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.
Cutting and grinding turquoise inNishapur， Iran， 1973IranIran （previously known in the West as Persia） has remained an important source of turquoise for at least 2，000 years. It was initially named by Iranians "pirouzeh" meaning "victory"， and later the Arabs called it "firouzeh".[citation needed] In Iranian architecture， the blue turquoise was used to cover the domes of palaces because its intense blue colour was also a symbol of heaven on earth.[citation needed]
SinaiThis deposit is blue naturally and turns green when heated due to dehydration. It is restricted to a mine-riddled region inNishapur， the 2，012-metre （6，601 ft） mountain peak of Ali-mersai which is tens of kilometers from Mashhad， the capital ofKhorasan Province， Iran. A 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.[5] Iran also has turquoise mines in Semnan and Kerman province.
Since at least the First Dynasty （3000 BCE）， and possibly before then， turquoise was used by the Egyptians and was mined by them in the Sinai Peninsula， called "Country of Turquoise" by the native Monitu. There are six mines in the region， all on the southwest coast of the peninsula， covering an area of some 650 square kilometres （250 sq mi）. The two most important of these mines， from a historic 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 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 Bedouinpeoples using homemade gunpowder.[citation needed] 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 is not unheard of. The colour of Sinai material is typically greener than 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.
Cerrillos turquoise was widely used by Native Americans prior to the Spanish conquest.Bisbee turquoise commonly has a hard chocolate brown coloured matrix.
Untreated turquoise， Nevada， United States. Rough nuggets from the McGinness Mine， Austin. Blue and green cabochons showing spiderweb， Bunker Hill Mine， RoystonThe Southwest United States is a significant source of turquoise； Arizona， California （San Bernardino， Imperial， Inyocounties）， Colorado （Conejos， El Paso， Lake， Saguache counties）， New Mexico （Eddy， Grant， Otero， Santa Fe counties） andNevada （Clark， Elko， Esmeralda County， Eureka， Lander， Mineral County and Nye counties） are （or were） especially rich. The deposits of California and New Mexico were mined by pre-Columbian Native Americans using stone tools， some local and some from as far away as central 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 jewellery.
Arizona is currently the most important producer of turquoise by value.[5] 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 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 Mine as of 2015 is 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 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 nuggets， fracture fillings and in breccias 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 and Esmeralda counties. Most of the turquoise deposits in Nevada occur along a wide belt of tectonic activity that coincides with the state's zone ofthrust faulting. It strikes about N15°E and extends from the northern part of Elko County， southward down to the California border southwest of 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， the total Nevada turquoise production since the 1870s has been estimated at more than 600 tons， including nearly 400 tons 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， and several properties in the Royston and Candelaria areas of Esmerelda County.
In 1912， the first deposit of distinct， single-crystal turquoise was discovered in Lynch Station， Campbell County， Virginia. The crystals， forming a druse over the mother rock， are very small； 1 mm （0.04 in） 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]
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）. There are however， 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 sourcesChina 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 Yunxian and 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.
Other notable localities include： Afghanistan； Australia （Victoria and Queensland）； north India； northern Chile （Chuquicamata）； Cornwall； Saxony； Silesia； andTurkestan.
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