Crystals

November 24, 2012 1:30 am

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Crystals
Look closely at some table salt through a magnifying glass. You’ll see that the bits of salt are made up of tiny cubes. Each cube is a salt crystal. The salt crystals within the particles can be different sizes, but they always have this shape.
TINY PARTICLES IN PATTERNS
A crystal contains identical particles that are arranged in a particular pattern such as a cube, rectangle, or hexagon. As a crystal grows in size, this pattern is repeated over and over.
Salt is made up of the elements sodium and chlorine. Extremely tiny particles of sodium and chlorine, called atoms, form a repeating cubic pattern in a crystal of table salt. The more times the pattern is repeated, the bigger the crystal that forms.
HOW DO CRYSTALS FORM?
Crystals form when some liquids turn into solids. A liquid may freeze into a crystal. Snow, for example, is made of tiny crystals of frozen water. Crystals can also be left behind when a liquid dries out. When seawater in a rock pool dries out, tiny crystals of salt remain.
Most of the rocks and minerals in ’s crust are crystals. Some crystals were formed from melted rock when it cooled and became solid. Others were left behind by the waters of a sea, lake, or river that dried up long ago.
HOW DO WE USE CRYSTALS?
Many crystals are beautiful. Diamonds, rubies, and emeralds are crystals that are made into attractive jewelry. Crystals also have many practical uses. Quartz crystals are used in clocks, radios, and sonar, the system that allows ships and submarines to see things underwater. Quartz crystals can also be pressed or heated to make electricity.
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