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Encyclopedia > Opal
Opal

An opal bracelet. The stone size is 18 by 15 mm (0.7 by 0.6 inch).
General
Category Mineraloid
Chemical formula Hydrated silica. SiO2·nH2O
Identification
Color White, black, red, orange, most of the full spectrum, colorless, iridescent. Very infrequently of a singular color
Crystal habit Irregular veins, in masses, in nodules
Crystal system Amorphous[1]
Cleavage None[1]
Fracture Conchoidal to uneven[1]
Mohs Scale hardness 5.5–6.5[1]
Luster Subvitreous to waxy[1]
Polish luster Vitreous to resinous[1]
Refractive index 1.450 (+.020, -.080) Mexican Opal may read as low as 1.37, but typically reads 1.42–1.43[1]
Optical Properties Single refractive, often anomalous double refractive due to strain[1]
Birefringence none[1]
Pleochroism None[1]
Ultraviolet fluorescence black or white body color: inert to white to moderate light blue, green, or yellow in long and short wave. May also phosphoresce; common opal: inert to strong green or yellowish green in long and short wave, may phosphoresce; fire opal: inert to moderate greenish brown in long and short wave, may phosphoresce.[1]
Absorption spectra green stones: 660nm, 470nm cutoff[1]
Streak White
Specific gravity 2.15 (+.08, -.90)[1]
Diagnostic Features darkening upon heating
Solubility hot saltwater, bases, methanol, humic acid, hydrofluoric acid
Diaphaneity opaque, translucent, transparent

The mineraloid opal is amorphous SiO2·nH2O, hydrated silicon dioxide, the water content sometimes being as high as 20% but is usually between three and ten percent. Opal ranges from clear through white, gray, red, yellow, green, shore, blue, magenta, brown, and black. Of these hues, red and black are the most rare and dear, whereas white and green are the most common; these are a function of growth size into the red and infrared wavelengths—see precious opal. Common opal is truly amorphous, but precious opal does have a structural element. The word opal comes from the Latin opalus, by Greek òpalliòs, and is from the same root as Sanskrit upálá[s] for "stone", originally a millstone with upárá[s] for slab.[2] (see Upal). Opals are also Australia's national gemstone.It is also known as rainbow mineral. Opal may refer to: Opal, a water hydrated gemstone OPAL is also the name of one of the four detectors of the Large Electron-Positron Collider Opal (fuel), is also the name of a brand of gasoline produced by BP Australia Hurricane Opal, a devastated hurricane in 1995 This is... Image File history File links Opal_Armband_800pix. ... A mineraloid is a mineral-like substance that does not demonstrate crystallinity. ... A chemical formula is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... Hydrate is a term which means different things in inorganic chemistry and organic chemistry. ... The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2. ... The iridescence of the Blue Morpho butterfly wings. ... In mineralogy, shape and size give rise to descriptive terms applied to the typical appearance, or habit of crystals. ... 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. ... 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 Fracture (disambiguation). ... A conchoidal fracture is produced when some types of fine-grained mineral, such as obsidian and flint, are broken. ... 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. ... The refractive index (or index of refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves) is reduced inside the medium. ... A calcite crystal laid upon a paper with some letters showing the double refraction Birefringence, or double refraction, is the decomposition of a ray of light into two rays (the ordinary ray and the extraordinary ray) when it passes through certain types of material, such as calcite crystals, depending on... Pleochroism is an optical phenomenon in which grains of a rock appear to be different colors when observed at different angles,under a petrographic microscope. ... Fluorescence induced by exposure to ultraviolet light in vials containing various sized Cadmium selenide (CdSe) quantum dots. ... Absorption spectroscopy refers to a wide range of techniques where one measures how much light of a particular wavelength (color) is absorbed by a sample. ... The streak (also called powder color) of a mineral is the color of the powder produced when it is dragged across a unweathered surface. ... Relative density (also known as specific gravity) is a measure of the density of a material. ... Solubility is a chemical property referring to the ability for a given substance, the solute, to dissolve in a solvent. ... For information on water from a sea or ocean, see sea water. ... Acids and bases: Acid-base extraction Acid-base reaction Acid dissociation constant Acidity function Buffer solutions pH Proton affinity Self-ionization of water Acids: Lewis acids Mineral acids Organic acids Strong acids Superacids Weak acids Bases: Lewis bases Organic bases Strong bases Superbases Non-nucleophilic bases Weak bases edit In... Methanol, also known as methyl alcohol, carbinol, wood alcohol, wood naptha or wood spirits, is a chemical compound with chemical formula CH3OH. It is the simplest alcohol, and is a light, volatile, colourless, flammable, poisonous liquid with a distinctive odor that is somewhat milder and sweeter than ethanol (ethyl alcohol). ... Humic acid is one of the major components of humic substances which are dark brown and major constituents of soil organic matter humus that contributes to soil chemical and physical quality and are also precursors of some fossil fuels. ... R-phrases , S-phrases , , , , Flash point nonflammable Related Compounds Other anions Hydrochloric acid Hydrobromic acid Hydroiodic acid Related compounds Hydrogen fluoride fluorosilicic acid Supplementary data page Structure and properties n, εr, etc. ... A mineraloid is a mineral-like substance that does not demonstrate crystallinity. ... An amorphous solid is a solid in which there is no long-range order of the positions of the atoms. ... For other uses, see Red (disambiguation). ... For other uses, see Infrared (disambiguation). ... For other uses, see Latin (disambiguation). ... Sanskrit ( , for short ) is a classical language of India, a liturgical language of Hinduism, Buddhism, Sikhism, and Jainism, and one of the 23 official languages of India. ... Overview of the Karakoram Highway Upal is a small town in western Xinjiang, China. ...


