Topaz is a silicate mineral from aluminum and fluorine with the chemical formula Al 2 SiO 4 (F, OH) 2 . Topaz crystallizes in orthorhombic systems, and its crystals are largely prismatic ends by pyramidal and other faces. It is one of the harshest natural minerals (Mohs 8 hardness) and is the harshest silicate mineral. This hardness combined with the usual transparency and various colors means that it has acquired extensive use in jewelry as a gemstone cut and intaglios and other gem carvings.
Video Topaz
Characteristics
Topas in its natural state is golden brown to yellow, a characteristic that means sometimes confused with less valuable citrine gemstones. Various dirt and treatments can make topaz red wine, pale gray, reddish orange, pale green, or pink (rare), and opaque to translucent/transparent. The pink and red varieties are derived from chromium which replaces aluminum in its crystal structure.
Topaz oranges, also known as valuable topaz, are the traditional November birthstones, symbols of friendship, and the gems of the state of Utah's US state.
Imperial topaz is yellow, pink (rare, if natural) or pink-orange. Topaz royal Brazil often has golden golden golden yellow, sometimes even purple. Many brown or pale topaz are treated to make them bright yellow, gold, pink or purple. Some imperial topazs can fade on exposure to the sun for long periods of time.
Blue topaz is a gemstone of the state of the US state of Texas. Natural blue topaz is quite rare. Typically, colorless, gray or pale yellow and blue materials are heated and irradiated to produce a more desirable blue color.
Mystic topaz is a colorless topaz that has been artificially coated through a vapor deposition process that provides a rainbow effect on its surface.
Although extremely harsh, topaz should be treated with better attention than other minerals of the same hardness (such as corundum) due to the weakness of the atomic bonds of the rock molecules along one or the other axial plane (whereas the diamond, for example, consists of carbon atoms bonded to each other with the same strength throughout all its fields). This gives the topaz a tendency to snap along such aircraft if hit with enough force.
Topaz has a relatively low refractive index for gems, and rocks with large aspect or tables do not glow as easily as rocks cut from minerals with a higher refractive index, although topaz shining qualities are colored and show more "life" than quartz the same cut. When given a typical "brilliant" piece, the topaz may show a sparkling table side surrounded by a crowning facade that looks dead or a glittering crown ring with a regular table.
Maps Topaz
Locality and events
Topaz is commonly associated with silicic frozen rocks of granite and rhyolite types. These are usually crystallized in granite pegmatites or in steam cavities in the loli flows of rhyolites including those at Topaz Mountain in western Utah and Chivinar in South America. Can be found with fluorite and kasiterit in various regions including Ural and Ilmen mountains in Russia, in Afghanistan, Sri Lanka, Czech Republic, Germany, Norway, Pakistan, Italy, Sweden, Japan, Brazil, Mexico; Flinders Island, Australia; Nigeria and the United States.
Brazil is one of the largest topaz producers, some clear topaz crystal of Brazilian pegmatites can reach stone sizes and weigh hundreds of pounds. Crystals of this magnitude can be seen in museum collections. Topaz Aurangzeb, observed by Jean Baptiste Tavernier, weighs 157.75 carats. The American Golden Topaz, a newer gem, weighed 22,892.5 carats. Large blue and living topaz specimens from St. Anns in Zimbabwe was discovered in the late 1980s.
Colored and blue-light topaz are found in the Precambrian granite in Mason County, Texas in Llano Uplift. There is no commercial mining topaz in the area.
Etymology
The name "topaz" usually originates (via Old French: Topace and Latin: Topazus) from the Greek ???????? (?? pÃÆ'¡zi? S) or ???????? (?? pÃÆ'¡zi? n), from ???? the, ancient name of St. Island. John on the Red Sea is hard to find and from which the yellow stone (now believed to be chrysolite: yellow olivine) mined in ancient times; topaz itself (not topazios ) was not really known before the classical era. Pliny says that Topazos is a legendary island in the Red Sea and minerals "topaz" was first mined there. Or, the word topaz might be related to the Sanskrit word ???? "tapas", which means "hot" or "fire".
Historical usage
Nicols, author of one of the first systematic treatises on minerals and gemstones, dedicated two chapters to the topic in 1652. In the Middle Ages, the name of the topaz was used to refer to yellow gemstones, but in modern times it simply signifies the silicates described above.
Many modern English Bible translations, including the King James Version, mention topaz. However, since this translation as topaz all comes from the Septuagint translation of topazi [os] , which as mentioned above refers to a yellow stones that are not topaz, but may be > chrysolite (chrysoberyl or peridot), it should be remembered that topaz may not be intended here.
Superstition
A superstition UK states that topaz cures madness.
References
External links
- Topaz - International Color Gemstone Association
- Topaz and other minerals found on Mount Topaz, Juab District, Utah Geology Survey
- Ã, "Topaz". EncyclopÃÆ'Â|dia Britannica . 23 (9th ed.). 1888.
Source of the article : Wikipedia
0 Comments