Opal - Knowledge

1060: 1197: 507: 716: 1243: 519: 637: 800: 374: 645: 1038:-age opalised teeth, bones, fish, and a snake head have been found. Some of the opal has high water content and may desiccate and crack when dried. The largest producing mines of Virgin Valley have been the famous Rainbow Ridge, Royal Peacock, Bonanza, Opal Queen, and WRT Stonetree/Black Beauty mines. The largest unpolished black opal in the Smithsonian Institution, known as the "Roebling opal", came out of the tunneled portion of the Rainbow Ridge Mine in 1917, and weighs 2,585 carats (517.0 g; 18.24 oz). The largest polished black opal in the 628:

more artificial appearance and are not classed as precious gemstones, but rather "composite" gemstones. Jewelry applications of precious opal can be somewhat limited by opal's sensitivity to heat due primarily to its relatively high water content and predisposition to scratching. Combined with modern techniques of polishing, a doublet opal can produce a similar effect to Natural black or boulder opal at a fraction of the price. Doublet opal also has the added benefit of having genuine opal as the top visible and touchable layer, unlike triplet opals.

2337:"The central stone on the thirteenth-century crown of the Holy Roman Emperor was an opal said to be the color of pure white snow, sparkling with splashes of bright red wine: it was called "the Orphanus", perhaps because there was no other stone like it.24 And on New Year's Day 1584,25 Queen Elizabeth I was delighted to receive an opal parure—a full set of matching jewelry—from one of her favorite courtiers, Sir Christopher Hatton." Finlay, Victoria. Jewels: A Secret History (Kindle Locations 2145–2148). Random House Publishing Group. Kindle Edition. 987: 1440: 1147: 4816: 4245: 1734: 52: 951: 4804: 1304: 1087:. During the 1960s through to the mid-1970s, the Querétaro mines were heavily mined. Today's opal miners report that it was much easier to find quality opals with a lot of fire and play of color back then, whereas today the gem-quality opals are very hard to come by and command hundreds of US dollars or more. The orange-red background color is characteristic of all "fire opals," including "Mexican fire opal". 812: 1292: 1189: 1000: 1267:

to be chemically and structurally indistinguishable from a genuine one, and genuine opal contains no resins or polymers. The finest modern lab-created opals do not exhibit the lizard skin or columnar patterning of earlier lab-created varieties, and their patterns are non-directional. They can still be distinguished from genuine opals, however, by their lack of

2346:"All of these early stones were almost certainly from the ancient mines of Slovakia—the same source as Nonius’ precious stone and the Holy Roman Emperor’s red-and-white one. The mines were worked until the late nineteenth century..." Finlay, Victoria. Jewels: A Secret History (Kindle Locations 2163–2165). Random House Publishing Group. Kindle Edition. 983:. The Wollo Province opal was different from the previous Ethiopian opal finds in that it more closely resembled the sedimentary opals of Australia and Brazil, with a light background and often vivid play-of-color. Wollo Province opal, more commonly referred to as "Welo" or "Wello" opal, has become the dominant Ethiopian opal in the gem trade. 953: 957: 956: 952: 958: 1403:

over very short length scales. The spheres of opal in microcrystalline opal are themselves made up of tiny nanocrystalline blades of cristobalite and tridymite. Microcrystalline opal has occasionally been further subdivided in the literature. Water content may be as high as 10 wt%. Opal-CT, also

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light, resulting in play-of-color. Depending on the conditions in which it formed, opal may be transparent, translucent, or opaque, and the background color may be white, black, or nearly any color of the visual spectrum. Black opal is considered the rarest, while white, gray, and green opals are the

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Opals which have been created in a laboratory are often termed "lab-created opals", which, while classifiable as man-made and synthetic, are very different from their resin-based counterparts which are also considered man-made and synthetic. The term "synthetic" implies that a stone has been created

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The oldest mine in Querétaro is Santa Maria del Iris. This mine was opened around 1870 and has been reopened at least 28 times since. At the moment there are about 100 mines in the regions around Querétaro, but most of them are now closed. The best quality of opals came from the mine Santa Maria del

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falls on the talisman, the opal turns into a colorless stone and the Baroness dies soon thereafter. Due to the popularity of Scott's novel, people began to associate opals with bad luck and death. Within a year of the publishing of Scott's novel in April 1829, the sale of opals in Europe dropped by

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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. The resulting material is distinguishable from natural opal by its regularity; under magnification, the patches

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in South Australia located about 250 km (160 mi) northwest of Coober Pedy has also produced large quantities of crystal opal and the rarer black opal. Over the years, it has been sold overseas incorrectly as Coober Pedy opal. The black opal is said to be some of the best examples found in

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data from the same period (2012), reveals Australian opal production to be $ 41 million. Because of the units of measurement, it is not possible to directly compare Australian and Ethiopian opal production, but these data and others suggest that the traditional percentages given for Australian

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or plastic on the top. The cap takes a high polish and acts as a protective layer for the opal. The top layer also acts as a magnifier, to emphasize the play of color of the opal beneath, which is often an inferior specimen or an extremely thin section of precious opal. Triplet opals tend to have a

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The primary sources of opal are Australia and Ethiopia, but because of inconsistent and widely varying accountings of their respective levels of extraction, it is difficult to accurately state what proportion of the global supply of opal comes from either country. Australian opal has been cited as

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opal that exhibits a bluish glow or sheen that follows the light source around. It is not a play of color as seen in precious opal, but rather an effect from microscopic inclusions. It is also sometimes referred to as water opal, too, when it is from Mexico. The two most notable locations of this

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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

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in Mexico; these opals are commonly called Mexican fire opals. Fire opals that do not show a play of color are sometimes referred to as jelly opals. Mexican opals are sometimes cut in their rhyolitic host material if it is hard enough to allow cutting and polishing. This type of Mexican opal is

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consists of a relatively thin layer of precious opal, backed by a layer of dark-colored material, most commonly ironstone, dark or black common opal (potch), onyx, or obsidian. The darker backing emphasizes the play of color and results in a more attractive display than a lighter potch. An opal

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Astratov, V. N.; Bogomolov, V. N.; Kaplyanskii, A. A.; Prokofiev, A. V.; Samoilovich, L. A.; Samoilovich, S. M.; Vlasov, Yu. A. (1995). "Optical spectroscopy of opal matrices with CdS embedded in its pores: Quantum confinement and photonic band gap effects".

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Two broad categories of noncrystalline opals, sometimes just referred to as "opal-A" ("A" stands for "amorphous"), have been proposed. The first of these is opal-AG consisting of aggregated spheres of silica, with water filling the space in between. Precious opal and potch opal are generally

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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

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of light passing through the microstructure of the opal. The regularity of the sizes and the packing of these spheres is a prime determinant of the quality of precious opal. Where the distance between the regularly packed planes of spheres is around half the wavelength of a component of

955: 723:"Girasol opal" is a term sometimes mistakenly and improperly used to refer to fire opals, as well as a type of transparent to semitransparent type milky quartz from Madagascar which displays an asterism, or star effect when cut properly. However, the true girasol opal is a type of 1568:

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. It was also said to grant invisibility if wrapped in a fresh

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Fire opal is a transparent to translucent opal with warm body colors of yellow to orange to red. Although fire opals don't usually show any play of color, they occasionally exhibit bright green flashes. The most famous source of fire opals is the state of

975:. This Shewa Province opal was mostly dark brown in color and had a tendency to crack. These qualities made it unpopular in the gem trade. In 2008, a new opal deposit was found approximately 180 km north of Shewa Province, near the town of 3696: 1106:, which produces an opaque opal similar to the opals from Australia (some of these opals are carefully treated with heat to improve their colors so high-quality opals from this area may be suspect). There are also some small opal mines in 493:); common opal does not. Play-of-color is defined as "a pseudo chromatic optical effect resulting in flashes of colored light from certain minerals, as they are turned in white light." The internal structure of precious opal causes it to 767:. This sedimentary rock is white, opaque, and chalky in texture. Diatomite has multiple industrial uses such as filtering or adsorbing since it has a fine particle size and very porous nature, and gardening to increase water absorption. 3339:

Graetsch, H. (1994). Heaney, P. J.; Prewitt, Connecticut; Gibbs, G. V. (eds.). "Structural characteristics of opaline and microcrystalline silica minerals. Silica, physical behavior, geochemistry and materials applications".

