Lapis-lazuli

"Lapis" redirects here. For other uses, see Lapis (disambiguation).
Lapis lazuli
Lapis lazuli from Afghanistan in its natural state
General
Category Rock
Formula
(repeating unit)
mixture of minerals with lazurite as the main constituent.
Identification
Color Blue, mottled with white calcite and brassy pyrite
Crystal habit Compact, massive
Crystal system None, as lapis is a rock. Lazurite, the main constituent, frequently occurs as dodecahedra
Cleavage None
Fracture Uneven-Conchoidal
Mohs scale hardness 5–5.5
Luster dull
Streak light blue
Specific gravity 2.7–2.9
Refractive index 1.5
Other characteristics The variations in composition cause a wide variation in the above values.

Lapis lazuli (/ˈlæpɪs ˈlæzjʉl/ or /ˈlæzjʉli/ ,[1]) (sometimes abbreviated to lapis) is a deep blue semi-precious stone that has been prized since antiquity for its intense color.

Lapis lazuli was being mined in the Sar-i Sang mines[2] and in other mines in the Badakhshan province in northeast Afghanistan as early as the 7th millennium BC,[3] Lapis beads have been found at neolithic burials in Mehrgarh, the Caucasus, and even as far from Afghanistan as Mauritania.[4] It was used for the eyebrows on the funeral mask of King Tutankhamun (1341–1323 BC).[5]

At the end of the Middle Ages, lapis lazuli began to be exported to Europe, where it was ground into powder and made into ultramarine, the finest and most expensive of all blue pigments. It was used by the most important artists of the Renaissance and Baroque, including Massaccio, Perugino, Titian and Vermeer, and was often reserved for the clothing of the central figure of the painting, especially the Virgin Mary.[2]

Today mines in northeast Afghanistan are still the major source of lapis lazuli. Important amounts are also produced from mines west of Lake Baikal in Russia, and in the Andes mountains in Chile. Smaller quantities are mined in Italy, Mongolia, the United States and Canada.[6]

Etymology

Lapis is the Latin word for "stone" and lazuli is the genitive form of the Medieval Latin lazulum, which is taken from the Arabic لازورد lāzaward, itself from the Persian لاژورد lāžaward, which is the name of the stone in Persian[7] and also of a place where lapis lazuli was mined.[8][9]

The name of the stone came to be associated with its color. The English word azure, French azur, the Italian azzurro, the Polish lazur, Romanian azur and azuriu, and the Portuguese and Spanish azul, Hungarian azúr all come from the name and color of lapis lazuli.

Science and uses

Composition

Lapis lazuli is a rock whose most important mineral component is lazurite[10] (25% to 40%), a feldspathoid silicate mineral with the formula (Na,Ca)8(AlSiO4)6(S,SO4,Cl)1-2.[11] Most lapis lazuli also contains calcite (white), sodalite (blue), and pyrite (metallic yellow). Other possible constituents: augite; diopside; enstatite; mica; hauynite; hornblende, and nosean. Some lapis lazuli contains trace amounts of the sulfur-rich löllingite variety geyerite.

Lapis lazuli usually occurs in crystalline marble as a result of contact metamorphism.

Color

The intense blue color is due to the presence of the S3- radical anion in the crystal.[12] An electronic excitation of one electron from the highest doubly filled molecular orbital (No. 24) into the lowest singly occupied orbital (No. 25)[13] results in a very intense absorption line at λmax ~617 nm.