Opal is a mineraloid gel which is deposited at relatively low temperature and may occur in the fissures of almost any kind of rock, being most commonly found with limonite, sandstone, rhyolite, and basalt. In optical filters and theatrical lighting a color gel is a transparent or translucent colored panel used to change the color of transmitted light. ... “Rock” redirects here. ... Limonite Limonite Limonite is a ferric hydrate of varying composition, the generic formula is frequently written as FeO(OH)·nH2O, although this is not entirely accurate as Limonite often contains a varying amount of oxide compared to hydroxide. ... Red sandstone interior of Lower Antelope Canyon, Arizona, worn smooth due to erosion by flash flooding over millions of years Sandstone is a sedimentary rock composed mainly of sand-size mineral or rock grains. ... This page is about a volcanic rock. ... For the cities, see Basalt, Colorado and Basalt, Idaho. ...


Opal is one of the mineraloids that can form or replace fossils. The resulting fossils, though not of any extra scientific interest, appeal to collectors. For other uses, see Fossil (disambiguation). ...

Contents

Precious opal

Precious opal shows a variable interplay of internal colors and does have an internal structure. At the micro scale precious opal is composed of silica spheres some 150 to 300 nm in diameter in a hexagonal or cubic closed-packed lattice. These ordered silica spheres produce the internal colors by causing the interference and diffraction of light passing through the microstructure of opal (Klein and Hurlbut, 1985, p. 444). It is the regularity of the sizes of the spheres, and of the packing of these spheres that determines the quality of precious opal. Where the distance between the regularly packed planes of spheres is approximately half the wavelength of a component of visible light, the light of that wavelength may be subject to diffraction from the grating created by the stacked planes. The spacing between the planes and the orientation of planes with respect to the incident light determines the colors observed. The process can be described by Bragg's Law of diffraction. Visible light of diffracted wavelengths cannot pass through large thicknesses of the opal. This is the basis of the optical band gap in a photonic crystal, of which opal is the best known natural example. A nanometre (American spelling: nanometer, symbol nm) is a unit of length in the metric system, equal to one thousand-millionth of a metre, which is the current SI base unit of length. ... Close-packing of spheres refers to arranging an infinite lattice of spheres so that they take up the greatest possible fraction of an infinite 3-dimensional space. ... Enargite crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... For other uses, see Interference (disambiguation). ... The intensity pattern formed on a screen by diffraction from a square aperture Diffraction refers to various phenomena associated with wave propagation, such as the bending, spreading and interference of waves passing by an object or aperture that disrupts the wave. ... The optical spectrum (light or visible spectrum) is the portion of the electromagnetic spectrum that is visible to the human eye. ... The intensity pattern formed on a screen by diffraction from a square aperture Diffraction refers to various phenomena associated with wave propagation, such as the bending, spreading and interference of waves passing by an object or aperture that disrupts the wave. ... Curb, gutter, and grating covering a storm drain A grating is any regularly spaced collection of essentially identical, parallel, elongated elements. ... In physics, Braggs law is the result of experiments into the diffraction of X-rays or neutrons off crystal surfaces at certain angles, derived by physicists Sir W.H. Bragg and his son Sir W.L. Bragg in 1912, and first presented on 1912-11-11 to the Cambridge... This article or section does not adequately cite its references or sources. ... The opal in this bracelet contains a natural periodic microstructure responsible for its iridescent color. ...

