What is Turquoise?

Turquoise is an opaque, blue-to-green mineral with the chemical formula CuAl6(PO4)4(OH)8·4H2O, a hydrated copper and aluminum phosphate. It is common and useful in higher grades and has been appreciated for thousands of years as a gemstone and ornamental stone due to its distinctive shade. Recently, the implementation of medicines, imitations and synthetics on the market has devalued turquoise, like most other opaque gems.

Turquoise Properties

The finest of turquoise, or slightly more than window glass, reaches a peak Mohs hardness of just under 6. A cryptocrystalline mineral characteristic, turquoise almost never creates single crystals, and all its characteristics are extremely variable. X-ray diffraction analysis proves to be triclinic in its crystal system. With reduced strength produces reduced particular pressure (2.60–2.90) and higher porosity; the grain size depends on these characteristics.

Turquoise luster is typically waxy to subvitreous, and its transparency is generally opaque, but in thin parts it may be semitranslucent. Color is as variable as the other characteristics of the mineral, varying from white to a blue powder to a purple sky, and from a green blue to a green yellow. The blue is ascribed to idiochromatic copper whereas the green may result from either iron impurities (aluminum replacement) or dehydration.

How Turquoise Is Formed?

Turquoise shapes as a secondary mineral by the activity of percolating acidic aqueous solutions during weathering and oxidation of pre-existing minerals. For instance, copper may come from main copper sulfides such as chalcopyrite or secondary carbonates malachite or azurite; aluminum may come from feldspar; and apatite phosphorus.

As turquoise is typically found in arid areas, filling or encrusting cavities and fractures in typically extremely modified volcanic rocks, often associated with limonite and other iron oxides, climatic variables appear to play an significant part. Turquoise is almost invariably combined with copper sulfide deposits weathering products in or around potassium-feldspar-bearing porphyritic intrusives in the southwestern United States.

Potassium aluminum sulfate is a prominent secondary mineral in some cases of alunite. Typically turquoise mineralization is limited to a comparatively shallow depth of less than 20 meters (66 feet), although it occurs in deeper fracture areas where secondary solutions have higher penetration or water table depth is higher.

Turquoise is almost always cryptocrystalline and huge and requires no clear internal form. Crystals are exceedingly uncommon even on a microscopic scale. Typically the shape is in habit of filling vein or fracture, nodular or botryoidal. Forms of stalactitis were recorded. Feldspar, apatite, other minerals, or even fossils can also be pseudomorphically replaced by turquoise. Odontolite is a fossil bone or ivory traditionally believed to have been changed by turquoise or similar minerals of phosphate such as iron phosphate vivianite. Also prevalent is intergrowth with other secondary minerals of copper such as chrysocolla.

Where Turquoise is found?

These are all small-scale activities, often seasonal due to the restricted deposit size and remoteness. Most of them are handmade with little or no mechanization. However, turquoise is often retrieved, particularly in the United States, as a by-product of large-scale copper mining activities.

United States

Arizona, California (San Bernardino, Imperial, Inyo counties), Colorado (Conejos, El Paso, Lake, Saguache counties), New Mexico (Eddy, Grant, Otero, Santa Fe counties) and Nevada (Clark, Elko, Esmeralda counties, Eureka, Lander, Mineral County and Nye counties) are (or were) particularly wealthy. Pre-Columbian Native Americans mined California and New Mexico’s reserves using stone tools, some local and some as far remote as southern Mexico. Cerrillos, New Mexico is believed to be the site of the earliest mines; the state was the biggest producer of the country before the 1920s; it is now more or less depleted. Today, only one mine at Apache Canyon in California works at a business capability.

The turquoise happens in the form of vein or seam fillings and as compact nuggets, most of which are tiny in number. While sometimes quite good fabric is discovered, rivaling Iranian fabric in both color and durability, most American turquoise is of small grade (called “chalk turquoise”); elevated iron levels imply predominance of greens and yellows, and a typically friendly consistency in the untreated state of the turquoise precludes jewelry use.

Currently Arizona is the most important value producer of turquoise. There are several mines in the state, two of which are renowned for their distinctive color and performance and regarded the finest in the sector: in August 2012, the Sleeping Beauty Mine in Globe stopped turquoise mining. Due to the increasing world market price of copper, the mine chose to ship all the ore to the crusher and focus on copper manufacturing. The cost of untreated natural sleeping beauty turquoise has increased dramatically since the closure of the mine. As of 2015, the Kingman Mine is still operating outside the town alongside a copper mine. Other mines include the Blue Bird mine, Castle Dome, and Ithaca Peak, but are largely inactive owing to elevated operating costs and federal laws. Bisbee’s Phelps Dodge Lavender Pit mine came to a halt in 1974 and never had a turquoise contractor. All the turquoise Bisbee was mined with “dinner pail.” It arrived in the dinner pails of miners from the copper ore mine. Morenci and Turkey Peak are either idle or exhausted.

