97-521: The Australia women's national basketball team , nicknamed the Opals after the brightly coloured gemstone common to the country, represents Australia in international basketball . From 1994 onwards, the Opals have been consistently competitive and successful having won nine medals at official FIBA international tournaments ( Olympics and World Cups ), highlighted by a gold medal winning performance at
194-563: 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 evil eye . Opal is considered the birthstone for people born in October. Jenny Cheesman Jennifer Cheesman AM (born 2 November 1957) is an Australian former basketball player and coach. Cheesman played 167 games for the national team between 1975 and 1988, competing at two Olympic Games , in 1984 and 1988 . Cheesman described making
291-436: 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. Besides the gemstone 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); resin opal, which
388-467: A fresh bay leaf and held in the hand. As a result, the opal was seen as the patron gemstone for thieves during the medieval period . Following the publication of Sir Walter Scott 's Anne of Geierstein in 1829, opal acquired a less auspicious reputation. In Scott's novel, the Baroness of Arnheim wears an opal talisman with supernatural powers. When a drop of holy water falls on the talisman,
485-403: A hazy-milky- turbid sheen from within the stone. In gemology , this optical effect is strictly defined as opalescence which is a form of adularescence. "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,
582-590: 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 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,
679-405: 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 triplet is similar to a doublet but has a third layer, a domed cap of clear quartz or plastic on the top. The cap takes
776-496: A rematch of the 2000 Olympic gold medal match against the US. The United States outlasted the Opals in the fourth quarter to win 74–63, giving the Opals their second straight Olympic silver medal. The Opals headed to Brazil for the 2006 World Championships looking to win their sixth straight medal in international competitions. Led by Lauren Jackson's 21.3 points per game and Penny Taylor 's 18 points per game, first and third best in
873-549: A rematch with the USSR for the bronze medal . Motivated by the previous loss, the USSR came out determined and outplayed the Opals 68–53. Despite the loss, the fourth-place finish equalled the Opals’ previous best international placing. Building from their success at Seoul, the Opals headed to Malaysia for the 1990 World Championships with high hopes. The team won their first two games against Malaysia and Italy, before suffering
970-662: A semi-finals match against the United States. The US won the game 93–71, sending the Opals to a rematch against Ukraine for the bronze medal. Australia held back a second half comeback by Ukraine to win the game 66–56, earning Australia its first ever international basketball medal for either men or women. In 1998, the Opals looked to build off the bronze medal at the World Championships in Germany . The team featured 17-year-old future star Lauren Jackson , and
1067-532: A silver medal. Kelsey Griffin was named tournament most valuable player . With basketball returning to the Commonwealth Games for the first time since 2006 , the Opals easily accounted for England in the final winning the gold-medal game 99–55. At the 2018 World Cup held in Spain, the Opals led their group with a 3–0 record. They then defeated China 83–42 in the quarter-final and Spain 72–66 in
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#17327910195661164-706: A single game with 37 against Japan. It was the third-highest haul by a woman in Olympic history, and the highest in 28 years. Following the early exit from the Rio Olympics, Brendan Joyce was replaced in April 2017 by former Opals player and Phoenix Mercury head coach, Sandy Brondello . Unlike previous years, the Opals qualified for the 2018 World Cup through the FIBA Women's Asia Cup held in India where they won
1261-404: A stone has been created 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 inclusions and
1358-493: A string of losses to Bulgaria , the Soviet Union , Yugoslavia and Czechoslovakia . In their final game, the Opals came back from seven-point halftime deficit to beat Bulgaria 73–71 and finish in sixth place. Fifteen teams competed for the five open spots at the 1992 Barcelona Olympics , and despite a respectable 4–2 record at the preliminary tournament, the Opals did not qualify. Two years later, Australia played host to
1455-578: 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 Wegeltena , in Ethiopia's Wollo Province . 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
1552-469: A third straight gold medal match against the United States . The Opals had trouble hitting the basket and shot just 24% en route to a 92–65 defeat. The team earned their third straight Olympic silver medal, and their seventh straight international medal finish. The 2000s was a golden era for the Opals, winning at least a bronze medal at every official FIBA tournament. In 2010, the 16th edition of
