Editing Quartz (section)

=== 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>