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Onyx

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Formula:
SiO2
System:
Trigonal
Colour:
Black and white
Lustre:
Waxy
Hardness:
6½ - 7
A variety of Agate

In correct usage, the name refers to a black and white banded variety of Agate, or sometimes a monochromatic agate with dark and light bands (brown and white for example) - but traditionally the name was reserved for black and white banded agate, and brown varieties named Sardonyx.

In recent times the name has become confused with other banded materials, in particular banded calcite formed in cave systems such as the material found in Mexico and Pakistan and often carved, in fact the majority of carved material (such as book-ends, chess-sets, etc) that are available today are made from this carbonate rock. This is a carbonate material and is not true Onyx. Other names have been used over time for this material, such as "Mexican Onyx" and "onyx-marble". Careless use of these names has resulted in the term 'Onyx' being incorrectly applied to a variety of banded materials that are not covered by the original definition of the name.

Visit gemdat.org for gemological information about Onyx.

Classification of Onyx

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Physical Properties of Onyx

Diaphaneity (Transparency):
Translucent, Opaque
Comment:
Vitreous when polished
Colour:
Black and white
Comment:
often produced by dying agates
Streak:
white
Hardness (Mohs):
6½ - 7
Fracture:
Conchoidal
Density:
2.6 - 2.65 g/cm3 (Measured)    
Comment:
varies with amount and type of impurities

Crystallography of Onyx

Crystal System:
Trigonal

Chemical Properties of Onyx

Formula:
SiO2
Essential elements:
All elements listed in formula:

Other Names for Onyx

Name in Other Languages:
Bulgarian:Оникс
Czech:Onyx
Dutch:Onyx
Finnish:Onyksi
French:Onyx
Galician:Ónix
German:Onyx
Italian:Onice
Latin:Onyx
Latvian:Onikss
Lithuanian:Oniksas
Polish:Onyks
Portuguese:Ónix
Romanian:Onix
Russian:Оникс
Serbian (Cyrillic Script):Оникс
Simplified Chinese:缟玛瑙
黑玛瑙
Spanish:Ónix
Swedish:Onyx

Other Information

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

Internet Links for Onyx

Localities for Onyx

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
Mineral and/or Locality  
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