Sky Blue Stone

Chapter 1

The Colored Earth

Flowers of Copper

From the depths of the earth comes a piece of the sky. Turquoise is a mineral substance formed in the seams of rocks below the surface of the earth. A hydrous phosphate of copper and aluminum, it is born in igneous rocks, as magma, fiery liquid deep within the earth, surges toward the surface, pools, and solidifies. In a geological process that lasts thousands of years, nature weathers, buries, and erodes these rocks, bringing their copper, aluminum, phosphorus, oxygen, hydrogen, and water together to create the chemistry of turquoise, CuAl₆(PO₄)₄(OH)₈·4H₂O (see table 1).1 An opaque stone whose pale blue results from the presence of copper, turquoise has surfaced in desert environments from Eurasia to Mesoamerica, been valued as a celestial object, and been traded across the world. 

A nineteenth-century Persian natural history compares the formation of turquoise to the ripening of fruit: "It is said turquoise is like a cherry-the more it ripens, the better. But all the cherry needs to ripen is the sun of one season, whereas for turquoise it takes one thousand years [yak hazar sal mudat lazim hast]."2 To reach the state at which it can be cut from its rock matrix and traded as a precious stone and ornament, it must undergo deep geological alterations in the layers of the earth. If turquoise is mined before it has aged, its color fades.

Igneous rocks rich in aluminum and copper minerals give birth to turquoise. Over centuries, deep-seated weathering and exposure to the elements alter their form. As rainwater seeps from the surface through these rocks, it breaks down and converts their minerals into new chemical substances.3 Waters containing phosphoric acid that flow through aluminous rocks decompose feldspar crystals into kaolin, a mineral substance that is associated with turquoise, freeing necessary aluminum silicates.4 All of this slow, nearly motionless change occurs in the zone of oxidation, in the first few hundred feet below the crust of the earth.

As these minerals solidify into rocks, they enclose the now crystallized turquoise, a naturally occurring mineral substance with a definite chemical composition.5 Contact with copper ores and the passing of time give turquoise, an opaque stone with a soft surface and a high index of light refraction, its defining physical property-a sky-blue color. While turquoise can have many shades, including a common pale green caused by traces of iron, the finest stones, deemed gems-those aged for thousands of years in the oldest rocks-are sky blue. But the color is inconstant and unstable and can fade to green. It is in the nature of turquoise to change. When exposed to the elements in the open air, turquoise weathers, decomposing into a dusty white powder.6

Turquoise was first found after wind and rain had eroded the surface rocks above it. Thus freed, turquoise stones in the open alluvial gravels at the foot of mountains and blown across deserts by high winds caught the eyes of passersby and came to be regarded as valuable natural objects. Because turquoise could be found only a few hundred feet below ground and was easily extracted, miners descended into caves and dug for it with rough tools, including shovels, pickaxes, and hammers, separating the blue stones from the veins of rocks. Windlasses raised the mineral, still encased in its matrix, from the mines. Removed from these broken pieces of rock, turquoise stones were cut and polished into gems and traded across the surface of the earth.

Desert Nature

The chemistry of turquoise occurs in desert environments from Mesoamerica to Eurasia. For centuries, the hub of its trade was Asia, where turquoise was unearthed in a mineral-bearing stratum extending from the Sinai in Egypt through Iran to Tibet, with the city of Nishapur in eastern Iran being the historic heartland for the finest stones, those the color of the sky. In Mesoamerica, turquoise (called chalchihuitl), the best of it mined from the Cerrillos district of New Mexico, became an object of tribute and sacred regalia in the Aztec Empire in the postclassical period (c. 900-1521 C.E.). Spanish explorers described a blue-green stone that the indigenous populations treasured, and in 1519, Montezuma II famously offered gifts of turquoise to the conquistador Hernán Cortés. The stone was first unearthed, however, thousands of years earlier on the other side of the world, in the predynastic Egyptian Sinai.7

