Earth System Science and Educational Technology: My Chronicle of Teaching at NMU: Mineral Identification

http://chemistry.about.com/od/growingcrystals/tp/Make-Crystals.htm

Making your own rock candy is a fun and tasty way to grow crystals and see the structure of sugar on a big scale. Sugar crystals in granulated sugar display a monoclinic form, but you can see the shape much better in homegrown large crystals. This recipe is for rock candy that you can eat. You can color and flavor the candy, too.

Rock Candy Materials

Basically all you need to make rock candy is sugar and hot water. The color of your crystals will depend on the type of sugar you use (raw sugar is more golden and refined granulated sugar) and whether or not you add coloring. Any food-grade colorant will work.

3 cups sugar (sucrose)
1 cup water
clean glass jar
cotton string
pencil or knife
food coloring (optional)
1/2 tsp to 1 tsp flavoring oil or extract (optional)
Lifesaver candy (optional)
pan
stove or microwave

Borax Crystals

Anne Helmenstine

These naturally clear crystals are easy to grow onto pipecleaner shapes. Choose a colored pipecleaner or add food coloring to get colored crystals. All you need to do to prepare the solution is pour boiling water into your container and stir in borax until no more will dissolve. An approximate recipe is:

3 tablespoons borax
1 cup boiling water

Epsom Salt Crystal Needles

Epsom salt crystals needles grow in a matter of hours. You can grow clear or colored crystals.

Anne Helmenstine

These delicate crystal spikes grow in a cup in your refrigerator within a couple of hours, or sometimes more quickly. Simply mix together:

1/2 cup Epsom salt
1/2 cup very hot tap water
food coloring (optional)

Place the cup in the refrigerator. Use care when scooping out the crystals to examine them, as they will be fragile.

Copper Sulfate Crystals

Anne Helmenstine

Copper sulfate crystals naturally form blue diamonds. These crystals are extremely easy to grow. Simply dissolve copper sulfate into a cup of boiling water until no more will dissolve. Allow the container to rest undisturbed overnight. It's best to collect the crystals with a spoon or toothpick, since touching the solution will turn your skin blue and may cause irritation.

Sodium Chloride or Table Salt Crystals

These are crystals of salt or sodium chloride.

Choba Poncho

This project works with any type of table salt, including iodized salt, rock salt and sea salt. Simply stir salt into boiling water until no more will dissolve. The solubility of salt is highly dependent on temperature, so hot tap water is not hot enough for this project. It's fine to boil the water on the stove while stirring in the salt. Allow the crystals to sit undisturbed. Depending on the concentration of your solution, the temperature and your humidity you can get crystals overnight or it may take a few days for them to form.

Chrome Alum Crystal

This is a crystal of chrome alum, also known as chromium alum.

Ra'ike, Wikipedia Commons

Chrome alum crystals are deep purple in color. Simply prepare the crystal growing solution and allow the crystals to form.

300 grams potassium chromium sulfate (chrome alum)
500 ml boiling water

The solution will be too dark to observe crystal growth. You can check for growth by shining a bright flashlight into the solution or by carefully tipping the solution to the side. Don't spill! Disturbing the solution may slow your results, so don't check more often than necessary.