Editing Turquoise (section)

== Occurrence ==
[[File:Turquoise with quartz.jpg|left|thumb|Massive Kingman blue turquoise in matrix with [[quartz]] from the [[Mineral Park mine]], [[Arizona]], US]]
Turquoise was among the first gems to be mined, and many historic sites have been depleted, though some are still worked to this day. These are all small-scale operations, often seasonal owing to the limited scope and remoteness of the deposits. Most are worked by hand with little or no mechanization. However, turquoise is often recovered as a byproduct of large-scale copper mining operations, especially in the United States.<ref>{{Cite journal |last=King |first=R. J. |date=2002 |title=Turquoise |url=http://www.blackwell-synergy.com/links/doi/10.1046/j.1365-2451.2002.00345.x/full/ |journal=Geology Today |volume=18 |issue=3 |pages=110–111}}</ref>
[[File:Turquoise of Nishapur - village of Ma'dan 14.JPG|alt=Turquoise of Madan-e Olya of Nishapur|thumb|Turquoise of [[Madan-e Olya]] of [[Nishapur]]]] Deposits typically take the form of small [[Vein (geology)|veins]] in partially decomposed volcanic rock in arid climates.<ref name=Hurlbut/>

=== Iran ===
[[Iran]] has been an important source of turquoise for at least 2,000 years. It was initially named by [[Iranian peoples|Iranians]] "''pērōzah''" meaning "victory", and later the [[Arabs]] called it "''fayrūzah''", which is pronounced in Modern Persian as "''fīrūzeh''". In Iranian architecture, the blue turquoise was used to cover the [[dome]]s of [[palace]]s because its intense blue colour was also a symbol of heaven on earth.<ref name="Beale-1973" /><ref>Farmani, Anousheh (2015) ''"Precious and semi-precious minerals and their roots in ancient Persian texts"'', Second International Congress of Science and Earth, Tehran [https://web.archive.org/web/20231028133214/https://fa.seminars.sid.ir/ViewPaper.aspx?ID=35943]</ref><ref>{{Cite book|last=zawush|first=Muhammad|title=mineralogy in Ancient Iran|publisher=Institute of Humanities and Cultural Studies|year=1996|isbn=9789644260315|location=tehran|pages=156}}</ref>
[[File:Persian Turquoise.jpg|thumb|Persian turquoise from Iran]]

This deposit is blue naturally and turns green when heated due to dehydration. It is restricted to a mine-riddled region in [[Nishapur]], the {{convert|2012|m|ft|adj=on|abbr=on}} mountain peak of [[Ali-mersai]] near [[Mashhad]], the capital of [[Khorasan Province]], [[Iran]]. Weathered and broken [[trachyte]] is host to the turquoise, which is found both ''in situ'' between layers of limonite and sandstone and amongst the [[scree]] at the mountain's base. These workings are the oldest known, together with those of the [[Sinai Peninsula]].<ref name=USGS /> Iran also has turquoise mines in [[Semnan Province|Semnan]] and [[Kerman]] provinces.<ref name="Beale-1973" />

=== Sinai ===
Since at least the [[First Dynasty of Egypt|First Dynasty]] (3000&nbsp;[[Common Era|BCE]]) in [[ancient Egypt]], and possibly before then, turquoise was used by the [[Egyptians]] and was [[mining|mined]] by them in the [[Sinai Peninsula]]. This region was known as the ''Country of Turquoise'' by the native [[Monitu]]. There are six mines in the peninsula, all on its southwest coast, covering an area of some {{convert|650|km2|abbr=on}}. The two most important of these mines, from a historical perspective, are [[Serabit el-Khadim]] and [[Wadi Maghareh]], believed to be among the oldest of known mines. The former mine is situated about 4 kilometres from an ancient temple dedicated to the deity [[Hathor]].

The turquoise is found in [[sandstone]] that is, or was originally, overlain by [[basalt]]. Copper and iron workings are present in the area. Large-scale turquoise mining is not profitable today, but the deposits are sporadically quarried by [[Bedouin]] peoples using homemade [[gunpowder]].{{Citation needed|date=March 2014}} In the rainy winter months, miners face a risk from [[flash flooding]]; even in the dry season, death from the collapse of the haphazardly exploited sandstone mine walls may occur. The colour of Sinai material is typically greener than that of Iranian material but is thought to be stable and fairly durable. Often referred to as "Egyptian turquoise", Sinai material is typically the most translucent, and under magnification, its surface structure is revealed to be peppered with dark blue discs not seen in material from other localities.

[[File:Chacoan turquoise with argillite.jpg|right|thumb|A selection of [[Ancestral Puebloans|Ancestral Pueblo]] (Anasazi) turquoise and orange [[argillite]] inlay pieces from [[Chaco Canyon]], [[New Mexico]], US (dated {{circa}} 1020–1140) show the typical colour range and mottling of American turquoise. Some likely came from [[Los Cerrillos, New Mexico|Los Cerrillos]].]]

