Editing Onyx

{{Short description|Black and white variety of agate}}
{{about|the mineral|the New York hip hop group|Onyx (hip hop group)|other uses}}
{{Infobox mineral
|boxtextcolor=#FFFFFF|boxbgcolor=#353935| name        = Onyx
| category    = [[Tectosilicate]] [[minerals]], [[quartz]] [[Mineral group|group]], [[chalcedony]] [[Mineral variety|variety]], [[agate]] variety
| image       = Agate-Quartz-49959.jpg
| imagesize   = 250
| alt         = Black onyx with concentric white bands
| caption     = Onyx with concentric banding
| formula     = SiO<sub>2</sub> ([[silicon dioxide]])
| molweight   = 60.08 g/mol
| color       = Black and white; red to brown with black or white (sardonyx)
| system      = [[hexagonal crystal family|Trigonal]] ([[quartz]]), [[Monoclinic]] ([[moganite]])
| cleavage    = None
| fracture    = Uneven, [[conchoidal fracture|conchoidal]]
| mohs        = 6.5–7
| luster      = Vitreous, silky
| streak      = White
| gravity     = 2.55–2.70
| diaphaneity = Translucent
| opticalprop = Uniaxial/+
| refractive  = 1.530–1.543
| birefringence =
| pleochroism =
| 2V          =
| dispersion  =
| extinction  =
| length fast/slow =
| fluorescence =
| absorption  =
| references  = <ref name=mindat>{{Mindat |id=2999 |name=Onyx |access-date=2025-02-14}}</ref><ref>{{cite web |url=https://gemdat.org/gem-2999.html |title=Onyx |publisher=gemdat.org |access-date=2015-08-22}}</ref>
}}

'''Onyx''' is a typically black-and-white banded variety of [[agate]], a [[silicate mineral]]. The bands can also be monochromatic with alternating light and dark bands. ''Sardonyx'' is a variety with red to brown bands alternated with black or white bands. The name "onyx" is also frequently used for [[Agate#Level-banded agates|level-banded]] (parallel-banded) agates, but in proper usage it refers to color pattern not band structure.<ref name=mindat/> Onyx, as a descriptive term, has also been incorrectly applied to parallel-banded varieties of [[alabaster]], [[marble]], [[calcite]], [[obsidian]], and [[opal]], and misleadingly to materials with contorted banding, such as "cave onyx" and "Mexican onyx".<ref name=mindat/><ref>{{cite book |last=Manutchehr-Danai|first=Mohsen |year=2013 |title=Dictionary of Gems and Gemology |location=New York |publisher=Springer |pages=340–341 |isbn=9783662042885}}</ref><ref>{{cite book |last=Schumann|first=Walter |year=2009 |title=Gemstones of the World |location=New York |publisher=[[Sterling Publishing|Sterling]] |page=158 |isbn=9781402768293}}</ref>

==Etymology==
''Onyx'' comes through Latin (of the same spelling), from the Ancient Greek {{lang|grc|ὄνυξ}} ({{Transliteration|grc|onyx}}), meaning {{gloss|claw}} or {{gloss|fingernail}}. Onyx with pink and white bands can sometimes resemble a fingernail.<ref>{{cite web|url=http://www.etymonline.com/index.php?term=onyx|title=Online Etymology Dictionary|work=etymonline.com|access-date=22 August 2015}}</ref> The English word "nail" is [[cognate]] with the Greek word.

==Varieties==
[[File:Red onyx - Handicraft.jpg|thumb|left|[[Cabochon]]s of red onyx, also called sardonyx]]
[[File:Black Onyx.jpg|thumb|left|alt=A photograph of 6 smooth black pebbles with white markings, arranged in a circle|Black onyx with white streaks]]

Onyx is formed of [[chalcedony]] bands in alternating colors. It is [[cryptocrystalline]], consisting of fine intergrowths of the [[silica]] minerals [[quartz]] and [[moganite]]. Its bands are parallel, unlike the more chaotic banding that often occurs in [[agate]]s.<ref>{{cite book |last1=Assaad|first1=Fakhry A. |last2=LaMoreaux|first2=Philip E. Sr. |title=Field Methods for Geologists and Hydrogeologists |year=2004 |publisher=[[Springer Science+Business Media|Springer-Verlag]] |location=Berlin, [[Heidelberg]], New York |isbn=3-540-40882-7 |editor-last=Hughes|editor-first=Travis H. |page=8}}</ref>