Precious opal consists of spheres of silica of fairly regular size, packed into close-packed planes which are stacked together with characteristic dimensions of several hundred nm.

In addition, microfractures may be filled with secondary silica and form thin lamellae inside the opal during solidification. The term opalescence is commonly and erroneously used to describe this unique and beautiful phenomenon, which is correctly termed play of color. Contrarily, opalescence is correctly applied to the milky, turbid appearance of common or potch opal. Potch does not show a play of color. Image File history File linksMetadata Size of this preview: 607 × 600 pixelsFull resolution (1024 × 1012 pixel, file size: 246 KB, MIME type: image/jpeg) Shown above is what the science of sphere packing calls a closest-packed arrangement. ... Image File history File linksMetadata Size of this preview: 607 × 600 pixelsFull resolution (1024 × 1012 pixel, file size: 246 KB, MIME type: image/jpeg) Shown above is what the science of sphere packing calls a closest-packed arrangement. ... OPAL is also the name of one of the four detectors of the Large Electron-Positron Collider. ... The iridescence of the Blue Morpho butterfly wings. ... Turbidity standards of 5, 50, and 500 NTU Turbidity is a cloudiness or haziness of a fluid caused by individual particles (suspended solids) that are generally invisible to the naked eye, similar to smoke in air. ...


The veins of opal displaying the play of color are often quite thin, and this has given rise to unusual methods of preparing the stone as a gem. An opal doublet is a thin layer of colorful material, backed by a black mineral, such as ironstone, basalt or obsidian. The darker backing emphasizes the play of color, and results in a more attractive display than a lighter potch. Given the texture of opals, they can be quite difficult to polish to a reasonable lustre. The triplet cut backs the colored material with a dark backing, and then has a domed cap of clear quartz (rock crystal) or plastic on top, which takes a high polish, and acts as a protective layer for the relatively fragile opal. Opal doublets and triplets are not classed as precious opal. A doublet is a type of gem composed in two sections. ... Black-band ironstone, 2. ... For the cities, see Basalt, Colorado and Basalt, Idaho. ... This article is about a type of volcanic glass. ... For other uses, see Quartz (disambiguation). ...


Common opal

Besides the gemstone varieties that show a play of color, there are other kinds of common opal such as the milk opal, milky bluish to greenish (which can sometimes be of gemstone quality); resin opal, honey-yellow with a resinous lustre; wood opal, caused by the replacement of the organic material in wood with opal; menilite brown or grey; hyalite, a colorless glass-clear opal sometimes called Muller's Glass; geyserite, (siliceous sinter) deposited around hot springs or geysers; and diatomite or diatomaceous earth, the accumulations of diatom shells or tests. For other uses, see Gemstone (disambiguation). ... A glass of cows milk. ... This article does not cite any references or sources. ... For other uses, see Wood (disambiguation). ... Menilite is a reddish-brown form of opal, also known as liver opal or leberopal. ... Hyalite is a form of opal with a glassy appearance. ... Geyserite is a form of opaline silica that is often found around hot springs and geysers. ... Geyserite is a form of opaline silica that is often found around hot springs and geysers. ... Green Dragon Spring at Norris Geyser A hot spring is a place where warm or hot groundwater issues from the ground on a regular basis for at least a predictable part of the year, and is significantly above the ambient ground temperature (which is usually around 55~57°F or... Strokkur geyser, Iceland A geyser is a type of hot spring that erupts periodically, ejecting a column of hot water and steam into the air. ... Diatomaceous earth (also known as diatomite, DE or kieselguhr) is a naturally occurring, light-colored, solid material that is easily crumbled into a fine dust. ... A sample of diatomaceous earth Diatomaceous earth (IPA: , also known as DE, diatomite, diahydro, kieselguhr, kieselgur and Celite) is a naturally occurring, soft, chalk-like sedimentary rock that is easily crumbled into a fine white to off-white powder. ... Orders Centrales Pennales Diatoms (Greek: (dia) = through + (temnein) = to cut, i. ...