=== United States ===
[[File:Turquoise Cerillos Smithsonian.jpg|thumb|A fine turquoise specimen from [[Los Cerrillos, New Mexico]], US, at the [[Smithsonian Museum]]. Cerrillos turquoise was widely used by Native Americans prior to the Spanish conquest.]]
[[File:turquoisecollection.jpg|thumb|Bisbee turquoise commonly has a hard chocolate brown coloured matrix.]]
[[File:Turq mcGuin bunker.jpg|thumb|right|Untreated turquoise, Nevada, US. Rough nuggets from the McGinness Mine, Austin. Blue and green cabochons showing spiderweb, Bunker Hill Mine, Royston]]

The [[Southwest United States]] is a significant source of turquoise; [[Arizona]], [[California]] ([[San Bernardino County, California|San Bernardino]], [[Imperial County, California|Imperial]], [[Inyo County, California|Inyo]] counties), [[Colorado]] ([[Conejos County, Colorado|Conejos]], [[El Paso County, Colorado|El Paso]], [[Lake County, Colorado|Lake]], [[Saguache County, Colorado|Saguache]] counties), [[New Mexico]] ([[Eddy County, New Mexico|Eddy]], [[Grant County, New Mexico|Grant]], [[Otero County, New Mexico|Otero]], [[Santa Fe County, New Mexico|Santa Fe]] counties) and [[Nevada]] ([[Clark County, Nevada|Clark]], [[Elko, Nevada|Elko]], [[Esmeralda County, Nevada|Esmeralda County]], [[Eureka, Nevada|Eureka]], [[Lander County, Nevada|Lander]], [[Mineral County, Nevada|Mineral County]] and [[Nye County, Nevada|Nye]] counties) are (or were) especially rich. The deposits of California and New Mexico were mined by [[pre-Columbian]] [[Native Americans in the United States|Native Americans]] using stone tools, some local and some from as far away as central [[Mexico]]. [[Cerrillos, New Mexico|Cerrillos]], New Mexico is thought to be the location of the oldest mines; prior to the 1920s, the state was the country's largest producer; it is more or less exhausted today. Only one mine in California, located at Apache Canyon, operates at a commercial capacity today.

The turquoise occurs as vein or seam fillings, and as compact nuggets; these are mostly small in size. While quite fine material is sometimes found, rivalling Iranian material in both colour and durability, most American turquoise is of a low grade (called "chalk turquoise"); high [[iron]] levels mean greens and yellows predominate, and a typically friable consistency in the turquoise's untreated state precludes use in [[jewelry]].

[[Arizona]] is currently the most important producer of turquoise by value.<ref name=USGS /> Several mines exist in the state, two of them famous for their unique colour and quality and considered the best in the industry: the Sleeping Beauty Mine in [[Globe, Arizona|Globe]] ceased turquoise mining in August 2012. The mine chose to send all ore to the crusher and to concentrate on copper production due to the rising price of copper on the world market. The price of natural untreated Sleeping Beauty turquoise has risen dramatically since the mine's closing. The [[Kingman, Arizona|Kingman]] Mine as of 2015 still operates alongside a copper mine outside of the city. Other mines include the Blue Bird mine, Castle Dome, and Ithaca Peak, but they are mostly inactive due to the high cost of operations and federal regulations. The [[Phelps Dodge]] [[Lavender Pit]] mine at [[Bisbee, Arizona|Bisbee]] ceased operations in 1974 and never had a turquoise contractor. All Bisbee turquoise was "lunch pail" mined. It came out of the copper ore mine in miners' lunch pails. Morenci and Turquoise Peak are either inactive or depleted.

