Opal - Knowledge (XXG)

1071: 1208: 518: 727: 1254: 530: 648: 1049:-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 639:

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.

811: 2348:"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. 385: 656: 998: 1451: 1158: 4827: 4256: 1745: 63: 1098:. 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". 4815: 1315: 823: 1278:

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

2357:"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. 1303: 1200: 1011: 994:. 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. 962: 1414:

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

508:

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

1277:

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

1101:

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

1610:

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

1265:

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

902:

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

842:

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

638:

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

833:

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

738:

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

323:

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

1066:

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

633:

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

2135:

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".

1431:

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

1385:

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

573:

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

734:"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 1579:

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

1061:

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

986:. 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 968: 967: 964: 963: 969: 3707: 1117:, 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 504:); 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 778:. 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. 3350:

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".

746:

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

1026:

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

981:

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

966: 1566:

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

1614:

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

549:

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

582:

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

1289:

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

3827: 3879: 3772: 1286:. 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. 3711: 629:. "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 1109:

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

843:

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

770:. Diatoms are a form of algae that, when they die, often form layers at the bottoms of lakes, bays, or oceans. Their cell walls are made up of hydrated silicon dioxide which gives them 786:

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

1545:. 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 1432:

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.

867:" was found in August 1956 at the "Eight Mile" opal field in Coober Pedy. It weighs 17,000 carats (3.4 kg; 7.5 lb) and is 11 inches (280 mm) long, with a height of 5868: 1067:

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.

838:

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.

3210: 965: 3750: 667:

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);

3823: 1233:

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

1571:, 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. 917:, 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 730:

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)

2454: 2559: 1322:

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

3875: 3764: 3798: 1172:

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

3467: 3232:

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

2188: 5861: 3975: 1113:. 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 2664: 2531: 2504: 1423:, is interpreted as consisting of localized order of α-cristobalite with a lot of stacking disorder. Typical water content is about 1.5 wt%. 3931: 2687: 6246: 6155: 3853: 3744: 3666: 2219: 2119: 1775: – metal foil sometimes used to create reflection and sparkle behind milky glass or quartz faces in costume jewelry simulating real opal 671:

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;

5854: 5111: 2941: 2258: 1362:, structures such as SiOH, generally form a lesser proportion of the total and can reside near the surface or in defects inside the opal. 1053:

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

6256: 6231: 4865: 4296: 3507: 977:

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

6087: 2795: 2582: 493: 3501: 3073: 1909: 2632: 1074:

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

1897: 1366: 910: 774:

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

2436: 1330:

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

839: 566: 565:. It was shown by J. V. Sanders in the mid-1960s that these ordered silica spheres produce the internal colors by causing the 2468: 2376: 559: 186: 1102:

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

422:

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

1253: 3968: 1439:

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

219: 1557:

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

4818: 4787: 3202: 3041: 1070: 6200: 1664: 3234:"Core–shell silica–rhodamine B nanosphere for synthetic opals: from fluorescence spectral redistribution to sensing" 2607: 6251: 6032: 5949: 2927: 2905: 2450: 1925: 1497:. The origin of this word in turn is a matter of debate, but most modern references suggest it is adapted from the 1266:

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

953:

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

909:

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

906: 2861: 2839: 2555: 5322: 4802: 3068: 3007: 2883: 2817: 2406: 2366:

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

1951: 1551:

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

899: 3299:

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

1394:

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

6236: 6147: 6117: 5929: 5924: 5158: 4980: 4797: 3961: 3794: 810: 3428: 1602:

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

5789: 5163: 4882: 4858: 4289: 1657: 1387: 1216: 1050: 1019: 329: 120: 2180: 1720: 1691: 1684: 1536: 918: 45: 1358:

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

1087: 5689: 2522: 2495: 1339: 997: 946: 771: 173: 38: 3928: 3682: 2683: 1086:. In this region the opal deposits are located mainly in the mountain ranges of three municipalities: 6102: 6022: 5526: 5183: 4165: 3443: 3394: 3308: 3245: 2145: 2077: 2034: 1837: 1668: 3734: 3567: 2649: 5521: 3849: 3146: 1730: 1391: 1279: 1146: 720: 599: 579: 481: 209: 199: 1680:

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

726: 590:

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

6170: 5959: 4930: 4910: 4851: 4725: 4282: 3459: 3429:"HRTEM of microcrystalline opal in chert and porcelanite from the Monterey Formation, California" 3332: 2324: 2161: 2050: 1855: 1598: 1519: 1110: 827: 775: 696: 630: 163: 2945: 1207: 1173: 500:

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

2254: 1450: 1157: 608:

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

6241: 6077: 6062: 6007: 6002: 5377: 4960: 4155: 4048: 3995: 3740: 3662: 3497: 3324: 3281: 3263: 3152: 2588: 2578: 2215: 2115: 1905: 1792: 1636: 1335: 1126: 934: 864: 562: 369: 3491: 2724:

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

5992: 5904: 5877: 5287: 5116: 5070: 4990: 4792: 4431: 4226: 3765:"Million-dollar opal Rainbow Virgin to go on display at SA exhibition celebrating centenary" 3623: 3451: 3402: 3316: 3271: 3253: 2987: 2766: 2737: 2153: 2085: 2042: 2025: 1845: 1675: 1283: 684: 618:

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

595: 542: 357: 274: 229: 88: 2787: 711:, this optical effect is strictly defined as opalescence which is a form of adularescence. 517: 6205: 6047: 5954: 5944: 5382: 5317: 5128: 5101: 4831: 4680: 4260: 4081: 3984: 3935: 3654: 3592: 3487: 1758: 1750: 1726: 1589: 1511: 1130: 1095: 914: 860: 835: 538: 522: 403: 5977: 3824:"$ 4 million worth of the South Australian Museum's opal collection for display in Qatar" 3177: 3063: 2273: 1514:, one theory attributed the name's origin to Roman mythology: to have been adapted from 3611: 3447: 3398: 3312: 3249: 2920:"Stonetree Opal Mine, WRT Stonetree group, Virgin Valley District, Humboldt Co., Nevada" 2149: 2081: 2038: 1841: 6226: 6184: 6179: 6137: 6037: 5735: 5679: 5667: 5596: 5240: 5178: 4955: 4688: 4525: 4236: 4115: 4094: 3947: 3916: 3549: 3276: 3233: 2636: 1646: 1334:

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

1230: 1166: 1042: 991: 584: 439: 130: 6220: 6127: 6112: 6052: 6042: 5939: 5934: 5919: 5909: 5899: 5810: 5740: 5699: 5367: 5121: 5106: 5055: 4720: 3406: 3336: 2428: 2165: 2108: 1859: 1476: 1258: 1091: 929:

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

760: 619: 575: 419: 295: 153: 3463: 6132: 6107: 6072: 6067: 6057: 5997: 5835: 5830: 5825: 5777: 5730: 5560: 5506: 5292: 5173: 5133: 5025: 4766: 4752: 4748: 4735: 4586: 4331: 4231: 4008: 3922: 3912: 3908: 3382: 2876:"Bonanza Opal Workings (Virgin Opal), Virgin Valley District, Humboldt Co., Nevada" 2298: 2054: 1650: 1593: 1407: 1378: 1307: 1274:

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

1267: 752: 353: 318: 3876:"World's finest piece of uncut opal finds new home at the South Australian Museum" 2472: 1142: 1083: 1063: 789: 529: 3535: 1257:

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

6082: 6017: 6012: 5894: 5772: 5662: 5501: 5451: 5446: 5362: 5204: 5080: 5030: 4905: 4900: 4592: 4503: 4360: 4160: 1998: 1781: 1704: 1640: 1584:

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

1444: 1271: 1212: 856: 834:

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

688: 655: 647: 610: 604: 598:. In addition, microfractures may be filled with secondary silica and form thin 570: 534: 505: 501: 315: 305: 1314: 6092: 5914: 5846: 5606: 5551: 5426: 5339: 5307: 5297: 5199: 5148: 5085: 5060: 4935: 4740: 4714: 4472: 4466: 4241: 4170: 4137: 4056: 4033: 4028: 3627: 3008:"If you've ever wanted an opal – it's time to visit Spencer | East Idaho News" 2089: 1801: 1795: – Observable events that result from the interaction of light and matter 1740: 1695: 1623: 1607: 1523: 1472: 1440: 1323: 1134: 1037:, which is considered a "lode" deposit. Opals which have weathered out of the 922: 423: 384: 365: 347: 178: 81: 3328: 3267: 3156: 3033: 2592: 6174: 6165: 6027: 5987: 5982: 5752: 5745: 5616: 5611: 5591: 5516: 5441: 5435: 5416: 5312: 5253: 5168: 5065: 5000: 4975: 4965: 4895: 4874: 4743: 4693: 4625: 4620: 4577: 4531: 4511: 4507: 4408: 4393: 4388: 4320: 4198: 4150: 4089: 4038: 3455: 1772: 1763: 1411: 1382: 1331: 1327: 1291: 1177: 1034: 987: 926: 844: 704: 680: 634:

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

615: 447: 399: 3320: 3285: 863:

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

3095: 2742: 2725: 2665:

Rare dinosaur fossil discovered on internet after disappearing for decades

822: 6122: 5820: 5794: 5783: 5720: 5647: 5586: 5576: 5571: 5531: 5471: 5461: 5421: 5403: 5392: 5387: 5302: 5258: 5143: 5138: 5075: 5015: 5005: 4970: 4945: 4920: 4915: 4762: 4730: 4709: 4655: 4643: 4597: 4572: 4562: 4520: 4482: 4426: 4383: 4355: 4305: 4221: 4216: 4018: 2992: 2975: 2854:"Royal Peacock Group Mines, Virgin Valley District, Humboldt Co., Nevada" 2771: 2758: 1616: 1581: 1568: 1498: 1464: 1242: 1165:

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

1114: 1078:

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

983: 978: 799: 795: 708: 672: 664: 626: 591: 525:

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

470: 451: 443: 361: 3941: 3904: 3529: 3369: 3120: 2919: 2897: 2494:

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

1921: 1850: 1825: 5815: 5725: 5637: 5546: 5511: 5496: 5481: 5466: 5456: 5329: 5263: 5214: 5153: 5010: 4985: 4950: 4756: 4683: 4567: 4494: 4443: 4350: 4340: 4193: 4013: 4003: 3987: 3258: 2853: 2831: 2157: 1973: 1786: 1585: 1468: 1433: 1359: 1302: 1199: 1122: 1118: 1103: 1046: 1029: 1010: 942: 735: 676: 435: 434:. It is deposited at a relatively low temperature and may occur in the 431: 427: 396: 248: 97: 62: 17: 2875: 2809: 2650:

