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Encyclopedia > Topaz
Topaz

a group of topaz crystals on matrix
General
Category Mineral
Chemical formula Al2SiO4(F,OH)2
Identification
Color Clear (if no impurities), blue, brown, orange, gray, yellow, green, pink and reddish pink.
Crystal system orthorhombic
Fracture conchoidal
Mohs Scale hardness 8
Luster Vitreous/glossy
Specific gravity 3.4–3.6

Topaz is a silicate mineral of aluminium and fluorine with the chemical formula Al2SiO4(F,OH)2. It crystallizes in the orthorhombic group and its crystals are mostly prismatic terminated by pyramidal and other faces, the basal pinacoid often being present. It has an easy and perfect basal cleavage, meaning that gemstones or other fine specimens have to be handled with care to avoid developing cleavage flaws. The fracture is conchoidal to uneven. Topaz has a hardness of 8, a specific gravity of 3.4–3.6, and a vitreous luster. Pure topaz is transparent but is usually tinted by impurities; typical topaz is wine or straw-yellow. They may also be white, gray, green, blue, pink or reddish-yellow and transparent or translucent. Topaz might refer to: // Topaz, a mineral or gemstone Topaz (1945 film), a documentary about World War II Japanese-American internment camps Topaz (1969 film), a film directed by Alfred Hitchcock Topaz (1991 film), a Japanese film Topaz (novel), a novel by Leon Uris Topaz (record label), part of RCA... Topaz Source: US Government File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... For other uses, see Crystal (disambiguation). ... For other uses, see Mineral (disambiguation). ... A chemical formula is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... A crystal system is a category of space groups, which characterize symmetry of structures in three dimensions with translational symmetry in three directions, having a discrete class of point groups. ... In crystallography, the orthorhombic crystal system is one of the 7 lattice point groups. ... For other uses, see Fracture (disambiguation). ... Conchoidal fracture describes the way that brittle materials break when they do not follow any natural planes of separation. ... Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. ... Lustre (American English: luster) is a description of the way light interacts with the surface of a crystal, rock or mineral. ... Relative density (also known as specific gravity) is a measure of the density of a material. ... The silicate minerals make up the largest and most important class of rock-forming minerals. ... Aluminum redirects here. ... Distinguished from fluorene and fluorone. ... In crystallography, the orthorhombic crystal system is one of the 7 lattice point groups. ... For other uses, see Crystal (disambiguation). ... Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite planes, creating smooth surfaces, of which there are several named types: Basal cleavage: cleavage parallel to the base of a crystal, or to the plane of the lateral axes. ... For other uses, see Gemstone (disambiguation). ... Conchoidal fracture describes the way that brittle materials break when they do not follow any natural planes of separation. ... The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. ... Relative density (also known as specific gravity) is a measure of the density of a material. ... A yellow Tulip. ... This article is about the color. ... Gray or grey is a color seen commonly in nature. ... For other uses, see Green (disambiguation). ... For other uses, see Blue (disambiguation). ... This article is about the color. ... For other uses, see Red (disambiguation). ...

Contents

Treatments

When heated, yellow topaz often becomes reddish-pink. The color change upon heating was first discovered by a Parisian jeweler around 1750. In particular the yellow Topaz of Brazil has been known to be treated frequently, by wrapping Topaz in Asbestos. Only stones of a brown-yellow color yield the pink; the pale yellow ones usually turn white. The pink color is stable. [1]. Topaz can also be irradiated, turning the stone blue, ranging from a light pure color to very dark almost electric blue. A recent trend in jewelry is the manufacture of topaz specimens that display iridescent colors, by applying a thin layer of titanium oxide via physical vapor deposition, this stone is then sold as 'mystic topaz'. For other uses, see Asbestos (disambiguation). ... Irradiation is the process by which an item is exposed to radiation. ... Titanium dioxide, also known as titanium(IV) oxide or titania, is the naturally occurring oxide of titanium, chemical formula TiO2. ... Physical vapor deposition (PVD) is a technique used to deposit thin films of various materials onto various surfaces (e. ...


Localities and occurrence

Topaz is commonly associated with silicic igneous rocks of the granite and rhyolite type. It typically crystallizes in granitic pegmatites or in vapor cavities in rhyolite lava flows like those at Topaz Mountain in western Utah. It may be found with fluorite and cassiterite. It can be found in the Ural and Ilmen mountains, Afghanistan, Czech Republic, Germany, Norway, Pakistan, Italy, Sweden, Japan, Brazil, Mexico, and the United States. A term used to describe magma or igneous rock rich in silica. ... For other uses, see granite (disambiguation). ... This page is about a volcanic rock. ... Pegmatite is a very coarse-grained igneous rock that has a grain size of 20 mm or more; such rocks are referred to as pegmatitic. ... Fluorite (also called fluor-spar) is a mineral composed of calcium fluoride, CaF2. ... Cassiterite is a tin oxide mineral, SnO2. ... Map of the Ural Mountains The Ural Mountains (Russian: , Uralskiye gory) (also known as the Urals, the Riphean Mountains in Greco-Roman antiquity, and known as the Stone Belt) are a mountain range that runs roughly north and south through western Russia. ...


Topaz crystals from Brazilian pegmatites are up to 80 cm x 60 cm x 60 cm in size.[2] The biggest topaz crystal ever found, named "El Dorado", was found in Brazil in 1984. It weighs 6.2 kg and belongs to the British Royal Collection. The famous Braganza diamond is in most likelihood a Topaz. The Topaz of Aurungzebe, observed by Jean Baptiste Tavernier measured 157.75 carats.[3] Jean-Baptiste Tavernier. ...