The turquoise mines of the Sinai materialized in sandstone ridges connected to the working of nearby copper mines and were known to the Egyptians before 5500 B.C.E.8 According to one Egyptologist, "The earliest signs in Egypt of intercourse with Sinai are the beads of turquoise" found among the remnants in early dynastic graves.9 The Monitu Bedouin clans of the Sinai likely first unearthed turquoise, known in ancient Egypt as mafkat, but not to any great extent. The stone became known as it was carried along the caravan routes that extended from Egypt across Asia and Africa.10 The pharaohs sent expeditions into the Sinai to secure mineral deposits necessary for their monumental building projects in the Nile Delta.11 Seekers of turquoise entered a distant and unforgiving environment, where they were forced to pay tribute to the local Bedouin populations and to protect their mining works from the raids of the fiercely independent Monitu, referred to in inscriptions as "Lords of the Sands."12

Numerous inscriptions, stelae, and graffiti record the details of mining expeditions and attest to dynastic exploits in mineral extraction.13 The turquoise mines in Wadi Maghara, or the Valley of Caves (or Grottoes), were the first to be exploited, as inscriptions found there record. These range from those of Sneferu (r. c. 2613-2589 B.C.E.), of the Fourth Dynasty, who recorded his conquest of the country and his discovery of the mines, to those detailing an expedition sent by Thutmose III, of the Eighteenth Dynasty. Captives worked the mines for more than two thousand years, the marks of their metal tools chiseled into the steep sandstone walls and cavernous rocks of Wadi Maghara.14

The age of the legendary Sneferu was especially connected with the Sinai, as indicated by a bas-relief on the northwestern slopes of Wadi Maghara depicting a Bedouin chief in a subservient pose before the Egyptian pharaoh. Sneferu's haul in turquoise was regarded as exceptional. An Egyptian tale about a lost jewel of "new turquoise" recovered by magic suggests the stone's value in Egypt during Sneferu's reign, when it was an object in patterns of wider economic and cultural consumption, ornamenting bodies and stories.15 Following the reign of Pepy II, circa 2185 B.C.E., the mining colonies in Wadi Maghara were "abandoned" and "lingered in comparative idleness, their veins of turquoise seemingly exhausted."16

But the demand for the stone remained great, and explorers soon discovered untouched turquoise deposits about ten miles away, at what is now Sarabit al-Khadim, or Heights of the Servant, named in reference to a statue of a slave carved in black stone, which the French are said to have carried away during their occupation of Egypt. These mines were also likely opened in the time of Sneferu, as inscriptions record his presence there.17 Starting in the reign of Amenemhat II (r. c. 1929-1895 B.C.E.), successive expeditions worked and exploited these new veins.

The workers dedicated the mines to Hathor, the goddess of the turquoise land, the goddess of turquoise, and built temples in her honor.18 She was represented as a moon-faced woman carved on a stone column. Near the mines at Sarabit was a shrine (hanafiya) of the Turquoise Goddess, where prayers, vows, and offerings could be made. The demand for new veins of turquoise led Queen Hatshepsut (c. 1508-1458 B.C.E.) to order the reopening of the Wadi Maghara mines, which had not been worked for nearly four hundred years, and she sent an agent "with orders to inspect the valleys, examine the veins, and restore there the temple of the goddess Hathor."19 Akhenaten in the Amarna Period (1353-1336 B.C.E.) and Rameses III of the Twentieth Dynasty (c. 1186-1069 B.C.E.) sent several expeditions to the turquoise mines in the Sinai.20 The last pharaoh to leave an inscription at Sarabit al-Khadim was Ramses VI (r. c. 1145-1137 B.C.E.), and the rocks have no further traces of mining after that.21 The turquoise mines were exhausted and abandoned, as was the temple of the turquoise goddess Hathor after the Twentieth Dynasty.

By the medieval period, the geography of turquoise and its trade had shifted to West, Central, and South Asia-to the Persianate world, where turquoise was known as firuza. The stone garnered such high esteem there that it became the name of victorious dynasts and of cities and mountains where it was not even to be found. The legendary lost kingdom of Firuzkuh, or Turquoise Mountain, thought to have been near the blue-tiled Minaret of Jam in the Hindu Kush of northwestern Afghanistan, was associated with the stone before the Mongols leveled it in the thirteenth century. Although there are no major turquoise deposits in its vicinity, northern Afghanistan being better known for the rich deposits of balas rubies and lapis lazuli from the mines of Badakhshan, the sultans of the Ghurid Empire (c. 1100-1215) founded and envisioned Firuzkuh as a city of turquoise, the center point of a network of fortified settlements. The Ghurids built their monumental imperial capital as a display of power and as a treasury to store the spoils of victorious wars in India and Iran.22 The source of inspiration for the now-lost city of Turquoise Mountain could be found in the blue stones mined to the west, outside the city of Nishapur.