Sardonyx is a variant in which the colored bands are [[sard]] ([[shades of red]]) rather than black. Black onyx is perhaps the most famous variety, but it is not as common as onyx with colored bands. Artificial treatments have been used since ancient times to produce the black color in "black onyx" and the reds and yellows in sardonyx. Most "black onyx" on the market is artificially colored.<ref>{{cite book |last=Sinkankas|first=John |title=Gemstones of North America |year=1959 |publisher=[[David Van Nostrand|Van Nostrand]] |location=[[Princeton, New Jersey]] |page=316 |volume=1}}</ref><ref name="SA July 1874">{{cite journal |title=The Manufacture of Gem Stones |journal=[[Scientific American]] |date=25 July 1874 |page=49 |publisher=Munn & Company |location=New York}}</ref>{{Better source needed|date=July 2024}}{{disputed inline|date=July 2024}}

==Imitations and treatments==
The name has also commonly been used to label other banded materials, such as banded [[calcite]] found in [[Mexico]], [[India]], and other places, and often carved, polished, and sold. This material is much softer than true onyx and more readily available. The majority of carved items sold as "onyx" today are this [[carbonate]] material.<ref name=Mindat>{{cite web |url=http://www.mindat.org/min-2999.html |title=Onyx |publisher=mindat.org |access-date=22 August 2015}}</ref><ref>{{cite book|last1=Hurlbut|first1=Cornelius S.|last2=Sharp|first2=W. Edwin|title=Dana's Minerals and How to Study Them|year=1998|publisher=Wiley|location=New York, New York|isbn=0-471-15677-9|page=[https://archive.org/details/danasmineralshow00hurl/page/200 200]|edition=4th|url-access=registration|url=https://archive.org/details/danasmineralshow00hurl/page/200}}</ref>

Artificial onyx types have also been produced from common chalcedony and plain agates. The first-century naturalist [[Pliny the Elder]] described these techniques used in Roman times.<ref name="O'Donoghue">{{cite book|last=O'Donoghue|first=Michael|title=Synthetic, Imitation, and Treated Gemstones |year=1997 |publisher=Butterworth-Heinemann |location=Boston |isbn=0-7506-3173-2|pages=125–127}}</ref> Treatments for producing black and other colors include soaking or boiling chalcedony in sugar solutions, then treating with [[Sulfuric acid|sulfuric]] or [[hydrochloric acid]] to carbonize sugars which had been absorbed into the top layers of the stone.<ref name="SA July 1874"/><ref>{{cite book|last=Read|first=Peter G.|title=Gemmology|year=1999|publisher=Butterworth-Heinemann|location=Oxford |isbn=0-7506-4411-7|page=160}}</ref> These techniques are still used, as well as other dyeing treatments, and most so-called "black onyx" sold is artificially treated.<ref>{{cite book|last=Liddicoat|first=Richard Thomas|title=Handbook of Gem Identification |year=1987|publisher=Gemological Institute of America|location=Santa Monica, California |isbn=0-87311-012-9 |pages=158–160 |edition=12th}}</ref> In addition to dye treatments, heating and treatment with [[nitric acid]] have been used to lighten or eliminate undesirable colors.<ref name="SA July 1874"/>

==Geographic occurrence==
Onyx can be found in various regions of the world, including Greece, Yemen, Uruguay, Argentina, Australia, Brazil, Canada, China, Czech Republic, Germany, Pakistan, India, Indonesia, Madagascar, Latin America, the UK, and various states in the US.<ref name=Mindat/>

==Historical use==

[[File:Kunsthistorisches Museum Vienna June 2006 031.jpg|thumb|right|alt=A photograph showing a roughly rectangular gem set in a gold frame with 2 carved panels with various figures carved in shallow from translucent white chalcedony against a solid black background|The [[Gemma Augustea]] is a Roman [[cameo (carving)|cameo]] produced 9–12&nbsp;AD and [[engraved gem|carved]] in a two-layered onyx gem (19 × 23 cm).]]

It has a long history of use for [[hardstone carving]] and [[jewelry]], where it is usually cut as a [[cabochon]] or into beads. It has also been used for [[intaglio (jewelry)|intaglio]] and hardstone [[cameo (carving)|cameo]] [[engraved gems]], where the bands make the image contrast with the ground.<ref>{{cite book|last1=Kraus|first1=Edward Henry|last2=Slawson|first2=Chester Baker|title=Gems and Gem Materials|url=https://archive.org/details/in.ernet.dli.2015.280103|year=1947|publisher=McGraw-Hill|location=New York, New York|page=[https://archive.org/details/in.ernet.dli.2015.280103/page/n234 227]}}</ref> Some onyx is natural but much of the material in commerce is produced by the staining of agate.<ref>{{cite book|last1=Liddicoat|first1=Richard Thomas|last2=Copeland|first2=Lawrence L.|title=The Jewelers' Manual|year=1974|publisher=Gemological Institute of America|location=Los Angeles, California|page=87}}</ref>