1649-528: 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 Querétaro 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
1746-514: Is a form of opal, as well as a type of petrified wood 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 opalized wood and opalized petrified wood . It is often used as a gemstone . 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
1843-721: Is a major source of opal. The world's largest and most valuable gem opal " Olympic Australis " 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 4 + 3 ⁄ 4 in (120 mm) and a width of 4 + 1 ⁄ 2 in (110 mm). The Mintabie Opal Field in South Australia located about 250 km (160 mi) northwest of Coober Pedy has also produced large quantities of crystal opal and
1940-419: 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 visible light , the light of that wavelength may be subject to diffraction from the grating 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
2037-708: 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 Oregon and Idaho in the Owyhee region, as well as from Nevada around the Virgin Valley . Opal is also formed by diatoms . 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 structural coloration and therefore
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#17327910195662134-614: Is adapted from the Latin term opalus . The origin of this word in turn is a matter of debate, but most modern references suggest it is adapted from the Sanskrit word úpala meaning ‘precious stone’. As references to the gem are made by Pliny the Elder , one theory attributed the name's origin to Roman mythology: to have been adapted from Ops , the wife of Saturn , and goddess of fertility. (The portion of Saturnalia devoted to Ops
2231-540: Is characteristic of all "fire opals," including "Mexican fire opal". 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 Iris, followed by La Hacienda la Esperanza, Fuentezuelas, La Carbonera, and La Trinidad. Important deposits in
2328-421: Is composed of silica spheres some 150–300 nm (5.9 × 10 –1.18 × 10 in) in diameter in a hexagonal or cubic close-packed lattice . It was shown by J. V. Sanders in the mid-1960s that these ordered silica spheres produce the internal colors by causing the interference and diffraction of light passing through the microstructure of the opal. The regularity of the sizes and the packing of these spheres
2425-542: Is considered a "lode" deposit. Opals which have weathered out of the in situ deposits are alluvial and considered placer deposits . Miocene -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
2522-481: Is determined by their official uniform number (and not alphabetically). As of the 2020 Olympic Games, 112 players have represented Australia at Olympic Games and World Cups. There were no debutants at the 2000 Olympic Games in Sydney . † Deceased Legend Legend Opal Opal is a hydrated amorphous form of silica (SiO 2 · n H 2 O); its water content may range from 3% to 21% by weight, but
2619-596: Is distinguishable from natural opal by its regularity; under magnification, the patches of color are seen to be arranged in a "lizard skin" or "chicken wire" pattern. Furthermore, synthetic opals do not fluoresce under ultraviolet light. Synthetics are also generally lower in density and are often highly porous. 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
2716-411: Is hard enough to allow cutting and polishing. This type of Mexican opal is 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. Opal occurs in significant quantity and variety in central Mexico, where mining and production first originated in the state of Querétaro . In this region
2813-428: Is honey-yellow with a resinous luster; wood opal, which is caused by the replacement of the organic material in wood with opal; menilite , which is brown or grey; hyalite , a colorless glass-clear opal sometimes called Muller's glass; geyserite , also called siliceous sinter , deposited around hot springs or geysers ; and diatomaceous earth , the accumulations of diatom shells or tests. Common opal often displays
2910-401: Is opal-AG consisting of aggregated spheres of silica, with water filling the space in between. Precious opal and potch opal are generally varieties of this, the difference being in the regularity of the sizes of the spheres and their packing. The second "opal-A" is opal-AN or water-containing amorphous silica-glass. Hyalite is another name for this. Noncrystalline silica in siliceous sediments
3007-435: Is reported to gradually transform to opal-CT and then opal-C as a result of diagenesis , due to the increasing overburden pressure in sedimentary rocks, as some of the stacking disorder is removed. The surface of opal in contact with water is covered by siloxane bonds (≡Si–O–Si≡) and silanol groups (≡Si–OH). This makes the opal surface very hydrophilic and capable of forming numerous hydrogen bonds . The word 'opal'
