Editing Quartz (section)

== Varieties (according to color) ==
[[File:Transparency.jpg|thumb|left|Quartz crystal demonstrating [[Transparency and translucency|transparency]]]]
Pure quartz, traditionally called rock crystal or clear quartz, is colorless and [[Transparency and translucency|transparent]] or translucent and has often been used for [[hardstone carving]]s, such as the [[Lothair Crystal]]. Common colored varieties include citrine, rose quartz, amethyst, smoky quartz, milky quartz, and others.<ref>{{Cite web|url=http://www.minerals.net/gemstone/quartz_gemstone.aspx|title=Quartz: The gemstone Quartz information and pictures|website=www.minerals.net|language=en-US|access-date=2017-08-29|archive-url=https://web.archive.org/web/20170827194835/http://www.minerals.net/gemstone/quartz_gemstone.aspx|archive-date=27 August 2017|url-status=live}}</ref> These color differentiations arise from the presence of impurities which change the molecular orbitals, causing some electronic transitions to take place in the visible spectrum causing colors.

{{multiple image
| align             = right
| perrow            = 2
| total_width       = 330
| image1            = Pure Quartz at Senckenberg Natural History Museum.jpg
| caption1          = Rock crystal
| image2            = Amethyst Siberia MNHN Minéralogie.jpg
| caption2          = Amethyst
| image3            = Shattuckite-Quartz-120842.jpg
| caption3          = Blue quartz
| image4            = Dumortierite-quartz (Brazil) 10.jpg
| caption4          = Dumortierite quartz
| image5            = Citrine 1 (Russie).jpg
| caption5          = Citrine quartz (natural)
| image6            = Citrine Macro - Large Vug.jpg
| caption6          = Citrine quartz (heat-altered amethyst)
| image7            = Quartz-221141.jpg
| caption7          = Milky quartz
| image8            = Quartz-194084.jpg
| caption8          = Rose quartz
| image9            = Quartz fumé 2(Brésil).jpg
| caption9          = Smoky quartz
| image10           = QuartzPrase.jpg
| caption10         = Prase
}}

===Amethyst===
[[Amethyst]] is a form of quartz that ranges from a bright vivid violet to a dark or dull lavender shade. The world's largest deposits of amethysts can be found in Brazil, Mexico, Uruguay, Russia, France, Namibia, and Morocco. Amethyst derives its color from traces of iron in its structure.<ref>{{cite journal |last1=Lehmann |first1=G. |last2=Moore |first2=W. J. |title=Color Center in Amethyst Quartz |journal=Science |date=20 May 1966 |volume=152 |issue=3725 |pages=1061–1062 |doi=10.1126/science.152.3725.1061|pmid=17754816 |bibcode=1966Sci...152.1061L |s2cid=29602180 }}</ref>

===Ametrine===
[[Ametrine]], as its name suggests, is commonly believed to be a combination of citrine and amethyst in the same crystal; however, this may not be technically correct. Like amethyst, the yellow quartz component of ametrine is colored by iron oxide inclusions. Some, but not all, sources define citrine solely as quartz with its color originating from aluminum-based color centers.<ref name=":0" /><ref>{{Cite web |title=Ametrine |url=https://www.mindat.org/min-7606.html |access-date=2025-01-10 |website=www.mindat.org}}</ref> Other sources do not make this distinction.<ref name=":2">{{Cite web |title=Quartz (var. ametrine) {{!}} Smithsonian National Museum of Natural History |url=https://naturalhistory.si.edu/explore/collections/geogallery/10002876 |access-date=2025-01-10 |website=naturalhistory.si.edu |language=en}}</ref> In the former case, the yellow quartz in ametrine is not considered true citrine. Regardless, most ametrine on the market is in fact partially heat- or radiation-treated amethyst.<ref name=":2" /> 

=== Blue quartz ===
Blue quartz contains inclusions of fibrous [[magnesio-riebeckite]] or [[crocidolite]].<ref>{{cite web|title=Blue Quartz|publisher=Mindat.org|url=https://www.mindat.org/min-26723.html|access-date=24 February 2017|archive-url=https://web.archive.org/web/20170224211828/https://www.mindat.org/min-26723.html|archive-date=24 February 2017|url-status=live}}</ref>

=== Dumortierite quartz ===
Inclusions of the mineral [[dumortierite]] within quartz pieces often result in silky-appearing splotches with a blue hue. Shades of purple or gray sometimes also are present. "Dumortierite quartz" (sometimes called "blue quartz") will sometimes feature contrasting light and dark color zones across the material.<ref name=Cally/><ref name=gemstone>{{cite web | url=http://www.minerals.net/gemstone/dumortierite_gemstone.aspx | title=The Gemstone Dumortierite | publisher=Minerals.net | access-date=23 April 2017 | archive-url=https://web.archive.org/web/20170506074639/http://www.minerals.net/gemstone/dumortierite_gemstone.aspx | archive-date=6 May 2017 | url-status=live | df=dmy-all }}</ref> "Blue quartz" is a minor gemstone.<ref name=Cally>{{cite book|title=Firefly Guide to Gems|first=Cally|last=Oldershaw|publisher=Firefly Books|date=2003|isbn=9781552978146|url=https://archive.org/details/fireflyguidetoge0000olde|url-access=registration|pages=[https://archive.org/details/fireflyguidetoge0000olde/page/100 100]|access-date=19 February 2017}}</ref><ref>{{cite web |last1=Friedman |first1=Herschel |title=THE GEMSTONE DUMORTIERITE |url=https://www.minerals.net/gemstone/dumortierite_gemstone.aspx |website=Minerals.net |access-date=28 November 2020}}</ref>