Onyx was used in [[Egypt]] as early as the Second Dynasty to make bowls and other pottery items.<ref>{{cite book|last=Porter|first=Mary Winearls|author-link=Mary Winearls Porter|title=What Rome was Built with: A Description of the Stones Employed|url=https://archive.org/details/whatromewasbuilt00portiala|year=1907|publisher=H. Frowde|location=Rome|page=[https://archive.org/details/whatromewasbuilt00portiala/page/108 108]}}</ref> Use of sardonyx appears in the art of [[Minoan civilization|Minoan]] [[Crete]], notably from the archaeological recoveries at [[Knossos]].<ref>C. Michael Hogan (2007) [http://www.themodernantiquarian.com/site/10854/knossos.html#fieldnotes ''Knossos fieldnotes'', The Modern Antiquarian]</ref>

Brazilian green onyx was often used as plinths for [[art deco]] sculptures created in the 1920s and 1930s. The German sculptor [[Ferdinand Preiss]] used Brazilian green onyx for the base on the majority of his [[chryselephantine]] sculptures.<ref name=Hickmet>{{cite web|title=Ferdinand Preiss|url=http://www.hickmet.com/artist/fritz-ferdinand-preiss|website=Hickmet.com|access-date=18 June 2015}}</ref> Green onyx was also used for trays and pin dishes – produced mainly in [[Austria]] – often with small bronze animals or figures attached.<ref>{{cite web |title=Lot 419, Schmidt-Hofer, Otto, 1873–1925 (Germany)|website=ArtValue.com| url=http://www.artvalue.com/auctionresult--schmidt-hofer-otto-1873-1925-g-art-deco-skulptur-in-form-eine-2160708.htm}}</ref>

Onyx is mentioned in the Bible many times.<ref>{{cite web|url=https://www.biblegateway.com/quicksearch/?quicksearch=Onyx&version=DRA&resultspp=25|title=BibleGateway|work=biblegateway.com|access-date=22 August 2015}}</ref> Sardonyx (onyx in which white layers alternate with sard – a brownish color) is mentioned in the Bible as well.<ref>{{cite web|url=https://www.biblegateway.com/quicksearch/?quicksearch=sardOnyx&qs_version=DRA|title=BibleGateway|work=biblegateway.com|access-date=22 August 2015}}</ref>

Onyx was known to the [[Ancient Greek]]s and [[Ancient Rome|Romans]].<ref>{{cite web|url=http://www.gemstone.org/gem-by-gem/english/onyx.html|title=Onyx|author=Administrator|work=gemstone.org|access-date=22 August 2015}}</ref> The first-century naturalist [[Pliny the Elder]] described both types of onyx and various artificial treatment techniques in his ''[[Natural History (Pliny)|Naturalis Historia]]''.<ref name="O'Donoghue"/>

Slabs of onyx (from the [[Atlas Mountains]]) were famously used by [[Mies van der Rohe]] in [[Villa Tugendhat]] at [[Brno]] (completed 1930) to create a shimmering semi-translucent interior wall.<ref>{{cite web|title=The Interiors|url=http://www.tugendhat.eu|publisher=Villa Tugendhat|access-date=2 September 2017}}</ref><ref>{{cite web|title=Tugendhat Villa in Brno|url=https://whc.unesco.org/en/list/1052|publisher=UNESCO|access-date=2 September 2017}}</ref>

The [[Hôtel de la Païva]] in Paris is noted for its yellow onyx décor, and the new [[Mariinsky Theatre Second Stage]] in St.Petersburg uses yellow onyx in the lobby.{{Citation needed|date=May 2025}}

===Superstitions===
The ancient Romans entered battle carrying amulets of sardonyx engraved with [[Mars (mythology)|Mars]], the god of war. This was believed to bestow courage in battle. In Renaissance Europe, wearing sardonyx was believed to bestow eloquence.<ref>Firefly Guide to Gems By Cally Oldershaw, p.168</ref> A traditional [[Persians|Persian]] belief is that it helped with [[epilepsy]].<ref>The Mining World, Volume 32, June 25, 1910, p.1267</ref> Sardonyx was traditionally used by English midwives to ease childbirth by laying it between the breasts of the mother.<ref>Three thousand years of mental healing By George Barton Cutten, 1911 P.202</ref>

==See also==
{{Portal|Minerals}}
* {{Annotated link|List of minerals}}
* {{Annotated link|Chalcedony}}
* {{Annotated link|Gemstone}}
* {{Annotated link|Jasper}}
* {{Annotated link|Birthstone}}

==References==
{{Reflist|2}}

==External links==
{{Commons}}
{{Wiktionary|onyx}}
* {{cite EB1911|first=Frederick William |last=Rudler |wstitle=Onyx |volume=20 |page=118 |short=x}}

{{Jewellery}}
{{Silica minerals}}
{{Shades of black}}
{{Authority control}}

[[Category:Chalcedony]]
[[Category:Quartz gemstones]]