Tiny atoms play a big part in how crystals are formed

Students in third grade at W.C. Petty School in Antioch had these questions about crystals: "How are crystals made?" asked Jared Betke, Christina Michaels and Daren Roman.

Mitchell Harris, a third-grader at Woodlands School in Gurnee, asked, "Where are crystals found?"

Crystals form almost anywhere atoms occur, from deep in the earth to high in the atmosphere, said Ed Duke, Ph.D., professor of geology and geological engineering at the South Dakota School of Mines in Rapid City.

Nature uses a special recipe for crystals. A liquid solution or vapor is the ingredient that all crystals have in common.

Crystals are formed by atoms -- the very smallest particles of all elements. The way the atoms are structured identifies that element. All crystal atoms are structured in a certain way, and the structure is very orderly.

"Atoms, of course, are too small to see, but that is why large crystals sometimes have orderly or symmetrical arrangements of crystal faces. We see them as smooth, flat surfaces that are parallel to a plane of atoms in the crystal," Duke said.

There are many kinds of crystals found in nature. Salt, sugar, minerals, even the atmosphere can create crystals. Atmospheric crystals are known as frost and snow.

"In order to form, the crystal must get these atoms from the environment --usually some sort of liquid that contains the atoms in solution," Duke said.

Even a bowl of water can end up with ice crystals.

"On cold days, my dogs' water bucket often has a few very large ice crystals that extend all the way across the top of the liquid water beneath," he said.

Duke reports that the human body can form crystals, too.

"Kidney stones (an unpleasant subject) are crystals formed in the human body."

A second ingredient in the recipe for crystals is temperature.

"Generally, crystals form at cooler temperatures than the corresponding liquid, like freezing of water. This is because at higher temperatures the atoms want to vibrate and will not stay in the regular arrangement of the crystal form, so the crystal would melt."

For more information

The Antioch Public Library suggests these books on crystals:

• "Collecting Rocks and Crystals" by John Farndon

• "Crystal & Gem" by Dr. R F Symes and Dr. R.R. Harding

• "Growing Crystals" by Ann O. Squire

• "The Magic Crystal" by Brigitte Weninger

• "Marvin Redpost: A Magic Crystal?" by Louis Sachar