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A 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 a play of color. Blue opal also comes from

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produce a wide variety of precious black, crystal, white, fire, and lemon opal. The black fire opal is the official gemstone of Nevada. Most of the precious opal is partial wood replacement. The precious opal is hosted and found

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appeared in 1994, with the discovery of precious opal in the Menz Gishe District, North Shewa Province. The opal, found mostly in the form of nodules, was of volcanic origin and was found predominantly within weathered layers of

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However, the argument for the Sanskrit origin is strong. The term first appears in Roman references around 250 BC, at a time when the opal was valued above all other gems. The opals were supplied by traders from the

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Even as recently as the beginning of the 20th century, it was believed that when a Russian saw an opal among other goods offered for sale, he or she should not buy anything more, as the opal was believed to embody the

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Precious opal shows a variable interplay of internal colors, and though it is a mineraloid, it has an internal structure. At microscopic scales, precious opal is composed of silica spheres some 150–300 nm

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created by the stacked planes. The colors that are observed are determined by the spacing between the planes and the orientation of planes with respect to the incident light. The process can be described by

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Other research in macroporous structures have yielded highly ordered materials that have similar optical properties to opals and have been used in cosmetics. Synthetic opals are also deeply investigated in

3816: 3868: 3761: 954: 1275:. While many genuine opals are cut and polished without a matrix, the presence of irregularities in their play-of-color continues to mark them as distinct from even the best lab-created synthetics. 3700: 618:. "Natural" opal refers to polished stones consisting wholly of precious opal. Opals too thin to produce a "natural" opal may be combined with other materials to form "composite" gems. An opal 1098:

In 1957, Alfonso Ramirez (of Querétaro) accidentally discovered the first opal mine in Jalisco: La Unica, located on the outer area of the volcano of Tequila, near the Huitzicilapan farm in

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opal production may be overstated. Yet, the validity of data in the USGS report appears to conflict with that of Laurs et al. and Mesfin, who estimated the 2012 Ethiopian opal output (from

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Opal was rare and very valuable in antiquity. In Europe, it was a gem prized by royalty. Until the opening of vast deposits in Australia in the 19th century the only known source was

1534:. This word has two meanings, one is related to "seeing" and forms the basis of the English words like "opaque"; the other is "other" as in "alias" and "alter". It is claimed that 1421:

varieties of this, the difference being in the regularity of the sizes of the spheres and their packing. The second "opal-A" is opal-AN or water-containing amorphous silica-glass.

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referred to as a Cantera opal. Another type of opal from Mexico, referred to as Mexican water opal, is a colorless opal that exhibits either a bluish or golden internal sheen.

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accounting for 80% of the world's supply. In 2012, Ethiopian opal production was estimated to be 14,000 kg (31,000 lb) by the United States Geological Survey.

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varieties that show a play of color, the other kinds of common opal include the milk opal, milky bluish to greenish (which can sometimes be of gemstone quality);

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which has developed an opalescent sheen or, more rarely, where the wood has been completely replaced by opal. Other names for this opalized sheen-like wood are

1560:, who claimed the gems were being supplied from India. Before this, the stone was referred to by a variety of names, but these fell from use after 250 BC. 906:, is the main source of black opal, opal containing a predominantly dark background (dark gray to blue-black displaying the play of color), collected from the 719:

Brazilian Precious Opal with patches of brilliant color throughout. The brightness of the fire in opal ranges on a scale of 1 to 5 (with 5 being the brightest)

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The lattice of spheres of opal that cause interference with light is several hundred times larger than the fundamental structure of crystalline silica. As a

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Other significant deposits of precious opal around the world can be found in the Czech Republic, Canada, Slovakia, Hungary, Turkey, Indonesia, Brazil (in

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Lova, Paola; Congiu, Simone; Sparnacci, Katia; Angelini, Angelo; Boarino, Luca; Laus, Michele; Stasio, Francesco Di; Comoretto, Davide (8 April 2020).

2177: 1102:. By 1960 there were around 500 known opal mines in this region alone. Other regions of the country that also produce opals (of lesser quality) are 2653: 2520: 2493: 1412:, is interpreted as consisting of localized order of α-cristobalite with a lot of stacking disorder. Typical water content is about 1.5 wt%. 3920: 2676: 3842: 1764: – metal foil sometimes used to create reflection and sparkle behind milky glass or quartz faces in costume jewelry simulating real opal 1646: 660:

opal, which is honey-yellow with a resinous luster; wood opal, which is caused by the replacement of the organic material in wood with opal;

2930: 2247: 1351:, structures such as SiOH, generally form a lesser proportion of the total and can reside near the surface or in defects inside the opal. 1042:

comes from the Royal Peacock opal mine in the Virgin Valley, weighing 160 carats (32 g; 1.1 oz), known as the "Black Peacock".

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It has been reported that Northern African opal was used to make tools as early as 4000 BC. The first published report of gem opal from

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Precious Mexican Fire Opal has bright green and yellow patches (play of color) with an orange-red background typical of Fire Opal.

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and therefore the appearance of tiny opals when viewed under a microscope. These cell walls or "tests" form the “grains” for the

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describes the structure of opal. Nevertheless, opals can be roughly divided into those that show no signs of crystalline order (

6235: 6144: 554:. It was shown by J. V. Sanders in the mid-1960s that these ordered silica spheres produce the internal colors by causing the 3733: 3655: 2457: 2365: 2208: 2108: 1091:

Iris, followed by La Hacienda la Esperanza, Fuentezuelas, La Carbonera, and La Trinidad. Important deposits in the state of

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may range from 3% to 21% by weight, but is usually between 6% and 10%. Due to its amorphous property, it is classified as a

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Noncrystalline silica in siliceous sediments is reported to gradually transform to opal-CT and then opal-C as a result of

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do not occur until after the Romans had taken over the Greek states in 180 BC and they had previously used the term

3191: 3030: 6076: 2571: 3490: 1898: 3223:"Core–shell silica–rhodamine B nanosphere for synthetic opals: from fluorescence spectral redistribution to sensing" 2596: 2916: 2894: 2439: 1914: 1886: 1486:. The origin of this word in turn is a matter of debate, but most modern references suggest it is adapted from the 1355: 1255:

of color are seen to be arranged in a "lizard skin" or "chicken wire" pattern. Furthermore, synthetic opals do not

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remains, including dinosaur bones in New South Wales and South Australia, and marine creatures in South Australia.

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in South Australia is also a major producer of matrix opal, crystal opal, and black opal. Another Australian town,

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Finlay, Victoria. Jewels: A Secret History (Kindle Location 1871). Random House Publishing Group. Kindle Edition.

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combined these uses, meaning "to see a change in color". However, historians have noted the first appearances of

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Tétreault, N.; Míguez, H.; Ozin, G. A. (2004). "Silicon Inverse Opal—A Platform for Photonic Bandgap Research".

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layers. It is therefore possible to have intermediate structures in which the layers are not regularly stacked.

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in 1829, opal acquired a less auspicious reputation. In Scott's novel, the Baroness of Arnheim wears an opal

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O of opals is present in the familiar form of clusters of molecular water. Isolated water molecules, and

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Opal cameo (jewellery-case) of a profile head of a helmeted warrior, attributed to Wilhelm Schmidt

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Visible light cannot pass through large thicknesses of the opal. This is the basis of the optical

5778: 4871: 4847: 4278: 3418:"HRTEM of microcrystalline opal in chert and porcelanite from the Monterey Formation, California" 2313: 1376: 1205: 1039: 1008: 318: 109: 5152: 2934: 1018: 489:

There are two broad classes of opal: precious and common. Precious opal displays play-of-color (

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is commonly used to describe this unique and beautiful phenomenon, which in gemology is termed

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Johnson, Mary L.; Kammerling, Robert C.; DeGhionno, Dino G.; Koivula, John I. (Summer 1996).

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sheen of common or potch opal which does not show a play of color. Opalescence is a form of

6091: 6011: 5908: 5515: 5172: 4154: 3432: 3383: 3297: 3234: 2776: 2134: 2066: 2023: 1826: 1657: 799: 700:, this optical effect is strictly defined as opalescence which is a form of adularescence. 8: 5510: 3813:"$ 4 million worth of the South Australian Museum's opal collection for display in Qatar" 3166: 3052: 2262: 1719: 1503:, one theory attributed the name's origin to Roman mythology: to have been adapted from 1380: 1268: 709: 588: 568: 198: 188: 3600: 3436: 3387: 3301: 3238: 2909:"Stonetree Opal Mine, WRT Stonetree group, Virgin Valley District, Humboldt Co., Nevada" 2138: 2070: 2027: 1830: 1135: 6159: 5948: 4919: 4899: 4840: 4714: 4271: 3936: 3448: 3321: 3265: 3222: 2625: 2150: 2039: 1844: 1587: 1508: 1323:

opal) and those that show signs of the beginning of crystalline order, commonly termed

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matrix. It is found sporadically in western Queensland, from Kynuna in the north, to

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light. Synthetics are also generally lower in density and are often highly porous.