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3104-469: Is several hundred times larger than the fundamental structure of crystalline silica. As a mineraloid , no unit cell describes the structure of opal. Nevertheless, opals can be roughly divided into those that show no signs of crystalline order ( amorphous opal) and those that show signs of the beginning of crystalline order, commonly termed cryptocrystalline or microcrystalline opal. Dehydration experiments and infrared spectroscopy have shown that most of
3201-486: Is termed play of color . In gemology, opalescence is applied to the hazy-milky- turbid sheen of common or potch opal which does not show a play of color. Opalescence is a form of adularescence . For gemstone use, most opal is cut and polished to form a cabochon . "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 doublet consists of
3298-427: Is usually between 6% and 10%. Due to the amorphous chemical structure, it is classified as a mineraloid , unlike crystalline forms of silica, which are considered minerals . It is deposited at a relatively low temperature and may occur in the fissures of almost any kind of rock , being most commonly found with limonite , sandstone , rhyolite , marl , and basalt . The name opal is believed to be derived from
3395-618: The 1983 World Championships , looking to demonstrate that their 1979 success was no accident. Despite an early victory over Japan , Australia failed to advance and finished in 11th place. The Opals were not expected to participate at the 1984 Olympic Games held in Los Angeles . However, following the decision by Cuba to boycott the games , the door was opened for the Opals to compete in their first ever Olympics. Led by head coach Brendan Flynn , and team captain Jenny Cheesman,
3492-431: The 1988 Seoul Olympics with a medal hope, but they lost the first game to host nation Korea . The Opals bounced back and defeated Bulgaria , meaning that only the powerful Soviet Union stood between them and a semi-finals berth. In a major upset, the Opals defeated the USSR 60–48, setting up a meeting against Yugoslavia . In a memorable game, the Opals lost a closely contested game at the buzzer 57–56, sending them to
3589-580: The 1989 Queen's Birthday Honours , Cheesman was appointed a Member of the Order of Australia for her contribution to basketball. She was awarded the Australian Sports Medal in 2000. In 2003, Basketball Australia introduced an annual Fair Play Award to all Australian Junior Championships. The Under 14 Girls Club Championship award for fair play was named the "Jenny Cheesman Fair Play Award", as recognition of her outstanding contribution to
3686-413: The 1994 FIBA World Championships . Led by guard Shelley Sandie 's 11.9 points per game, the team scored victories over Japan , Italy , Slovakia and Canada to set up a semi-finals match against China . The Opals held an early lead, but China mounted a second half comeback led by Haixia Zheng 's 36 points, and Australia just lost by a single point 66–65. In the bronze medal game, Australia played
3783-618: The 2006 World Championship in Brazil . At the now-defunct regional Oceania Championship for Women , the Opals won 15 titles. In 2017, FIBA combined its Oceanian and Asian zones for official senior competitions; following this change, the Opals compete in the FIBA Women's Asia Cup . Basketball arrived in Melbourne in 1905, but the first major international women's tournament was the 1953 FIBA World Championships held in Chile . Although
3880-601: The 2016 Olympics in Rio de Janeiro following a series win against New Zealand in August 2015. On 31 March 2016, Lauren Jackson announced her retirement from basketball, citing a chronic knee injury as the reason for her decision. The Olympic squad was announced on 12 July 2016 and included seven Olympic debutants and only three players from the 2012 squad. Notable exclusions included three-time Olympic medallist Suzy Batkovic , reigning WNBL MVP Abby Bishop and Rebecca Allen . Despite slow starts which had plagued Australia throughout
3977-486: The Opals as its nickname. At the 1996 Summer Olympics held in Atlanta , the Olympic tournament was expanded to twelve teams, making an easier path for Australia to qualify. Captained by Robyn Maher , the Opals started off with strong wins over South Korea , Zaire , and Cuba before losing to eventual gold medalist United States and Ukraine . Australia then persevered through an overtime game against Russia to set up
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4074-585: The Sanskrit word upala ( उपल ), which means 'jewel', and later the Greek derivative opállios ( ὀπάλλιος ). There are two broad classes of opal: precious and common. Precious opal displays play-of-color ( iridescence ); 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 diffract light, resulting in play-of-color. Depending on
4171-418: The United States , and despite a small halftime lead, the Opals lost a close game 100–95. The loss however, resulted in a respectable fourth-place finish. The young 1994 team featured the backbone of Australian teams over the next decade; Rachael Sporn , Trisha Fallon , Michelle Brogan , Allison Tranquilli , Sandy Brondello , Annie La Fleur and Jenny Whittle . At the 1994 tournament, the team also adopted
