Turquoise: meaning, properties and lore

The mineral

Turquoise is a porous, semitranslucent to opaque compound of hydrated copper and aluminum phosphate. GIA describes it as a hydrous copper aluminum phosphate with the general formula CuAl6(PO4)4(OH)8•4H2O, and its ideal formula by weight percentage of oxides is 37.60% Al2O3, 34.90% P2O5, 9.78% CuO and 17.72% H2O. Iron can replace some of the aluminum and zinc can replace copper in the structure.²³¹

Turquoise is typically a polycrystalline aggregate, an aggregate of microscopic crystals that form a solid mass. Its structure is triclinic and mostly cryptocrystalline with very large pores, which is why low porosity and fine texture are valued above high porosity and coarse texture. Fine-textured stone has an attractive waxy luster when polished, while coarse, porous stone has a dull luster.³¹

Turquoise has a Mohs hardness of 5 to 6, a refractive index of 1.610 to 1.650, and a specific gravity of 2.76 (+0.14, -0.36). It shows no detectable birefringence. Its color is an opaque, blue to green gem material, and the copper absorption band near 620–750 nm is produced by the d-d electron transition of Cu2+.²³¹⁵

Turquoise forms in dry and barren regions where acidic, copper-rich groundwater seeps downward and reacts with phosphorus- and aluminum-bearing minerals. Deposits usually form in iron-rich limonite or sandstone, and the host rock remnants are called matrix. Limonite creates dark brown markings, while sandstone creates tan markings, and matrix appears as veins running through the stone.²³⁶

Turquoise color ranges from dull greens to grass greens to a bright, medium-toned sky blue. The most-prized color is an even, intense, medium blue, sometimes called robin's egg blue or sky blue in the trade, while green to greenish blue is generally less desirable than pure blue, though this depends on personal preference. Color variation in Neyshabur turquoise is caused by the host geological units and elemental anomalies.³⁶⁵⁴

Turquoise is found in only a few places on earth, and it is plentiful and available in a wide range of sizes. Its main sources include China, Egypt, Chile, the United States, Iran and Mexico, and Zhushan County in Hubei is the world's largest commercial source. The Neyshabur mine in Razavi Khorasan Province of northeastern Iran has yielded most Iranian turquoise for more than a millennium.²³⁴⁷¹⁵

Turquoise is typically judged on three basic quality factors: color, texture, and the presence or absence of matrix. The most valuable turquoise is an even medium blue, with no matrix and the ability to take a good polish. Exposure to chemicals, oils, perfume, sweat, sunlight and heat can cause the color of turquoise to change, and about 60% of the yield from Neyshabur requires treatment.⁶⁵

History and lore

Turquoise buried in Ancient Egyptian tombs is among the world's oldest jewelry, dating to around 4,000 BC, and archaeological excavations show that rulers of ancient Egypt adorned themselves with it. Ancient Egyptians called turquoise mefkat, a word that also means joy and delight. King Tut's golden funeral mask was adorned with gemstones, including turquoise.²⁷⁴

Turquoise was first utilized around 7000 BCE, according to archaeological discoveries from the Deh Luran Plain in western Iran. Chinese artisans were carving turquoise more than 3,000 years ago. Turquoise has a rich history with the ancient Egyptians and Chinese people, and it has been mined in Sinai, Persia, China, Iran, the southwest of the United States, and Mesoamerica.⁵⁷⁴⁸

In Persia turquoise was called pērōzah, meaning victory, and the colour was regarded as sacred and representing heaven on earth. In Persian culture the name piruzeh carries the meanings of victory, triumph, and prosperity. Various legends and beliefs are associated with turquoise in Persian literature, where poets have celebrated it.⁸⁵

The Aztecs used locally sourced turquoise on masks, shields, knives, and jewelry for religious ceremonies and rituals, and their word for turquoise, xihuitl, can also mean year. In 1519, Montezuma, thinking Cortes was Quetzalcoatl, gave him the god's favorite gem, turquoise. Turquoise was a ceremonial gem and a medium of exchange for Native American tribes in the southwestern United States.⁸²⁴⁷

The word turquoise comes from a French expression, pierre tourques, meaning 'Turkish stone', a name that originated in the thirteenth century. The material probably first arrived in Europe from Turkish sources.⁷⁸⁴

Pliny, Aristotle, and Marco Polo are said to mention turquoise in their writings, and Marco Polo's Book of the Wonders of the World mentioned the Shahr-i Babak deposit in western Kerman Province. The Apaches believed that turquoise attached to a bow or firearm increased a hunter's or warrior's accuracy. Turquoise is valued highly for its combination of ancient heritage and unforgettable color.⁸⁵⁷³

Birthstone and other links

Turquoise is the traditional birthstone for the month of December, and the Gemological Institute of America lists it as a December birthstone. These are listings of the birthstone for December rather than links drawn from practitioners.²⁶⁷

Turquoise is the gem of the 11th anniversary, a link given by the Gemological Institute of America. The anniversary list is a modern convention and does not come from the historical writers.²

What crystal practitioners say

Crystal practitioners associate turquoise with calm and emotional balance. According to The Healing Crystals First Aid Book, the stone has a harmonising emotional effect and reduces stress. Readers are told that it can be used to settle the emotions in everyday life.⁹

Turquoise is often fashioned into talismans with Native American significance, such as carved bird and animal fetishes. Crystal practitioners regard these carvings as connected to the stone's older role in Native American jewelry. Believers consider turquoise to be a stone that guarantees good fortune and protection from evil.³⁷

Crystal healers suggest wearing turquoise as a bracelet, necklace or pendant with direct body contact for a lengthy period. Beyond jewellery, they say the stone can be taken as gem essence, at 5-7 drops three times daily, or as gem water sipped over the day.⁹

Crystal healers say turquoise can be taken as gem essence or gem water, as set out in The Healing Crystals First Aid Book. Turquoise chips from the mine are widely used in Iran for inlay, a craft that originated in Mashhad. Queen Victoria's turquoise ring was regarded as a symbol of fidelity by crystal practitioners, in addition to the stone's healing powers.⁹⁵

What testing has found

Edzard Ernst found that scientific proof of any effect from crystals beyond placebo is lacking. Believers in crystal healing, he suggests, may credit pleasant feelings or apparent successes to a strong placebo effect and cognitive bias.¹⁰

In 2001, British psychologist Christopher French tested 80 volunteers who held crystals and meditated, asking them to distinguish real crystals from fake ones. They could not, and researchers attributed the result to placebo.¹⁰¹¹¹²

Scientists remain skeptical of crystal therapy because rigorous research is lacking and few studies compare it to other therapies. Ted Kaptchuk, a Harvard Medical School professor, argued that discarding all placebo effects diminishes knowledge of important dimensions of health care.¹¹

Some researchers suggest crystals probably do not act directly on physical or psychological complaints, though indirect benefits may arise through placebo. Crystal therapy proponents say no proven link exists between crystals and the body, and its mechanisms are poorly understood.¹¹¹⁰