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

2521:

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

2398: 2046: 578:, the light of that wavelength may be subject to diffraction from the 148:

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

6097: 5715: 5621: 5581: 5556: 5491: 5476: 5372: 5357: 5352: 5268: 5219: 5209: 4925: 4890: 4675: 4638: 4635: 4631: 4515: 4499: 4398: 4208: 4071: 4023: 2379:. Australian Government, Department of the Prime Minister and Cabinet 1713:

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

1603: 1370: 1310:. Locally, the structures of some opals, opal-C, are similar to this. 1138: 1079: 1023: 950: 938: 767: 756: 748: 740: 700: 692: 635: 486: 459: 100: 2210:

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

1169:. A high percentage of the opal found there occurs in thin layers. 290:

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

5694: 5684: 5674: 5657: 5652: 5642: 5601: 5431: 5411: 5347: 5279: 5020: 4995: 4940: 4615: 4582: 4488: 4478: 4437: 4365: 4145: 4120: 4066: 4061: 3953: 3207:

Office for Technology Commercialization, Technology Marketing Site

1947: 1488: 1449: 1313: 1301: 1252: 1206: 1198: 1156: 1069: 1009: 996: 960: 930: 821: 815: 809: 725: 668: 654: 646: 528: 516: 383: 269:

Single refractive, often anomalous double refractive due to strain

2709:

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

5566: 5536: 5486: 5248: 4770: 4704: 4345: 4314:

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

4175: 3818: 3816: 2898:"Opal Queen group, Virgin Valley District, Humboldt Co., Nevada" 1188: 1184: 679:, a colorless glass-clear opal sometimes called Muller's glass; 455: 31: 5850: 4847: 4278: 3957: 1373:

consists of frameworks of fully corner bonded tetrahedra of SiO

1014:

Multicolored rough opal specimen from Virgin Valley, Nevada, US

1515: 2068:

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

1694:

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

1660:

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

1558: 1552: 1540: 4843: 4274: 1707:, listed as the "World's Largest Polished Opal" in the 1992 1535:

Another common claim was that the term was adapted from the

3427:

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

1639:, the world's largest and most valuable gem opal, found in 3595:(1997). "A Chronological History and Mythology of Opals". 1406:

has been interpreted as consisting of clusters of stacked

719:"Girasol" redirects here. For the American sunflower, see 625:

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

703:

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

2976:"Opal from Querétaro, Mexico: Occurrence and Inclusions" 2759:"Play-of-color from Wegeltena, Wollo Province, Ethiopia" 1690:

Although the clock faces above the information stand in

1463:

The surface of opal in contact with water is covered by

614:. In gemology, opalescence is applied to the hazy-milky- 3661:. Chichester: John Wiley & Sons. pp. 67, 126. 2524:

United States Geological Survey, 2012 Minerals Yearbook

2497:

United States Geological Survey, 2012 Minerals Yearbook

2023:

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

1797:

Pages displaying short descriptions of redirect targets

485:), which means 'jewel', and later the Greek derivative 3950:

Australian Opal Fields – Map of precious opal deposits

3203:"Macroporous Structures, Metal Oxides, Highly Ordered" 1454:

Schematic representation of the hydrated opal surface.

1338:

or microcrystalline opal. Dehydration experiments and

937:

in the south. Its largest quantities are found around

474: 2678: 2676: 2179:

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

3710:. National Museum of Natural History. Archived from 2944:. National Museum of Natural History. Archived from 1777:

Pages displaying wikidata descriptions as a fallback

1768:

Pages displaying wikidata descriptions as a fallback

1729:, the first known example of an opal with an insect 1723:, assumed to be "the finest uncut opal in existence" 1716:

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

1663:

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

1447:

rocks, as some of the stacking disorder is removed.