Nevada is the other major producer of the country, with more than 120 mines producing large amounts of turquoise. Unlike elsewhere in the US, most of the Nevada mines were mainly used for their turquoise gem and very little was retrieved as a by-product of other mining activities. Nevada turquoise is discovered as nuggets, fracture fillings and interstices between pieces are discovered in breccias as the cement coating. A majority of the material produced is hard and dense because of the geology of the deposits of Nevada, being of sufficient quality that no treatment or improvement is required. Although almost every state county has yielded some turquoise, the main manufacturers are in the counties of Lander and Esmeralda. Most of Nevada’s turquoise deposits happen along a broad range of tectonic activity coinciding with the thrust fault area of the state. It strikes at a bearing of about 15 ° and stretches from the southern portion of Elko County to the south-west boundary of Tonopah in California. Nevada has created a broad variety of colors and combinations of multiple matrix motifs, with Nevada turquoise coming in distinct colors of blue, blue-green, and green. Some of this unusually colored turquoise may involve important zinc and iron, causing the lovely tones of light green to yellow-green. Some of the colors of blue to green-yellow may effectively be variscite or faustite, which is comparable in shape to turquoise secondary phosphate minerals.

Egypt

Since at least the First Dynasty (3000 BCE) in ancient Egypt, and probably before that, the Egyptians used turquoise and the Sinai Peninsula was mined by them. This area was regarded by the indigenous Monitu as the Turkey Country. The peninsula has six mines, all on its southwest shore, spanning an area of approximately 650 km2 (250 sq mi). From a historical view, the two most significant of these mines are Serabit el-Khadim and Wadi Maghareh, one of the earliest recognized mines. The former mine is about 4 kilometers from an old temple devoted to the Hathor deity.

The turquoise is discovered in basalt-covered sandstone, or was initially overlain. There are works of copper and iron in the region. Large-scale turquoise mining is not lucrative today, but Bedouin populations use homemade weapons to quarry the deposits sporadically. Miners face a danger of flash flooding in the rainy summer months; mortality from the fall of the haphazardly utilized sandstone mine walls is not unheard of even in the dry season. The color of material from Sinai is typically greener than material from Iran, but is believed to be stable and relatively durable. Sinai fabric is typically the most translucent, often referred to as “Egyptian jade,” and its surface structure is found to be peppered with light green disks not seen in fabric from other locations.

Iran

For at least 2,000 years, Iran has been a major source of turquoise. It was originally called “pērōzah” by Iranians meaning “win,” and subsequently it was called “fayrūzah” by the Arabs, which is described as “fīrūzeh” in modern Persian. The black turquoise was used in Iranian architecture to cover the palace towers as its intense red color was also a sign of heaven on earth.

This sample is obviously black and becomes green owing to dehydration when heated. It is limited to a mine-riddled region in Nishapur, Ali-mersai’s 2,012 m (6,601 ft) summit close Mashhad, the capital of Khorasan Province, Iran. A battered and crushed trachyte is the host of the turquoise, discovered both in situ between limonite and sandstone strata and between the scree at the top of the mountain. Together with the Sinai Peninsula, these works are the longest known. Iran also has turquoise mines in the provinces of Semnan and Kerman.

Bulgaria

Turquoise prehistoric artifacts (beads) have been known from sites in the Eastern Rhodope Mountains in Bulgaria since the fifth millennium BCE – the source of the raw material may be related to the nearby Spahievo field of lead – zinc ore.

China

For 3,000 years or more, China has been a small source of turquoise. Gem-quality material in the shape of compact nodules is discovered in Yunxian and Zhushan, Hubei county, broken, silicized calcareous. Marco Polo also revealed turquoise discovered in Sichuan today. Most of the Chinese product is imported, but there are a few jade-like sculptures that have operated. In Tibet, there are allegedly gem-quality deposits in the Derge and Nagari-Khorsum hills in the region’s north and south respectively.

Other sources

Other notable locations include: Afghanistan ; Australia (Victoria and Queensland) ; northern India ; northern Chile (Chuquicamata) ; Cornwall ; Saxony ; Silesia ; and Turkestan.