THURSDAY 29 SEPTEMBER, 2005 |

What is a Crystal ?

by Mario | 1 comments

What is a Crystal ?

A crystal is a solid in which the constituent atoms, molecules, or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions.

A solid formed by the solidification of a chemical and having a highly regular atomic structure

A mineral in which the systematic internal arrangement of atoms is outwardly reflected as a latticework of repeated three-dimensional units that form a geometric solid with a surface consisting of symmetrical planes.

From the definitions above we can see that a crystal forms a particular arrangement of molecules or atoms. There are only 7 types of crystalline structure.

The 7 Types of Crystalline Structure.

As the atoms or molecules of a crystal form together, they utilise only one shape and repeat it over and over again in a lattice structure. Imagine a Bees honeycomb, continued repetition of hexagons without any gaps between the shapes.

As you can see there are no gaps. This hexagonal orientation is exhibited by crystals such as Emerald, Morganite and Aquamarine.

Other shapes that produce lattice structures are listed below.

Cubic Crystal System

Three axis of equal length and at right angles to each other.

Tetragonal Crystal System

Three axis at right angles to each other, two on the same plane of equal length and the third perpendicular to them.

Hexagonal Crystal System

Three axis on one plane radiate out equally from a central point. The fourth axis is at right angles and is unequal to the other lengths. This creates six distinctive planes of symmetry parallel to the length.

Trigonal Crystal System

Three equal axis radiating from a single pointing the same plane . A fourth axis is at right angles. This creates three distinct planes of symmetry parallel to the long axis.

Orthorhombic Crystal System

Three axis of equal length set at right angles to one another.

Monoclinic Crystal System

Prism with inclined top and bottom faces. Three axis of unequal lengths, two at right angles to each other and the third at an incline to the plane of the others.

Amorphous

There is an exception to the rule! The amorphous system has no lattice structure at all. Crystals formed in this way are usually formed so quickly by the action of cooling that they do not form a lattice structure. Crystals in this family include moldavite and obsidian, which cool from super high temperatures to ambient temperatures in seconds.

Mario 2005

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