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Make Your Own Magic Rocks

Grow a Chemical Garden

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Magic Rocks are a classic chemistry project that doesn't take a lot of time to complete.

Magic Rocks are a classic chemistry project that doesn't take a lot of time to complete. The sodium silicate in the growing solution reacts with the metal salts in the 'rocks' of Magic Rocks to produce an underwater chemical garden.

Anne Helmenstine Magic Rocks contain liquid sodium silicate and colored

Magic Rocks contain liquid sodium silicate and colored "rocks".

Wrinehart, wikipedia.org
What Are Magic Rocks?

Magic Rocks, sometimes called Chemical Garden or Crystal Garden, are a product that includes a small packet of multicolored 'rocks' and some 'magic solution'. You scatter the rocks at the bottom of a glass container, add the magic solution, and the rocks grow into magical-looking chemical towers within a day. It's crystal-growing at its finest for people who prefer not to wait days/weeks for results. After the chemical garden has grown, the magic solution is (carefully) poured off and replaced with water. At this point, the garden can be maintained as a decoration almost indefinitely. Magic rocks tend to be recommended for ages 10+ because the rocks and solution are not edible! However, younger children will also enjoy growing magic rocks, providing they have close adult supervision.

How Magic Rocks Work

The Magic Rocks are chunks of metal salts that have been stabilized by being dispersed in aluminum hydroxide or alum. The magic solution is a solution of sodium silicate (Na2SiO3) in water. The metal salts react with the sodium silicate to form the characteristic colored precipitant (chemical towers about 4" high).

Grow Your Own Chemical Garden

Magic rocks are available on the Internet and are quite inexpensive, but you can make them yourself. These are the salts used to make magic rocks. Some of the colorants are readily available; most require access to a general chemistry lab.

  • White - calcium chloride (found on the laundry aisle of some stores)
  • White - lead (II) nitrate
  • Purple - manganese (II) chloride
  • Blue - copper (II) sulfate (common chemistry lab chemical, also used for aquaria and as an algicide for pools)
  • Red - cobalt (II) chloride
  • Pink - manganese (II) chloride
  • Orange - iron (III) chloride
  • Yellow - iron (III) chloride
  • Green - nickel (II) nitrate

Make the garden by placing a thin layer of sand on the bottom of a 600-ml beaker (or equivalent glass container). Add a mixture consisting of 100-ml sodium silicate solution with 400 ml distilled water. (You can make sodium silicate yourself.) Add crystals or chunks of the metal salts. If you add too many 'rocks' the solution will turn cloudy and immediate precipitation will occur. A slower precipitation rate will give you a nice chemical garden. Once the garden has grown, you can replace the sodium silicate solution with pure water.

Watch Magic Rocks Grow

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