6193: 6146: 5968: 5885: 5765: 5708: 5630: 5401: 5338: 5277: 5239: 5232: 5192: 5094: 5048: 5041: 4881: 4780: 4668: 4606: 4553: 4544: 4457: 4417: 4374: 4329: 4319: 4207: 4184: 4136: 4129: 4108: 4080: 4047: 3994: 3599:. New York: John Wiley & Sons. pp. 53–118. 2399:"Yowah Nut: Yowah Nut mineral information and data" 2214:(27th ed.). London: Unwin Hyman. p. 431. 1789: – Trade name for opal and moonstone simulants 1611:50%, and remained low for the next 20 years or so. 375: 346: 338: 328: 314: 304: 294: 273: 265: 257: 247: 228: 218: 208: 198: 185: 172: 162: 152: 144: 139: 129: 119: 87: 77: 72: 55: 2107: 1471:groups (≡Si–OH). This makes the opal surface very 1082:and production first originated in the state of 558:10 in) in diameter in a hexagonal or cubic 67:A rich seam of iridescent opal encased in matrix 2471:. Government of South Australia. Archived from 2106:Klein, Cornelis; Hurlbut, Cornelius S. (1985). 1443:, due to the increasing overburden pressure in 602:inside the opal during its formation. The term 2810:"Virgin Valley District, Humboldt Co., Nevada" 2325:"diatomite – The Mineral and Gemstone Kingdom" 1502: 1377:. The higher temperature polymorphs of silica 1001:Gem grade Ethiopian Welo precious opal pendant 5862: 4859: 4290: 3969: 3929:Opal Fossils from the South Australian Museum 2670:, 3 December 2018. Retrieved 3 December 2018. 2655:, 5 December 2018. Retrieved 5 December 2018. 2608:"The black-opal hunters of outback Australia" 2575:A history of South Australian opal, 1840–2005 334:green stones: 660 nm, 470 nm cutoff 8: 4448: 3151:. Washington: Gov. Print. Off. p. 238. 3064:"NASA probe finds opals in Martian crevices" 2606:Osborne, Zoe; Kitanov, Alex (17 July 2022). 1522:, and goddess of fertility. (The portion of 1282:and the absence of any surrounding non-opal 1187:announced the discovery of opal deposits on 787: 44:"Opals" redirects here. For other uses, see 2248: 2246: 1546: 1527: 1492: 1294:for sensing and light management purposes. 5869: 5855: 5847: 5236: 5045: 4866: 4852: 4844: 4814: 4550: 4326: 4297: 4283: 4275: 4133: 3976: 3962: 3954: 3534:. Bristol: John Wright & Co. pp. 1700:The Roebling Opal, Smithsonian Institution 1229:, is a form of opal, as well as a type of 1106:were not discovered until the late 1950s. 925:and fracture fillings in a dark siliceous 847:) to be only 750 kg (1,650 lb). 61: 3925:: International Colored Stone Association 3523: 3521: 3519: 3517: 3482: 3480: 3275: 3257: 3209:. University of Minnesota. 25 June 2010. 3034:"Boi Morto Mine, Pedro II, Piauí, Brazil" 2991: 2770: 2741: 1849: 1606:with supernatural powers. When a drop of 1526:devoted to Ops was "Opalia", similar to 1261:) viewed by darkfield optical microscopy 3496:. John Wiley and Sons. pp. 56–57. 2798:from the original on 24 September 2014. 2101: 2099: 1816: 1306:The crystal structure of crystalline α- 1033:within a subsurface horizon or zone of 826:Boulder opal, Carisbrooke Station near 3644:, University of California Press, 1961 2451:"Rapaport Magazine – A Designer Stone" 1893: 1891: 1889: 1687:, the world's largest uncut black opal 881: in (120 mm) and a width of 430:forms of silica, which are considered 158:Irregular veins, in masses, in nodules 52: 3942:Opal Mineral data and specimen images 3830:from the original on 17 December 2017 3801:from the original on 29 December 2015 3775:from the original on 17 December 2017 2690:from the original on 13 February 2014 2439:from the original on 29 January 2011. 2261:from the original on 7 November 2011. 2191:from the original on 23 November 2016 1887: 1885: 1883: 1881: 1879: 1877: 1875: 1873: 1871: 1869: 1510:As references to the gem are made by 1041:deposits are alluvial and considered 541:, displays nearly every color of the 521:Precious opal consists of spheres of 7: 3753:from the original on 26 August 2016. 3473:from the original on 1 October 2011. 3383:"The structure of opal-CT revisited" 3076:from the original on 19 January 2009 2726:"Opal from Shewa Province, Ethiopia" 2562:from the original on 6 October 2014. 2556:"Rapaport Magazine – Ethiopian Opal" 2457:from the original on 6 October 2014. 1928:from the original on 18 October 2011 1826:"IMA–CNMNC approved mineral symbols" 1487:The word 'opal' is adapted from the 3510:from the original on 26 April 2016. 2930:from the original on 30 April 2012. 2908:from the original on 30 April 2012. 2886:from the original on 30 April 2012. 2864:from the original on 30 April 2012. 2842:from the original on 30 April 2012. 2820:from the original on 30 April 2012. 2788:"Opal Trade Transforms North Wollo" 2537:from the original on 6 October 2014 2510:from the original on 6 October 2014 2469:"Opal – South Australia's Gemstone" 1954:from the original on 6 October 2011 1592:. Following the publication of Sir 1215:backbone, as a display specimen in 469:is believed to be derived from the 5910:Extrusion / Drawing (glass fibers) 4403: 3856:from the original on 19 March 2017 3736:"The Guinness Book of Records 1993 3213:from the original on 24 March 2012 3148:Catalogue of minerals and synonyms 2577:. Lightning Ridge, NSW: Len Cram. 2299:"Opal – Nevada Mining Association" 25: 5905:Blowing and pressing (containers) 3882:from the original on 26 June 2017 3850:"Largest black opal in the world" 3531:Precious Stones for Curative Wear 3387:Journal of Non-Crystalline Solids 2757:Rondeau, Benjamin (Summer 2010). 2253:Swisher, James; Anthony, Edna B. 1018:The Virgin Valley opal fields of 659:White and blue opal from Slovakia 442:, being most commonly found with 27:Hydrated amorphous form of silica 4825: 4813: 4254: 3407:10.1016/j.jnoncrysol.2014.08.052 3044:from the original on 12 May 2011 2786:Gashaw, Yidneka (8 April 2012). 2409:from the original on 12 May 2011 2181:"Opal Value, Price, and Jewelry" 1978:Gemological Institute of America 1898:Gemological Institute of America 1743: 1653:, also known as the Queen's Opal 1475:and capable of forming numerous 707:sheen from within the stone. In 224:opaque, translucent, transparent 4427:Yellow, Green, Violet Sapphires 3733:Guinness, Medd (October 1992). 3616:Chemical & Engineering News 3528:Fernie, William Thomas (1907). 2212:Rutley's Elements of Mineralogy 1176:), Honduras (more precisely in 3610:Goldberg-Gist, Arlene (2003). 2377:"Australian National Gemstone" 2272:Page, Geology (21 June 2016). 1365:The structure of low-pressure 949:. Australia also has opalized 533:This precious rough opal from 1: 6247:National symbols of Australia 3905:Farlang opal Hist. References 2237:Opal Identification and Value 1342:have shown that most of the H 1180:), Guatemala, and Nicaragua. 794:beyond the Roman frontier in 388:Main opal producing countries 6088:Machine drawn cylinder sheet 4819:List of gemstones by species 4788:List of individual gemstones 4449:Precious White and Fire Opal 3568:"Opal Symbolism and Legends" 2255:"Let's Talk Gemstones: Opal" 1626:for people born in October. 1559: 1553: 1541: 1459:Opal surface chemical groups 487: 6201:Glossary of glass art terms 3878:. South Australian Museum. 3826:. South Australian Museum. 3797:. South Australian Museum. 2686:. South Australian Museum. 1503: 921:. Boulder opal consists of 475: 6273: 6257:Symbols of New South Wales 6232:Emblems of South Australia 1507:meaning ‘precious stone’. 1436:is another name for this. 718: 675:, which is brown or grey; 492: 43: 36: 29: 5803: 4811: 4803:List of sapphires by size 4312: 4250: 3938:Accessed 19 October 2016. 3907:Localities, anecdotes by 3628:10.1021/cen-v081n004.p058 3612:"What's that Stuff? Opal" 3572:International Gem Society 3069:Jet Propulsion Laboratory 2963:: 1522, 1542. March 1971. 2435:. Australian Government. 2235:Downing, Paul B. (1992). 2090:10.1107/S0567739468000860 1999:"Glossary: Play of Color" 1669:Napoleon I of France 1402:Microcrystalline opal or 788: 480: 60: 6118:Satsuma Kiriko cut glass 5930:Overflow downdraw method 5925:Precision glass moulding 5920:Drawing (optical fibers) 4798:List of emeralds by size 3934:13 February 2014 at the 3739:. Guinness. p. 22. 