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Crystal Ststems

 


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.

cubic

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.

tetragonal

zirconZircon

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:

hexagonal

Trigonal

Again, the trigonal system is a subsystem of the hexagonal. Most gem references will list these as hexagonal.

trigonal

amethystAmethyst
citrineCitrine
corundumCorundum
rubyRuby
sapphireSapphire

tourmalineTourmaline
eudialite
Eudialyte
quartzQuartz


Orthorhombic

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

orthorhombic

Monoclinic

. The above crystal systems all have axes sides that meet at 90°. In the monoclinic system all the axes are different lengths. Two of them, the A and C axes, meet at 90°, but the third one does not.

monoclinic

Triclinic

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

triclinic

turquoiseTurquoise