The Turquoise City

Nishapur is in a vast plain at the foot of the Binalud Mountains in the eastern Iranian province of Khurasan. For more than a thousand years, these mountains have been the most important source of turquoise in the world. Along with Herat, Balkh, and Marv, the medieval city of Nishapur was once among the most important urban centers in western and central Asia.23 It was a thriving oasis and entrepôt along the Silk Roads and a cultural hub that was the birthplace of such Perso-Islamic figures as the mathematician and philosopher Omar Khayyam and the Sufi poet Farid al-Din {ayn}Attar. In the twelfth and thirteenth centuries, repeated earthquakes, exacerbated by the Mongols' sudden and violent conquest of the city in 1221, reduced Nishapur to a modest provincial town. Devastating earthquakes in 1209 and 1270 destroyed the first two sites of city, which had to be moved and rebuilt.24 Despite this decline from its former stature, just a few miles north of Nishapur were still the most valuable turquoise mines on earth and the hub of the world turquoise trade.

By the Islamic period, turquoise was mined in six valleys of caves about thirty-five miles north of Nishapur in the villages of Ma{ham}dan. The most famous of these was Abd al-Razzaqi, containing an old and extensive mine of the same name (also known as Abu Ishaqi, or Isaac's Mine), so esteemed for the quality of its stones that the Persian poet Hafiz hinted at it in a verse on the mutability of the earthly world: "In truth the turquoise ring of Abu Ishaq / Flashed finely but then faded away."25 The stones were taken from the mines to the nearby cities of Nishapur and Mashhad, where craftsmen cut them, pasted them onto strips of wood, and polished them on a grinding wheel. Shined with pieces of leather, the stones were set in rings, inlaid in metal objects, and arranged as tesserae, then brought to markets across Asia and the Near East.26

Classical Arab and Persian geographers identified the mountains of Nishapur as the source of this turquoise. In the tenth-century Ahsan al-Taqasim fi Ma{ham}rifat al-Aqalim (The best of the divisions of the knowledge of regions), the Arab geographer al-Muqaddasi (c. 945-91) accounts turquoise, which he calls fayruziyya, the main export of Nishapur, noting that the city's stones were used to ornament the prayer niches (mihrab) of mosques as far away as Damascus.27 Abu Mansur al-Tha{ayn}alibi (961-1038), a literary figure who hailed from Nishapur, praised its exceptional turquoises and edible earth.28 Writing in the mid-fourteenth century, Hamdallah Mustawfi (1281-1349) left an account of precious stones in his world geography Nuzhat al-Qulub. Of turquoise, he wrote, "There are many mines of this stone, but the best mine is that of Nishapur, by reason of the good quality of the stones and the little labor in getting them. In the mountains of Nishapur there are pits dug where the turquoises are found, and thence come the best stones."29 Still, Mustawfi reported that the mines had to be maintained or else could fall into disuse, thus affecting the trade and circulation of the stones: "These Nishapur turquoises were famous; but of late years, scorpions have come to be found in these pits, and in fear of them people have ceased to work the mines."30

Finding Turquoise

The most comprehensive sources on turquoise and its early trade are medieval Arabic and Persian books of precious stones. This genre of books, which the imperial courts of Islamic Eurasia regularly sponsored, classifies the mineral substances of the earth and their properties, including their value as jewels and materia medica. One of the earliest surviving examples is Kitab al-Jamahir fi Ma{ham}rifat al-Jawahir (Compendium on the knowledge of precious stones), an eleventh-century Arabic work of cosmography and mineralogy attributed to Abu Rayhan al-Biruni (973-1050), a central Asian Muslim scholar and traveler in the service of the Ghaznavid Empire, in what is now Afghanistan. In this treatise on rare objects found in the mines of the earth and the treasuries of kings, al-Biruni promises "the description, categorization, and assessment of the precious objects and jewels that lay buried as treasures."31 He refers to and frequently cites from an earlier book on jewels and "treasures interred in the earth," by the Kufan philosopher and polymath Abu Yusuf Ya{ham}qub bin Ishaq al-Kindi (c. 801-66).32 Al-Kindi's text is one of a number of lost early Arabic scientific books on precious stones, with others including the anonymous and undated Durar al-Kamina (Hidden pearls) and Kinz al-Tujjar fi Ma{ham}rifat al-Ahjar (The treasury of merchants and the knowledge of stones) and the many works of the eighth-century scholar Jabir al-Kharaqi, such as Kitab al-Ahjar (Book of stones) and Rasa{ham}il fil Hajar (Treatise on rocks and stones). Another lost text, Rasa{ham}il Ba{ham}ad al-Hukama wa-l-{ayn}Ulama al-Qudama{ham} fil Jawahir wa-l-Khawass (Treatises written by ancient philosophers and scholars on precious stones and their properties), is attributed to the Bukharan scientist and philosopher Abu {ayn}Ali al-Husayn ibn {ayn}Abd Allah ibn Sina (c. 980-1037).33

