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Lapis lazuli ( or ) (sometimes abbreviated to lapis) is a relatively rare, semi-precious stone that has been prized since antiquity for its intense blue color.

Lapis lazuli has been mined in the Badakhshan province of Afghanistanmarker for over 6,000 years, and trade in the stone is ancient enough for lapis jewelry to have been found at Predynastic Egyptian sites (as archaeologists have frequently stated, but lapis could also be found in, e.g. the Siwa Oasis in the Western Lybian desert), and lapis beads at neolithic burials in Mehrgarhmarker, the Caucasus, and even as far from Afghanistan as Mauritaniamarker.

Description

Rough and polished Lapis lazuli.
Lapis lazuli is a rock, not a mineral: whereas a mineral has only one constituent, lapis lazuli is formed from more than one mineral.

The main component of lapis lazuli is lazurite (25% to 40%), a feldspathoid silicate mineral composed of sodium, aluminium, silicon, oxygen, sulfur, and chloride. Its formula is (Na,Ca)8(AlSiO4)6(S,SO4,Cl)1-2. Most lapis lazuli also contains calcite (white), sodalite (blue), and pyrite (metallic yellow). Other possible constituents are augite, diopside, enstatite, mica, hauynite, hornblende, and nosean. Some contain trace amounts of the sulfur rich lollingite variety geyerite.

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

The finest color is intense blue, lightly dusted with small flecks of golden pyrite. Stones with no white calcite veins and only small pyrite inclusions are more prized. Patches of pyrite are an important help in identifying the stone as genuine and do not detract from its value. Often, inferior lapis is dyed to improve its color, producing a very dark blue with a noticeable grey cast which may also appear as a milky shade.

Uses

Lapis takes an excellent polish and can be made into jewelry, carvings, boxes, mosaics, ornaments, and vases. In architecture it has been used for cladding the walls and columns of palaces and churches.

It was also ground and processed to make the pigment ultramarine for tempera paint and, more rarely, oil paint. Its usage as a pigment in oil paint ended in the early 19th century as a chemically identical synthetic variety, often called French Ultramarine, became available.

Etymology

is the Latin for 'stone' and the genitive form of the Medieval Latin , which is from the Arabic , which is ultimately from the Persian , the name of a place where lapis lazuli was mined. The name of the place came to be associated with the stone mined there and, eventually, with its color. The English word azure, the French azur, the Spanish and Portuguese , and the Italian are cognates. Taken as a whole, lapis lazuli means 'stone of Lāzhvard'.

Sources

The best lapis lazuli is found in limestone in the Kokcha River valley of Badakhshan province in northeastern Afghanistanmarker, and these deposits in the mines of Sar-e-Sang have been worked for more than 6,000 years. Afghanistan was the source of lapis for the ancient Egyptian and Mesopotamian civilizations, as well as the later Greek and Roman; during the height of the Indus valley civilization about 2000 B.C., the Harappan colony now known as Shortugai was established near the lapis mines.

In addition to the Afghan deposits, lapis has been extracted for years in the Andes near Ovallemarker, Chilemarker, where the deep blue stones compete in quality with those from Afghanistan. Other less important sources include the Lake Baikalmarker region of Russiamarker, Siberiamarker, Angolamarker, Burmamarker, Pakistanmarker, USAmarker (Californiamarker and Coloradomarker), Canadamarker, and Indiamarker.

Historical usage

In ancient Egypt lapis lazuli was a favorite stone for amulets and ornaments such as scarabs; it was also used by the Assyrians and Babylonians for seals. Lapis jewelry has been found at excavations of the Predynastic Egyptian site Naqadamarker (3300–3100 BC), and powdered lapis was used as eyeshadow by Cleopatra.

In ancient times, lapis lazuli was known as sapphire, which is the name that is used today for the blue corundum variety sapphire.


See also



Notes

  1. *The New Penguin English Dictionary, 2000
  2. Mindat.org
  3. Mindat - Lazurite
  4. http://www.cst.cmich.edu/users/dietr1rv/lapis.htm Gemrocks, Lapis Lazuli


References

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External links




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