4268-637: The World Championship was held in the Czech Republic . Pre-tournament favourites Australia, United States, and Russia, dominated play in the first two rounds. In the quarterfinals, however, Australia suffered a shock 79–68 loss to the Czech Republic. The loss meant that the Opals could not finish any higher than 5th place, its worst international result since the early 1990s. Looking to rebound from their disappointing 2010 result,
4365-485: The 1967 squad selected. Although the Opals finished in ninth place, they had victories over Madagascar (twice), Argentina , Ecuador and Canada . In 1975, the team headed to Colombia with another new head coach, Jim Madigan. Despite a 74–25 confidence building win over Senegal , as well as victories over Japan , Brazil and Hungary , the team finished in 10th place. The 1976 Olympics held in Montreal marked
4462-483: The 1984 Olympic Games as "a life-long dream come true... Since I was twelve years old my aim has been to play basketball at an Olympic Games". At the 1984 Los Angeles Olympic Games , Cheesman and her husband, Phil Smyth , became the first husband and wife to captain Australian teams at the same Olympics. Cheesman also represented Australia at four World Championships , in 1975 , 1979 , 1983 , and 1986 . She
4559-527: The H 2 O in the formula of SiO 2 · n H 2 O of opals is present in the familiar form of clusters of molecular water. Isolated water molecules, and silanols , structures such as SiOH, generally form a lesser proportion of the total and can reside near the surface or in defects inside the opal. The structure of low-pressure polymorphs of anhydrous silica consists of frameworks of fully corner bonded tetrahedra of SiO 4 . The higher temperature polymorphs of silica cristobalite and tridymite are frequently
4656-481: The Oceania championships for both women and men after their respective 2015 editions, combining FIBA Asia and FIBA Oceania into a single zone for purposes of World Cup and Olympic qualification. Commencing in 2017, teams from Oceania and Asia zones competed together for the first time ever with the top four finishing teams qualifying for the 2018 World Cup. Roster for the 2024 Summer Olympics . A 26-player roster
4753-598: The Olympic qualification process in 2017, Australia will qualify for future Olympics through a two-stage process, starting with an Olympic pre-qualifying tournament involving Asian and Oceanian national teams in the year before the Olympics and followed by a worldwide Olympic qualifying tournament held in the year of the Games. The first official Women's World Cup , known as the Women's World Championship through its 2014 edition,
4850-793: The Olympic tournament. However, in 1996 at Atlanta the tournament was expanded to twelve teams. Through the 2016 Olympics, Australia qualified for the Olympic Games through competing in the FIBA Oceania Basketball Championship held each four years in the year preceding the games. Typically, this tournament featured either a two or three-game series between Australia and New Zealand . With the Oceania Championship having been discontinued after its 2015 edition, and FIBA having removed all women's continental championships except for EuroBasket Women from
4947-554: The Opals again fell short losing 86–73. The Opals would however, win their fifth consecutive Olympic medal with an 83–74 win over Russia to claim the bronze . Leading up to the 2014 World Championship in Turkey , a number of long-serving players announced their retirements or declared themselves unavailable. Those players included Kristi Harrower , Jenni Screen , Kristen Veal , Abby Bishop , Kathleen MacLeod , Samantha Richards , Suzy Batkovic and Jenna O'Hea . Three weeks before
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#17327910195665044-406: The Opals did not qualify for the first tournament, they did, however, qualify for the 1957 Championships held in Brazil . Captained by Lorraine Eiler , the Opals defeated Cuba and Peru . Sixteen year-old Bronte Cockburn led the scoring for Australia with an average of 9.5 points per game, but the inexperienced team ultimately finished in 10th place. Since then, the Opals have helped increase
5141-511: The Opals gained automatic entry into the tournament. Captained by Michele Timms , the team started out with dominating performances winning all of their first seven games, sending them to their first ever gold medal match, against the US . The American team proved too strong for the Opals however, as they won 76–54. Australia won the Silver Medal , their best result in international competition at
5238-475: The Opals played competitively in every game, but finished fifth out of the six teams. The next tournament for the Opals was the 1986 World Championships in Moscow . The first game against Hungary was a two overtime thriller that the Opals lost 79–77. The game set the tone for the tournament, and despite some close finishes against the top rated teams, Australia finished in ninth place. The Opals then headed into
5335-485: The Opals qualified for the 2012 Olympic Games in London by beating New Zealand three games to nil in the 2011 FIBA Oceania Championship . They finished the Olympic preliminary series with a 4 – 1 record, losing to France in game 2, but after Belinda Snell sank a well behind the half-court line 3-point shot with less than one second on the clock to send the game into overtime . Against Russia , Liz Cambage became
