This page will contain wikis about Topaz, as they become available.

Topaz

This article is about the mineral or gemstone, for other uses see: Topaz (disambiguation).

Topaz 4 Carat Oval Shape Topaz Gemstone Ring Enhanced with Azotic(r)Treatment Heart Cut Sky Blue Topaz Ring

The mineral topaz is a silicate of aluminium and fluorine with the chemical formula Al2SiO4(F,OH)2. It crystallizes in the orthorhombic system 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 and so gemstones or other fine specimens should 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 lustre. 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, or reddish-yellow and transparent or translucent. When heated, yellow topaz often becomes reddish-pink. It can also be irradiated, turning the stone a light and distinctive shade of 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.

Topaz is found associated with the more acid rocks of the granite and rhyolite type and may be found with fluorite and cassiterite. It can be found in the Ural and Ilmen mountains, Czech Republic, Saxony, Norway, Sweden, Japan, Brazil, Mexico, and the United States.

Etymology and historical/mythical usage

The name "topaz" is derived from the Greek topazos, "to seek," which was the name of an island in the Red Sea that was difficult to find and from which a yellow stone (now believed to be a yellowish olivine) was mined in ancient times. 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.

According to Rebbenu Bachya, the word "Leshem" in the verse Exodus 28:19 means "Topaz" and was the stone on the Ephod representing the tribe of Dan.

Topaz is also the birthstone of November.

Example of Heat Treated Topaz-Pink Topaz Pear Cut Ring

References

  • Webmineral
  • Mindat with location data
  • Mineral galleries

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Topaz is also the birthstone of November. Liflander also details the life of Edgar Leeteg (1904-1953), "the father of American black velvet kitsch," whose "raucous and bawdy" life was previously captured by James Michener in Rascals in Paradise (1957). According to Rebbenu Bachya, the word "Leshem" in the verse Exodus 28:19 means "Topaz" and was the stone on the Ephod representing the tribe of Dan. These paintings were religious in nature, portraying the iconic artwork of the Caucasus region by Russian Orthodox priests." She further wrote that Marco Polo and others introduced the West to this art form, and that some of these early works still hang in the Vatican. 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. She notes that "The birthplace of black velvet paintings can be traced to ancient Kashmir, which is considered to be the fabric's original homeland. The name "topaz" is derived from the Greek topazos, "to seek," which was the name of an island in the Red Sea that was difficult to find and from which a yellow stone (now believed to be a yellowish olivine) was mined in ancient times. A brief history of black velvet paintings is presented by Pamela Liflander in Black Velvet Artist, a booklet published by Running Press, Philadelphia, 2003, and included in an identically-titled art kit.

It can be found in the Ural and Ilmen mountains, Czech Republic, Saxony, Norway, Sweden, Japan, Brazil, Mexico, and the United States. Somewhat later the art was taken up by Flemish weavers, and in the 16th century Bruges attained a reputation for velvets not inferior to that of the great Italian cities. Topaz is found associated with the more acid rocks of the granite and rhyolite type and may be found with fluorite and cassiterite. The earliest sources of European artistic velvets were Lucca, Genoa, Florence and Venice, and Genoa continues to send out rich velvet textures. 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. These were ornamentated by such techniques as varying the color of the pile, by producing pile of different lengths (pile upon pile, or double pile), and by brocading with plain silk, with uncut pile or with a ground of gold tissue, etc. It can also be irradiated, turning the stone a light and distinctive shade of blue. The most magnificent textiles of medieval times were Italian velvets.

When heated, yellow topaz often becomes reddish-pink. The peculiar properties of velvet, the splendid yet softened depth of dye colour it exhibited, made it obviously fit for official robes and sumptuous hangings. They may also be white, gray, green, blue, or reddish-yellow and transparent or translucent. Earliest references occur about the beginning of the 14th century. Pure topaz is transparent but is usually tinted by impurities; typical topaz is wine or straw-yellow. In all probability the art of velvet-weaving originated in the Far East. Topaz has a hardness of 8, a specific gravity of 3.4-3.6, and a vitreous lustre. Corduroy and velveteen were considered the "poor man's velvet" when they were first produced.

The fracture is conchoidal to uneven. Velvet was very expensive and was considered to be among the luxury goods together with silk. It has an easy and perfect basal cleavage and so gemstones or other fine specimens should be handled with care to avoid developing cleavage flaws. Velvet's knitted counterpart is velour. It crystallizes in the orthorhombic system and its crystals are mostly prismatic terminated by pyramidal and other faces, the basal pinacoid often being present. The two pieces are then cut apart and the two lengths of fabric are wound on separate take-up rolls. The mineral topaz is a silicate of aluminium and fluorine with the chemical formula Al2SiO4(F,OH)2. It is woven on a special loom that weaves two pieces of velvet at the same time.

This article is about the mineral or gemstone, for other uses see: Topaz (disambiguation).. Velvet can be made from any fiber. Mineral galleries. Velvet is a type of tufted fabric in which the cut threads are very evenly distributed, with a short dense pile, giving it its distinct feel. Mindat with location data. Webmineral.

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