=== Citrine ===
[[Citrine (quartz)|Citrine]] is a variety of quartz whose color ranges from yellow to yellow-orange or yellow-green. The cause of its color is not well agreed upon. Evidence suggests the color of citrine is linked to the presence of aluminum-based [[F-center|color centers]] in its crystal structure, similar to those of [[smoky quartz]]. Both smoky quartz and citrine are [[Dichroism|dichroic]] in [[Polarization (waves)|polarized light]] and will fade when heated sufficiently or exposed to [[Ultraviolet|UV light]]. They may occur together in the same crystal as “smoky citrine.” Smoky quartz can also be converted to citrine by careful heat treatment. Alternatively, it has been suggested that the color of citrine may be due to trace amounts of iron, but synthetic crystals grown in iron-rich solutions have failed to replicate the color or dichroism of natural citrine. The UV-sensitivity of natural citrine further indicates that its color is not caused solely by trace elements.<ref name=":0">{{Cite web |title=Citrine |url=https://www.mindat.org/min-1054.html |access-date=2025-01-10 |website=www.mindat.org}}</ref>

Natural citrine is rare; most commercial citrine is heat-treated [[amethyst]] or [[smoky quartz]]. Amethyst loses its natural violet color when heated to above 200-300°C and turns a color that resembles natural citrine, but is often more brownish.<ref name=":1">{{Cite web |title=Amethyst |url=https://www.mindat.org/min-198.html |access-date=2025-01-10 |website=www.mindat.org}}</ref> Unlike natural citrine, the color of heat-treated amethyst comes from trace amounts of the iron oxide minerals [[hematite]] and [[goethite]]. Clear quartz with natural iron inclusions or [[limonite]] staining may also resemble citrine, but it is not true citrine.<ref name=":0" /> Like amethyst, heat-treated amethyst often exhibits color zoning, or uneven color distribution throughout the crystal. In geodes and clusters, the color is usually deepest near the tips.<ref name=":1" /> This does not occur in natural citrine. 

It is nearly impossible to differentiate between cut citrine and yellow [[topaz]] visually, but they differ in [[Mohs scale of mineral hardness|hardness]]. Brazil is the leading producer of citrine, with much of its production coming from the state of [[Rio Grande do Sul]]. The name is derived from the Latin word ''citrina'' which means "yellow" and is also the origin of the word "[[citron]]".<ref>[http://www.mindat.org/min-1054.html Citrine] {{Webarchive|url=https://web.archive.org/web/20100502064111/http://www.mindat.org/min-1054.html |date=2 May 2010 }}. Mindat.org (2013-03-01). Retrieved 2013-03-07.</ref> Citrine has been referred to as the "merchant's stone" or "money stone", due to a superstition that it would bring prosperity.<ref>{{cite encyclopedia |encyclopedia=The Encyclopedia of Superstitions |first = Richard|last = Webster|date = 8 September 2012 |url = https://books.google.com/books?id=m1-xCL47_7QC&q=citrine&pg=PA59|entry = Citrine |page = 59|isbn = 9780738725611}}</ref>

Citrine was first appreciated as a golden-yellow gemstone in Greece between 300 and 150&nbsp;BC, during the [[Hellenistic Age]]. Yellow quartz was used prior to that to decorate jewelry and tools but it was not highly sought after.<ref>{{Cite web |url=http://thehealingchest.com/crystals-stones/citrine-meaning/ |title=Citrine Meaning |date=7 January 2016 |access-date=18 August 2017 |archive-url=https://web.archive.org/web/20170818175635/http://thehealingchest.com/crystals-stones/citrine-meaning/ |archive-date=18 August 2017 |url-status=live  }}</ref>

=== Milky quartz ===
Milk quartz or milky quartz is the most common variety of crystalline quartz. The white color is caused by minute [[fluid inclusions]] of gas, liquid, or both, trapped during crystal formation,<ref>{{Cite book|url=https://books.google.com/books?id=KLSTDgAAQBAJ&pg=PA97|title=Gemstones: A Complete Color Reference for Precious and Semiprecious Stones of the World|last1=Hurrell|first1=Karen|last2=Johnson|first2=Mary L.|year=2016|publisher=Book Sales|isbn=978-0-7858-3498-4|page=97}}</ref> making it of little value for optical and quality gemstone applications.<ref>[http://www.galleries.com/minerals/silicate/milky_qu/milky_qu.htm Milky quartz at Mineral Galleries] {{Webarchive|url=https://web.archive.org/web/20081219020818/http://www.galleries.com/minerals/silicate/milky_qu/milky_qu.htm |date=19 December 2008 }}. Galleries.com. Retrieved 2013-03-07.</ref>

