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Solid Structure of Crystals

Matter can exist in three different states--as solids, liquids, and as gases. Gases, like air and helium, are very lightweight, and their molecules are not bonded to each other. They tend to have a lot of energy and move about freely. They are also very diffuse. Liquids are denser. Like water, all liquids are runny to some extent or other. Liquid molecules are not bonded together but are packed tightly enough together that movement is not entirely free. Solids are very dense and have shape and structure. Their molecules are bonded to each other and are not free to move. Some solids form into shapes called crystals.

Geometric Molecules
- In a crystal the molecules link together to form flat planes that themselves link together at regular angles to form geometric shapes. The exact shape that is formed is determined by the nature of the material's molecules and the environment they bond together in. The properties the crystal has are also determined by these factors.
Carbon Crystals
- Nowhere is this more apparent than with carbon crystals. Carbon forms two kinds of crystal: diamond and graphite. Both are made out of the same substance, yet they are very different in both nature and appearance. Diamond is transparent and hard. Graphite is black and soft. Because the carbon atoms in diamond are connected together as tightly as possible and the atoms of graphite are much more loosely connected, the crystals they form have very different properties.
Crystalline Properties
- Other crystalline properties vary with structure too. Different crystals conduct heat differently. They react to electricity and magnetism differently. They have different colors and even break differently. Some even have special properties, like the Iceland spar crystal, which polarizes light shining through it.
Types of Crystal
- Many different sorts of materials are crystals. Precious stones like rubies, diamonds, and emeralds are crystals. So is the material many pencils are made out of. Ice is a crystal. So are snowflakes. Salts are mineral crystals made up out of ions, which are electrically charged atoms. Metals are also a kind of crystal.
Crystals in Living Beings
- Crystals are even found in living things. Proteins can have a crystalline structure. Viruses are living crystals according to A. J. Malkin and team at the University of California Department of Biochemistry. Most living beings incorporate various crystalline substances into their bodies. Blood, for instance, is based on iron, and iron is a crystalline metal.

Rocks & Minerals