What is "opal"

Opal \O"pal\, n. [L. opalus: cf. Gr. ?, Skr. upala a rock, stone, precious stone: cf. F. opale.] (Min.) A mineral consisting, like quartz, of silica, but inferior to quartz in hardness and specific gravity.

Note: The precious opal presents a peculiar play of colors of delicate tints, and is highly esteemed as a gem. One kind, with a varied play of color in a reddish ground, is called the harlequin opal. The fire opal has colors like the red and yellow of flame. Common opal has a milky appearance. Menilite is a brown impure variety, occurring in concretions at Menilmontant, near Paris. Other varieties are cacholong, girasol, hyalite, and geyserite.

1590s, from Middle French opalle (16c.), from Latin opalus (Pliny), supposedly from Greek opallios, possibly ultimately from Sanskrit upala-s "gem, precious stone." Used in Middle English in Latin form (late 14c.).

n. (context mineralogy English) A mineral consisting, like quartz, of silica, but inferior to quartz in hardness and specific gravity, of the chemical formula siliconoxygen₂'''·'''nwater.

n. a translucent mineral consisting of hydrated silica of variable color; some varieties are used as gemstones

Opal is a hydrated amorphous form of silica (SiO·nHO); its water content may range from 3 to 21% by weight, but is usually between 6 and 10%. Because of its amorphous character, it is classed as a mineraloid, unlike crystalline forms of silica, which are classed as 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. Opal is the national gemstone of Australia.

The internal structure of precious opal makes it diffract light; depending on the conditions in which it formed, it can take on many colors. Precious opal ranges from clear through white, gray, red, orange, yellow, green, blue, magenta, rose, pink, slate, olive, brown, and black. Of these hues, the black opals are the most rare, whereas white and greens are the most common. It varies in optical density from opaque to semitransparent.

OPAL (OPtimized Applicative Language) is a functional programming language first developed at the Technical University of Berlin.

Opal is a variety of low-aromatic 91 RON petrol developed in 2005 by BP Australia to combat the rising use of petrol as an inhalant in remote Indigenous Australian communities.

Though more expensive to produce, requiring a $0.33/litre Federal subsidy, a 2006 report found it would likely save at least $27 million per year when the social and health costs of petrol-sniffing were taken into account.

A 2010 senate report showed that the introduction of Opal in 106 communities across remote and regional Australia had led to a 70% drop in petrol sniffing in those communities.

Typical unleaded petrol contains 25% aromatics, such as toluene, ortho-xylene and para-xylene. In contrast, Opal contains only 5% aromatics, which means that it has less of the toluene and other solvents which produce the intoxication (or "high") that inhalant users are seeking. The Australian Government subsidizes Opal's provision and restricts traditional unleaded petrol in some remote communities. According to BP, the lower volatile component in Opal means that cars using it are less prone to vapor lock.

Prior to the introduction of Opal, Comgas (a brand of the aviation fuel avgas) has been used in many communities to discourage use of fuel as an inhalant. Unlike Opal, however, Comgas contains tetraethyllead (TEL), a substance that is poisonous and is banned throughout most of the world for automobile use after the discovery that it was creating an increase in lead particles over the entire earth, including the poles.

An opal is a gemstone.

Opal may also refer to:

The Opal-I is a multi-purpose fully amphibious armoured personnel carrier developed and produced by HSW S.A.. APC is a development of MT-LB that was produced in HSW on licence. Major changes are with reworked nose section and propellers for better in water speed and manoeuvrability, new turret with 12.7 mm NSVT machine-gun instead of old with 7.62 PKT and powered-up engine. Opal-II is a stretched variant with longer chassis with 7 road wheels on each side, like the 2S1 and MT-LBu and 300 hp (220 kW) SW680T engine.

The Open Physics Abstraction Layer (OPAL) is an open source realtime physics engine API similar to PAL. It is currently supported only by ODE, but can be extended to run off of other engines. OPAL is free software, released under both the LGPL and the BSD license. It was originally designed and written by Tyler Streeter, Andres Reinot, and Alan Fischer while working at Iowa State University's Virtual Reality Applications Center (VRAC).

OPAL is a high-level interface for low-level physics engines used in games, robotics simulations, and other 3D applications. Features a simple C++ API, intuitive objects (e.g. Solids, Joints, Motors, Sensors), and XML-based file storage for complex objects.

The latest version of OPAL is 0.4.0. On June 23, 2010, OPAL development officially ended.

Opal were an American rock band in the 1980s. They were part of the Paisley Underground musical style.

The group formed in the mid-'80s under the name Clay Allison, featuring guitarist David Roback (previously of Rain Parade), bassist Kendra Smith (from Dream Syndicate) and drummer Keith Mitchell. After one single, they released the remaining Clay Allison tracks under the band's new name, Opal, on the 1984 Fell from the Sun EP. Another EP, Northern Line, followed in 1985. These EPs were later compiled and released as Early Recordings

Happy Nightmare Baby, Opal's first full-length album, was released in 1987. Smith left the group during the Happy Nightmare tour after a show in Providence, Rhode Island. Roback continued with vocalist Hope Sandoval, playing shows as Opal and planning an album to be titled Ghost Highway but in 1989 this band became Mazzy Star and Ghost Highway was presumably released as She Hangs Brightly. Kendra Smith released a number of solo singles, EPs, and one album before retiring to the woods of northern California.

The song "She's a Diamond" was included in the film Boys Don't Cry but was not included on the CD release of the film soundtrack.

Opal is a feminine given name derived from the name of the gemstone opal. The gemstone is the birthstone for October. Its name is derived from the Sanskrit उपल or upala, which means "jewel". It came into use along with other gemstone names during the late Victorian era.

Opal was among the 100 most popular names for girls born in the United States from 1900 to 1920 and remained among the top 500 most popular names for girls there until 1950. It was last ranked among the 1,000 most popular names for girls in the United States in the 1950s. It was the 344th most common name for females in the United States in the 1990 census. Eighty girls born in the United States in 2010 were given the name and 92 girls born in 2011 were given the name.

Opal® is the brand name for a cultivar of apple also known as 'UEB32642', produced by crossing ' Golden Delicious' with 'Topaz'. Developed by the Institute of Experimental Botany in Prague and FruitSelect in 1999, it is grown by Broetje Orchards in Washington and marketed by the First Fruits company. It is also cultivated in Austria, the Netherlands and France. Opal is a variety registered with the Community Plant Variety Office of the European Union.