You can make salt crystals from either table salt or Epsom salt, and each forms crystals of a different shape. Use food coloring to make your crystals dazzling and colorful.
Boil about 1 c. water.
Pour the water into a glass jar.
Stir in the salt slowly, about a teaspoon at a time. Don't rush this step.
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Continue until the salt is no longer dissolving but is starting to collect at the bottom of the jar.
Choose a color for your crystals and add a couple drops of food coloring.
Tie one end of piece of a string around a pencil and tie a paper clip to the other end.
Place the pencil over the jar so that the string hangs down and the paper clip almost touches the bottom of the jar.
Allow jar to sit someplace where it will be undisturbed.
Check after about 24 hours, and you'll see crystals forming in cubical shapes on the paper clip.
Follow steps 1 through 4 above, substituting Epsom salt for table salt, and using a glass bowl instead of a jar.
Choose a color for your crystals and put a few drops of food coloring on two charcoal briquettes.
Place charcoal briquettes in the bottom of the bowl.
Allow bowl to sit someplace where it will be undisturbed.
Check after five days, and you'll see crystals growing in the shape of prisms.
You can use other items instead of a paper clip as the "seed," or area where crystals start growing, such as a fishing weight. You can substitute rock salt for table salt. If the string hanging from the pencil is too long when you place it in the solution, just roll the pencil between your hands until the string wraps around it and the piece of string hanging down becomes shorter. Place a paper towel over the top of the jar to keep dust from getting into the crystals.