Editing Green (section)

=== Pigments, food coloring and fireworks ===
{{See also|Green pigments}}
[[File:Chicago River dyed green, focus on river.jpg|thumb|The [[Chicago River]] is dyed green every year to mark [[St. Patrick's Day]]]]
Many minerals provide [[pigment]]s which have been used in green paints and dyes over the centuries. Pigments, in this case, are minerals which reflect the color green, rather that emitting it through [[luminescent]] or [[phosphorescent]] qualities. The large number of green pigments makes it impossible to mention them all. Among the more notable green minerals, however is the [[emerald]], which is colored green by trace amounts of [[chromium]] and sometimes [[vanadium]].<ref>
{{cite book
 |last1=Hurlbut    |first1=Cornelius S. Jr
 |last2=Kammerling |first2=Robert C.
 |year=1991
 |title=Gemology
 |page=203
 |publisher=John Wiley & Sons
 |place=New York, NY
}}
</ref>
Chromium(III) oxide (Cr<sub>2</sub>O<sub>3</sub>), is called [[Chromium(III) oxide|chrome green]], also called [[viridian]] or institutional green when used as a pigment.<ref name=Holleman-Wiberg-2001/> For many years, the source of [[amazonite]]'s color was a mystery. Widely thought to have been due to [[copper]] because copper compounds often have blue and green colors, the blue-green color is likely to be derived from small quantities of [[lead]] and water in the [[feldspar]].<ref>
{{cite journal
 | author1=Hoffmeister
 | author2=Rossman
 | year=1985
 | title=A spectroscopic study of irradiation coloring of amazonite; structurally hydrous, Pb-bearing feldspar
 | journal=[[American Mineralogist]]
 | volume=70 | pages=794–804
}}
</ref>
Copper is the source of the green color in [[malachite]] pigments, chemically known as basic [[copper(II) carbonate]].<ref>
{{cite web
 | title = Malachite
 | year = 2001
 | website = WebExhibits
 | url = http://webexhibits.org/pigments/indiv/overview/malachite.html
 | access-date = December 8, 2007
}}
</ref>

[[Verdigris]] is made by placing a plate or blade of copper, brass or bronze, slightly warmed, into a vat of fermenting wine, leaving it there for several weeks, and then scraping off and drying the green powder that forms on the metal. The process of making verdigris was described in ancient times by [[Pliny the Elder|Pliny]]. It was used by the Romans in the murals of Pompeii, and in Celtic medieval manuscripts as early as the 5th century AD. It produced a blue-green which no other pigment could imitate, but it had drawbacks: it was unstable, it could not resist dampness, it did not mix well with other colors, it could ruin other colors with which it came into contact, and it was [[toxic]]. [[Leonardo da Vinci]], in his treatise on painting, warned artists not to use it. It was widely used in miniature paintings in Europe and Persia in the 16th and 17th centuries. Its use largely ended in the late 19th century, when it was replaced by the safer and more stable [[chrome green]].{{sfn|Varichon|2000|pp=214–15}} Viridian, as described above, was [[patent]]ed in 1859. It became popular with painters, since, unlike other synthetic greens, it was stable and not toxic. [[Vincent van Gogh]] used it, along with [[Prussian blue]], to create a dark blue sky with a greenish tint in his painting ''[[Café Terrace at Night]]''.<ref name=Holleman-Wiberg-2001/>

[[Green earth]] is a natural pigment used since the time of the [[Roman Empire]]. It is composed of clay colored by [[iron oxide]], [[magnesium]], [[aluminum silicate]], or [[potassium]]. Large deposits were found in the South of France near [[Nice]], and in Italy around [[Verona]], on [[Cyprus]], and in [[Bohemia]]. The clay was crushed, washed to remove impurities, then powdered. It was sometimes called Green of Verona.{{sfn|Varichon|2000|pp=210–11}}

Mixtures of oxidized [[cobalt]] and [[zinc]] were also used to create green paints as early as the 18th century.<ref>
{{cite web
 | title = Cobalt green
 | year = 2001
 | website = WebExhibits
 | url = http://webexhibits.org/pigments/indiv/overview/cogreen.html
 | access-date = December 8, 2007
}}
</ref>

