Difference between revisions of "Crystal Systems"

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! Examples
 
! Examples
 
|-
 
|-
| '''Cubic''' <br>
+
| '''Cubic''' <br />
The cube is composed of 6 square faces<br>
+
The cube is composed of 6 square faces<br />
at 90° angles to each other. Each<br>
+
at 90° angles to each other. Each<br />
face intersects one of the crystallographic<br>
+
face intersects one of the crystallographic<br />
axes and is parallel to the other two.<br>
+
axes and is parallel to the other two.<br />
 
| [[image:cubic.jpg]]
 
| [[image:cubic.jpg]]
 
|[[Diamond]] <br />
 
|[[Diamond]] <br />
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| '''Tetragonal''' <br />
 
| '''Tetragonal''' <br />
  
The tetragonal system also has three axes<br>
+
The tetragonal system also has three axes<br />
that all meet at 90°. It differs from the<br>
+
that all meet at 90°. It differs from the<br />
isometric system in that the C axis is longer<br>
+
isometric system in that the C axis is longer or<br />
than the A axes, which are the same length.<br>
+
shorter than the A axes.<br />
All meet at 90°.
+
than the A axes, which are the same length.<br />
 
| [[image:tetragonal.jpg]]
 
| [[image:tetragonal.jpg]]
 
|[[Zircon]]  
 
|[[Zircon]]  
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In this system, there are three axes all of which<br />  
 
In this system, there are three axes all of which<br />  
 
meet at 90° to each other. However, all the axes<br />  
 
meet at 90° to each other. However, all the axes<br />  
are a different length.
+
are of different length.
|[[image:xl_orthorhombic.gif|left|]]
+
|[[image:Orthorhombic.jpg]]
 
|[[Alexandrite]]<br />
 
|[[Alexandrite]]<br />
 
[[Andalusite]]<br />
 
[[Andalusite]]<br />

Revision as of 09:49, 27 June 2007

Crystal System Diagram Examples
Cubic

The cube is composed of 6 square faces
at 90° angles to each other. Each
face intersects one of the crystallographic
axes and is parallel to the other two.

Cubic.jpg Diamond

Garnet
Spinel

Tetragonal

The tetragonal system also has three axes
that all meet at 90°. It differs from the
isometric system in that the C axis is longer or
shorter than the A axes.
than the A axes, which are the same length.

Tetragonal.jpg Zircon
Hexagonal

In the hexagonal system, we have an additional axis,
giving the crystals six sides. Three of these
are equal in length and meet at 120° to each other.
The C or vertical axis is at 90° to the horizontal axes.
Mineralogists sometimes divide this into two systems,
the hexagonal and the trigonal, based on their external
appearance (see following).

Aquamarine

Beryl
Emerald
Heliodor
Morganite

Trigonal

The trigonal system is a subsystem of the
hexagonal system according to some institutes,
therefore some gem references will list these as
hexagonal.

Amethyst

Benitoite
Citrine
Corundum
Quartz
Ruby
Sapphire
Tourmaline

Orthorhombic

In this system, there are three axes all of which
meet at 90° to each other. However, all the axes
are of different length.

Orthorhombic.jpg Alexandrite

Andalusite
Chrysoberyl
Iolite
Peridot
Tanzanite
Topaz
Varisite

Monoclinic

The above crystal systems all have axes sides
that meet at 90°. In the monoclinic system, all
the axes are different lengths. The A axis is inclined
to the C axis. The B axis is at 90° to them.

Azurite

Diopside
Feldspar
Kunzite
Nephrite

Triclinic

In this system all the axes are different
lengths and none of them meet at 90°.

Turquoise