Other varieties of opal

Fire opal, or Girasol, is a translucent to semi-opaque stone that is generally yellow to bright orange and sometimes nearly red and displays pleochroism at certain angles. Pleochroism is an optical phenomenon in which grains of a rock appear to be different colors when observed at different angles,under a petrographic microscope. ...


Peruvian opal (also called blue opal) is a semi-opaque to opaque blue-green stone found in Peru which is often cut to include the matrix in the more opaque stones. It does not display pleochroism.

Boulder opal carving of a walrus, showing flashes of color from the exposed opal. The carving is 9 cm (3.5 inches) long.
Boulder opal carving of a walrus, showing flashes of color from the exposed opal. The carving is 9 cm (3.5 inches) long.

Image File history File links Download high-resolution version (800x648, 138 KB) Dieses Bild wurde von wikipedia:de kopiert. ... Image File history File links Download high-resolution version (800x648, 138 KB) Dieses Bild wurde von wikipedia:de kopiert. ...

Sources of opal

Until the nineteenth century the only source of precious opal known to Europeans was the mining district of Červenica in Slovakia. Location of PreÅ¡ov District in the PreÅ¡ov Region. ...


Opal without play of color is very common and can be found all over the world, unlike precious opal deposits that are in greater scope found today only in Australia, U.S., Mexico and Ethiopia. The precious Ethiopian opal was discovered some years ago and now Ethiopian opal is being appreciated all over the world.


Australia produces around 97% of the world’s opal. 90% is called ‘light opal’ or white and crystal opal. White makes up 60% but not all the opal fields produce white opal; Crystal opal or pure hydrated silica makes up 30%; 8% is black and only 2% is boulder opal.[citation needed]


The town of Coober Pedy in South Australia is a major source of opal. Another Australian town, Lightning Ridge in New South Wales, is the main source of black opal, opal containing a predominantly dark background (dark-gray to blue-black displaying the play of color). Boulder opal consists of concretions and fracture fillings in a dark siliceous ironstone matrix. It is found sporadically in western Queensland, from Kynuna in the north, to Yowah and Koroit in the south.[3] Coober Pedy ( ), population 3,500, is a small town in northern South Australia, 846 kilometres north of Adelaide on the Stuart Highway. ... Capital Adelaide Government Constitutional monarchy Governor Marjorie Jackson-Nelson Premier Mike Rann (ALP) Federal representation  - House seats 11  - Senate seats 12 Gross State Product (2004-05)  - Product ($m)  $59,819 (5th)  - Product per capita  $38,838/person (7th) Population (End of September 2006)  - Population  1,558,200 (5th)  - Density  1. ... Lightning Ridge is a town of approximately 2000 persons in north-western New South Wales, Australia. ... “NSW” redirects here. ... Black-band ironstone, 2. ... There are very few or no other articles that link to this one. ...

Multi-color rough opal specimen from Virgin Valley, Nevada, USA
Multi-color rough opal specimen from Virgin Valley, Nevada, USA

Fire opal is found mostly in Mexico and Mesoamerica. In South America opal discovered in 1930 in a city called Pedro II in Brazil is still produced. In Honduras there was also some fine black opal mined from volcanic ash deposits. This opal is known for its stability.[citation needed] Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... This article is about the culture area. ...


The Virgin Valley Opal Fields Of Humboldt County in Northern Nevada produce a wide variety black, crystal, white, and fire opal.The Fire Opal mined from this locality is designated as the official gemstone of the State of Nevada. Most precious opals are wood replacements. Many specimens have a high water content, and as a result, have a greater tendency to desiccate and crack than most precious opal. Discovered in 1904 the mines are still producing gem materials in large amounts to hundreds of seasonal visitors. Three Fee Dig Mines provide the general public an opportunity to dig the gems themselves. The largest black opal in the Smithsonian Museum, possibly worth in excess of $1 million, comes from the Royal Peacock Opal Mine in the Virgin Valley.