5432-747: 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 Smithsonian Institution comes from the Royal Peacock opal mine in the Virgin Valley, weighing 160 carats (32 g; 1.1 oz), known as the "Black Peacock". Fire opal is
5529-579: The absence of any surrounding non-opal matrix . 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. 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 photonics for sensing and light management purposes. The lattice of spheres of opal that cause interference with light
5626-434: The appearance of tiny opals when viewed under a microscope. These cell walls or "tests" form the “grains” for the diatomaceous earth . 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. Opal was rare and very valuable in antiquity. In Europe, it
5723-427: 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 most common. 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
5820-419: The dominant Ethiopian opal in the gem trade. The Virgin Valley opal fields of Humboldt County in northern Nevada 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 in situ within a subsurface horizon or zone of bentonite , which
5917-468: The early days of women's Olympic basketball , only six countries competed in the tournament, and the host country received an automatic entry. Therefore, there were 22 countries competing for the remaining five spots in 1980 Olympics held in Moscow . In the preliminary tournament, the Opals fell to the US and Hungary, and did not qualify for the Olympics. Three years later, the team traveled to Brazil for
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#17327910195666014-528: The final buzzer, the scoreboard read Australia 91, Russia 74; a convincing victory that delivered Australia's first ever basketball gold medal . Penny Taylor was named the Most Valuable Player of the tournament. At the 2008 Beijing Olympics , the Opals looked to reaffirm their title as World Champions. In the lead up, Australia went undefeated against Belarus , Brazil, South Korea, Latvia , Russia , Czech Republic and host China to set up
6111-838: The first Olympic medals awarded for women's basketball, but Opals did not qualify for the tournament. Their next major competition would be the 1979 World Championships in South Korea , which would prove to be their first taste of success. The coach again was Jim Madigan, and the squad featured some of the faces of the Opals for the next decade such as Jenny Cheesman , Robyn Maher , Julie Nykiel , Karin Maar and Patricia Mickan . The team would have early success defeating Italy and France , as well as thrashing Malaysia 119–14. Australia would lose their next three games, but bounced back winning their final game over Japan to finish in fourth place, their best international result to that time. In
6208-638: The first appearances of opallios do not occur until after the Romans had taken over the Greek states in 180 BC and they had previously used the term paederos . 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 Bosporus , who claimed
6305-778: The first to crystallize from amorphous anhydrous silica, and the local structures of microcrystalline opals also appear to be closer to that of cristobalite and tridymite than to quartz. The structures of tridymite and cristobalite are closely related and can be described as hexagonal and cubic close-packed layers. It is therefore possible to have intermediate structures in which the layers are not regularly stacked. Microcrystalline opal or Opal-CT has been interpreted as consisting of clusters of stacked cristobalite and tridymite 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
6402-406: The first woman in Olympic history to successfully slam dunk a basketball. In the quarterfinal against China , Lauren Jackson became the Olympic Games record holder for points scored, overtaking Brazilian legend Janeth Arcain 's tally of 535 points. The Opals accounted for China 75–60 to set up a semi-final game with their long-time rivals United States . Despite holding a half-time lead,
6499-489: The game. Although Cheesman was not involved in any international medal winning teams, she was described a very important figure in the development of Australian women's basketball. Cheesman has been described as "a truly world-class basketball player". Cheesman was inducted into the Australian Basketball Hall of Fame in 2004. In 2006, Cheesman polled as the eighth greatest Australian female player in
6596-470: 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. 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
6693-556: The global supply of opal comes from either country. Australian opal has been cited as accounting for 95–97% of the world's supply of precious opal, with the state of South Australia 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. USGS data from the same period (2012), reveals Australian opal production to be $ 41 million. Because of