[[Cobalt green]], sometimes known as [[Cobalt green#Rinman's green|Rinman's green]] or zinc green, is a translucent green pigment made by heating a mixture of cobalt (II) oxide and zinc oxide. [[Sven Rinman]], a Swedish chemist, discovered this compound in 1780.<ref>
{{cite news
 |title = Green pigment spins chip promise
 |date = 9 August 2006
 |website = [[BBC News]]
 |url = http://news.bbc.co.uk/2/hi/technology/4776479.stm
}}
</ref>
Green chrome oxide was a new synthetic green created by a chemist named Pannetier in Paris in about 1835. Emerald green was a synthetic deep green made in the 19th century by hydrating chrome oxide. It was also known as Guignet green.<ref name=Holleman-Wiberg-2001>
{{cite book
 |first1=A.F. |last1=Holleman 
 |first2=E.   |last2=Wiberg
 |year=2001
 |title=Inorganic Chemistry
 |publisher=[[Academic Press]]
 |place=New York, NY
}}
</ref>

[[File:Fireworks 2.JPG|thumb|left|[[Fireworks]] typically use [[barium]] salts to create green sparks]]
There is no natural source for green [[food coloring]]s which has been approved by the US [[Food and Drug Administration]]. Chlorophyll, the [[E number]]s E140 and E141, is the most common green chemical found in nature, and only allowed in certain medicines and cosmetic materials.<ref>
{{cite magazine
 | first = Victoria | last = Gilman
 | date = 25 August 2003
 | title = Food coloring: Synthetic and natural additives impart a rainbow of possibilities to the foods we eat
 | magazine = [[Chemical & Engineering News]]
 | url = http://pubs.acs.org/cen/whatstuff/stuff/8134foodcoloring.html
 | access-date = December 8, 2007
}}
</ref>
[[Quinoline Yellow WS|Quinoline Yellow]] (E104) is a commonly used coloring in the United Kingdom but is banned in Australia, Japan, Norway and the United States.<ref>
{{cite web
 | url = http://www.ukfoodguide.net/e104.htm
 | archive-url = https://web.archive.org/web/20030508004821/http://www.ukfoodguide.net/e104.htm
 | url-status = usurped
 | archive-date = May 8, 2003
 | title = E104 Quinoline Yellow, FD&C Yellow No.10
 | website = UK Food Guide
 | access-date = 9 December 2007
}}
</ref>
[[Green S]] (E142) is prohibited in many countries, for it is known to cause [[hyperactivity]], [[asthma]], [[urticaria]], and [[insomnia]].<ref>
{{cite web
 | title = E142 Green S
 | website = UK Food Guide
 | url = http://www.ukfoodguide.net/e142.htm
 | archive-url = https://web.archive.org/web/20030511014619/http://www.ukfoodguide.net/e142.htm
 | url-status = usurped
 | archive-date = May 11, 2003
 | access-date = 9 December 2007
}}
</ref>

To create green sparks, [[firework]]s use [[barium]] [[Salt (chemistry)|salts]], such as [[barium chlorate]], [[barium nitrate]] crystals, or [[barium chloride]], also used for green fireplace logs.<ref name=firework/> Copper salts typically burn blue, but [[cupric chloride]] (also known as "campfire blue") can also produce green flames.<ref name=firework/> Green pyrotechnic flares can use a mix ratio 75:25 of [[boron]] and [[potassium nitrate]].<ref name=firework/> Smoke can be turned green by a mixture: solvent yellow 33, solvent green 3, [[lactose]], [[magnesium carbonate]] plus [[sodium carbonate]] added to [[potassium chlorate]].<ref name=firework>
{{cite web
 | title = Firework Chemicals (list)
 | year = 2008
 | website = Sylighter
 | url=http://www.skylighter.com/mall/chemicals.asp
 | access-date=11 January 2008
}}
</ref>
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