3121:"Wood Opal - mindat.org" 2114:(20th ed.). Wiley. 2070:Acta Crystallographica A 1709:Guinness Book of Records 1671:and the first named opal 1665:Joséphine de Beauharnais 1575:Historical superstitions 1241:. It is often used as a 1211:Precious opal replacing 895: in (110 mm). 755:region, as well as from 715:Varieties of common opal 6171:Shock metamorphic glass 5368:Nickel silver (alpacca) 3683:"cameo; jewellery-case" 3456:10.2138/am-1996-11-1211 1902:GIA Gem Reference Guide 1766: – variety of opal 1622:Opal is considered the 1346:O in the formula of SiO 1239:opalized petrified wood 1217:South Australian Museum 1051:Smithsonian Institution 818:(Yowah Nut), Queensland 798:. Opal is the national 766:Opal is also formed by 699:, the accumulations of 3795:"Opals media releases" 3321:10.1002/adma.200400618 2974:Koivula, John (1983). 2503:, pp. 17.1–17.5, 1830:Mineralogical Magazine 1692:Grand Central Terminal 1547: 1528: 1493: 1467:bonds (≡Si–O–Si≡) and 1455: 1319: 1311: 1298:Local atomic structure 1262: 1219: 1204: 1162: 1075: 1015: 1002: 974: 919:Griman Creek Formation 830: 819: 731: 660: 652: 546: 526: 438:of almost any kind of 389: 342:darkening upon heating 46:Opals (disambiguation) 5709:Other natural objects 4366:Natural marine pearls 3436:American Mineralogist 3381:Wilson, M.J. (2014). 3353:Reviews in Mineralogy 3145:Egleston, T. (1887). 2743:10.5741/GEMS.32.2.112 2530:, pp. 3.1–3.27, 1453: 1398:Microcrystalline opal 1340:infrared spectroscopy 1317: 1305: 1256: 1210: 1202: 1160: 1073: 1013: 1006:Virgin Valley, Nevada 1000: 972: 947:South West Queensland 825: 813: 772:structural coloration 729: 658: 650: 532: 520: 387: 39:Opal (disambiguation) 30:For the company, see 6033:Cylinder blown sheet 5184:Wire wrapped jewelry 5164:Repoussé and chasing 4485:, pink, yellow-green 3442:(11–12): 1380–1395. 2993:10.5741/GEMS.19.2.87 2832:"Rainbow Ridge Mine" 2772:10.5741/GEMS.46.2.90 2405:. 20 February 2011. 2303:www.nevadamining.org 2144:(11–12): 1349–1354. 2110:Manual of Mineralogy 261:Vitreous to resinous 37:For other uses, see 6156:Radiative processes 5971:historic techniques 5895:Float glass process 5726:Ebonite (vulcanite) 4832:Minerals portal 4404:Precious Black Opal 4261:Minerals portal 3944:Mineralogy Database 3852:. 25 October 2016. 3708:"The Dynamic Earth" 3554:Wicca Candle Magick 3448:1996AmMin..81.1380C 3399:2014JNCS..405...68W 3313:2004AdM....16.1471T 3250:2020RSCAd..1014958L 3244:(25): 14958–14964. 2980:Gems & Gemology 2948:on 7 November 2012. 2763:Gems & Gemology 2730:Gems & Gemology 2639:on 13 October 2007. 2150:1995NCimD..17.1349A 2082:1968AcCrA..24..427S 2039:1964Natur.204.1151S 1851:10.1180/mgm.2021.43 1842:2021MinM...85..291W 1824:Warr, L.N. (2021). 1685:Halley's Comet Opal 1427:Noncrystalline opal 1318:Lussatite (opal-CT) 900:Mintabie Opal Field 814:Polished opal from 721:Jerusalem artichoke 687:, deposited around 339:Diagnostic features 204:Subvitreous to waxy 5950:Chemical polishing 5071:Jewellery designer 4654:Opaque iridescent 4545:Jewelry-Industrial 4491:yellow, blue, pink 3687:The British Museum 3659:The World of Opals 3597:The World of Opals 3493:The World of Opals 3301:Advanced Materials 3259:10.1039/D0RA02245D 2573:Cram, Len (2006). 2305:. 19 December 2017 2158:10.1007/bf02457208 2138:Il Nuovo Cimento D 2033:(496): 1151–1153. 1974:"Opal Description" 1658:Addyman Plesiosaur 1651:Queen Elizabeth II 1599:Anne of Geierstein 1456: 1392:cubic close-packed 1320: 1312: 1263: 1220: 1205: 1163: 1076: 1016: 1003: 975: 973:Opal from Ethiopia 831: 828:Winton, Queensland 820: 776:diatomaceous earth 732: 697:diatomaceous earth 661: 653: 547: 527: 390: 330:Absorption spectra 266:Optical properties 6252:Silica polymorphs 6214: 6213: 6148:Natural processes 6063:Fourcault process 5844: 5843: 5761: 5760: 5631:Organic gemstones 5228: 5227: 4841: 4840: 4669:Industrial stones 4664: 4663: 4540: 4539: 4272: 4271: 4268: 4267: 4156:Chrome chalcedony 4130:Notable varieties 4049:Cryptocrystalline 3771:. 2 August 2015. 3746:978-0-85112-978-5 3668:978-0-471-13397-1 3556:. pp. 84–85. 3307:(16): 1471–1476. 2633:"Queensland opal" 2239:. pp. 55–61. 2221:978-0-04-549011-0 2121:978-0-471-80580-9 2047:10.1038/2041151a0 1793:Optical phenomena 1721:Fire of Australia 1637:Olympic Australis 1336:cryptocrystalline 970: 865:Olympic Australis 751:and Idaho in the 739:type of opal are 651:Common rough opal 382: 381: 370:hydrofluoric acid 16:(Redirected from 6264: 5878:Glass production 5871: 5864: 5857: 5848: 5288:Britannia silver 5237: 5046: 4868: 4861: 4854: 4845: 4830: 4829: 4828: 4817: 4816: 4793:List of diamonds 4551: 4327: 4299: 4292: 4285: 4276: 4259: 4258: 4257: 4227:Herkimer diamond 4134: 3978: 3971: 3964: 3955: 3892: 3891: 3889: 3887: 3872: 3866: 3865: 3863: 3861: 3846: 3840: 3839: 3837: 3835: 3820: 3811: 3810: 3808: 3806: 3791: 3785: 3784: 3782: 3780: 3761: 3755: 3754: 3730: 3724: 3723: 3721: 3719: 3704: 3698: 3697: 3695: 3693: 3679: 3673: 3672: 3655:Eckert, Allan W. 3651: 3645: 3638: 3632: 3631: 3607: 3601: 3600: 3593:Eckert, Allan W. 3589: 3583: 3582: 3580: 3578: 3564: 3558: 3557: 3546: 3540: 3539: 3525: 3512: 3511: 3488:Eckert, Allan W. 3484: 3475: 3474: 3472: 3433: 3424: 3418: 3417: 3415: 3413: 3378: 3372: 3370:Opal-CT on Midat 3367: 3361: 3360: 3347: 3341: 3340: 3296: 3290: 3289: 3279: 3261: 3229: 3223: 3222: 3220: 3218: 3199: 3193: 3192: 3190: 3188: 3174: 3168: 3167: 3165: 3163: 3142: 3136: 3135: 3133: 3131: 3117: 3111: 3110: 3108: 3106: 3092: 3086: 3085: 3083: 3081: 3060: 3054: 3053: 3051: 3049: 3030: 3024: 3023: 3021: 3019: 3004: 2998: 2997: 2995: 2971: 2965: 2964: 2961:Lapidary Journal 2956: 2950: 2949: 2938: 2932: 2931: 2916: 2910: 2909: 2894: 2888: 2887: 2872: 2866: 2865: 2850: 2844: 2843: 2828: 2822: 2821: 2806: 2800: 2799: 2783: 2777: 2776: 2774: 2754: 2748: 2747: 2745: 2721: 2715: 2714: 2706: 2700: 2699: 2697: 2695: 2680: 2671: 2662: 2656: 2647: 2641: 2640: 2635:. Archived from 2629: 2623: 2622: 2620: 2618: 2603: 2597: 2596: 2570: 2564: 2563: 2552: 2546: 2545: 2544: 2542: 2536: 2529: 2518: 2512: 2511: 2509: 2502: 2491: 2485: 2484: 2482: 2480: 2465: 2459: 2458: 2447: 2441: 2440: 2425: 2419: 2418: 2416: 2414: 2395: 2389: 2388: 2386: 2384: 2373: 2367: 2364: 2358: 2355: 2349: 2346: 2340: 2339: 2337: 2335: 2329:www.minerals.net 2321: 2315: 2314: 2312: 2310: 2295: 2289: 2288: 2286: 2284: 2269: 2263: 2262: 2250: 2241: 2240: 2232: 2226: 2225: 2207: 2201: 2200: 2198: 2196: 2176: 2170: 2169: 2132: 2126: 2125: 2113: 2103: 2094: 2093: 2065: 2059: 2058: 2020: 2014: 2013: 2011: 2009: 1995: 1989: 1988: 1986: 1984: 1970: 1964: 1963: 1961: 1959: 1944: 1938: 1937: 1935: 1933: 1918: 1912: 1895: 1864: 1863: 1853: 1821: 1798: 1778: 1769: 1753: 1748: 1747: 1746: 1696:opalescent glass 1676:Flame Queen Opal 1562: 1556: 1550: 1544: 1531: 1506: 1496: 1225:, also known as 1147:Estado de México 990:, in Ethiopia's 971: 894: 893: 889: 886: 880: 879: 875: 872: 793: 792: 685:siliceous sinter 596:photonic crystal 587:of diffraction. 557: 553: 543:visible spectrum 496: 490: 484: 478: 288: 287: 286: 275:Refractive index 243: 242: 241: 230:Specific gravity 191: 94: 93:(repeating unit) 65: 53: 21: 6272: 6271: 6267: 6266: 6265: 6263: 6262: 6261: 6237:Glass in nature 6217: 6216: 6215: 6210: 6206:Glass recycling 6189: 6142: 6048:Enamelled glass 5970: 5964: 5955:Diamond turning 5945:Flame polishing 5887: 5881: 5875: 5845: 5840: 5799: 5757: 5746:Spondylus shell 5704: 5626: 5397: 5383:Stainless steel 5334: 5318:Sterling silver 5278:Precious metal 5273: 5241:Precious metals 5224: 5188: 5090: 5037: 4877: 4872: 4842: 4837: 4826: 4824: 4807: 4776: 4660: 4602: 4546: 4536: 4453: 4413: 4370: 4315: 4308: 4303: 4273: 4264: 4255: 4253: 4246: 4203: 4180: 4125: 4104: 4076: 4043: 3990: 3982: 3936:Wayback Machine 3923:ICA's Opal Page 3901: 3896: 3895: 3885: 3883: 3874: 3873: 3869: 3859: 3857: 3848: 3847: 3843: 3833: 3831: 3822: 3821: 3814: 3804: 3802: 3793: 3792: 3788: 3778: 3776: 3763: 3762: 3758: 3747: 3732: 3731: 3727: 3717: 3715: 3706: 3705: 3701: 3691: 3689: 3681: 3680: 3676: 3669: 3653: 3652: 3648: 3639: 3635: 3609: 3608: 3604: 3591: 3590: 3586: 3576: 3574: 3566: 3565: 3561: 3550:Dunwich, Gerina 3548: 3547: 3543: 3527: 3526: 3515: 3504: 3486: 3485: 3478: 3470: 3431: 3426: 3425: 3421: 3411: 3409: 3380: 3379: 3375: 3368: 3364: 3349: 3348: 3344: 3298: 3297: 3293: 3231: 3230: 3226: 3216: 3214: 3201: 3200: 3196: 3186: 3184: 3178:"Opalised Wood" 3176: 3175: 3171: 3161: 3159: 3144: 3143: 3139: 3129: 3127: 3119: 3118: 3114: 3104: 3102: 3094: 3093: 3089: 3079: 3077: 3062: 3061: 3057: 3047: 3045: 3032: 3031: 3027: 3017: 3015: 3014:. 