=== Rose quartz ===
{{redirect|Rose Quartz|other uses}} 
Rose quartz is a type of quartz that exhibits a pale pink to rose red hue. The color is usually considered as due to trace amounts of [[titanium]], [[iron]], or [[manganese]] in the material. Some rose quartz contains microscopic [[rutile]] needles that produce [[Asterism (gemology)|asterism]] in transmitted light. Recent [[X-ray crystallography|X-ray diffraction]] studies suggest that the color is due to thin microscopic fibers of possibly [[dumortierite]] within the quartz.<ref>{{cite web |url=http://www.mindat.org/show.php?id=3456 |title=Rose Quartz |archive-url=https://web.archive.org/web/20090401031656/http://www.mindat.org/show.php?id=3456 |archive-date=1 April 2009 |website=Mindat.org |url-status=live |access-date=11 May 2023}}</ref>

Additionally, there is a rare type of pink quartz (also frequently called crystalline rose quartz) with color that is thought to be caused by trace amounts of [[phosphate]] or [[aluminium]]. The color in crystals is apparently photosensitive and subject to fading. The first crystals were found in a [[pegmatite]] found near [[Rumford, Maine|Rumford]], [[Maine]], US, and in [[Minas Gerais]], Brazil.<ref>{{cite web |url=http://minerals.caltech.edu/ge114/Lecture_Topics/Quartz/Index.htm |url-status=dead |title=Quartz and its colored varieties |archive-url=https://web.archive.org/web/20110719160220/http://minerals.caltech.edu/ge114/Lecture_Topics/Quartz/Index.htm |archive-date=19 July 2011 |publisher=California Institute of Technology}}</ref> The crystals found are more transparent and euhedral, due to the impurities of phosphate and aluminium that formed crystalline rose quartz, unlike the [[iron]] and microscopic [[dumortierite]] fibers that formed rose quartz.<ref>{{cite web |url=http://www.quartzpage.de/pink.html |title=Pink Quartz |website=The Quartz Page |access-date=11 May 2023}}</ref>

=== Smoky quartz ===
[[Smoky quartz]] is a gray, translucent version of quartz. It ranges in clarity from almost complete transparency to a brownish-gray crystal that is almost opaque. Some can also be black. The translucency results from natural irradiation acting on minute traces of aluminum in the crystal structure.<ref>{{cite journal |last1=Fridrichová |first1=Jana |last2=Bačík |first2=Peter |last3=Illášová |first3=Ľudmila |last4=Kozáková |first4=Petra |last5=Škoda |first5=Radek |last6=Pulišová |first6=Zuzana |last7=Fiala |first7=Anton |title=Raman and optical spectroscopic investigation of gem-quality smoky quartz crystals |journal=Vibrational Spectroscopy |date=July 2016 |volume=85 |pages=71–78 |doi=10.1016/j.vibspec.2016.03.028|bibcode=2016VibSp..85...71F }}</ref>

=== Prase ===
Prase is a [[leek]]-green variety of quartz that gets its color from inclusions of the [[amphibole]] [[actinolite]].<ref name="Klemme_etal_2018">{{cite journal | title=On the Color and Genesis of Prase (Green Quartz) and Amethyst from the Island of Serifos, Cyclades, Greece | first1=S. | last1=Klemme | first2=J. | last2=Berndt | first3=C. | last3=Mavrogonatos | first4=S. | last4=Flemetakis | first5=I. | last5=Baziotis | first6=P. | last6=Voudouris | first7=S. | last7=Xydous | journal=Minerals | date=2018 | volume=8 | issue=11 | page=487 | doi=10.3390/min8110487 | bibcode=2018Mine....8..487K | doi-access=free }}</ref><ref name=":3">{{Cite web |title=Prase |url=https://www.mindat.org/min-6703.html |access-date=2025-01-21 |website=www.mindat.org}}</ref> However, the term has also variously been used for a type of [[quartzite]], a microcrystalline variety of quartz or jasper, or any leek-green quartz.<ref name=":3" />

=== Prasiolite ===
{{distinguish|Praseolite}}

[[Prasiolite]], also known as ''vermarine'', is a variety of quartz that is green in color.<ref name=QtzPage>{{cite web |url=http://www.quartzpage.de/prasiolite.html |title=Prasiolite |publisher=quarzpage.de |date=28 October 2009 |access-date=28 November 2010 |archive-url=https://web.archive.org/web/20110713052049/http://www.quartzpage.de/prasiolite.html |archive-date=13 July 2011 |url-status=live  }}</ref> The green is caused by iron ions.<ref name="Klemme_etal_2018"/> It is a rare mineral in nature and is typically found with amethyst; most "prasiolite" is not natural – it has been artificially produced by heating of amethyst. {{citation needed span|text=Since 1950|date=April 2023}}, almost all natural prasiolite has come from a small [[Brazil]]ian mine, but it is also seen in [[Lower Silesia]] in [[Poland]]. Naturally occurring prasiolite is also found in the [[Thunder Bay]] area of [[Canada]].<ref name=QtzPage />