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Artificial opal (made by drying a monodisperse sub-micrometer polystyrene sphere

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and held in the hand. As a result, the opal was seen as the patron gemstone for

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accounting for 95–97% of the world's supply of precious opal, with the state of

587:. In addition, microfractures may be filled with secondary silica and form thin 6215: 6173: 6168: 6126: 6026: 5966: 5724: 5668: 5656: 5585: 5229: 5167: 4677: 4514: 4225: 4104: 4083: 3905: 3538: 1635: 1439: 1219: 1155: 1146: 1031: 980: 573: 428: 119: 5835: 4944: 3616: 2997:"If you've ever wanted an opal – it's time to visit Spencer | East Idaho News" 2078: 1784: – Observable events that result from the interaction of light and matter 1026:, which is considered a "lode" deposit. Opals which have weathered out of the 6209: 6116: 6101: 6041: 6031: 5928: 5923: 5888: 5799: 5729: 5688: 5356: 5110: 5095: 5044: 4709: 3317: 3256: 3145: 3022: 2581: 1465: 1247: 1080: 749: 608: 564: 408: 284: 142: 4620: 4354: 3444: 623:

triplet is similar to a doublet but has a third layer, a domed cap of clear

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is a major source of opal. The world's largest and most valuable gem opal "

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Rare dinosaur fossil discovered on internet after disappearing for decades

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Another source of white base opal or creamy opal in the United States is

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Opal occurs in significant quantity and variety in central Mexico, where

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molecules arranged in regular, closely packed planes (idealized diagram).

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Yager, Thomas R. (1 December 2013), "The Mineral Industry of Ethiopia",

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First dinosaur named in NSW in nearly a century after chance discovery

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Tse, Pui-Kwan (1 December 2013), "The Mineral Industry of Australia",

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Colorless, white, yellow, red, orange, green, brown, black, blue, pink

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The Rainbow Virgin, "the finest crystal opal specimen ever unearthed"

1400: 1371: 1320: 1316: 1299:. Locally, the structures of some opals, opal-C, are similar to this. 1280: 1166: 1023: 976: 915: 833: 693: 669: 604: 518: 475: 436: 388: 2199:

Gribble, C. D. (1988). "Tektosilicates (framework silicates)".

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Mexican opal may read as low as 1.37, but typically reads 1.42–1.43

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Office for Technology Commercialization, Technology Marketing Site

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Single refractive, often anomalous double refractive due to strain

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Barot, N. (1994). "New precious opal deposit found in Ethiopia".

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Gemmological classifications by E. Ya. Kievlenko (1980), updated

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consists of frameworks of fully corner bonded tetrahedra of SiO

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Multicolored rough opal specimen from Virgin Valley, Nevada, US

939: 927: 811: 756: 745: 737: 729: 689: 681: 624: 448: 89: 5683: 5673: 5663: 5646: 5641: 5631: 5590: 5420: 5400: 5336: 5268: 5009: 4984: 4929: 4604: 4571: 4477: 4467: 4426: 4134: 4109: 4055: 4050: 3802: 2057:

Sanders, J. V. (1968). "Diffraction of light by opals".

1683:

in New York City are often said to be opal, they are in fact

1649:

from Andamooka, "the finest known opalised skeleton on Earth"

1547: 1541: 1529: 1477: 1291: 1188: 999: 919: 804: 657: 51: 4832: 4263: 1696:, listed as the "World's Largest Polished Opal" in the 1992 1524:

Another common claim was that the term was adapted from the

5555: 5525: 5475: 5237: 4759: 4693: 4334: 4164: 3416:

Cady, S. L.; Wenk, H.-R.; Downing, K. H. (1996).

3220: 1628:, the world's largest and most valuable gem opal, found in 1177: 1173: 444: 20: 3584:(1997). "A Chronological History and Mythology of Opals". 1395:

has been interpreted as consisting of clusters of stacked

708:"Girasol" redirects here. For the American sunflower, see 614:

For gemstone use, most opal is cut and polished to form a

1504: 692:

shells or tests. Common opal often displays a hazy-milky-

2965:"Opal from Querétaro, Mexico: Occurrence and Inclusions" 2748:"Play-of-color from Wegeltena, Wollo Province, Ethiopia" 1679:

Although the clock faces above the information stand in

1452:

The surface of opal in contact with water is covered by

603:. In gemology, opalescence is applied to the hazy-milky- 3650:. Chichester: John Wiley & Sons. pp. 67, 126. 2513:

United States Geological Survey, 2012 Minerals Yearbook

2486:

United States Geological Survey, 2012 Minerals Yearbook

2012:

Sanders, J. V. (1964). "Colour of precious opal".

1786:

Pages displaying short descriptions of redirect targets

474:), which means 'jewel', and later the Greek derivative 3939:

Australian Opal Fields – Map of precious opal deposits

3192:"Macroporous Structures, Metal Oxides, Highly Ordered" 1443:

Schematic representation of the hydrated opal surface.

1327:

or microcrystalline opal. Dehydration experiments and

926:

in the south. Its largest quantities are found around

463: 2667: 2665: 2168:

Dr. Joel Arem; Donald Clark, CSM IMG (23 June 2015).

3699:. National Museum of Natural History. Archived from 2933:. National Museum of Natural History. Archived from 1766:

Pages displaying wikidata descriptions as a fallback

1757:

Pages displaying wikidata descriptions as a fallback

1729: 1718:, the first known example of an opal with an insect 1712:, assumed to be "the finest uncut opal in existence" 1705:

The Sea of Opal, the largest black opal in the world

1652:

The Burning of Troy, the now-lost opal presented to

1436:

rocks, as some of the stacking disorder is removed.

