals, so the outlines of the different shapes will be thick.
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    Hook the pipe cleaners over the edge of the jar. Submerge the shaped part of the each pipe cleaner in the jar so that the shape is suspended in the center of the jar, not touching the sides or bottom. Hook the other end of the pipe cleaner over the edge of the jar, bending it a little to keep it in place.
    • If you have jars with solution dyed more than one color, choose colors that match the shapes you created with the pipe cleaner. For example, if you made a tree pipe cleaner you could suspend it in a jar with green solution.
    • If you suspend more than one pipe cleaner in the same jar, don't let them touch each other.
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    Wait for the crystals to form. Let the pipe cleaners sit in the jar or jars for a week or two, until you like the size of the crystals. When you're satisfied with the way they look, remove your new crystal ornaments from the jars. Pat them dry with paper towels. The ornaments are now ready to hang.

Method 3
Making Crystal Rock Candy

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    Make a water and sugar solution. To make rock candy, use sugar as your crystal base, rather than alum or salt. Fill a jar halfway with warm water and stir in as much sugar as you can until it dissolves.
    • The most common type of sugar to use is white granulated sugar, but you can experiment with brown sugar, raw sugar, and other types of sugar.
    • Don't use artificial sweeteners in place of sugar.
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    Add color and flavor. Make your rock candy more appetizing by adding a few drops of food coloring and natural flavoring to the solution. Try these different flavor and color combinations, or create your own:
    • Red food coloring with cinnamon flavoring.
    • Yellow food coloring with lemon flavoring.
    • Green food coloring with spearmint flavoring.
    • Blue food coloring with raspberry flavoring.
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    Suspend wooden chopsticks in the solution. Place a few wooden chopsticks in the jar and lean their ends against the rim. If you don't have chopsticks, you can use wooden skewers or popsicle sticks.
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    Cover the jar with plastic wrap. Since you're working with sugar, the solution may attract bugs while the crystals are forming. Cover the jars with plastic wrap to prevent bugs from getting inside.
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    Wait for the crystals to form. After one or two weeks, the sticks will be covered with pretty crystals. Remove them from the jar, let them dry, then enjoy and share them with your friends.


  • You can also use rock salt and Epsom salts.
  • If you boil the water it will grow bigger.
  • You can tie a string around the toothpick too.
  • You can also use CuSO4ยท5(H2O) (cupric sulfate or copper sulphate)

Things You'll Need

Alum Crystals

  • 2 glass jars
  • Water
  • Alum (salt or borax will also work)
  • String
  • Tweezers

Crystal Ornaments

  • Glass jars
  • Water
  • Alum, salt or borax
  • Pipe cleaners
  • Food coloring

Crystal Rock Candy

  • Glass jar
  • Water
  • Food coloring
  • Flavoring
  • Chopsticks, wooden skewers or popsicle sticks
  • Plastic wrap

Article Info

Categories: Science for Kids