6790-455: The incident light. The process can be described by Bragg's law of diffraction. Visible light cannot pass through large thicknesses of the opal. This is the basis of the optical band gap in a photonic crystal . In addition, microfractures may be filled with secondary silica and form thin lamellae inside the opal during its formation. The term opalescence is commonly used to describe this unique and beautiful phenomenon, which in gemology
6887-411: The literature. Water content may be as high as 10 wt%. Opal-CT, also called lussatine or lussatite , is interpreted as consisting of localized order of α-cristobalite with a lot of stacking disorder. Typical water content is about 1.5 wt%. Two broad categories of noncrystalline opals, sometimes just referred to as "opal-A" ("A" stands for "amorphous"), have been proposed. The first of these
6984-474: The opal deposits are located mainly in the mountain ranges of three municipalities: Colón , Tequisquiapan , and Ezequiel Montes . 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
7081-515: The opal found there occurs in thin layers. Other significant deposits of precious opal around the world can be found in the Czech Republic, Canada, Slovakia, Hungary, Turkey, Indonesia, Brazil (in Pedro II, Piauí ), Honduras (more precisely in Erandique ), Guatemala, and Nicaragua. In late 2008, NASA announced the discovery of opal deposits on Mars . Wood opal , also known as xylopal ,
7178-465: 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 50%, and remained low for the next 20 years or so. Even as recently as the beginning of the 20th century, it was believed that when
7275-479: 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 Morelos , Durango , Chihuahua , Baja California , Guanajuato , Puebla , Michoacán , and Estado de México . Another source of white base opal or creamy opal in the United States is Spencer, Idaho . A high percentage of
7372-787: The play of color), collected from the Griman Creek Formation . Boulder opal consists of concretions and fracture fillings in a dark siliceous ironstone matrix. It is found sporadically in western Queensland, from Kynuna in the north, to Yowah and Koroit in the south. Its largest quantities are found around Jundah and Quilpie in South West Queensland . Australia also has opalized fossil remains, including dinosaur bones in New South Wales and South Australia, and marine creatures in South Australia. It has been reported that Northern African opal
7469-693: The popularity of the sport in Australia. Australia would not get the opportunity to participate at the 1959 World Championship held in Moscow because at the time, the Australian Government would not allow the team to travel to the USSR . The Opals would not qualify for a World Championship again until the 1967 contest in Czechoslovakia . With an entirely new team and a single victory over Italy , Australia finished in 10th position for
7566-438: The preliminary rounds and quarter-final undefeated, setting up a semi-final clash with the US. In a hard-fought game, the Opals cut the lead from 16 points to just six early in the final quarter, before losing 82–70. The Opals would however claim their third bronze medal at world championships with a comfortable 74–44 win against host nation Turkey . Penny Taylor was named to the tournament All-Star Five. The Opals qualified for
7663-557: The quarterfinal. In the semi-finals, the Opals lost to eventual gold medalist United States, but recovered the next day to capture the bronze medal with a convincing 91–63 win over South Korea . At the 2004 Olympics held in Athens , Greece , the Opals were led by Lauren Jackson's tournament best 22.9 points and 10 rebounds per game. With Penny Taylor contributing with 14.8 points per game, Australia dominated early winning their first seven games, all by double digits. The Opals set up
7760-522: 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 Australia. Andamooka in South Australia is also a major producer of matrix opal, crystal opal, and black opal. Another Australian town, Lightning Ridge in New South Wales , is the main source of black opal, opal containing a predominantly dark background (dark gray to blue-black displaying
7857-414: The second time. Team captain, Jean Forster , led the scoring for Australia with an average of 21.2 points per game, with a tournament high of 34 against Brazil . Her 21.2 points per game would remain unchallenged for 35 years. In 1971 , the Opals travelled once again to Brazil. Led by new head coach Merv Harris, and featuring Jill Hammond , the team made several improvements with only three players from
7954-518: The semi-final to set up a gold-medal final with their long-time rivals United States. The Opals lost the game 73–56 with head coach Sandy Brondello stating a lack of offence proved their downfall. Liz Cambage led the tournament scoring with an average of 23.8 points per game and was named to the All-Star Five. Women's basketball was introduced as an Olympic sport at Montreal in 1976. From 1976 to 1992, only six countries (teams) participated in