Sources

Lapis lazuli is found in limestone in the Kokcha River valley of Badakhshan province in northeastern Afghanistan, where the Sar-e-Sang mine deposits have been worked for more than 6,000 years.[14] Afghanistan was the source of lapis for the ancient Egyptian and Mesopotamian civilizations, as well as the later Greeks and Romans. During the height of the Indus valley civilization about 2000 BC, the Harappan colony now known as Shortugai was established near the lapis mines.[4]

In addition to the Afghan deposits, lapis is also extracted in the Andes (near Ovalle, Chile); and to the west of Lake Baikal in Siberia, Russia, at the Tultui Lazurite deposit. It is mined in smaller amounts Angola; Argentina; Burma; Pakistan; Canada; Italy, India; and in the USA in California and Colorado.[15]

Alternatives

Lapis lazuli is commercially synthesized or simulated by the Gilson process, which is used to make artificial ultramarine and hydrous zinc phosphates.[16] It may also be substituted by spinel or sodalite, or by dyed jasper or howlite.[17]

Uses

Lapis takes an excellent polish and can be made into jewelry, carvings, boxes, mosaics, ornaments, and vases. It was also ground and processed to make the pigment ultramarine, widely used during the Renaissance in frescoes and oil painting. Its usage as a pigment in oil paint largely ended in the early 19th century when a chemically identical synthetic variety became available (See history and art).

History and art

In the Ancient World

Lapis lazuli has been mined in Afghanistan and exported to the Mediterranean world and South Asia since the Neolithic age.[18] Lapis lazuli beads have been found at Mehrgarh, a neolithic site near Quetta in Pakistan, on the ancient trade route between Afghanistan and the Indus Valley, dating to the 7th millennium. Quantities of these beads have also been found at 4th millennium BC settlements in Northern Mesopotamia, and at the Bronze Age site of Shahr-e Sukhteh in southeast Iran (3rd millennium BC). A dagger handle with a lapis handle, a bowl inlaid with lapis, and amulets, beads, and inlays representing eyebrows and beards, were found in the Royal Tombs of the Sumerian city-state of Ur from the 3rd Millennium BC.[18]

Lapis was also used in ancient Mesopotamia by the Akkadians, Assyrians, and Babylonians for seals and jewelry. In the Mesopotamian poem, the Epic of Gilgamesh (17th-18th Century BC); one of the oldest known works of literature, lapis lazuli is mentioned several times. The Statue of Ebih-Il, a 3rd millennium BC statue found in the ancient city-state of Mari in modern-day Syria, now in the Louvre, uses lapis lazuli inlays for the irises of the eyes.[19]

Lapis lazuli also made its way across the Mediterranean to ancient Egypt, where it was a favorite stone for amulets and ornaments such as scarabs; Lapis jewelry has been found at excavations of the Predynastic Egyptian site Naqada (3300–3100 BC). At Karnak, the relief carvings of Thutmose III (1479-1429 BC) show fragments and barrel-shaped pieces lapis lazuli being delivered to him as tribute. Powdered lapis was used as eyeshadow by Cleopatra.[4][20]

In late classical times and as late as the Middle Ages, lapis lazuli was often called sapphire (sapphirus in Latin, sappir in Hebrew),[21] though it had little to do with the stone today known as the blue corundum variety sapphire. In his book on stones, the Greek scientist Theophrastus described "the sapphirus, which is speckled with gold," a description which matches lapis lazuli.[22]

There are many references to sapphires in the Old Testament, but most scholars agree that, since sapphires were not known before the Roman Empire, they most likely are references to lapis lazuli. For instance, Exodus 24:10: "As they saw the God of Israel, and there was under his feet as it were a paved work of a sapphire stone.." (KJV). The term used in the Latin Vulgate bible in this citation is "lapidus sapphiri," the term for lapis lazuli.[23]

See also

References

Notes and citations

Bibliography

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External links

  • Lapis lazuli at Gemstone.org
  • Documentation from online course produced by University of California at Berkeley
  • Lapis Lazuli from Afghanistan, Sar-e-Sang Mine, Jurm, Afghanistan
  • Thomas Krassmann : Lapislzuli – occurrence, mining and market potential of a classic blue mineral pigment pdf, in German
  • Lazulita: Informative site about Lapis Lazuli with an emphasis on Chilean Lapis

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