3588:. New York: John Wiley & Sons. pp. 53–118. 3287: 2388:"Yowah Nut: Yowah Nut mineral information and data" 2203:(27th ed.). London: Unwin Hyman. p. 431. 1778: – Trade name for opal and moonstone simulants 1600:50%, and remained low for the next 20 years or so. 2662: 2096: 1460:groups (≡Si–OH). This makes the opal surface very 6207: 1071:and production first originated in the state of 547:10 in) in diameter in a hexagonal or cubic 56:A rich seam of iridescent opal encased in matrix 5865: 3415: 2460:. Government of South Australia. Archived from 2095:Klein, Cornelis; Hurlbut, Cornelius S. (1985). 1447: 1432:, due to the increasing overburden pressure in 591:inside the opal during its formation. The term 2799:"Virgin Valley District, Humboldt Co., Nevada" 2594: 2314:"diatomite – The Mineral and Gemstone Kingdom" 1491: 1366:. The higher temperature polymorphs of silica 990:Gem grade Ethiopian Welo precious opal pendant 5851: 4848: 4279: 3958: 3918:Opal Fossils from the South Australian Museum 3598: 2659:, 3 December 2018. Retrieved 3 December 2018. 2644:, 5 December 2018. Retrieved 5 December 2018. 2597:"The black-opal hunters of outback Australia" 2564:A history of South Australian opal, 1840–2005 323:green stones: 660 nm, 470 nm cutoff 4437: 3140:. Washington: Gov. Print. Off. p. 238. 3053:"NASA probe finds opals in Martian crevices" 2595:Osborne, Zoe; Kitanov, Alex (17 July 2022). 2094: 1511:, and goddess of fertility. (The portion of 1271:and the absence of any surrounding non-opal 1176:announced the discovery of opal deposits on 776: 33:"Opals" redirects here. For other uses, see 2237: 2235: 1563: 1535: 1516: 1481: 1283:for sensing and light management purposes. 703: 5858: 5844: 4855: 4841: 4803: 4286: 4272: 3965: 3951: 3523:. Bristol: John Wright & Co. pp. 2241: 1689:The Roebling Opal, Smithsonian Institution 1218:, is a form of opal, as well as a type of 1095:were not discovered until the late 1950s. 914:and fracture fillings in a dark siliceous 836:) to be only 750 kg (1,650 lb). 50: 3914:: International Colored Stone Association 3512: 3510: 3508: 3506: 3471: 3469: 3264: 3246: 3198:. University of Minnesota. 25 June 2010. 3023:"Boi Morto Mine, Pedro II, Piauí, Brazil" 2980: 2759: 2730: 2380: 1838: 1595:with supernatural powers. When a drop of 1286: 3721: 3338: 3133: 2232: 1515:devoted to Ops was "Opalia", similar to 1438: 1386: 1302: 1290: 1250:) viewed by darkfield optical microscopy 1241: 1195: 1187: 1145: 1058: 998: 994: 985: 949: 810: 798: 714: 643: 635: 517: 505: 372: 3537: 3485:. John Wiley and Sons. pp. 56–57. 2962: 2787:from the original on 24 September 2014. 2745: 2223: 2198: 2090: 2088: 2056: 2011: 1295:The crystal structure of crystalline α- 1022:within a subsurface horizon or zone of 815:Boulder opal, Carisbrooke Station near 6208: 3642: 3633:, University of California Press, 1961 3580: 3516: 3503: 3475: 3466: 3369: 2774: 2440:"Rapaport Magazine – A Designer Stone" 1882: 1880: 1878: 1676:, the world's largest uncut black opal 1415: 870: in (120 mm) and a width of 419:forms of silica, which are considered 147:Irregular veins, in masses, in nodules 5839: 4836: 4267: 3946: 3931:Opal Mineral data and specimen images 3819:from the original on 17 December 2017 3790:from the original on 29 December 2015 3764:from the original on 17 December 2017 2697: 2679:from the original on 13 February 2014 2482: 2428:from the original on 29 January 2011. 2250:from the original on 7 November 2011. 2180:from the original on 23 November 2016 1876: 1874: 1872: 1870: 1868: 1866: 1864: 1862: 1860: 1858: 1499:As references to the gem are made by 1030:deposits are alluvial and considered 530:, displays nearly every color of the 510:Precious opal consists of spheres of 3742:from the original on 26 August 2016. 3462:from the original on 1 October 2011. 3372:"The structure of opal-CT revisited" 3065:from the original on 19 January 2009 2715:"Opal from Shewa Province, Ethiopia" 2561: 2551:from the original on 6 October 2014. 2545:"Rapaport Magazine – Ethiopian Opal" 2446:from the original on 6 October 2014. 2260: 2085: 1917:from the original on 18 October 2011 1815:"IMA–CNMNC approved mineral symbols" 1812: 1476:The word 'opal' is adapted from the 3972: 3499:from the original on 26 April 2016. 2919:from the original on 30 April 2012. 2897:from the original on 30 April 2012. 2875:from the original on 30 April 2012. 2853:from the original on 30 April 2012. 2831:from the original on 30 April 2012. 2809:from the original on 30 April 2012. 2777:"Opal Trade Transforms North Wollo" 2526:from the original on 6 October 2014 2509: 2499:from the original on 6 October 2014 2458:"Opal – South Australia's Gemstone" 1943:from the original on 6 October 2011 1581:. Following the publication of Sir 1204:backbone, as a display specimen in 458:is believed to be derived from the 13: 5899:Extrusion / Drawing (glass fibers) 4392: 3845:from the original on 19 March 2017 3725:"The Guinness Book of Records 1993 3202:from the original on 24 March 2012 3137:Catalogue of minerals and synonyms 2566:. Lightning Ridge, NSW: Len Cram. 2288:"Opal – Nevada Mining Association" 1855: 1141: 14: 6257: 5894:Blowing and pressing (containers) 3887: 3871:from the original on 26 June 2017 3839:"Largest black opal in the world" 3520:Precious Stones for Curative Wear 3376:Journal of Non-Crystalline Solids 2746:Rondeau, Benjamin (Summer 2010). 2242:Swisher, James; Anthony, Edna B. 1237: 1007:The Virgin Valley opal fields of 648:White and blue opal from Slovakia 431:, being most commonly found with 16:Hydrated amorphous form of silica 4814: 4802: 4243: 3396:10.1016/j.jnoncrysol.2014.08.052 3033:from the original on 12 May 2011 2775:Gashaw, Yidneka (8 April 2012). 2398:from the original on 12 May 2011 2170:"Opal Value, Price, and Jewelry" 1967:Gemological Institute of America 1887:Gemological Institute of America 1732: 1642:, also known as the Queen's Opal 1464:and capable of forming numerous 696:sheen from within the stone. In 501: 213:opaque, translucent, transparent 4416:Yellow, Green, Violet Sapphires 3857: 3831: 3776: 3746: 3722:Guinness, Medd (October 1992). 3715: 3689: 3664: 3636: 3623: 3605:Chemical & Engineering News 3592: 3574: 3549: 3531: 3517:Fernie, William Thomas (1907). 