Another source of white base opal in the United States is Spencer, Idaho. A high percentage of the opal found there occurs in thin layers. As a result, most of the production goes into the making of doublets and triplets. Spencer is a city located in Clark County, Idaho. ...


Other significant deposits of precious opal around the world can be found in the Czech Republic, Slovakia, Hungary, Turkey, Indonesia, Brazil, Honduras, Guatemala, Nicaragua and Ethiopia.


Synthetic opal

As well as occurring naturally, opals of all varieties have been synthesized experimentally and commercially. The discovery of the ordered sphere structure of precious opal led to its synthesis by Pierre Gilson in 1974 (Klein and Hurlbut, 1985, p.528). The resulting material is distinguishable from natural opal by its regularity; under magnification, the patches of color are seen to be arranged in a "lizard skin" or "chicken wire" pattern. Synthetics are further distinguished from naturals by the former's lack of fluorescence under UV light. Synthetics are also generally lower in density and are often highly porous; some may even stick to the tongue. Fluorescence induced by exposure to ultraviolet light in vials containing various sized Cadmium selenide (CdSe) quantum dots. ... Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. ...


Two notable producers of synthetic opal are the companies Kyocera and Inamori of Japan. Most so-called synthetics, however, are more correctly termed imitations, as they contain substances not found in natural opal (e.g., plastic stabilizers). The imitation opals seen in vintage jewellery are often "Slocum Stone" consisting of laminated glass with bits of foil interspersed. Kyocera Corporation ) (TYO: 6971 , NYSE: KYO) is a Japanese company based in Kyoto, Japan. ...


The Hamamatsu Photonics Group will utilise the International Space Station's Japanese Experiment Module in 2006 to grow perfect crystalline opals in microgravity over four months, as compared with five million years for naturals. Such opals will be the object of study and elements for optical filters, displays, and data storage.[4][5] “ISS” redirects here. ... ISS JAXA JEM module The Japanese Experiment Module (JEM) Kibō (希望, Hope) is the Japanese contribution to the International Space Station and is produced by Japan Aerospace Exploration Agency (JAXA) and is the largest module for the ISS. It consists of 4 components: The Pressurized Module (PM) is the core component. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... Astronauts on the International Space Station display an example of weightlessness Weightlessness is the experience (by people and objects) during freefall, of having no weight. ... The terms storage (U.K.) or memory (U.S.) refer to the parts of a digital computer that retain physical state (data) for some interval of time, possibly even after electrical power to the computer is turned off. ...


Local atomic structure of opals

The lattice of spheres of opal that cause the interference with light are several hundred times larger than the fundamental structure of crystalline silica. As a mineraloid, there is no unit cell that describes the structure of opal. Nevertheless, opals can be roughly divided into those that have show no signs of crystalline order, i.e., amorphous opal, and those that show signs of the beginning of crystalline order, commonly termed cryptocrystalline or microcrystalline opal (Graetsch, 1994). Dehydration experiments and infrared spectroscopy have shown that most of the H2O in the formula of SiO2.nH2O of opals is present in the familiar form of clusters of molecular water. Isolated water molecules, and silanols, structures such as Si-O-H, generally form a lesser proportion of the total and can reside near the surface or in defects inside the opal. A mineraloid is a mineral-like substance that does not demonstrate crystallinity. ... In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... An amorphous solid is a solid in which there is no long-range order of the positions of the atoms. ... A cryptocrystal is a rock whose texture is so finely crystalline—that is, made up of such minute crystals—that its crystalline nature is only vaguely revealed even in a thin section by transmitted polarized light. ... Infrared spectroscopy (IR spectroscopy) is the subset of spectroscopy that deals with the infrared region of the electromagnetic spectrum. ... General Silanols are compounds containing silicon atoms to which hydroxy substituents bond directly. ...