6 August 2015 3012:East Idaho News 3006: 3005: 3001: 2973: 2972: 2968: 2958: 2957: 2953: 2942:"Roebling Opal" 2940: 2939: 2935: 2918: 2917: 2913: 2896: 2895: 2891: 2874: 2873: 2869: 2852: 2851: 2847: 2830: 2829: 2825: 2808: 2807: 2803: 2785: 2784: 2780: 2756: 2755: 2751: 2723: 2722: 2718: 2708: 2707: 2703: 2693: 2691: 2682: 2681: 2674: 2663: 2659: 2648: 2644: 2631: 2630: 2626: 2616: 2614: 2605: 2604: 2600: 2585: 2572: 2571: 2567: 2554: 2553: 2549: 2540: 2538: 2534: 2527: 2520: 2519: 2515: 2507: 2500: 2493: 2492: 2488: 2478: 2476: 2475:on 16 July 2012 2467: 2466: 2462: 2449: 2448: 2444: 2427: 2426: 2422: 2412: 2410: 2397: 2396: 2392: 2382: 2380: 2375: 2374: 2370: 2365: 2361: 2356: 2352: 2347: 2343: 2333: 2331: 2323: 2322: 2318: 2308: 2306: 2297: 2296: 2292: 2282: 2280: 2274:"Types of Opal" 2271: 2270: 2266: 2252: 2251: 2244: 2234: 2233: 2229: 2222: 2209: 2208: 2204: 2194: 2192: 2178: 2177: 2173: 2134: 2133: 2129: 2122: 2105: 2104: 2097: 2067: 2066: 2062: 2022: 2021: 2017: 2007: 2005: 1997: 1996: 1992: 1982: 1980: 1972: 1971: 1967: 1957: 1955: 1946: 1945: 1941: 1931: 1929: 1920: 1919: 1915: 1896: 1867: 1823: 1822: 1818: 1813: 1796: 1776: 1767: 1759:Biogenic silica 1751:Minerals portal 1749: 1744: 1742: 1739: 1727:Beverly the Bug 1649:, presented to 1632: 1590:medieval period 1577: 1512:Pliny the Elder 1485: 1461: 1429: 1400: 1376: 1357: 1349: 1345: 1300: 1251: 1197: 1174:Pedro II, Piauí 1155: 1153:Other locations 1131:Baja California 1096:Ezequiel Montes 1059: 1043:placer deposits 1020:Humboldt County 1008: 961: 959: 915:New South Wales 911:Lightning Ridge 891: 887: 884: 882: 877: 873: 870: 868: 861:South Australia 853: 836:South Australia 808: 784: 724: 717: 645: 555: 551: 539:South Australia 515: 417: 409: 289: 284: 282: 281: 279: 239: 237: 236: 234: 189: 114: 106: 92: 91: 68: 49: 42: 35: 28: 23: 22: 15: 12: 11: 5: 6270: 6268: 6260: 6259: 6254: 6249: 6244: 6239: 6234: 6229: 6219: 6218: 6212: 6211: 6209: 6208: 6203: 6197: 6195: 6191: 6190: 6188: 6187: 6185:Volcanic glass 6182: 6180:Vitrified sand 6177: 6168: 6163: 6161:Opal formation 6158: 6152: 6150: 6144: 6143: 6141: 6140: 6138:Tempered glass 6135: 6130: 6125: 6120: 6115: 6110: 6105: 6103:Polished plate 6100: 6095: 6090: 6085: 6080: 6075: 6070: 6065: 6060: 6055: 6050: 6045: 6040: 6035: 6030: 6025: 6020: 6015: 6010: 6005: 6000: 5995: 5990: 5985: 5980: 5974: 5972: 5966: 5965: 5963: 5962: 5957: 5952: 5947: 5942: 5937: 5932: 5927: 5922: 5917: 5912: 5907: 5902: 5897: 5891: 5889: 5883: 5882: 5876: 5874: 5873: 5866: 5859: 5851: 5842: 5841: 5839: 5838: 5833: 5828: 5823: 5818: 5813: 5808: 5807:Related topics 5804: 5801: 5800: 5798: 5797: 5792: 5787: 5781: 5775: 5769: 5767: 5763: 5762: 5759: 5758: 5756: 5755: 5750: 5749: 5748: 5738: 5733: 5728: 5723: 5718: 5712: 5710: 5706: 5705: 5703: 5702: 5697: 5692: 5687: 5682: 5677: 5672: 5671: 5670: 5665: 5655: 5650: 5645: 5640: 5634: 5632: 5628: 5627: 5625: 5624: 5619: 5614: 5609: 5604: 5599: 5594: 5589: 5584: 5579: 5574: 5569: 5564: 5554: 5549: 5544: 5539: 5534: 5529: 5524: 5519: 5514: 5509: 5504: 5499: 5494: 5489: 5484: 5479: 5474: 5469: 5464: 5459: 5454: 5449: 5444: 5439: 5429: 5424: 5419: 5414: 5408: 5406: 5399: 5398: 5396: 5395: 5390: 5385: 5380: 5375: 5370: 5365: 5360: 5355: 5350: 5344: 5342: 5336: 5335: 5333: 5332: 5327: 5326: 5325: 5315: 5310: 5305: 5300: 5295: 5290: 5284: 5282: 5275: 5274: 5272: 5271: 5266: 5261: 5256: 5251: 5245: 5243: 5234: 5230: 5229: 5226: 5225: 5223: 5222: 5217: 5212: 5207: 5202: 5196: 5194: 5190: 5189: 5187: 5186: 5181: 5179:Wire sculpture 5176: 5171: 5166: 5161: 5156: 5151: 5146: 5141: 5136: 5131: 5126: 5125: 5124: 5119: 5114: 5104: 5098: 5096: 5092: 5091: 5089: 5088: 5083: 5078: 5073: 5068: 5063: 5058: 5052: 5050: 5043: 5039: 5038: 5036: 5035: 5034: 5033: 5028: 5018: 5013: 5008: 5003: 4998: 4993: 4988: 4983: 4978: 4973: 4968: 4963: 4958: 4953: 4948: 4943: 4938: 4933: 4928: 4923: 4918: 4913: 4908: 4903: 4898: 4893: 4887: 4885: 4879: 4878: 4873: 4871: 4870: 4863: 4856: 4848: 4839: 4838: 4836: 4835: 4812: 4809: 4808: 4806: 4805: 4800: 4795: 4790: 4784: 4782: 4778: 4777: 4775: 4774: 4760: 4746: 4738: 4733: 4728: 4723: 4718: 4712: 4707: 4701: 4691: 4689:Petrified wood 4686: 4678: 4672: 4670: 4666: 4665: 4662: 4661: 4659: 4658: 4652: 4646: 4641: 4628: 4623: 4618: 4612: 4610: 4604: 4603: 4601: 4600: 4595: 4590: 4580: 4575: 4570: 4565: 4559: 4557: 4548: 4542: 4541: 4538: 4537: 4535: 4534: 4528: 4523: 4518: 4497: 4492: 4486: 4476: 4475:, polychromous 4470: 4463: 4461: 4455: 4454: 4452: 4451: 4446: 4441: 4434: 4429: 4423: 4421: 4415: 4414: 4412: 4411: 4406: 4401: 4396: 4391: 4386: 4380: 4378: 4372: 4371: 4369: 4368: 4363: 4358: 4353: 4348: 4343: 4337: 4335: 4324: 4317: 4316: 4313: 4310: 4309: 4304: 4302: 4301: 4294: 4287: 4279: 4270: 4269: 4266: 4265: 4251: 4248: 4247: 4245: 4244: 4239: 4237:Shocked quartz 4234: 4229: 4224: 4219: 4213: 4211: 4205: 4204: 4202: 4201: 4196: 4190: 4188: 4182: 4181: 4179: 4178: 4173: 4168: 4163: 4158: 4153: 4148: 4142: 4140: 4131: 4127: 4126: 4124: 4123: 4118: 4112: 4110: 4106: 4105: 4103: 4102: 4097: 4095:Lechatelierite 4092: 4086: 4084: 4078: 4077: 4075: 4074: 4069: 4064: 4059: 4053: 4051: 4045: 4044: 4042: 4041: 4036: 4031: 4026: 4021: 4016: 4011: 4006: 4000: 3998: 3992: 3991: 3983: 3981: 3980: 3973: 3966: 3958: 3952: 3951: 3945: 3939: 3926: 3920: 3917:Georg Agricola 3900: 3899:External links 3897: 3894: 3893: 3867: 3841: 3812: 3786: 3756: 3745: 3725: 3714:on 7 June 2011 3699: 3674: 3667: 3646: 3633: 3602: 3584: 3559: 3541: 3513: 3502: 3476: 3419: 3373: 3362: 3342: 3291: 3224: 3194: 3169: 3137: 3112: 3087: 3055: 3025: 2999: 2966: 2951: 2933: 2911: 2889: 2867: 2845: 2823: 2801: 2778: 2749: 2736:(2): 112–120. 2716: 2701: 2684:"Opal Fossils" 2672: 2657: 2642: 2624: 2598: 2584:978-0975721407 2583: 2565: 2547: 2513: 2486: 2460: 2442: 2433:It's an Honour 2420: 2390: 2368: 2359: 2350: 2341: 2316: 2290: 2264: 2242: 2227: 2220: 2202: 2185:Gemsociety.org 2171: 2127: 2120: 2095: 2076:(4): 427–434. 2060: 2015: 1990: 1965: 1950:. Mindat.org. 1939: 1924:. Webmineral. 1913: 1865: 1836:(3): 291–320. 1815: 1814: 1812: 1809: 1808: 1807: 1799: 1790: 1784: 1779: 1770: 1761: 1755: 1754: 1738: 1735: 1734: 1733: 1724: 1717: 1714: 1711: 1701: 1698: 1688: 1681: 1678: 1672: 1661: 1654: 1647:Andamooka Opal 1643: 1631: 1628: 1576: 1573: 1518:, the wife of 1484: 1481: 1477:hydrogen bonds 1460: 1457: 1428: 1425: 1399: 1396: 1374: 1355: 1347: 1343: 1299: 1296: 1250: 1249:Synthetic opal 1247: 1231:petrified wood 1196: 1193: 1183:In late 2008, 1167:Spencer, Idaho 1161:Brazilian opal 1154: 1151: 1058: 1055: 1007: 1004: 992:Wollo Province 958: 955: 852: 849: 807: 804: 802:of Australia. 