8051-415: The start of the tournament, Lauren Jackson withdrew from the team because of a knee injury. Two weeks later Liz Cambage ruptured her achilles tendon during a pre-tournament game and was ruled-out because of the injury. This resulted in the selection of seven debutants into the squad of 12, a move seen as ushering in a new era of Opals basketball. Despite the loss of veteran players, the Opals went through
8148-655: The state of Jalisco were not discovered until the late 1950s. 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 Magdalena . 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 Guerrero , which produces an opaque opal similar to
8245-523: The time. In 2002, the Opals looked to continue their success in China at the World Championships . Coached by Jan Stirling, captained by Kristi Harrower , and powered by Lauren Jackson's 23.1 points per game (which led the tournament), Australia won its first five games all by double figures. In the second round the Opals lost to Brazil , but bounced back with a 78–52 victory over France in
8342-421: The tournament respectively, the Opals played their best tournament to date. Australia began the tournament with a forfeit victory over Lithuania . They continued the trend by winning their next seven games decisively, with only one contest being decided by less than 10 points. In the gold medal game against Russia , the Opals led throughout, paced by Penny Taylor's 28 points and Lauren Jackson's 11 rebounds. At
8439-525: The tournament, the Opals finished on top of their group with a 5–0 record, outscoring Japan 33–15 in the final quarter to win by six points. In the Quarter-final, the Opals suffered a shock 73–71 loss to Serbia , conceding 26 turnovers and eliminating them from medal contention. This ended a run of five successive Olympic medals dating back 20 years. One highlight was Liz Cambage breaking Lauren Jackson's Australian Olympic record of points scored in
8536-424: The true girasol opal is a type of hyalite 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 type of opal are Oregon and Mexico. A Peruvian opal (also called blue opal)
8633-602: 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 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 Wegeltena ) to be only 750 kg (1,650 lb). The town of Coober Pedy in South Australia
8730-532: Was "Opalia", similar to opalus .) Another common claim was that the term was adapted from the Ancient Greek word, opallios . 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 opalus combined these uses, meaning "to see a change in color". However, historians have noted
8827-497: Was a gem prized by royalty. Until the opening of vast deposits in Australia in the 19th century the only known source was Červenica beyond the Roman frontier in Slovakia . Opal is the national gemstone of Australia. 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
8924-745: Was an assistant coach with the Opals at 2000 Sydney Olympics . Cheesman won the Halls Medal for the best and fairest player in the South Australian state league on three occasions; 1974, 1977 and 1978. In 1985, Cheesman was named the most valuable player of the Women's Basketball Conference playing for the Canberra Capitals . She continued with the Capitals following their move to the Women's National Basketball League . In
9021-403: Was announced on 26 March 2024. The final squad was revealed on 7 July 2024. The following is a chronological list of Australian players who have played at official senior FIBA international tournaments ( Olympic Games and World Cups ). The list includes both past and present players. Active players are shown in bold . Where two or more players debuted in the same series, their cap number
9118-589: Was held in Chile in 1953. The tournament was expanded to 16 countries (teams) in 1990. Since 2017, Australia qualifies for the World Cup through competing in the FIBA Women's Asia Cup , held each four years in the year preceding the Women's World Cup. Before then, Australia qualified through the FIBA Oceania Championship . Typically, this tournament featured either a two or three-game series between Australia and New Zealand . FIBA discontinued
9215-415: Was led by Michelle Brogan 's average of 13.1 points per game. Australia put together a dominant performance, winning their first seven games before losing to Russia 82–76 in a close semi-final match. In the bronze medal game, Carla Boyd 's 26 points proved too much for Brazil, and the Opals won 72–67 to earn their second bronze medal in international play. With Sydney hosting the 2000 Olympic Games ,
9312-471: Was the captain of the team from 1980 until the end of her career and went on to be the Opals assistant coach from 1993 to 2000. While she was still playing at the highest level with the Opals, Cheesman was an assistant coach with the AIS program, taking over the head coach role for one year in 1990. As a talented junior, Cheesman eventually had to choose between stellar basketball and netball careers. Cheesman
9409-477: Was used to make tools as early as 4000 BC. The first published report of gem opal from Ethiopia 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 rhyolite . This Shewa Province opal was mostly dark brown in color and had
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