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Weekend Science Fun: Growing Crystals

Growing crystals can be fun because crystals grow and change in amazing ways and they can be incredibly beautiful. At times growing crystals can be frustrating because it may demand unusual and potentially hazardous materials, because it can requires patience when the crystals take a long period of time to grow, and because there is no guarantee of success. In fact, I was inspired to look into growing crystals because someone else had difficulty growing sugar crystals and wanted to know why. Do give it a try, however, because often you can learn more about science from the projects that didn’t work out as you planned than from those that turn out picture perfect. And once you are successful, crystals are awesome!

What are crystals? A crystal is a solid material that has its atoms or molecules arranged in a regular, repeating pattern. This causes the crystal to be symmetrical, and leads to many fascinating geometric shapes. For example, some form cube shapes, like table salt. Others form hexagonal shapes, like six-sided snowflakes.

If you get a chance, look at table salt or a snowflake under a hand lens or microscope. To catch a snowflake, put your hand in a dark (black works best) sock or dark, plain-colored mitten and allow snowflakes to fall on it.

Here are some photographs of naturally occurring crystals. This is rock salt, sometimes used for making homemade ice cream.

rock salt

This is a geode. A geode comes from gas pockets that formed in magma when it cooled. The crystals can grow slowly within the protected pocket, reaching their full potential shape.

geode

Let’s try a few crystal-growing experiments. They will almost all require an adult’s help.

1.    Growing Salt Crystals -fairly easy
Gather:

  • Drinking glass or small, clear glass jar
  • Hot water (requires adult help)
  • Table salt and Tablespoon size measuring spoon
  • Nail
  • Pencil
  • String

Fill the glass or jar about ¾ way full. Start adding salt to the water one tablespoon at a time. Stir after each addition until the salt dissolves. Keep adding salt until a bit remains undissolved. This is a saturated solution.

Now, tie one end of the string around the nail and drop the nail into the solution suspended by the string. Lay the pencil across the top of the glass or jar and tie the other end of the string around it. The nail is a weight to keep the string straight in the water, supported by the pencil.
Now it is time to wait. Over the next few days the solution should dry and leave salt crystals on the string.

2. Grow Ice Crystals – a Snowy Day Project
Gather:

  • A drinking glass or clear jar
  • Enough snow or frost from the freezer compartment of the fridge to fill the glass half way
  • Table salt and Tablespoon size measuring spoon
  • Small test tube
  • Water

Fill the glass half way with snow or powdered frost. Press down to compress. Add one Tablespoon of table salt. Now fill the bottom of the test tube with one inch of water. Place the test tube into the snow mixture. The snow and salt should start to melt, and at the same time the water in the test tube should start to freeze into ice crystals. Add more salt to the snow and swirl a bit to mix if things aren’t progressing.

3.    Sugar -Rocky Candy Crystals – A bit more detailed

The person who had trouble with the sugar crystals tried using the same method as the salt crystals above. She added sugar to hot water until it was saturated and then let it dry on a string. Making a sugar syrup by boiling the sugar in the water, and seeding the string with some dry sugar crystals works better. See the instructions for making rock candy at  About. Com.

4. Almost everyone has tried or seen the crystal gardens that use laundry bluing and ammonia. Both these ingredients need to been handled with caution.

Gather:

  • 2 Tablespoons table salt
  • 2 Tablespoons laundry bluing (available in the laundry section, read the warnings on the label first)
  • 2 Tablespoons household ammonia (read the warnings on the label first)
  • 2 Tablespoons water
  • disposable aluminum dish
  • Food coloring (optional)

Check the bluing bottle, it may have a recipe for a crystal garden on the side which you could use, as well. Otherwise, simply mix the ingredients in a disposable aluminum container. In the video below a cardboard toilet tissue was placed upright in the dish. Note:  you will see that strips have been cut in the top of the roll. Those were actually supposed to go into the liquid to help wick up the solution. Obviously it worked quite well anyway.

You can also pour the liquid over pieces of coal or even bits of clean, dry sponge.

Growing Salt Crystal Garden Video

You can grow crystals from kits as well. This example is aluminum potassium sulfate crystals grown on a granite base.

crystal

If you grow a cool crystal, be sure to take a picture, load it on a blog or website and send me the link. I look forward to seeing them.

For more information, ideas and links visit the crystal projects for kids page at About.com.

You can also buy kits (check customer reviews, images are affiliate links to Amazon)

Smithsonian Crystal Growing Kit

Amethyst and Diamond Crystal Growing Kit

Crystal Growing Tree

 

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