3409: 3363: 3352: 3332: 3281: 3214: 3184: 3159: 3127: 3102: 3077: 3045: 3015: 2989: 2956: 2941: 2923: 2901: 2879: 2857: 2835: 2813: 2791: 2768: 2739: 2706: 2691: 2647: 2632: 2614: 2588: 2555: 2537: 2503: 2476: 2450: 2432: 2410: 2358: 2349: 2340: 2331: 2306: 2280: 2254: 2217: 2201:Rutley's Elements of Mineralogy 2192: 2161: 2117: 1165:), Honduras (more precisely in 3599:Goldberg-Gist, Arlene (2003). 2366:"Australian National Gemstone" 2261:Page, Geology (21 June 2016). 2050: 2005: 1980: 1955: 1929: 1903: 1806: 1354:The structure of low-pressure 1183: 938:. Australia also has opalized 631: 522:This precious rough opal from 1: 6236:National symbols of Australia 4862: 4293: 3894:Farlang opal Hist. References 2226:Opal Identification and Value 1799: 1331:have shown that most of the H 1169:), Guatemala, and Nicaragua. 783:beyond the Roman frontier in 377:Main opal producing countries 6077:Machine drawn cylinder sheet 4808:List of gemstones by species 4777:List of individual gemstones 4438:Precious White and Fire Opal 3557:"Opal Symbolism and Legends" 2244:"Let's Talk Gemstones: Opal" 1615:for people born in October. 1548: 1542: 1530: 1471: 1448:Opal surface chemical groups 839: 476: 7: 6190:Glossary of glass art terms 3867:. South Australian Museum. 3815:. South Australian Museum. 3786:. South Australian Museum. 2675:. South Australian Museum. 1725: 1618: 1492: 945: 910:. Boulder opal consists of 464: 10: 6262: 6246:Symbols of New South Wales 6221:Emblems of South Australia 1496:meaning ‘precious stone’. 1425:is another name for this. 794: 770: 707: 664:, which is brown or grey; 481: 32: 25: 18: 6182: 6135: 5957: 5874: 5792: 5754: 5697: 5619: 5390: 5327: 5266: 5228: 5221: 5181: 5083: 5037: 5030: 4870: 4800: 4792:List of sapphires by size 4769: 4657: 4595: 4542: 4533: 4446: 4406: 4363: 4318: 4308: 4301: 4239: 4196: 4173: 4125: 4118: 4097: 4069: 4036: 3983: 3927:Accessed 19 October 2016. 3896:Localities, anecdotes by 3617:10.1021/cen-v081n004.p058 3601:"What's that Stuff? Opal" 3561:International Gem Society 3058:Jet Propulsion Laboratory 2952:: 1522, 1542. March 1971. 2424:. Australian Government. 2224:Downing, Paul B. (1992). 2079:10.1107/S0567739468000860 1988:"Glossary: Play of Color" 1658:Napoleon I of France 1391:Microcrystalline opal or 1045: 777: 469: 364: 335: 327: 317: 303: 293: 283: 262: 254: 246: 236: 217: 207: 197: 187: 174: 161: 151: 141: 133: 128: 118: 108: 76: 66: 61: 49: 44: 6107:Satsuma Kiriko cut glass 5919:Overflow downdraw method 5914:Precision glass moulding 5909:Drawing (optical fibers) 4787:List of emeralds by size 3923:13 February 2014 at the 3728:. Guinness. p. 22. 3110:"Wood Opal - mindat.org" 2103:(20th ed.). Wiley. 2059:Acta Crystallographica A 1698:Guinness Book of Records 1660:and the first named opal 1654:Joséphine de Beauharnais 1564:Historical superstitions 1230:. It is often used as a 1200:Precious opal replacing 884: in (110 mm). 744:region, as well as from 704:Varieties of common opal 6160:Shock metamorphic glass 5357:Nickel silver (alpacca) 3672:"cameo; jewellery-case" 3445:10.2138/am-1996-11-1211 1891:GIA Gem Reference Guide 1755: – variety of opal 1611:Opal is considered the 1335:O in the formula of SiO 1228:opalized petrified wood 1206:South Australian Museum 1040:Smithsonian Institution 807:(Yowah Nut), Queensland 787:. Opal is the national 755:Opal is also formed by 688:, the accumulations of 3784:"Opals media releases" 3310:10.1002/adma.200400618 2963:Koivula, John (1983). 2492:, pp. 17.1–17.5, 1819:Mineralogical Magazine 1681:Grand Central Terminal 1536: 1517: 1482: 1456:bonds (≡Si–O–Si≡) and 1444: 1308: 1300: 1287:Local atomic structure 1251: 1208: 1193: 1151: 1064: 1004: 991: 963: 908:Griman Creek Formation 819: 808: 720: 649: 641: 535: 515: 427:of almost any kind of 378: 331:darkening upon heating 35:Opals (disambiguation) 5698:Other natural objects 4355:Natural marine pearls 3425:American Mineralogist 3370:Wilson, M.J. (2014). 3342:Reviews in Mineralogy 3134:Egleston, T. (1887). 2732:10.5741/GEMS.32.2.112 2519:, pp. 3.1–3.27, 1442: 1387:Microcrystalline opal 1329:infrared spectroscopy 1306: 1294: 1245: 1199: 1191: 1149: 1062: 1002: 995:Virgin Valley, Nevada 989: 961: 936:South West Queensland 814: 802: 761:structural coloration 718: 647: 639: 521: 509: 376: 28:Opal (disambiguation) 19:For the company, see 6022:Cylinder blown sheet 5173:Wire wrapped jewelry 5153:Repoussé and chasing 4474:, pink, yellow-green 3431:(11–12): 1380–1395. 2982:10.5741/GEMS.19.2.87 2821:"Rainbow Ridge Mine" 2761:10.5741/GEMS.46.2.90 2394:. 20 February 2011. 2292:www.nevadamining.org 2133:(11–12): 1349–1354. 2099:Manual of Mineralogy 250:Vitreous to resinous 26:For other uses, see 6145:Radiative processes 5960:historic techniques 5884:Float glass process 5715:Ebonite (vulcanite) 4821:Minerals portal 4393:Precious Black Opal 4250:Minerals portal 3933:Mineralogy Database 3841:. 25 October 2016. 3697:"The Dynamic Earth" 3543:Wicca Candle Magick 3437:1996AmMin..81.1380C 3388:2014JNCS..405...68W 3302:2004AdM....16.1471T 3239:2020RSCAd..1014958L 3233:(25): 14958–14964. 2969:Gems & Gemology 2937:on 7 November 2012. 2752:Gems & Gemology 2719:Gems & Gemology 2628:on 13 October 2007. 2139:1995NCimD..17.1349A 2071:1968AcCrA..24..427S 2028:1964Natur.204.1151S 1840:10.1180/mgm.2021.43 1831:2021MinM...85..291W 1813:Warr, L.N. (2021). 1674:Halley's Comet Opal 1416:Noncrystalline opal 1307:Lussatite (opal-CT) 889:Mintabie Opal Field 803:Polished opal from 710:Jerusalem artichoke 676:, deposited around 328:Diagnostic features 193:Subvitreous to waxy 5939:Chemical polishing 5060:Jewellery designer 4643:Opaque iridescent 4534:Jewelry-Industrial 4480:yellow, blue, pink 3676:The British Museum 3648:The World of Opals 3586:The World of Opals 3482:The World of Opals 3290:Advanced Materials 3248:10.1039/D0RA02245D 2562:Cram, Len (2006). 2294:. 19 December 2017 2147:10.1007/bf02457208 2127:Il Nuovo Cimento D 2022:(496): 1151–1153. 