Friday, 11 January 2013

What is a Crystal?

CRYSTALS ARE ASSOCIATED WITH PERFECTION, transparency, and clarity. Many crystals fit these ideals, especially those cut as gemstones, but most are neither perfect nor transparent. Crystals are solid materials in which the atoms are arranged in a regular pattern. Many substances can grow in characteristic geometric forms enclosed by smooth plane surfaces. They are said to have crystallized, and the plane surfaces are known as faces. The word crystal is based on the Greek word krystallos, derived from kryos meaning icy cold. In ancient times it was thought that rock crystal, a colourless variety of quartz, was ice that had frozen so hard it would never melt. 

It is though that the centre of the Earth, the inner core, may be similar in composition to this iron meteorite. It has been cut, polished, and acid-etched to reveal its crystalline structure.

A world of crystals

CRYSTALS ARE ALL AROUND US. We live on a crystal planet in a crystal world. The rocks which form the Earth, the moon, and meteorites, pieces of rock from space, are made up of minerals and virtually all of these minerals are made up of crystals. Minerals are naturally occurring crystalline solids composed of atoms of various elements. The most important of these are oxygen, silicon, and six common metallic elements including iron and calcium. Crystalline particles make up mountains and form the ocean floors. When we cross the beach we tread on crystals. We use them at home and at work, indeed crystals are vital to today's technology. 

Organic crystals

Crystals do not only grow in rocks. The elements that make up most rock-forming minerals are also important to life on Earth. For example, minerals such as calcite and apatite crystallize inside plants and animals.

Writer – Dr. R.F. SYMES and Dr. R.R. HARDING
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