Etymology and historical and mythical usage

Colorless topaz, Minas Gerais, Brazil
Colorless topaz, Minas Gerais, Brazil

The name "topaz" is derived from the Greek Τοπάζιος (Τοpáziοs), which was the ancient name of St. John's Island in the Red Sea which was difficult to find and from which a yellow stone (now believed to be chrysolite: yellowish olivine) was mined in ancient times; topaz itself (rather than topazios) wasn't really known about before the classical era. [4] In the Middle Ages the name topaz was used to refer to any yellow gemstone, but now the name is only properly applied to the silicate described above. Image File history File linksMetadata Download high-resolution version (782x853, 108 KB) Licensing File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Topaz Metadata This file contains additional information, probably added from the digital camera or scanner used to... Image File history File linksMetadata Download high-resolution version (782x853, 108 KB) Licensing File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Topaz Metadata This file contains additional information, probably added from the digital camera or scanner used to... St. ... Location of the Red Sea The Red Sea is an inlet of the Indian Ocean between Africa and Asia. ... Olivine The mineral olivine is a magnesium iron silicate with the formula (Mg,Fe)2SiO4 in which the ratio of magnesium and iron varies between the two endmembers of the series: forsterite (Mg-rich) and fayalite (Fe-rich). ... The mineral olivine (also called chrysolite and, when gem-quality, peridot) is a magnesium iron silicate with the formula (Mg,Fe)2SiO4. ... The Middle Ages formed the middle period in a traditional schematic division of European history into three ages: the classical civilization of Antiquity, the Middle Ages, and modern times, beginning with the Renaissance. ...


Many modern English translations of the Bible, including the King James Version mention topaz in Exodus 28:17 in reference to a stone in the Hoshen: "And thou shalt set in it settings of stones, even four rows of stones: the first row shall be a sardius, a topaz, and a carbuncle: this shall be the first row." However, since these translations as topaz all derive from the Septuagint translation tòpazi[òs], which as mentioned above referred to a yellow stone that wasn't topaz, probably chrysolite, it should be borne in mind that topaz is not meant here. [5] The masoretic text (the Hebrew on which most modern bible translations of the Old Testament are based) has pitdah as the gem the stone is made from; pitdah is of unknown meaning, though scholars think it is related to an Assyrian word meaning flashed. There is a wide range of views among traditional sources about which tribe of the Israelites the stone refers to. This page is about the version of the Bible; for the Harvey Danger album, see King James Version (album). ... This article is about the second book in the Torah. ... The Hoshen (Khosen) was the breastplate of Judgment worn by the High Priest in the book of Exodus in the Bible, covered by 12 stones that represented the 12 tribes of Israel. ... The Septuagint: A column of uncial text from 1 Esdras in the Codex Vaticanus, the basis of Sir Lancelot Charles Lee Brentons Greek edition and English translation. ... The Masoretic Text (MT) is the Hebrew text of the Tanakh approved for general use in Judaism. ... blah ... Look up Israelite in Wiktionary, the free dictionary. ...


Yellow topaz is the traditional November birthstone (Blue Topaz for December), and the state gemstone for Utah. // Not every state has an official state mineral, rock, stone or gemstone. ...


References

Wikimedia Commons has media related to:
Topaz
  • Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., ISBN 0-471-80580-7
  1. ^ Several Books at the "Pink Topaz" section on Farlang: Fernie: Precious Stones for Curative Wear, London, 1907; Oliver Farrington: Gems and Gem Minerals, Chicago, 1903. Wodiska, A Book of Precious Stones, New York, 1910 (see external links)
  2. ^ The Complete Encyclopedia of Minerals by P. Korbel and M. Novak
  3. ^ Famous and Notheworthy Topazes Rao Bahadur, A Handbook of Precious Stones, Geological Survey of India
  4. ^ Nicols who wrote one of the first systematic treatises on minerals and gemstones dedicated two chapters on the topic in 1652: A Lapidary or History of Gemstones, University of Cambridge, 1652
  5. ^ see for extensive discussion Oliver Farrington, Gems and Gem Minerals, Chicago, 1903. Farrington was curator of Natural History Museum in Chicago.

Image File history File links Commons-logo. ...

External links


  Results from FactBites:
 
Topaz - english (414 words)
The topaz has been known for at least 2000 years and is one of the gemstones which form the foundations of the twelve gates to the Holy City of the New Jerusalem.
The colour in which the topaz is most commonly found is yellow, and that is the colour in which it occurs in one of the major German gemstone rocks, the Schneckenstein (a topaz-bearing rock said to resemble a snail) in Saxony.
Since then, the topaz has been a rather exotic figure in the jewellery trade, and has been given the additional predicate 'pure' to make it clear that the topaz, not the quartz topaz, is meant.
Topaz - LoveToKnow 1911 (1125 words)
It is believed that the topaz of modern mineralogists was unknown to the ancients, and that the stone described under the name of ToWcos, in allusion to its occurrence on an island in the Red Sea known as T01r4cos vij ros, was the mineral which is now termed chrysolite or peridot.
Topaz usually occurs in granitic and gneissose rocks, often in greisen, and is commonly associated with cassiterite, tourmaline and beryl.
Topaz occurs in the tin-drifts of New South Wales, especially in the New England district; it has been discovered in the Coolgardie goldfield, West Australia; and it is found also in the tinfields of Tasmania and on Flinders Island in Bass's Strait.
  More results at FactBites »

 
 

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