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What Is a Crystal?

A Crystal Is Matter with Structure

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The ordered internal structure of large crystals, like these spinels, is reflected in their geometric shapes.

The ordered internal structure of large crystals, like these spinels, is reflected in their geometric shapes.

S. Kitahashi Rock candy is made of colored and flavored sugar crystals.

Rock candy is made of colored and flavored sugar crystals.

Anne Helmenstine

A crystal consists of matter that is formed from an ordered arrangement of atoms, molecules, or ions. Because there are repeated units, crystals have recognizable structures. There are seven systems of crystal structures, which are also called lattices or space lattices.

Examples of everyday materials you encounter as crystals are table salt (sodium chloride or halite crystals), sugar (sucrose), and snow. Many gemstones are crystals, including quartz and diamond.

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