In the thirteenth century, Ahmad ibn Yusuf al-Tifaschi (1184-1253), a jeweler and scholar from Cairo, thoroughly described the formation, geography, properties, and values of twenty-five types of precious stone. His Azhar al-Afkar fi Jawahir al-Ahjar (Best thoughts on the best of stones), written in the days of the Ayyubid dynasty (1171-1250) in Egypt, on the eve of the rise of the Mamluk dynasty (1250-1517), promises "strange information . . . of great benefit" on "a variety of precious stones that no great king or important nobleman can do without in view of their unusual benefits and great properties."34

Works in the Persian genre of javahirnama (books of precious stones) took the measure of the minerals and metals of the earth even further over the course of the medieval and early modern periods. The Javahirnama-yi Nizami (Ordered book of precious stones) by Muhammad bin Abi Barakat Javahiri Nishapuri, a jewel maker and merchant of stones from Nishapur, is a compendium of knowledge on metals, minerals, and precious stones written circa 1196 and perhaps the earliest extant work on minerals and precious stones in the Persian language. It is the presumed source of the later, Mongol-era Persian text Tansuqnama-yi Ilkhani (The Ilkhanid book of rarities, gifts, and tributes), written circa 1265 by the Muslim astronomer and savant Nasir al-Din Tusi, and Abu{ham}l Qasim {ayn}Abdallah Kashani's fourteenth-century {ayn}Ara{ham}is al-Javahir va Nafa{ham}is al-Ata{ham}ib (Statements on jewels and gifts of rarities).35

These Perso-Islamic works of natural history hold the four principle elements ({ayn}anasir)-earth (khak), water (ab), air (hava), and fire (atash)-to be the source of everything in the world.36 According to Islamic scientific traditions related in books of precious stones, "the rays of the sun [aftab] and stars [kavakib] and the heat from celestial bodies combined with the coldness of earth to form stones. Mines are born in this way."37 The four principle elements, also known as chahar unsurb, described the earth's relation to the universe: earths were the base, water was on their surface, air was on the surface of water, and fire loomed above. Unusual changes in environmental conditions-such as exposure to heat (hararat) and cold (barudat) and smoke and vapors (bukhar)-were thought to form mines, creating mineral deposits in the mountains.38 These precious mineral substances were moved across high deserts by winds and washed up in the beds of rivers, where they were found.

Islamic books of stones from the medieval period described all the known gems of the world, identifying their origins, qualities, and trade. They praised turquoise (firuza or fayruz) for the lustrous color that was the essence of its value and that brought it into high demand across the lands of Islam. One of the earliest descriptions of its attributes and value appeared in al-Biruni's Kitab al-Jamahir: "A bluish stone, harder than lapis lazuli . . . mined from the mountain of San in Khan Ruyand [Nishapur]. If rubbed on a rock or stone after dilution with water, it will readily accept moisture. It is then oiled and filed so as to be made soft. The more humid it is, the better it would be. In the course of time it gains sharpness and color."39 The "best kind," al-Biruni wrote, was mined from the Azhari and Bu Sahaqi mines of Nishapur and fetched a price of ten dinars for one dirham of stone.40

Subsequent Islamic books of precious stones written in Persian went much further in their accounts of the turquoise of Nishapur and its trade. The author of Javahirnama-yi Nizami hailed from Nishapur and gathered his information directly from the turquoise mines while also drawing extensively on his wide travels, including to the western Indian Ocean ports of Siraf and Bahrain, to detail the mining and trade of precious stones and minerals. This jeweler's compendium provides an extensive account of the geography of the Eurasian turquoise trade. According to Nishapuri, there were only four known deposits of turquoise on earth, in the vicinity of Nishapur and in the central Asian lands of Khvarazm, Transoxiana, and Turkistan. Stonecutters and jewelers could discern from which mine a stone originated when they saw it.41