783: 780: 716: 713: 683:, also called 644: 641: 514: 513:Precious opal 511: 415: 407: 380: 379: 377: 373: 372: 350: 344: 343: 340: 336: 335: 332: 326: 325: 321: 312: 311: 308: 302: 301: 298: 292: 291: 277: 271: 270: 267: 263: 262: 259: 255: 254: 251: 245: 244: 232: 226: 225: 222: 216: 215: 212: 206: 205: 202: 196: 195: 192: 183: 182: 176: 170: 169: 166: 160: 159: 156: 150: 149: 146: 142: 141: 140:Identification 137: 136: 133: 131:Crystal system 127: 126: 123: 117: 116: 112: 104: 95: 85: 84: 79: 75: 74: 70: 69: 66: 58: 57: 26: 24: 14: 13: 10: 9: 6: 4: 3: 2: 6269: 6258: 6255: 6253: 6250: 6248: 6245: 6243: 6240: 6238: 6235: 6233: 6230: 6228: 6225: 6224: 6222: 6207: 6204: 6202: 6199: 6198: 6196: 6192: 6186: 6183: 6181: 6178: 6176: 6172: 6169: 6167: 6164: 6162: 6159: 6157: 6154: 6153: 6151: 6149: 6145: 6139: 6136: 6134: 6131: 6129: 6128:Stained glass 6126: 6124: 6121: 6119: 6116: 6114: 6113:Rippled glass 6111: 6109: 6106: 6104: 6101: 6099: 6096: 6094: 6091: 6089: 6086: 6084: 6081: 6079: 6076: 6074: 6071: 6069: 6066: 6064: 6061: 6059: 6056: 6054: 6053:Flashed glass 6051: 6049: 6046: 6044: 6041: 6039: 6036: 6034: 6031: 6029: 6026: 6024: 6021: 6019: 6016: 6014: 6011: 6009: 6006: 6004: 6001: 5999: 5996: 5994: 5991: 5989: 5986: 5984: 5981: 5979: 5976: 5975: 5973: 5967: 5961: 5958: 5956: 5953: 5951: 5948: 5946: 5943: 5941: 5938: 5936: 5933: 5931: 5928: 5926: 5923: 5921: 5918: 5916: 5913: 5911: 5908: 5906: 5903: 5901: 5900:Fritted glass 5898: 5896: 5893: 5892: 5890: 5884: 5879: 5872: 5867: 5865: 5860: 5858: 5853: 5852: 5849: 5837: 5834: 5832: 5829: 5827: 5824: 5822: 5819: 5817: 5814: 5812: 5811:Body piercing 5809: 5806: 5805: 5802: 5796: 5793: 5791: 5788: 5785: 5782: 5779: 5776: 5774: 5771: 5770: 5768: 5764: 5754: 5751: 5747: 5744: 5743: 5742: 5739: 5737: 5734: 5732: 5729: 5727: 5724: 5722: 5719: 5717: 5714: 5713: 5711: 5707: 5701: 5700:Tortoiseshell 5698: 5696: 5693: 5691: 5688: 5686: 5683: 5681: 5678: 5676: 5673: 5669: 5666: 5664: 5661: 5660: 5659: 5656: 5654: 5651: 5649: 5646: 5644: 5641: 5639: 5636: 5635: 5633: 5629: 5623: 5620: 5618: 5615: 5613: 5610: 5608: 5605: 5603: 5600: 5598: 5595: 5593: 5590: 5588: 5585: 5583: 5580: 5578: 5575: 5573: 5570: 5568: 5565: 5562: 5558: 5555: 5553: 5550: 5548: 5545: 5543: 5540: 5538: 5535: 5533: 5530: 5528: 5525: 5523: 5520: 5518: 5515: 5513: 5510: 5508: 5505: 5503: 5500: 5498: 5495: 5493: 5490: 5488: 5485: 5483: 5480: 5478: 5475: 5473: 5470: 5468: 5465: 5463: 5460: 5458: 5455: 5453: 5450: 5448: 5445: 5443: 5440: 5437: 5433: 5430: 5428: 5425: 5423: 5420: 5418: 5415: 5413: 5410: 5409: 5407: 5405: 5400: 5394: 5391: 5389: 5386: 5384: 5381: 5379: 5376: 5374: 5371: 5369: 5366: 5364: 5361: 5359: 5356: 5354: 5351: 5349: 5346: 5345: 5343: 5341: 5337: 5331: 5328: 5324: 5321: 5320: 5319: 5316: 5314: 5311: 5309: 5306: 5304: 5301: 5299: 5296: 5294: 5291: 5289: 5286: 5285: 5283: 5281: 5276: 5270: 5267: 5265: 5262: 5260: 5257: 5255: 5252: 5250: 5247: 5246: 5244: 5242: 5238: 5235: 5231: 5221: 5218: 5216: 5213: 5211: 5208: 5206: 5203: 5201: 5198: 5197: 5195: 5191: 5185: 5182: 5180: 5177: 5175: 5172: 5170: 5167: 5165: 5162: 5160: 5157: 5155: 5152: 5150: 5147: 5145: 5142: 5140: 5137: 5135: 5132: 5130: 5127: 5123: 5120: 5118: 5115: 5113: 5110: 5109: 5108: 5105: 5103: 5100: 5099: 5097: 5093: 5087: 5084: 5082: 5079: 5077: 5074: 5072: 5069: 5067: 5064: 5062: 5059: 5057: 5056:Bench jeweler 5054: 5053: 5051: 5047: 5044: 5040: 5032: 5029: 5027: 5024: 5023: 5022: 5019: 5017: 5014: 5012: 5009: 5007: 5004: 5002: 4999: 4997: 4994: 4992: 4989: 4987: 4984: 4982: 4979: 4977: 4974: 4972: 4969: 4967: 4964: 4962: 4959: 4957: 4954: 4952: 4949: 4947: 4944: 4942: 4939: 4937: 4934: 4932: 4929: 4927: 4924: 4922: 4919: 4917: 4914: 4912: 4909: 4907: 4904: 4902: 4899: 4897: 4894: 4892: 4889: 4888: 4886: 4884: 4880: 4876: 4869: 4864: 4862: 4857: 4855: 4850: 4849: 4846: 4834: 4833: 4822: 4821: 4820: 4810: 4804: 4801: 4799: 4796: 4794: 4791: 4789: 4786: 4785: 4783: 4779: 4772: 4768: 4764: 4761: 4758: 4754: 4750: 4747: 4745: 4742: 4739: 4737: 4734: 4732: 4729: 4727: 4724: 4722: 4719: 4716: 4713: 4711: 4708: 4706: 4702: 4699: 4695: 4692: 4690: 4687: 4685: 4682: 4679: 4677: 4674: 4673: 4671: 4667: 4657: 4653: 4651: 4647: 4645: 4642: 4640: 4637: 4633: 4629: 4627: 4624: 4622: 4619: 4617: 4614: 4613: 4611: 4609: 4605: 4599: 4596: 4594: 4591: 4588: 4584: 4581: 4579: 4576: 4574: 4571: 4569: 4566: 4564: 4561: 4560: 4558: 4556: 4552: 4549: 4543: 4533: 4529: 4527: 4524: 4522: 4519: 4517: 4513: 4509: 4505: 4501: 4498: 4496: 4493: 4490: 4487: 4484: 4480: 4477: 4474: 4471: 4468: 4465: 4464: 4462: 4460: 4456: 4450: 4447: 4445: 4442: 4439: 4435: 4433: 4430: 4428: 4425: 4424: 4422: 4420: 4416: 4410: 4407: 4405: 4402: 4400: 4397: 4395: 4392: 4390: 4387: 4385: 4384:Pink sapphire 4382: 4381: 4379: 4377: 4373: 4367: 4364: 4362: 4359: 4357: 4356:Blue Sapphire 4354: 4352: 4349: 4347: 4344: 4342: 4339: 4338: 4336: 4334: 4333: 4328: 4325: 4322: 4318: 4311: 4307: 4300: 4295: 4293: 4288: 4286: 4281: 4280: 4277: 4263: 4262: 4249: 4243: 4240: 4238: 4235: 4233: 4230: 4228: 4225: 4223: 4220: 4218: 4215: 4214: 4212: 4210: 4206: 4200: 4197: 4195: 4192: 4191: 4189: 4187: 4183: 4177: 4174: 4172: 4169: 4167: 4164: 4162: 4159: 4157: 4154: 4152: 4149: 4147: 4144: 4143: 4141: 4139: 4135: 4132: 4128: 4122: 4119: 4117: 4114: 4113: 4111: 4109:Miscellaneous 4107: 4101: 4098: 4096: 4093: 4091: 4088: 4087: 4085: 4083: 4079: 4073: 4070: 4068: 4065: 4063: 4060: 4058: 4055: 4054: 4052: 4050: 4046: 4040: 4037: 4035: 4032: 4030: 4027: 4025: 4022: 4020: 4017: 4015: 4012: 4010: 4007: 4005: 4002: 4001: 3999: 3997: 3993: 3989: 3986: 3979: 3974: 3972: 3967: 3965: 3960: 3959: 3956: 3949: 3946: 3943: 3940: 3937: 3933: 3930: 3927: 3924: 3921: 3918: 3914: 3910: 3906: 3903: 3902: 3898: 3881: 3877: 3871: 3868: 3855: 3851: 3845: 3842: 3829: 3825: 3819: 3817: 3813: 3800: 3796: 3790: 3787: 3774: 3770: 3766: 3760: 3757: 3752: 3748: 3742: 3738: 3737: 3729: 3726: 3713: 3709: 3703: 3700: 3688: 3684: 3678: 3675: 3670: 3664: 3660: 3656: 3650: 3647: 3643: 3642:The opal book 3640:Leechman, F; 3637: 3634: 3629: 3625: 3621: 3617: 3613: 3606: 3603: 3598: 3594: 3588: 3585: 3573: 3569: 3563: 3560: 3555: 3551: 3545: 3542: 3537: 3533: 3532: 3524: 3522: 3520: 3518: 3514: 3509: 3505: 3503:9780471133971 3499: 3495: 3494: 3489: 3483: 3481: 3477: 3469: 3465: 3461: 3457: 3453: 3449: 3445: 3441: 3437: 3430: 3423: 3420: 3408: 3404: 3400: 3396: 3392: 3388: 3384: 3377: 3374: 3371: 3366: 3363: 3358: 3354: 3346: 3343: 3338: 3334: 3330: 3326: 3322: 3318: 3314: 3310: 3306: 3302: 3295: 3292: 3287: 3283: 3278: 3273: 3269: 3265: 3260: 3255: 3251: 3247: 3243: 3239: 3235: 3228: 3225: 3212: 3208: 3204: 3198: 3195: 3183: 3179: 3173: 3170: 3158: 3154: 3150: 3149: 3141: 3138: 3126: 3122: 3116: 3113: 3101: 3097: 3091: 3088: 3075: 3071: 3070: 3065: 3059: 3056: 3043: 3039: 3035: 3029: 3026: 3013: 3009: 3003: 3000: 2994: 2989: 2985: 2981: 2977: 2970: 2967: 2962: 2955: 2952: 2947: 2943: 2937: 2934: 2929: 2925: 2921: 2915: 2912: 2907: 2903: 2899: 2893: 2890: 2885: 2881: 2877: 2871: 2868: 2863: 2859: 2855: 2849: 2846: 2841: 2837: 2833: 2827: 2824: 2819: 2815: 2811: 2805: 2802: 2797: 2793: 2792:Addis Fortune 2789: 2782: 2779: 2773: 2768: 2764: 2760: 2753: 2750: 2744: 2739: 2735: 2731: 2727: 2720: 2717: 2712: 2705: 2702: 2689: 2685: 2679: 2677: 2673: 2669: 2666: 2661: 2658: 2654: 2651: 2646: 2643: 2638: 2634: 2628: 2625: 2613: 2609: 2602: 2599: 2594: 2590: 2586: 2580: 2576: 2569: 2566: 2561: 2557: 2551: 2548: 2533: 2526: 2525: 2517: 2514: 2506: 2499: 2498: 2490: 2487: 2474: 2470: 2464: 2461: 2456: 2452: 2446: 2443: 2438: 2434: 2430: 2424: 2421: 2408: 2404: 2400: 2394: 2391: 2378: 2372: 2369: 2363: 2360: 2354: 2351: 2345: 2342: 2330: 2326: 2320: 2317: 2304: 2300: 2294: 2291: 2279: 2275: 2268: 2265: 2260: 2256: 2249: 2247: 2243: 2238: 2231: 2228: 2223: 2217: 2213: 2206: 2203: 2190: 2186: 2182: 2175: 2172: 2167: 2163: 2159: 2155: 2151: 2147: 2143: 2139: 2131: 2128: 2123: 2117: 2112: 2111: 2102: 2100: 2096: 2091: 2087: 2083: 2079: 2075: 2071: 2064: 2061: 2056: 2052: 2048: 2044: 2040: 2036: 2032: 2028: 2027: 2019: 2016: 2004: 2000: 1994: 1991: 1979: 1975: 1969: 1966: 1953: 1949: 1943: 1940: 1927: 1923: 1917: 1914: 1911: 1910:0-87311-019-6 1907: 1903: 1899: 1894: 1892: 1890: 1888: 1886: 1884: 1882: 1880: 1878: 1876: 1874: 1872: 1870: 1866: 1861: 1857: 1852: 1847: 1843: 1839: 1835: 1831: 1827: 1820: 1817: 1810: 1806: 1804: 1800: 1794: 1791: 1788: 1785: 1783: 1780: 1774: 1771: 1765: 1762: 1760: 1757: 1756: 1752: 1741: 1736: 1732: 1728: 1725: 1722: 1718: 1715: 1712: 1710: 1706: 1702: 1699: 1697: 1693: 1689: 1686: 1682: 1679: 1677: 1673: 1670: 1666: 1662: 1659: 1655: 1652: 1648: 1644: 1642: 1638: 1634: 1633: 1629: 1627: 1625: 1620: 1618: 1612: 1609: 1605: 1601: 1600: 1595: 1591: 