A simple crystal growing experiment that can be done at home is to bring 250 milliliters of distilled water to a slow boil and continue dissolving a few teaspoons of table salt, sugar or Epsom salts into the water until over saturated. Pour the solution into a clean glass or beaker and dangle a string into the water from a pencil laid across the rim of the glass. Cover, and observe the growth of the crystals every day.
Edible crystals, also known as rock candy, are made by using sugar as the starter chemical. Using the string in a glass method, crystals continue to grow until there is no more sugar or salt left in the solution. The color and shape of the crystals are altered by using different chemicals as the starter. Produce cubic dark purple crystals by using potassium chromium sulfate as the starter or colorless monoclinic crystals by using Borax.
Another simple crystal experiment that is safe to perform at home explores the growth of crystal deposits in caves. Fill two clean pint jars three-quarters of the way with hot water, and place them on a cookie sheet. Add a water-soluble salt such as Epsom salt while stirring until no more can dissolve. Tie washers to the end of an 18-inch length of cotton that is 1-inch wide. Hang each end of the towel in one of the jars and spread the jars so that the towel is suspended above the tray and the stalactites and stalagmites have room to form over the next week.