1963:"Opal Description" 1647:Addyman Plesiosaur 1640:Queen Elizabeth II 1588:Anne of Geierstein 1445: 1381:cubic close-packed 1309: 1301: 1252: 1209: 1194: 1152: 1065: 1005: 992: 964: 962:Opal from Ethiopia 820: 817:Winton, Queensland 809: 765:diatomaceous earth 721: 686:diatomaceous earth 650: 642: 536: 516: 379: 319:Absorption spectra 255:Optical properties 6241:Silica polymorphs 6203: 6202: 6137:Natural processes 6052:Fourcault process 5833: 5832: 5750: 5749: 5620:Organic gemstones 5217: 5216: 4830: 4829: 4658:Industrial stones 4653: 4652: 4529: 4528: 4261: 4260: 4257: 4256: 4145:Chrome chalcedony 4119:Notable varieties 4038:Cryptocrystalline 3760:. 2 August 2015. 3735:978-0-85112-978-5 3657:978-0-471-13397-1 3545:. pp. 84–85. 3296:(16): 1471–1476. 2622:"Queensland opal" 2228:. pp. 55–61. 2210:978-0-04-549011-0 2110:978-0-471-80580-9 2036:10.1038/2041151a0 1782:Optical phenomena 1710:Fire of Australia 1626:Olympic Australis 1325:cryptocrystalline 959: 854:Olympic Australis 740:and Idaho in the 728:type of opal are 640:Common rough opal 371: 370: 359:hydrofluoric acid 6253: 5867:Glass production 5860: 5853: 5846: 5837: 5836: 5277:Britannia silver 5226: 5225: 5035: 5034: 4857: 4850: 4843: 4834: 4833: 4819: 4818: 4817: 4806: 4805: 4782:List of diamonds 4540: 4539: 4316: 4315: 4288: 4281: 4274: 4265: 4264: 4248: 4247: 4246: 4216:Herkimer diamond 4123: 4122: 3967: 3960: 3953: 3944: 3943: 3881: 3880: 3878: 3876: 3861: 3855: 3854: 3852: 3850: 3835: 3829: 3828: 3826: 3824: 3809: 3800: 3799: 3797: 3795: 3780: 3774: 3773: 3771: 3769: 3750: 3744: 3743: 3719: 3713: 3712: 3710: 3708: 3693: 3687: 3686: 3684: 3682: 3668: 3662: 3661: 3644:Eckert, Allan W. 3640: 3634: 3627: 3621: 3620: 3596: 3590: 3589: 3582:Eckert, Allan W. 3578: 3572: 3571: 3569: 3567: 3553: 3547: 3546: 3535: 3529: 3528: 3514: 3501: 3500: 3477:Eckert, Allan W. 3473: 3464: 3463: 3461: 3422: 3413: 3407: 3406: 3404: 3402: 3367: 3361: 3359:Opal-CT on Midat 3356: 3350: 3349: 3336: 3330: 3329: 3285: 3279: 3278: 3268: 3250: 3218: 3212: 3211: 3209: 3207: 3188: 3182: 3181: 3179: 3177: 3163: 3157: 3156: 3154: 3152: 3131: 3125: 3124: 3122: 3120: 3106: 3100: 3099: 3097: 3095: 3081: 3075: 3074: 3072: 3070: 3049: 3043: 3042: 3040: 3038: 3019: 3013: 3012: 3010: 3008: 2993: 2987: 2986: 2984: 2960: 2954: 2953: 2950:Lapidary Journal 2945: 2939: 2938: 2927: 2921: 2920: 2905: 2899: 2898: 2883: 2877: 2876: 2861: 2855: 2854: 2839: 2833: 2832: 2817: 2811: 2810: 2795: 2789: 2788: 2772: 2766: 2765: 2763: 2743: 2737: 2736: 2734: 2710: 2704: 2703: 2695: 2689: 2688: 2686: 2684: 2669: 2660: 2651: 2645: 2636: 2630: 2629: 2624:. Archived from 2618: 2612: 2611: 2609: 2607: 2592: 2586: 2585: 2559: 2553: 2552: 2541: 2535: 2534: 2533: 2531: 2525: 2518: 2507: 2501: 2500: 2498: 2491: 2480: 2474: 2473: 2471: 2469: 2454: 2448: 2447: 2436: 2430: 2429: 2414: 2408: 2407: 2405: 2403: 2384: 2378: 2377: 2375: 2373: 2362: 2356: 2353: 2347: 2344: 2338: 2335: 2329: 2328: 2326: 2324: 2318:www.minerals.net 2310: 2304: 2303: 2301: 2299: 2284: 2278: 2277: 2275: 2273: 2258: 2252: 2251: 2239: 2230: 2229: 2221: 2215: 2214: 2196: 2190: 2189: 2187: 2185: 2165: 2159: 2158: 2121: 2115: 2114: 2102: 2092: 2083: 2082: 2054: 2048: 2047: 2009: 2003: 2002: 2000: 1998: 1984: 1978: 1977: 1975: 1973: 1959: 1953: 1952: 1950: 1948: 1933: 1927: 1926: 1924: 1922: 1907: 1901: 1884: 1853: 1852: 1842: 1810: 1787: 1767: 1758: 1742: 1737: 1736: 1735: 1685:opalescent glass 1665:Flame Queen Opal 1551: 1545: 1539: 1533: 1520: 1495: 1485: 1214:, also known as 1136:Estado de México 979:, in Ethiopia's 960: 883: 882: 878: 875: 869: 868: 864: 861: 782: 781: 674:siliceous sinter 585:photonic crystal 576:of diffraction. 546: 542: 532:visible spectrum 485: 479: 473: 467: 277: 276: 275: 264:Refractive index 232: 231: 230: 219:Specific gravity 180: 83: 82:(repeating unit) 54: 42: 41: 6261: 6260: 6256: 6255: 6254: 6252: 6251: 6250: 6226:Glass in nature 6206: 6205: 6204: 6199: 6195:Glass recycling 6178: 6131: 6037:Enamelled glass 5959: 5953: 5944:Diamond turning 5934:Flame polishing 5876: 5870: 5864: 5834: 5829: 5788: 5746: 5735:Spondylus shell 5693: 5615: 5386: 5372:Stainless steel 5323: 5307:Sterling silver 5267:Precious metal 5262: 5230:Precious metals 5213: 5177: 5079: 5026: 4866: 4861: 4831: 4826: 4815: 4813: 4796: 4765: 4649: 4591: 4535: 4525: 4442: 4402: 4359: 4304: 4297: 4292: 4262: 4253: 4244: 4242: 4235: 4192: 4169: 4114: 4093: 4065: 4032: 3979: 3971: 3925:Wayback Machine 3912:ICA's Opal Page 3890: 3885: 3884: 3874: 3872: 3863: 3862: 3858: 3848: 3846: 3837: 3836: 3832: 3822: 3820: 3811: 3810: 3803: 3793: 3791: 3782: 3781: 3777: 3767: 3765: 3752: 3751: 3747: 3736: 3720: 3716: 3706: 3704: 3695: 3694: 3690: 3680: 3678: 3670: 3669: 3665: 3658: 3641: 3637: 3628: 3624: 3597: 3593: 3579: 3575: 3565: 3563: 3555: 3554: 3550: 3539:Dunwich, Gerina 3536: 3532: 3515: 3504: 3493: 3474: 3467: 3459: 3420: 3414: 3410: 3400: 3398: 3368: 3364: 3357: 3353: 3337: 3333: 3286: 3282: 3219: 3215: 3205: 3203: 3190: 3189: 3185: 3175: 3173: 3167:"Opalised Wood" 3165: 3164: 3160: 3150: 3148: 3132: 3128: 3118: 3116: 3108: 3107: 3103: 3093: 3091: 3083: 3082: 3078: 3068: 3066: 3051: 3050: 3046: 3036: 3034: 3021: 3020: 3016: 3006: 3004: 3003:. 6 August 2015 3001:East Idaho News 2995: 2994: 2990: 2961: 2957: 2947: 2946: 2942: 2931:"Roebling Opal" 2929: 2928: 2924: 2907: 2906: 2902: 2885: 2884: 2880: 2863: 2862: 2858: 2841: 2840: 2836: 2819: 2818: 2814: 2797: 2796: 2792: 2773: 2769: 2744: 2740: 2711: 2707: 2696: 2692: 2682: 2680: 2671: 2670: 2663: 2652: 2648: 2637: 2633: 2620: 2619: 2615: 2605: 2603: 2593: 2589: 2574: 2560: 2556: 2543: 2542: 2538: 2529: 2527: 2523: 2516: 2508: 2504: 2496: 2489: 2481: 2477: 2467: 2465: 2464:on 16 July 2012 2456: 2455: 2451: 2438: 2437: 2433: 2416: 2415: 2411: 2401: 2399: 2386: 2385: 2381: 2371: 2369: 2364: 2363: 2359: 2354: 2350: 2345: 2341: 2336: 2332: 2322: 2320: 2312: 2311: 2307: 2297: 2295: 2286: 2285: 2281: 2271: 2269: 2263:"Types of Opal" 2259: 2255: 2240: 2233: 2222: 2218: 2211: 2197: 2193: 2183: 2181: 2166: 2162: 2122: 2118: 2111: 2093: 2086: 2055: 2051: 2010: 2006: 1996: 1994: 1986: 1985: 1981: 1971: 1969: 1961: 1960: 1956: 1946: 1944: 1935: 1934: 1930: 1920: 1918: 1909: 1908: 1904: 1885: 1856: 1811: 1807: 1802: 1785: 1765: 1756: 1748:Biogenic silica 1740:Minerals portal 1738: 1733: 1731: 1728: 1716:Beverly the Bug 1638:, presented to 1621: 1579:medieval period 1566: 1501:Pliny the Elder 1474: 1450: 1418: 1389: 1365: 1346: 1338: 1334: 1289: 1240: 1186: 1163:Pedro II, Piauí 1144: 1142:Other locations 1120:Baja California 1085:Ezequiel Montes 1048: 