1587: 1583: 1574: 1572: 1570: 1564: 1561: 1555: 1549: 1543: 1538: 1537:Ancient Greek 1533: 1530: 1525: 1521: 1517: 1513: 1508: 1505: 1500: 1495: 1490: 1482: 1480: 1478: 1474: 1470: 1466: 1458: 1452: 1448: 1446: 1442: 1437: 1435: 1426: 1424: 1422: 1418: 1413: 1409: 1405: 1397: 1395: 1393: 1389: 1384: 1380: 1372: 1369:of anhydrous 1368: 1363: 1361: 1353: 1341: 1337: 1333: 1329: 1325: 1316: 1309: 1304: 1297: 1295: 1293: 1287: 1285: 1281: 1275: 1273: 1269: 1260: 1255: 1248: 1246: 1244: 1240: 1236: 1235:opalized wood 1232: 1228: 1224: 1218: 1214: 1209: 1201: 1194: 1192: 1190: 1186: 1181: 1179: 1175: 1170: 1168: 1159: 1152: 1150: 1148: 1144: 1140: 1136: 1132: 1128: 1124: 1120: 1116: 1112: 1107: 1105: 1099: 1097: 1093: 1092:Tequisquiapan 1089: 1085: 1081: 1072: 1068: 1065: 1056: 1054: 1052: 1048: 1044: 1040: 1036: 1032: 1031: 1025: 1021: 1012: 1005: 999: 995: 993: 989: 985: 980: 956: 954: 952: 948: 944: 940: 936: 932: 928: 924: 920: 916: 912: 908: 904: 901: 896: 866: 862: 858: 850: 848: 846: 841: 837: 829: 824: 817: 812: 805: 803: 801: 797: 791: 781: 779: 777: 773: 769: 764: 762: 761:Virgin Valley 758: 754: 750: 744: 742: 737: 728: 722: 714: 712: 710: 706: 702: 698: 694: 690: 686: 682: 678: 674: 670: 666: 657: 649: 642: 640: 637: 632: 628: 623: 621: 620:adularescence 617: 613: 612: 611:play of color 607: 606: 601: 597: 593: 588: 586: 581: 577: 576:visible light 572: 568: 564: 561: 544: 540: 536: 531: 524: 519: 512: 510: 509:most common. 507: 503: 498: 495: 489: 483: 477: 472: 468: 463: 461: 457: 453: 449: 445: 441: 437: 433: 429: 425: 421: 420:water content 413: 405: 401: 398: 394: 386: 378: 374: 371: 367: 363: 359: 355: 351: 349: 345: 341: 337: 333: 331: 327: 322: 320: 317: 313: 309: 307: 303: 299: 297: 296:Birefringence 293: 278: 276: 272: 268: 264: 260: 258:Polish luster 256: 252: 250: 246: 233: 231: 227: 223: 221: 217: 213: 211: 207: 203: 201: 197: 193: 188: 184: 180: 177: 175: 171: 167: 165: 161: 157: 155: 154:Crystal habit 151: 147: 143: 138: 134: 132: 128: 124: 122: 118: 110: 102: 99: 96: 90: 86: 83: 80: 76: 71: 64: 59: 54: 51: 47: 40: 33: 19: 6160: 6133:Studio glass 6108:Porous glass 6073:Glass mosaic 6058:Forest glass 5969:Artistic and 5836:Wearable art 5831:Phaleristics 5826:Metalworking 5731:Gutta-percha 5541: 5507:Lapis lazuli 5293:Colored gold 5174:Stonesetting 4823: 4767:Pyrophyllite 4736:Serpentinite 4717:(green mica) 4697: 4649: 4607: 4587:Baltic amber 4554: 4458: 4418: 4375: 4330: 4252: 4232:Smoky quartz 4185: 4099: 4009:Cristobalite 3913:Isaac Newton 3909:Theophrastus 3884:. Retrieved 3870: 3858:. Retrieved 3844: 3832:. Retrieved 3803:. Retrieved 3789: 3777:. Retrieved 3768: 3759: 3735: 3728: 3716:. Retrieved 3712:the original 3702: 3690:. Retrieved 3686: 3677: 3658: 3649: 3641: 3636: 3619: 3615: 3605: 3596: 3587: 3575:. Retrieved 3571: 3562: 3553: 3544: 3530: 3492: 3439: 3435: 3422: 3410:. Retrieved 3390: 3386: 3376: 3365: 3356: 3352: 3345: 3304: 3300: 3294: 3241: 3238:RSC Advances 3237: 3227: 3215:. Retrieved 3206: 3197: 3185:. Retrieved 3181: 3172: 3160:. Retrieved 3147: 3140: 3128:. Retrieved 3124: 3115: 3103:. Retrieved 3099: 3090: 3078:. Retrieved 3067: 3058: 3046:. Retrieved 3037: 3028: 3016:. Retrieved 3011: 3002: 2986:(2): 87–96. 2983: 2979: 2969: 2960: 2954: 2946:the original 2936: 2923: 2914: 2901: 2892: 2879: 2870: 2857: 2848: 2835: 2826: 2813: 2804: 2791: 2781: 2762: 2752: 2733: 2729: 2719: 2710: 2704: 2692:. Retrieved 2667: 2660: 2652: 2645: 2637:the original 2627: 2615:. Retrieved 2611: 2601: 2574: 2568: 2550: 2541:20 September 2539:, retrieved 2523: 2516: 2496: 2489: 2477:. Retrieved 2473:the original 2463: 2445: 2432: 2423: 2411:. Retrieved 2402: 2393: 2381:. Retrieved 2371: 2362: 2353: 2344: 2332:. Retrieved 2328: 2319: 2307:. Retrieved 2302: 2293: 2281:. Retrieved 2278:Geology Page 2277: 2267: 2236: 2230: 2211: 2205: 2193:. Retrieved 2184: 2174: 2141: 2137: 2130: 2109: 2073: 2069: 2063: 2030: 2024: 2018: 2006:. Retrieved 2002: 1993: 1981:. Retrieved 1977: 1968: 1956:. Retrieved 1942: 1930:. Retrieved 1916: 1901: 1833: 1829: 1819: 1802: 1708: 1621: 1613: 1597: 1594:Walter Scott 1578: 1565: 1534: 1509: 1486: 1462: 1438: 1430: 1420: 1416: 1408:cristobalite 1403: 1401: 1379:cristobalite 1364: 1351: 1321: 1308:cristobalite 1288: 1276: 1264: 1238: 1234: 1226: 1222: 1221: 1182: 1171: 1164: 1108: 1100: 1077: 1060: 1038: 1028: 1022:in northern 1017: 976: 905: 897: 855:The town of 854: 832: 785: 765: 745: 743:and Mexico. 733: 663:Besides the 662: 624: 609: 603: 589: 567:interference 560:close-packed 548: 499: 466: 464: 411: 392: 391: 324:phosphoresce 319:fluorescence 108: 50: 6083:Lampworking 6023:Crown glass 6018:Cased glass 6013:Caneworking 6008:Broad sheet 6003:Blown plate 5773:Art jewelry 5597:Tiger's eye 5502:Labradorite 5452:Chrysocolla 5447:Chrysoberyl 5363:Mokume-gane 5340:Base metals 5112:centrifugal 5081:Silversmith 4956:Ferronnière 4906:Belt buckle 4901:Belly chain 4749:Ophicalcite 4630:Colorless, 4593:Chrysoprase 4504:Spessartine 4469:– Verdelite 4361:Alexandrite 4161:Chrysoprase 4116:Tiger's eye 3996:Crystalline 3182:geology.com 3018:14 February 2711:ICA Gazette 2283:29 December 2195:22 November 1805:(2019 film) 1782:Labradorite 1705:Galaxy Opal 1641:Coober Pedy 1588:during the 1473:hydrophilic 1445:sedimentary 1272:ultraviolet 1213:ichthyosaur 1195:Fossil opal 923:concretions 903:Australia. 857:Coober Pedy 759:around the 689:hot springs 643:Common opal 605:opalescence 585:Bragg's law 571:diffraction 535:Coober Pedy 502:iridescence 428:crystalline 316:Ultraviolet 306:Pleochroism 220:Diaphaneity 6221:Categories 6093:Millefiori 5993:Beadmaking 5915:Glass wool 5888:techniques 5886:Commercial 5880:techniques 5607:Tourmaline 5552:Prasiolite 5427:Aventurine 5298:Crown gold 5200:Draw plate 5149:Metal clay 5086:Watchmaker 5076:Lapidarist 5061:Clockmaker 4936:Collar pin 4931:Chatelaine 4753:Serpentine 4741:Aventurine 4715:Listwanite 4506:(malaya), 4473:Indicolite 4467:Tourmaline 4440:(Imperial) 4432:Aquamarine 4242:Prasiolite 4171:Moss agate 4166:Heliotrope 4138:Chalcedony 4057:Chalcedony 4034:Stishovite 4029:Seifertite 3805:13 January 3779:13 January 3577:16 October 3125:mindat.org 3100:mindat.org 3080:29 October 3038:Mindat.org 2924:mindat.org 2902:mindat.org 2880:mindat.org 2858:mindat.org 2836:mindat.org 2814:mindat.org 2612:Al Jazeera 2429:"Gemstone" 2403:Mindat.org 1811:References 1803:Uncut Gems 1624:birthstone 1608:holy water 1524:Saturnalia 1441:diagenesis 1367:polymorphs 1324:mineraloid 1280:inclusions 1135:Guanajuato 424:mineraloid 376:References 366:humic acid 354:salt water 348:Solubility 187:Mohs scale 179:Conchoidal 121:IMA symbol 82:Mineraloid 6175:Impactite 6166:Sea glass 6078:Glassware 6038:Engraving 6028:Cut glass 5988:Glass art 5983:Art glass 5978:Āina-kāri 5753:Toadstone 5690:Operculum 5617:Variscite 5612:Turquoise 5592:Tanzanite 5527:Moonstone 5522:Marcasite 5517:Malachite 5442:Carnelian 5417:Amazonite 5404:gemstones 5378:Pinchbeck 5323:Argentium 5313:Shibuichi 5254:Palladium 5233:Materials 5169:Soldering 5159:Polishing 5134:Engraving 5129:Enameling 5095:Processes 5066:Goldsmith 5001:Tie chain 4976:Neck ring 4966:Lapel pin 4875:Jewellery 4744:quartzite 4696:(Porouse 4694:Cacholong 4656:feldspars 4626:Rhodonite 4621:Amazonite 4608:2nd order 4578:Malachite 4555:1st order 4532:Turquoise 4512:Almandine 4508:Rhodolite 4459:4th order 4419:3rd order 4409:Tanzanite 4394:Tsavorite 4389:Demantoid 4376:2nd order 4332:1st order 4306:Gemstones 4199:Geyserite 4151:Carnelian 4090:Fulgurite 4082:Amorphous 4039:Tridymite 3948:Opalworld 3718:8 October 3692:7 January 3337:137194866 3329:1521-4095 3268:2046-2069 3217:8 October 3157:918261679 3096:"Xylopal" 3048:8 October 2593:225050989 2166:121167426 1958:8 October 1932:8 October 1860:235729616 1773:Foil opal 1764:Cacholong 1731:inclusion 1483:Etymology 1421:lussatite 1417:lussatine 1412:tridymite 1388:hexagonal 1383:tridymite 1332:amorphous 1328:unit cell 1292:photonics 1268:fluoresce 1223:Wood opal 1203:Wood opal 1178:Erandique 1143:Michoacán 1127:Chihuahua 1111:Magdalena 1084:Querétaro 1064:Querétaro 1035:bentonite 988:Wegeltena 927:ironstone 907:Andamooka 851:Australia 845:Wegeltena 790:Červenica 681:geyserite 465:The name 448:sandstone 426:, unlike 400:amorphous 253:2.09 g/cm 181:to uneven 135:Amorphous 6242:Hydrates 6123:Slumping 5935:Pressing 5821:Gemology 5795:Fineness 5786:(purity) 5721:Bog-wood 5668:Precious 5648:Ammolite 5587:Sunstone 5577:Sodalite 5572:Sapphire 5532:Obsidian 5472:Fluorite 5462:Diopside 5422:Amethyst 5402:Mineral 5393:Tungsten 5388:Titanium 5303:Electrum 5259:Platinum 5144:Kazaziye 5139:Filigree 5117:lost-wax 5016:Toe ring 5006:Tie clip 4981:Pectoral 4971:Necklace 4946:Cufflink 4921:Bracelet 4916:Bolo tie 4896:Barrette 4763:Pagodite 4731:Fluorite 4726:Selenite 4710:Obsidian 4644:Hematite 4598:Charoite 4573:Nephrite 4563:Lazurite 4521:Amethyst 4483:Heliodor 4222:Ametrine 4217:Amethyst 4019:Moganite 3988:minerals 3932:Archived 3880:Archived 3860:18 March 3854:Archived 3828:Archived 3799:Archived 3773:Archived 3769:ABC News 3751:Archived 3657:(1997). 