The structure of low-pressure polymorphs of anhydrous silica consist of frameworks of fully-corner bonded tetrahedra of SiO4. The higher temperature polymorphs of silica cristobalite and tridymite are frequently the first to crystallize from amorphous anhydrous silica, and the local structures of microcrystalline opals also appear to be closer to that of cristobalite and tridymite than to quartz. The structures of tridymite and cristobalite are closely related and can be described as hexagonal and cubic close-packed layers. It is therefore possible to have intermediate structures in which the layers are not regularly stacked. The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2. ... Common in volcanic rocks, cristobalite is a high-temperature polymorph of quartz and tridymite. ... Tridymite Tridymite is a high-temperature polymorph of quartz and usually occurs as minute tabular white or colorless pseudo-hexagonal triclinic crystals, or scales, in cavities in acidic volcanic rocks. ... Common in volcanic rocks, cristobalite is a high-temperature polymorph of quartz and tridymite. ... Tridymite Tridymite is a high-temperature polymorph of quartz and usually occurs as minute tabular white or colorless pseudo-hexagonal triclinic crystals, or scales, in cavities in acidic volcanic rocks. ... Fig. ...

The crystal structure of crystalline α-cristobalite. Locally, the structures of some opals, opal-C, are similar to this.
The crystal structure of crystalline α-cristobalite. Locally, the structures of some opals, opal-C, are similar to this.

Image File history File links Size of this preview: 800 × 546 pixelsFull resolution (1473 × 1006 pixel, file size: 56 KB, MIME type: image/jpeg) Ian Swainson I, the creator of this work, hereby release it into the public domain. ... Image File history File links Size of this preview: 800 × 546 pixelsFull resolution (1473 × 1006 pixel, file size: 56 KB, MIME type: image/jpeg) Ian Swainson I, the creator of this work, hereby release it into the public domain. ...

Microcrystalline opal

Opal-CT has been interpreted as consisting of clusters of stacking of cristobalite and tridymite over very short length scales. The spheres of opal in opal-CT are themselves made up of tiny microcrystalline blades of cristobalite and tridymite. Opal-CT has occasionally been further subdivided in the literature. Water content may be as high as 10 wt%. Lussatite is a synonym. There are very few or no other articles that link to this one. ...


Opal-C is interpreted as consisting of localized order of α-cristobalite with a lot of stacking disorder. Typical water content is about 1.5wt%. Lussatine is a synonym.


Non-crystalline opal

Two broad categories of non-crystalline opals, sometimes just referred to as opal-A, have been proposed


Opal-AG: Aggregated spheres of silica, with water filling the space in between. Precious opal and potch opal are generally varieties of this, the difference being in the regularity of the sizes of the spheres and their packing.


Opal-AN: Water-containing amorphous silica-glass. Hyalite is a synonym. Hyalite is a form of opal with a glassy appearance. ...


Non-crystalline silica in siliceous sediments is reported to gradually transform to opal-CT and then opal-C as a result of diagenesis, due to the increasing overburden pressure in sedimentary rocks, as some of the stacking disorder is removed (Cady et al., 1996)PDF. In geology and oceanography, diagenesis is any chemical, physical, or biological change undergone by a sediment after its initial deposition and during and after its lithification, exclusive of surface alteration (weathering) and metamorphism. ... Two types of sedimentary rock: limey shale overlaid by limestone. ... “PDF” redirects here. ...


Historical superstitions

In the middle ages, opal was considered a stone that could provide great luck because it was believed to possess all the virtues of each gemstone whose color was represented in the color spectrum of the opal. [6] However, modern superstition attributes bad luck to the stone, though some believe this is avoided if opal is the owner's birthstone (that is, the owner was born in October) or if the stone is a gift. Even under the last czar at the beginning of the 20th century, it was believed that when a Russian of any sex, of any rank, saw an opal, amongst other goods offered for sale, he or she would not buy anything more, since, in the judgement of subjects of the czar, the opal embodied the evil eye. [6] It's possible that the stone's extreme fragility (when compared to other gemstones) has contributed to this bad reputation. A birthday is the date on which a person was born. ... For other uses, see October (disambiguation). ...