1032:placer deposits 1009:Humboldt County 997: 950: 948: 904:New South Wales 900:Lightning Ridge 880: 876: 873: 871: 866: 862: 859: 857: 850:South Australia 842: 825:South Australia 797: 773: 713: 706: 634: 544: 540: 528:South Australia 504: 406: 398: 278: 273: 271: 270: 268: 228: 226: 225: 223: 178: 103: 95: 81: 80: 57: 38: 31: 24: 17: 12: 11: 5: 6259: 6249: 6248: 6243: 6238: 6233: 6228: 6223: 6218: 6201: 6200: 6198: 6197: 6192: 6186: 6184: 6180: 6179: 6177: 6176: 6174:Volcanic glass 6171: 6169:Vitrified sand 6166: 6157: 6152: 6150:Opal formation 6147: 6141: 6139: 6133: 6132: 6130: 6129: 6127:Tempered glass 6124: 6119: 6114: 6109: 6104: 6099: 6094: 6092:Polished plate 6089: 6084: 6079: 6074: 6069: 6064: 6059: 6054: 6049: 6044: 6039: 6034: 6029: 6024: 6019: 6014: 6009: 6004: 5999: 5994: 5989: 5984: 5979: 5974: 5969: 5963: 5961: 5955: 5954: 5952: 5951: 5946: 5941: 5936: 5931: 5926: 5921: 5916: 5911: 5906: 5901: 5896: 5891: 5886: 5880: 5878: 5872: 5871: 5863: 5862: 5855: 5848: 5840: 5831: 5830: 5828: 5827: 5822: 5817: 5812: 5807: 5802: 5797: 5796:Related topics 5793: 5790: 5789: 5787: 5786: 5781: 5776: 5770: 5764: 5758: 5756: 5752: 5751: 5748: 5747: 5745: 5744: 5739: 5738: 5737: 5727: 5722: 5717: 5712: 5707: 5701: 5699: 5695: 5694: 5692: 5691: 5686: 5681: 5676: 5671: 5666: 5661: 5660: 5659: 5654: 5644: 5639: 5634: 5629: 5623: 5621: 5617: 5616: 5614: 5613: 5608: 5603: 5598: 5593: 5588: 5583: 5578: 5573: 5568: 5563: 5558: 5553: 5543: 5538: 5533: 5528: 5523: 5518: 5513: 5508: 5503: 5498: 5493: 5488: 5483: 5478: 5473: 5468: 5463: 5458: 5453: 5448: 5443: 5438: 5433: 5428: 5418: 5413: 5408: 5403: 5397: 5395: 5388: 5387: 5385: 5384: 5379: 5374: 5369: 5364: 5359: 5354: 5349: 5344: 5339: 5333: 5331: 5325: 5324: 5322: 5321: 5316: 5315: 5314: 5304: 5299: 5294: 5289: 5284: 5279: 5273: 5271: 5264: 5263: 5261: 5260: 5255: 5250: 5245: 5240: 5234: 5232: 5223: 5219: 5218: 5215: 5214: 5212: 5211: 5206: 5201: 5196: 5191: 5185: 5183: 5179: 5178: 5176: 5175: 5170: 5168:Wire sculpture 5165: 5160: 5155: 5150: 5145: 5140: 5135: 5130: 5125: 5120: 5115: 5114: 5113: 5108: 5103: 5093: 5087: 5085: 5081: 5080: 5078: 5077: 5072: 5067: 5062: 5057: 5052: 5047: 5041: 5039: 5032: 5028: 5027: 5025: 5024: 5023: 5022: 5017: 5007: 5002: 4997: 4992: 4987: 4982: 4977: 4972: 4967: 4962: 4957: 4952: 4947: 4942: 4937: 4932: 4927: 4922: 4917: 4912: 4907: 4902: 4897: 4892: 4887: 4882: 4876: 4874: 4868: 4867: 4860: 4859: 4852: 4845: 4837: 4828: 4827: 4825: 4824: 4801: 4798: 4797: 4795: 4794: 4789: 4784: 4779: 4773: 4771: 4767: 4766: 4764: 4763: 4749: 4735: 4727: 4722: 4717: 4712: 4707: 4701: 4696: 4690: 4680: 4678:Petrified wood 4675: 4667: 4661: 4659: 4655: 4654: 4651: 4650: 4648: 4647: 4641: 4635: 4630: 4617: 4612: 4607: 4601: 4599: 4593: 4592: 4590: 4589: 4584: 4579: 4569: 4564: 4559: 4554: 4548: 4546: 4537: 4531: 4530: 4527: 4526: 4524: 4523: 4517: 4512: 4507: 4486: 4481: 4475: 4465: 4464:, polychromous 4459: 4452: 4450: 4444: 4443: 4441: 4440: 4435: 4430: 4423: 4418: 4412: 4410: 4404: 4403: 4401: 4400: 4395: 4390: 4385: 4380: 4375: 4369: 4367: 4361: 4360: 4358: 4357: 4352: 4347: 4342: 4337: 4332: 4326: 4324: 4313: 4306: 4305: 4302: 4299: 4298: 4291: 4290: 4283: 4276: 4268: 4259: 4258: 4255: 4254: 4240: 4237: 4236: 4234: 4233: 4228: 4226:Shocked quartz 4223: 4218: 4213: 4208: 4202: 4200: 4194: 4193: 4191: 4190: 4185: 4179: 4177: 4171: 4170: 4168: 4167: 4162: 4157: 4152: 4147: 4142: 4137: 4131: 4129: 4120: 4116: 4115: 4113: 4112: 4107: 4101: 4099: 4095: 4094: 4092: 4091: 4086: 4084:Lechatelierite 4081: 4075: 4073: 4067: 4066: 4064: 4063: 4058: 4053: 4048: 4042: 4040: 4034: 4033: 4031: 4030: 4025: 4020: 4015: 4010: 4005: 4000: 3995: 3989: 3987: 3981: 3980: 3970: 3969: 3962: 3955: 3947: 3941: 3940: 3934: 3928: 3915: 3909: 3906:Georg Agricola 3889: 3888:External links 3886: 3883: 3882: 3856: 3830: 3801: 3775: 3745: 3734: 3714: 3703:on 7 June 2011 3688: 3663: 3656: 3635: 3622: 3591: 3573: 3548: 3530: 3502: 3491: 3465: 3408: 3362: 3351: 3331: 3280: 3213: 3183: 3158: 3126: 3101: 3076: 3044: 3014: 2988: 2955: 2940: 2922: 2900: 2878: 2856: 2834: 2812: 2790: 2767: 2738: 2725:(2): 112–120. 2705: 2690: 2673:"Opal Fossils" 2661: 2646: 2631: 2613: 2587: 2573:978-0975721407 2572: 2554: 2536: 2502: 2475: 2449: 2431: 2422:It's an Honour 2409: 2379: 2357: 2348: 2339: 2330: 2305: 2279: 2253: 2231: 2216: 2209: 2191: 2174:Gemsociety.org 2160: 2116: 2109: 2084: 2065:(4): 427–434. 2049: 2004: 1979: 1954: 1939:. Mindat.org. 1928: 1913:. Webmineral. 1902: 1854: 1825:(3): 291–320. 1804: 1803: 1801: 1798: 1797: 1796: 1788: 1779: 1773: 1768: 1759: 1750: 1744: 1743: 1727: 1724: 1723: 1722: 1713: 1706: 1703: 1700: 1690: 1687: 1677: 1670: 1667: 1661: 1650: 1643: 1636:Andamooka Opal 1632: 1620: 1617: 1565: 1562: 1507:, the wife of 1473: 1470: 1466:hydrogen bonds 1449: 1446: 1417: 1414: 1388: 1385: 1363: 1344: 1336: 1332: 1288: 1285: 1239: 1238:Synthetic opal 1236: 1220:petrified wood 1185: 1182: 1172:In late 2008, 1156:Spencer, Idaho 1150:Brazilian opal 1143: 1140: 1047: 1044: 996: 993: 981:Wollo Province 947: 944: 841: 838: 796: 793: 791:of Australia. 772: 769: 705: 702: 672:, also called 633: 630: 503: 502:Precious opal 500: 404: 396: 369: 368: 366: 362: 361: 339: 333: 332: 329: 325: 324: 321: 315: 314: 310: 301: 300: 297: 291: 290: 287: 281: 280: 266: 260: 259: 256: 252: 251: 248: 244: 243: 240: 234: 233: 221: 215: 214: 211: 205: 204: 201: 195: 194: 191: 185: 184: 181: 172: 171: 165: 159: 158: 155: 149: 148: 145: 139: 138: 135: 131: 130: 129:Identification 126: 125: 122: 120:Crystal system 116: 115: 112: 106: 105: 101: 93: 84: 74: 73: 68: 64: 63: 59: 58: 55: 47: 46: 15: 9: 6: 4: 3: 2: 6258: 6247: 6244: 6242: 6239: 6237: 6234: 6232: 6229: 6227: 6224: 6222: 6219: 6217: 6214: 6213: 6211: 6196: 6193: 6191: 6188: 6187: 6185: 6181: 6175: 6172: 6170: 6167: 6165: 6161: 6158: 6156: 6153: 6151: 6148: 6146: 6143: 6142: 6140: 6138: 6134: 6128: 6125: 6123: 6120: 6118: 6117:Stained glass 6115: 6113: 6110: 6108: 6105: 6103: 6102:Rippled glass 6100: 6098: 6095: 6093: 6090: 6088: 6085: 6083: 6080: 6078: 6075: 6073: 6070: 6068: 6065: 6063: 6060: 6058: 6055: 6053: 6050: 6048: 6045: 6043: 6042:Flashed glass 6040: 6038: 6035: 6033: 6030: 6028: 6025: 6023: 6020: 6018: 6015: 6013: 6010: 6008: 6005: 6003: 6000: 5998: 5995: 