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    Crystal Rings and Ferns

    This is a quick and easy crystal growing project.  All you need is a bit of table salt, water, a steel pan, and a stove to produce interesting salt crystal rings, ferns, and other shapes. Specifically, get these materials together along with an adult partner:

    • steel or iron pot - don't use a non-stick pan since the non-stick coating could overheat and release fumes
    • table salt (sodium chloride)
    • water
    • food coloring (optional)
    • kitchen stove

    Please note:  All chemicals and experiments can entail an element of risk, and no experiments should be performed without proper adult supervision.

    Now just sprinkle a little salt in the pot and a few drops of water. You can add a drop of food coloring if you want colored crystals. Have an adult partner heat the water until you see the liquid starting to evaporate off the pan. Turn off the heat. Watch the crystals form as the water evaporates to form artful crystal shapes like rings and ferns. You can add more water and repeat the project over and over. All you do for clean-up is rinse out the pan.

    There are many variables to this experiment that you can examine, such as:

    • type of salt - iodized, uniodized, sea salt, etc.
    • concentration of salt - results are greatly affected by how much/little salt you add
    • rate of evaporation - affects how crystals form
    • rate of cooling - also affects crystal growth

    Notes: The best results are obtained when using a very small amount of salt. We’re told that a fern shape can sometimes occur from boiling salted pasta. If you use uniodized salt, you may get salt crystal cubes rather than rings. More complex shapes occur with sea salt and aquarium salt. Other salts will work for this project too (e.g., borax, epsom salts). Sugar is not a good choice because it will burn and possibly ruin your cookware.

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    Kathleen Carrado Gregar, PhD, Argonne National Labs 
    kcarrado@anl.gov
    September 2009

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    References:  Dr. Anne Marie Helmenstine at http://chemistry.about.com/od/crystalrecipes/a/saltcrystalring.htm?nl=1