# Difference between revisions of "Crystal Systems"

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{| {{table}} | {| {{table}} | ||

! Crystal System | ! Crystal System | ||

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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 | + | 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: | + | | [[image:cubic.jpg]] |

− | | [[Diamond]] <br> | + | |[[Diamond]] <br /> |

− | [[Garnet]] <br> | + | [[Garnet]] <br /> |

[[Spinel]] | [[Spinel]] | ||

|- | |- | ||

− | | '''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 | + | shorter than the A axes,<br /> |

− | + | which are the same length.<br /> | |

− | + | | [[image:tetragonal.jpg]] | |

− | + | |[[Zircon]] | |

− | | [[image: | ||

− | | [[Zircon]] | ||

|- | |- | ||

| '''Hexagonal''' | | '''Hexagonal''' | ||

− | In the hexagonal system we have an additional | + | In the hexagonal system, we have an additional axis,<br> |

− | + | giving the crystals six sides. Three of these<br> | |

− | are equal in length and meet at | + | are equal in length and meet at 120° to each other. <br> |

− | The C or vertical axis is at 90° to the | + | The C or vertical axis is at 90° to the horizontal axes.<br> |

Mineralogists sometimes divide this into two systems, <br> | Mineralogists sometimes divide this into two systems, <br> | ||

the hexagonal and the trigonal, based on their external<br> | the hexagonal and the trigonal, based on their external<br> | ||

− | appearance | + | appearance (see following). |

− | |[[image: | + | |[[image:hexagonal.jpg]] |

− | |[[Aquamarine]]<br | + | |[[Aquamarine]]<br /> |

− | + | [[Beryl]] <br /> | |

− | [[Beryl]] <br | + | [[Emerald]]<br /> |

− | + | [[Heliodor]]<br /> | |

− | [[Emerald]]<br> | + | [[Morganite]]<br /> |

− | [[Heliodor]]<br> | + | [[Apatite]] |

− | [[Morganite]]<br> | ||

− | [[ | ||

− | |||

− | |||

|- | |- | ||

− | | '''Trigonal'''<br> | + | | '''Trigonal'''<br /> |

− | + | The trigonal system is a subsystem of the <br /> | |

− | hexagonal | + | hexagonal system according to some institutes,<br /> |

+ | therefore some gem references will list these as<br /> | ||

hexagonal. | hexagonal. | ||

− | | [[image: | + | | [[image:trigonal.jpg]] |

− | + | |[[Amethyst]]<br /> | |

− | [[Corundum]]<br> | + | [[Benitoite]]<br /> |

− | [[Tourmaline]] <br> | + | [[Citrine]]<br /> |

+ | [[Corundum]]<br /> | ||

+ | [[Quartz]] <br /> | ||

+ | [[Ruby]] <br /> | ||

+ | [[Sapphire]] <br /> | ||

+ | [[Tourmaline]] <br /> | ||

+ | |||

|- | |- | ||

− | | '''Orthorhombic'''<br> | + | | '''Orthorhombic'''<br /> |

− | In this system there are three axes | + | 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 | + | are of different length. |

− | | [[image: | + | |[[image:Orthorhombic.jpg]] |

− | |[[Alexandrite]]<br> | + | |[[Alexandrite]]<br /> |

− | [[Andalusite]]<br> | + | [[Andalusite]]<br /> |

− | [[Chrysoberyl]]<br> | + | [[Chrysoberyl]]<br /> |

− | [[Iolite]]<br> | + | [[Iolite]]<br /> |

− | [[Peridot]]<br> | + | [[Peridot]]<br /> |

− | [[Tanzanite]] <br> | + | [[Tanzanite]] <br /> |

− | [[Topaz]]<br> | + | [[Topaz]]<br /> |

− | [[Varisite]]<br> | + | [[Varisite]]<br /> |

|- | |- | ||

− | | '''Monoclinic'''<br> | + | | '''Monoclinic'''<br /> |

+ | |||

+ | The above crystal systems all have axes sides<br /> | ||

+ | that meet at 90°. In the monoclinic system, all<br /> | ||

+ | the axes are different lengths. The A axis is inclined<br /> | ||

+ | to the C axis. The B axis is at 90° to them. <br /> | ||

− | + | You can imagine this as a matchbox that slants to one side. | |

− | that | + | |[[image:monoclinic.jpg]] |

− | + | |[[Azurite]]<br /> | |

− | + | [[Diopside]] <br /> | |

− | + | [[Feldspar]]<br /> | |

− | | [[image: | + | [[Kunzite]] <br /> |

− | |[[Azurite]]<br> | + | [[Nephrite]] <br /> |

− | [[Diopside]] <br> | ||

− | [[Feldspar]]<br> | ||

− | [[Kunzite]] <br> | ||

− | [[Nephrite]] <br> | ||

|- | |- | ||

− | | '''Triclinic'''<br> | + | | '''Triclinic'''<br /> |

− | In this system all the axes are different <br> | + | In this system all the axes are different <br /> |

lengths and none of them meet at 90°. | lengths and none of them meet at 90°. | ||

− | | [[image: | + | |

+ | You can imagine this as a matchbox which slants to two sides. | ||

+ | | [[image:triclinic.jpg]] | ||

|[[Turquoise]] | |[[Turquoise]] | ||

|} | |} | ||

+ | <br > | ||

+ | '''Next:[[Form| Form]]''' | ||

+ | <br /><br /> | ||

+ | '''[[Table_Of_Contents| Return to the Table of Contents]]''' |

## Latest revision as of 10:42, 13 December 2012

Crystal System | Diagram | Examples |
---|---|---|

Cubic The cube is composed of 6 square faces |
Diamond | |

Tetragonal The tetragonal system also has three axes |
Zircon | |

Hexagonal
In the hexagonal system, we have an additional axis, |
Aquamarine | |

TrigonalThe trigonal system is a subsystem of the |
Amethyst | |

OrthorhombicIn this system, there are three axes all of which |
Alexandrite Andalusite | |

MonoclinicThe above crystal systems all have axes sides You can imagine this as a matchbox that slants to one side. |
Azurite | |

TriclinicIn this system all the axes are different You can imagine this as a matchbox which slants to two sides. |
Turquoise |