5993: 5990: 5988: 5985: 5983: 5980: 5978: 5975: 5973: 5970: 5968: 5965: 5964: 5962: 5956: 5950: 5947: 5945: 5942: 5940: 5937: 5935: 5932: 5930: 5927: 5925: 5922: 5920: 5917: 5915: 5912: 5910: 5907: 5905: 5902: 5900: 5897: 5895: 5892: 5890: 5889:Fritted glass 5887: 5885: 5882: 5881: 5879: 5873: 5868: 5861: 5856: 5854: 5849: 5847: 5842: 5841: 5838: 5826: 5823: 5821: 5818: 5816: 5813: 5811: 5808: 5806: 5803: 5801: 5800:Body piercing 5798: 5795: 5794: 5791: 5785: 5782: 5780: 5777: 5774: 5771: 5768: 5765: 5763: 5760: 5759: 5757: 5753: 5743: 5740: 5736: 5733: 5732: 5731: 5728: 5726: 5723: 5721: 5718: 5716: 5713: 5711: 5708: 5706: 5703: 5702: 5700: 5696: 5690: 5689:Tortoiseshell 5687: 5685: 5682: 5680: 5677: 5675: 5672: 5670: 5667: 5665: 5662: 5658: 5655: 5653: 5650: 5649: 5648: 5645: 5643: 5640: 5638: 5635: 5633: 5630: 5628: 5625: 5624: 5622: 5618: 5612: 5609: 5607: 5604: 5602: 5599: 5597: 5594: 5592: 5589: 5587: 5584: 5582: 5579: 5577: 5574: 5572: 5569: 5567: 5564: 5562: 5559: 5557: 5554: 5551: 5547: 5544: 5542: 5539: 5537: 5534: 5532: 5529: 5527: 5524: 5522: 5519: 5517: 5514: 5512: 5509: 5507: 5504: 5502: 5499: 5497: 5494: 5492: 5489: 5487: 5484: 5482: 5479: 5477: 5474: 5472: 5469: 5467: 5464: 5462: 5459: 5457: 5454: 5452: 5449: 5447: 5444: 5442: 5439: 5437: 5434: 5432: 5429: 5426: 5422: 5419: 5417: 5414: 5412: 5409: 5407: 5404: 5402: 5399: 5398: 5396: 5394: 5389: 5383: 5380: 5378: 5375: 5373: 5370: 5368: 5365: 5363: 5360: 5358: 5355: 5353: 5350: 5348: 5345: 5343: 5340: 5338: 5335: 5334: 5332: 5330: 5326: 5320: 5317: 5313: 5310: 5309: 5308: 5305: 5303: 5300: 5298: 5295: 5293: 5290: 5288: 5285: 5283: 5280: 5278: 5275: 5274: 5272: 5270: 5265: 5259: 5256: 5254: 5251: 5249: 5246: 5244: 5241: 5239: 5236: 5235: 5233: 5231: 5227: 5224: 5220: 5210: 5207: 5205: 5202: 5200: 5197: 5195: 5192: 5190: 5187: 5186: 5184: 5180: 5174: 5171: 5169: 5166: 5164: 5161: 5159: 5156: 5154: 5151: 5149: 5146: 5144: 5141: 5139: 5136: 5134: 5131: 5129: 5126: 5124: 5121: 5119: 5116: 5112: 5109: 5107: 5104: 5102: 5099: 5098: 5097: 5094: 5092: 5089: 5088: 5086: 5082: 5076: 5073: 5071: 5068: 5066: 5063: 5061: 5058: 5056: 5053: 5051: 5048: 5046: 5045:Bench jeweler 5043: 5042: 5040: 5036: 5033: 5029: 5021: 5018: 5016: 5013: 5012: 5011: 5008: 5006: 5003: 5001: 4998: 4996: 4993: 4991: 4988: 4986: 4983: 4981: 4978: 4976: 4973: 4971: 4968: 4966: 4963: 4961: 4958: 4956: 4953: 4951: 4948: 4946: 4943: 4941: 4938: 4936: 4933: 4931: 4928: 4926: 4923: 4921: 4918: 4916: 4913: 4911: 4908: 4906: 4903: 4901: 4898: 4896: 4893: 4891: 4888: 4886: 4883: 4881: 4878: 4877: 4875: 4873: 4869: 4865: 4858: 4853: 4851: 4846: 4844: 4839: 4838: 4835: 4823: 4822: 4811: 4810: 4809: 4799: 4793: 4790: 4788: 4785: 4783: 4780: 4778: 4775: 4774: 4772: 4768: 4761: 4757: 4753: 4750: 4747: 4743: 4739: 4736: 4734: 4731: 4728: 4726: 4723: 4721: 4718: 4716: 4713: 4711: 4708: 4705: 4702: 4700: 4697: 4695: 4691: 4688: 4684: 4681: 4679: 4676: 4674: 4671: 4668: 4666: 4663: 4662: 4660: 4656: 4646: 4642: 4640: 4636: 4634: 4631: 4629: 4626: 4622: 4618: 4616: 4613: 4611: 4608: 4606: 4603: 4602: 4600: 4598: 4594: 4588: 4585: 4583: 4580: 4577: 4573: 4570: 4568: 4565: 4563: 4560: 4558: 4555: 4553: 4550: 4549: 4547: 4545: 4541: 4538: 4532: 4522: 4518: 4516: 4513: 4511: 4508: 4506: 4502: 4498: 4494: 4490: 4487: 4485: 4482: 4479: 4476: 4473: 4469: 4466: 4463: 4460: 4457: 4454: 4453: 4451: 4449: 4445: 4439: 4436: 4434: 4431: 4428: 4424: 4422: 4419: 4417: 4414: 4413: 4411: 4409: 4405: 4399: 4396: 4394: 4391: 4389: 4386: 4384: 4381: 4379: 4376: 4374: 4373:Pink sapphire 4371: 4370: 4368: 4366: 4362: 4356: 4353: 4351: 4348: 4346: 4345:Blue Sapphire 4343: 4341: 4338: 4336: 4333: 4331: 4328: 4327: 4325: 4323: 4322: 4317: 4314: 4311: 4307: 4300: 4296: 4289: 4284: 4282: 4277: 4275: 4270: 4269: 4266: 4252: 4251: 4238: 4232: 4229: 4227: 4224: 4222: 4219: 4217: 4214: 4212: 4209: 4207: 4204: 4203: 4201: 4199: 4195: 4189: 4186: 4184: 4181: 4180: 4178: 4176: 4172: 4166: 4163: 4161: 4158: 4156: 4153: 4151: 4148: 4146: 4143: 4141: 4138: 4136: 4133: 4132: 4130: 4128: 4124: 4121: 4117: 4111: 4108: 4106: 4103: 4102: 4100: 4098:Miscellaneous 4096: 4090: 4087: 4085: 4082: 4080: 4077: 4076: 4074: 4072: 4068: 4062: 4059: 4057: 4054: 4052: 4049: 4047: 4044: 4043: 4041: 4039: 4035: 4029: 4026: 4024: 4021: 4019: 4016: 4014: 4011: 4009: 4006: 4004: 4001: 3999: 3996: 3994: 3991: 3990: 3988: 3986: 3982: 3978: 3975: 3968: 3963: 3961: 3956: 3954: 3949: 3948: 3945: 3938: 3935: 3932: 3929: 3926: 3922: 3919: 3916: 3913: 3910: 3907: 3903: 3899: 3895: 3892: 3891: 3870: 3866: 3860: 3844: 3840: 3834: 3818: 3814: 3808: 3806: 3789: 3785: 3779: 3763: 3759: 3755: 3749: 3741: 3737: 3731: 3727: 3726: 3718: 3702: 3698: 3692: 3677: 3673: 3667: 3659: 3653: 3649: 3645: 3639: 3632: 3631:The opal book 3629:Leechman, F; 3626: 3618: 3614: 3610: 3606: 3602: 3595: 3587: 3583: 3577: 3562: 3558: 3552: 3544: 3540: 3534: 3526: 3522: 3521: 3513: 3511: 3509: 3507: 3498: 3494: 3492:9780471133971 3488: 3484: 3483: 3478: 3472: 3470: 3458: 3454: 3450: 3446: 3442: 3438: 3434: 3430: 3426: 3419: 3412: 3397: 3393: 3389: 3385: 3381: 3377: 3373: 3366: 3360: 3355: 3347: 3343: 3335: 3327: 3323: 3319: 3315: 3311: 3307: 3303: 3299: 3295: 3291: 3284: 3276: 3272: 3267: 3262: 3258: 3254: 3249: 3244: 3240: 3236: 3232: 3228: 3224: 3217: 3201: 3197: 3193: 3187: 3172: 3168: 3162: 3147: 3143: 3139: 3138: 3130: 3115: 3111: 3105: 3090: 3086: 3080: 3064: 3060: 3059: 3054: 3048: 3032: 3028: 3024: 3018: 3002: 2998: 2992: 2983: 2978: 2974: 2970: 2966: 2959: 2951: 2944: 2936: 2932: 2926: 2918: 2914: 2910: 2904: 2896: 2892: 2888: 2882: 2874: 2870: 2866: 2860: 2852: 2848: 2844: 2838: 2830: 2826: 2822: 2816: 2808: 2804: 2800: 2794: 2786: 2782: 2781:Addis Fortune 2778: 2771: 2762: 2757: 2753: 2749: 2742: 2733: 2728: 2724: 2720: 2716: 2709: 2701: 2694: 2678: 2674: 2668: 2666: 2658: 2655: 2650: 2643: 2640: 2635: 2627: 2623: 2617: 2602: 2598: 2591: 2583: 2579: 2575: 2569: 2565: 2558: 2550: 2546: 2540: 2522: 2515: 2514: 2506: 2495: 2488: 2487: 2479: 2463: 2459: 2453: 2445: 2441: 2435: 2427: 2423: 2419: 2413: 2397: 2393: 2389: 2383: 2367: 2361: 2352: 2343: 2334: 2319: 2315: 2309: 2293: 2289: 2283: 2268: 2264: 2257: 2249: 2245: 2238: 2236: 2227: 2220: 2212: 2206: 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