[[Nevada]] is the country's other major producer, with more than 120 mines which have yielded significant quantities of turquoise. Unlike elsewhere in the US, most Nevada mines have been worked primarily for their gem turquoise and very little has been recovered as a byproduct of other mining operations. Nevada turquoise is found as [[wikt:nugget|nugget]]s, fracture fillings and in [[breccia]]s as the cement filling interstices between fragments. Because of the geology of the Nevada deposits, a majority of the material produced is hard and dense, being of sufficient quality that no treatment or enhancement is required. While nearly every county in the state has yielded some turquoise, the chief producers are in [[Lander County, Nevada|Lander]] and [[Esmeralda County, Nevada|Esmeralda counties]]. Most of the turquoise deposits in Nevada occur along a wide belt of [[tectonic]] activity that coincides with the state's zone of [[thrust fault]]ing. It [[Strike and dip|strikes]] at a bearing of about 15° and extends from the northern part of [[Elko County]], southward down to the California border southwest of [[Tonopah, Nevada|Tonopah]]. Nevada has produced a wide diversity of colours and mixes of different matrix patterns, with turquoise from Nevada coming in various shades of blue, blue-green, and green. Some of this unusually-coloured turquoise may contain significant [[zinc]] and [[iron]], which is the cause of the beautiful bright green to yellow-green shades. Some of the green to green-yellow shades may actually be [[variscite]] or [[faustite]], which are secondary phosphate minerals similar in appearance to turquoise. A significant portion of the Nevada material is also noted for its often attractive brown or black limonite veining, producing what is called "spiderweb matrix". While a number of the Nevada deposits were first worked by Native Americans,{{which|date=April 2019}} the total [[Nevada]] turquoise production since the 1870s has been estimated at more than {{convert|600|ST}}, including nearly {{convert|400|ST}} from the Carico Lake mine. In spite of increased costs, small scale mining operations continue at a number of turquoise properties in Nevada, including the Godber, Orvil Jack and Carico Lake mines in Lander County, the Pilot Mountain Mine in [[Mineral County, Nevada|Mineral County]], and several properties in the Royston and [[Candelaria, Nevada|Candelaria]] areas of Esmerelda County.<ref>{{cite book|title=Minerals of Nevada|publisher=Nevada Bureau of Mines|series=Special Publication 31|pages=78–81, 443–445}}</ref>

In 1912, the first deposit of distinct, single-crystal turquoise was discovered at [[Lynch Station, Virginia|Lynch Station]] in [[Campbell County, Virginia|Campbell County]], [[Virginia]]. The crystals, forming a [[Druse (geology)|druse]] over the mother rock, are very small; {{convert|1|mm|in|2|abbr=on}} is considered large. Until the 1980s Virginia was widely thought to be the only source of distinct crystals; there are now at least 27 other localities.{{citation needed|date=May 2015}}

In an attempt to recoup profits and meet demand, some American turquoise is treated or ''enhanced'' to a certain degree. These treatments include innocuous waxing and more controversial procedures, such as dyeing and impregnation (see [[#Treatments|Treatments]]). There are some American mines which produce materials of high enough quality that no treatment or alterations are required. Any such treatments which have been performed should be disclosed to the buyer on sale of the material.

=== Other sources ===
Turquoise prehistoric artifacts (beads) are known since the fifth millennium BCE from sites in the [[Eastern Rhodopes]] in [[Bulgaria]] – the source for the raw material is possibly related to the nearby [[Spahievo]] lead–zinc ore field.<ref>{{cite journal|last1=Kostov|first1=R. I.|first2=J.|last2=Chapman|first3=B.|last3=Gaydarska|first4=I.|last4=Petrov|first5=A.|last5=Raduntcheva|date=2007|title=Turquoise – archaeomineralogical evidences from the Orlovo prehistoric site (Haskovo district, Southern Bulgaria)|journal=Geology and Mineral Resources|volume=14|issue=7–8|pages=17–22}}</ref> In Spain, turquoise has been found as a minor mineral in the variscite deposits exploited during prehistoric times in Palazuelos de las Cuevas (Zamora) and in Can Tintorer, Gavá (Barcelona).<ref>{{Cite book |last=Calvo Rebollar |first=Miguel |title=Minerales y Minas de España. Vol. VII. Fosfatos, Arseniatos y Vanadatos. |publisher=Escuela Técnica Superior de Ingenieros de Minas de Madrid. Fundación Gómez Pardo. |year=2015 |isbn=978-84-95063-96-0 |location=Zaragoza, Spain |pages=347–348 |language=es |trans-title=Minerals and mines of Spain}}</ref>

[[China]] has been a minor source of turquoise for 3,000 years or more. Gem-quality material, in the form of compact nodules, is found in the fractured, silicified [[limestone]] of [[Yun County, Hubei|Yunxian]] and [[Zhushan County|Zhushan]], [[Hubei]] province. Additionally, [[Marco Polo]] reported turquoise found in present-day [[Sichuan]]. Most Chinese material is exported, but a few carvings worked in a manner similar to [[jade]] exist. In [[Tibet]], gem-quality deposits purportedly exist in the mountains of [[Derge]] and [[Nagari-Khorsum]] in the east and west of the region respectively.<ref name="dharamsalanet.com">{{cite web|url=http://www.dharamsalanet.com/links/articles/turquoise.htm |title=Turquoise – The Gemstone of Tibet|first=Martin|last=Watson |access-date=2007-06-01 |url-status=dead |archive-url=https://web.archive.org/web/20070319222057/http://www.dharamsalanet.com/links/articles/turquoise.htm |archive-date=March 19, 2007 }}</ref>

Other notable localities include: [[Afghanistan]]; [[Australia]] ([[Victoria (Australia)|Victoria]] and [[Queensland]]); north [[India]]; northern [[Chile]] ([[Chuquicamata]]); [[Cornwall]]; [[Saxony]]; [[Silesia]]; and [[Turkestan]].