3552:(1996). 3508:Archived 3490:(1997). 3468:Archived 3464:53527412 3286:35497145 3211:Archived 3074:Archived 3042:Archived 2959:"Opal". 2928:Archived 2906:Archived 2884:Archived 2862:Archived 2840:Archived 2818:Archived 2796:Archived 2688:Archived 2668:ABC News 2653:ABC News 2617:8 August 2560:Archived 2532:archived 2505:archived 2455:Archived 2437:Archived 2407:Archived 2259:Archived 2189:Archived 1952:Archived 1926:Archived 1737:See also 1630:Examples 1617:evil eye 1604:talisman 1582:bay leaf 1569:Bosporus 1560:paederos 1554:opallios 1542:opallios 1499:Sanskrit 1465:siloxane 1360:silanols 1243:gemstone 1115:Guerrero 984:rhyolite 979:Ethiopia 957:Ethiopia 800:gemstone 796:Slovakia 709:gemology 673:menilite 665:gemstone 627:cabochon 600:lamellae 592:band gap 506:diffract 494:ὀπάλλιος 488:opállios 471:Sanskrit 452:rhyolite 444:limonite 436:fissures 432:minerals 418:O); its 402:form of 397:hydrated 362:methanol 190:hardness 174:Fracture 164:Cleavage 98:Hydrated 78:Category 6194:Related 6043:Etching 5998:Blowing 5960:Rolling 5940:Casting 5816:Fashion 5790:Finding 5638:Abalone 5547:Peridot 5512:Larimar 5497:Kyanite 5482:Howlite 5467:Emerald 5457:Diamond 5330:Tumbaga 5308:Shakudō 5264:Rhodium 5215:Mandrel 5154:Plating 5107:Casting 5102:Carving 5011:Tie pin 4986:Pendant 4961:Genital 4951:Earring 4781:Related 4757:Calcite 4703:Marble 4684:granite 4681:Graphic 4648:Common 4568:Jadeite 4526:Citrine 4500:Garnets 4495:Peridot 4444:Elbaite 4436:Orange 4351:Emerald 4341:Diamond 4321:Jewelry 4194:Fiorite 4014:Keatite 4004:Coesite 3444:Bibcode 3412:16 June 3395:Bibcode 3309:Bibcode 3277:9052040 3246:Bibcode 3162:10 July 2694:3 March 2479:11 July 2413:8 March 2383:10 June 2309:18 June 2146:Bibcode 2078:Bibcode 2055:4169953 2035:Bibcode 1838:Bibcode 1787:Opalite 1586:thieves 1469:silanol 1434:Hyalite 1415:called 1404:Opal-CT 1227:xylopal 1123:Durango 1119:Morelos 1104:Jalisco 1047:Miocene 1039:in situ 1030:in situ 943:Quilpie 890:⁄ 876:⁄ 806:Sources 782:History 768:diatoms 736:hyalite 693:geysers 677:hyalite 631:doublet 580:grating 563:lattice 554:10–1.18 249:Density 89:Formula 73:General 18:Girasol 6098:Mirror 6068:Fusing 5780:(mass) 5716:Bezoar 5622:Zircon 5582:Spinel 5557:Quartz 5492:Jasper 5477:Garnet 5373:Pewter 5358:Copper 5353:Bronze 5280:alloys 5269:Silver 5220:Pliers 5210:Hammer 5122:vacuum 5049:People 5042:Making 5026:pocket 4926:Brooch 4891:Anklet 4676:Jasper 4639:quartz 4547:stones 4516:Pyrope 4399:Spinel 4323:stones 4209:Quartz 4072:Jasper 4024:Quartz 3985:Silica 3886:7 July 3834:7 July 3743: 3665: 3500: 3462: 3393:: 68. 3335: 3327: 3284: 3274: 3266: 3187:6 June 3155: 3130:6 June 3105:6 June 2591: 2581: 2334:15 May 2218: 2164: 2118: 2053: 2026:Nature 2008:4 June 2003:Mindat 1983:4 June 1948:"Opal" 1922:"Opal" 1908: 1904:1995, 1858: 1548:opalus 1539:word, 1529:opalus 1520:Saturn 1494:opalus 1371:silica 1284:matrix 1270:under 1145:, and 1139:Puebla 1094:, and 1080:mining 1057:Mexico 1024:Nevada 951:fossil 939:Jundah 935:Koroit 757:Nevada 753:Owyhee 749:Oregon 741:Oregon 705:turbid 701:diatom 695:; and 636:quartz 616:turbid 523:silica 460:basalt 458:, and 404:silica 285:−0.080 283:+0.020 210:Streak 200:Luster 101:silica 6227:Opals 5784:Carat 5778:Carat 5766:Terms 5741:Shell 5695:Pearl 5685:Nacre 5675:Ivory 5663:Black 5658:Coral 5653:Copal 5643:Amber 5602:Topaz 5561:smoky 5432:Beryl 5412:Agate 5348:Brass 5193:Tools 5031:strap 5021:Watch 4996:Tiara 4941:Crown 4911:Bindi 4883:Forms 4632:smoky 4616:Agate 4583:Amber 4530:Blue 4489:Topaz 4479:Beryl 4438:topaz 4146:Agate 4121:Aqeeq 4067:Flint 4062:Chert 3622:(4). 3538:–249. 3471:(PDF) 3460:S2CID 3432:(PDF) 3333:S2CID 2535:(PDF) 2528:(PDF) 2508:(PDF) 2501:(PDF) 2162:S2CID 2051:S2CID 1856:S2CID 1504:úpala 1501:word 1491:term 1489:Latin 1326:, no 1088:Colón 931:Yowah 816:Yowah 669:resin 594:in a 476:upala 473:word 395:is a 358:bases 280:1.450 240:−0.90 238:+0.08 214:White 194:5.5–6 145:Color 103:. SiO 5736:Hair 5567:Ruby 5542:Opal 5537:Onyx 5487:Jade 5249:Gold 5205:File 4991:Ring 4771:Talc 4705:onyx 4698:opal 4650:opal 4636:pink 4634:and 4346:Ruby 4186:Opal 4176:Onyx 4100:Opal 3919:etc. 3888:2017 3862:2017 3836:2017 3807:2016 3781:2016 3741:ISBN 3720:2011 3694:2024 3663:ISBN 3579:2022 3498:ISBN 3414:2022 3325:ISSN 3282:PMID 3264:ISSN 3219:2011 3189:2023 3164:2023 3153:OCLC 3132:2023 3107:2023 3082:2008 3050:2011 3020:2018 2696:2014 2619:2022 2589:OCLC 2579:ISBN 2543:2014 2481:2012 2415:2011 2385:2018 2336:2018 2311:2020 2285:2022 2216:ISBN 2197:2016 2116:ISBN 2010:2018 1985:2018 1960:2011 1934:2011 1906:ISBN 1719:The 1703:The 1683:The 1674:The 1656:The 1645:The 1635:The 1410:and 1390:and 1381:and 1237:and 1189:Mars 1185:NASA 941:and 933:and 898:The 840:USGS 569:and 550:(5.9 467:opal 456:marl 440:rock 406:(SiO 393:Opal 352:hot 310:None 300:none 235:2.15 168:None 56:Opal 32:Opel 5680:Jet 5436:red 4721:Jet 3624:doi 3536:248 3452:doi 3403:doi 3391:405 3317:doi 3272:PMC 3254:doi 2988:doi 2767:doi 2738:doi 2154:doi 2086:doi 2043:doi 2031:204 1846:doi 1667:by 1596:'s 1532:.) 1516:Ops 1419:or 1259:sol 945:in 913:in 859:in 691:or 497:). 482:उपल 125:Opl 6223:: 4514:, 4510:, 4502:– 4481:– 3915:, 3911:, 3815:^ 3767:. 3749:. 3685:. 3620:81 3618:. 3614:. 3570:. 3516:^ 3506:. 3479:^ 3466:. 3458:. 3450:. 3440:81 3438:. 3434:. 3401:. 3389:. 3385:. 3357:29 3355:. 3331:. 3323:. 3315:. 3305:16 3303:. 3280:. 3270:. 3262:. 3252:. 3242:10 3240:. 3236:. 3205:. 3180:. 3123:. 3098:. 3072:. 3066:. 3040:. 3036:. 3010:. 2984:19 2982:. 2978:. 2926:. 2922:. 2904:. 2900:. 2882:. 2878:. 2860:. 2856:. 2838:. 2834:. 2816:. 2812:. 2794:. 2790:. 2765:. 2761:. 2734:32 2732:. 2728:. 2675:^ 2610:. 2587:. 2558:. 2453:. 2431:. 2401:. 2327:. 2301:. 2276:. 2257:. 2245:^ 2187:. 2183:. 2160:. 2152:. 2142:17 2140:. 2098:^ 2084:. 2074:24 2072:. 2049:. 2041:. 2029:. 2001:. 1976:. 1900:, 1868:^ 1854:. 1844:. 1834:85 1832:. 1828:. 1619:. 1563:. 1479:. 1245:. 1191:. 1149:. 1141:, 1137:, 1133:, 1129:, 1125:, 1121:, 1090:, 1045:. 763:. 622:. 537:, 462:. 454:, 450:, 446:, 368:, 364:, 360:, 356:, 6173:/ 5870:e 5863:t 5856:v 5563:) 5559:( 5438:) 5434:( 4867:e 4860:t 4853:v 4773:) 4769:/ 4765:( 4759:) 4755:/ 4751:( 4700:) 4589:) 4585:( 4298:e 4291:t 4284:v 3977:e 3970:t 3963:v 3890:. 3864:. 3838:. 3809:. 3783:. 3722:. 3696:. 3671:. 3630:. 3626:: 3581:. 3454:: 3446:: 3416:. 3405:: 3397:: 3359:. 3339:. 3319:: 3311:: 3288:. 3256:: 3248:: 3221:. 3191:. 3166:. 3134:. 3109:. 3084:. 3052:. 3022:. 2996:. 2990:: 2775:. 2769:: 2746:. 2740:: 2713:. 2698:. 2621:. 2595:. 2483:. 2417:. 2387:. 2338:. 2313:. 2287:. 2224:. 2199:. 2168:. 2156:: 2148:: 2124:. 2092:. 2088:: 2080:: 2057:. 2045:: 2037:: 2012:. 1987:. 1962:. 1936:. 1862:. 1848:: 1840:: 1375:4 1356:2 1354:H 1352:n 1350:· 1348:2 1344:2 892:2 888:1 885:+ 883:4 878:4 874:3 871:+ 869:4 723:. 556:× 552:× 545:. 491:( 479:( 416:2 414:H 412:n 410:· 408:2 115:O 113:2 111:H 109:n 107:· 105:2 48:. 41:. 34:. 20:)

Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.

Index