Opals in popular culture

The opal is the official gemstone of South Australia and the Commonwealth of Australia, and the country's women's national team in basketball is nicknamed The Opals. For other uses, see Gemstone (disambiguation). ... Capital Adelaide Government Constitutional monarchy Governor Marjorie Jackson-Nelson Premier Mike Rann (ALP) Federal representation  - House seats 11  - Senate seats 12 Gross State Product (2004-05)  - Product ($m)  $59,819 (5th)  - Product per capita  $38,838/person (7th) Population (End of September 2006)  - Population  1,558,200 (5th)  - Density  1. ... The Australia Womens National Basketball Team named The Opals is the womens National Basketball team for Australia. ... This article is about the sport. ...


The official state gem stone for Nevada is precious black Fire Opal, in recognition of the black opal found in Virgin Valley, Humboldt County, Nevada. Humboldt County is a county located in the state of Nevada. ...


Opal is the traditional birthstone of the month of October. A birthstone is a gemstone or other semi-precious stone which is associated with a month of the Gregorian Calendar. ...


Famous opals

  • The Andamooka Opal, presented to Queen Elizabeth II, also known as the Queen's Opal
  • The Aurora Australis Opal, considered to be the most valuable black opal
  • The Black Prince Opal, originally known as Harlequin Prince
  • The Empress of Australia Opal
  • The Fire Queen Opal
  • The Flame Queen Opal
  • The Flamingo Opal
  • The Halley's Comet Opal, the world's largest uncut black opal
  • The Jupiter Five Opal
  • The Olympic Australis Opal, reported to be the largest and most valuable gem opal ever found
  • The Pride of Australia Opal, also known as the Red Emperor Opal
  • The Red Admiral Opal, also known as the Butterfly Stone

The Andamooka Opal is a famous opal which was presented to Queen Elizabeth II in the 1950s on the occasion of her first visit to Australia. ... Elizabeth II in an official portrait as Queen of Canada (on the occasion of her Golden Jubilee in 2002, wearing the Sovereigns badges of the Order of Canada and the Order of Military Merit) Her Majesty Queen Elizabeth II (Elizabeth Alexandra Mary) (born 21 April 1926), styled HM The...

See also

Wikisource has original text related to this article:

Image File history File links Wikisource-logo. ... The original Wikisource logo. ... An optical phenomenon is any observable event which results from the interaction of light and matter. ... Overview of the Karakoram Highway Upal is a small town in western Xinjiang, China. ...

References

Wikimedia Commons has media related to:
Opal
  1. ^ a b c d e f g h i j k l m Gemological Institute of America, GIA Gem Reference Guide 1995, ISBN 0-87311-019-6
  2. ^ Sanskrit, Tamil, and Pahlavi Dictionaries. U. of Cologne.
  3. ^ http://www.nrw.qld.gov.au/mines/fossicking/opal.html Queensland opal
  4. ^ "Utilization of "KIBO" in Nano-technology and Nano-science—Nature's Beauty to Be Reproduced in SpacePDF". Science & Technology in Japan No. 85. (2005).
  5. ^ 27th Space Station Utilization Workshop in Japan -outline -
  6. ^ a b Fernie M.D., W.T. (1907). Precious Stones for Curative Wear. Bristol, John Wright & Co.. , cpages 249
  • Graetsch, H., "Structural Characteristics of opaline and microcrystalline silica minerals", "Silica, physical behavior, geochemistry and materials applications". Reviews in Mineralogy, Vol. 29, 1994. Editors PJ Heaney, CT Prewitt, GV Gibbs, Mineralogical Society of America,
  • Klein, Cornelis, and Hurlbut, Cornelius S.; 1985, Manual of Mineralogy, 20th ed., ISBN 0-471-80580-7

Image File history File links Commons-logo. ... The Gemological Institute of America, or GIA, is a non-profit institute dedicated to research and education in the field of gemology. ... “PDF” redirects here. ... The opal in this bracelet contains a natural periodic microstructure responsible for its iridescent color. ...

External Links


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Hurricane Opal 1995 (1017 words)
Although Opal was barely a major hurricane - in a weakening mode - when the eye crossed the coast, property damage was rather severe.
Opal reached hurricane intensity on October 2nd, and begin a slow northward motion in response to an upper level trough moving the through the central United States.
The storm surge that occurred during Hurricane Opal, unlike the wind speeds, was constistent with a major hurricane.
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