Difference between revisions of "Crystal Systems"

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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<br>
 
than the A and B axis which are the same length<br>
 
than the A and B axis which are the same length<br>
that all meet at 90°. It differs from the isometric <br>
+
that all meet at 90°. It differs from the isometric<br>
 
system in that the C axis is longer than the A<br>
 
system in that the C axis is longer than the A<br>
 
and B axis which are the same length.
 
and B axis which are the same length.
 
| [[image:xl_tetragonal.gif|left|]]
 
| [[image:xl_tetragonal.gif|left|]]
 
| [[Zircon]]  
 
| [[Zircon]]  
 +
 +
|-
 +
| '''Hexagonal'''
 +
 +
In the hexagonal system we have an additional axes,<br>
 +
which gives the crystals six sides. Three of these<br>
 +
are equal in length and meet at 60° to each other. <br>
 +
The C or vertical axis is at 90° to the shorter axes.<br>
 +
Mineralogists sometimes divide this into two systems, <br>
 +
the hexagonal and the trigonal, based on their external<br>
 +
appearance, as follows:
 +
|[[image:xl_hexagonal.gif|left|]]
 +
|[[Aquamarine]]<br>
 +
[[Benitoite]]<br>
 +
[[Beryl]] <br>
 +
[[Citrine]]<br>
 +
[[Emerald]]<br>
 +
[[Heliodor]]<br>
 +
[[Morganite]]<br>
 +
[[Quartz]] <br>
 +
[[Ruby]] <br>
 +
[[Sapphire]] <br>
 
|}
 
|}

Revision as of 16:47, 1 October 2006

Crystal Systems & Forms

Crystal System Diagram Examples
Cubic

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

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
than the A and B axis which are the same length
that all meet at 90°. It differs from the isometric
system in that the C axis is longer than the A
and B axis which are the same length.

Zircon
Hexagonal

In the hexagonal system we have an additional axes,
which gives the crystals six sides. Three of these
are equal in length and meet at 60° to each other.
The C or vertical axis is at 90° to the shorter axes.
Mineralogists sometimes divide this into two systems,
the hexagonal and the trigonal, based on their external
appearance, as follows:

Aquamarine

Benitoite
Beryl
Citrine
Emerald
Heliodor
Morganite
Quartz
Ruby
Sapphire