Medieval Persian mineralogical texts identified the seven turquoise mines of Nishapur. They noted that the bluest, most brilliantly colored (rangin) and coveted stones were unearthed at the Abu Ishaqi mine outside Nishapur. The other Nishapur mines known to contain fine blue turquoise, in the order in which the books treat them, were Azhari, Sulaymani, Zarhuni (whose turquoise was streaked with gold), {ayn}Abd al-Majidi, {ayn}Andalibi, and Asuman Gun (or Khaki).42 In Tansuqnama-yi Ilkhani, Tusi links the color of the stone to the sky and air (hava), noting that a dustless, clear blue firmament gives the stone more radiance (lun).43 Adding to the mystery of turquoise was the fact that its color could change, even fade to green, lowering the stone's value. Medieval authors, such as al-Biruni, attributed this instability to the effects of atmosphere and climate-cloudy skies, winds, and sun-on the stone.44 Because of this unstable nature, some people would have nothing to do with turquoise. When a stone lost its color, it lost its worth as well, being known in the language of jewelers as a dead stone (sang-i murda), although it could be brought back to life through contact with water and sun.45

The blue of turquoise transcended its physical properties, and folkloric beliefs attached to the stone and its celestial hues. A reflection of the ethereal sky found in the dusty earth, turquoise held a marvelous appeal. In bazaars and markets across Asia, it was priced by color and weight. The Javahirnama-yi Nizami notes that in Nishapur circa 1200, one dirham of turquoise was worth sixty dinars.46 The most valuable turquoise of the age, according to Nishapuri, was a stone from the Abu Ishaqi mine that weighed less than a dirham but was appraised at one hundred dinars because of its radiant luster and color.47 It belonged to Sultan Sanjar Bin Malikshah of the Saljuq dynasty, on the hand of whose wife, Khatun Ajjal, the author of Javarinama-yi Nizami saw the incomparable stone worn.48 Writing in the following century, Tusi also left a record of the market value of turquoise: half a mithqal of Abu Ishaqi and Azhari stones was priced at seven to ten dinars, one mithqal at twenty to thirty dinars, two mithqal at fifty to seventy dinars, and three mithqal at one hundred to one hundred and fifty dinars. Lesser-quality turquoise could be procured at little cost.49

Traded along the Silk Roads, turquoise stones passed eastward across Asia, reaching "the people of Chin, Machin, Tughmakh, and Tangut" and becoming talismans and ornaments to be placed on Buddhist idols.50 The trade also passed westward, reaching the Mediterranean world, where, according to al-Tifaschi's Azhar al-Afkar, the Berber princes of the Maghrib and their followers coveted the stone as adornment for swords and rings and paid ten Moroccan dinars for a single specimen from Nishapur.51

The Color of the Sky

Some thousands of years ago, turquoise was born underneath the earth's crust in seams of rocks rich in aluminum and copper that weathered and aged over time until the mineral substance crystallized as an opaque sky-blue phosphate. Through erosion, turquoise separated from its outer rock and became exposed as a precious stone and object. Mined in the high desert of eastern Iran, turquoise spread through trade, from Nishapur across Asia, as ornament, tessera, talisman, and jewel-a piece of earth and sky.

By the fifteenth century, the turquoise trade-a transmission of stone and color-had entered into currents and networks of Eurasian cross-cultural exchange unprecedented in distance or volume, and its traffic acquired new purchase across the Near East, Central Asia, and South Asia.52 Among the early modern Islamic empires of the Timurids, the Safavids, the Mughals, and the Ottomans, turquoise became an object of tribute and interimperial rivalry and exchange, as well as a reflection of imperial encounters with the natural world and its resources.53 It evolved into a substance in the display of conquest and power: an object of tribute and plunder among Eurasian empires, and the sky blue of fabled cities and their monuments. Reaching early modern Europe as one of the exotic, colorful objects and luxuries to be collected from the East, it sparked the synthesis and the culture of the color blue. So unique was its hue in nature that turquoise became the classification of its signature shade.