opal

¹ American  

[oh-puhl] / ˈoʊ pəl /

noun

1. a mineral, an amorphous form of silica, SiO 2 with some water of hydration, found in many varieties and colors, including a form that is milky white.

2. an iridescent variety of this that is used as a gem.

3. a gem of this.

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Opal ² American  

[oh-puhl] / ˈoʊ pəl /

noun

1. a female given name.

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opal British  

/ ˈəʊpəl /

noun

1. an amorphous, usually iridescent, mineral that can be of almost any colour, found in igneous rocks and around hot springs. It is used as a gemstone. Composition: hydrated silica. Formula: SiO 2 . n H 2 O

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opal Scientific  

/ ō′pəl /

1. A usually transparent mineral consisting of hydrous silica. Opal can occur in almost any color, but it is often pinkish white with a milky or pearly appearance. It typically forms within cracks in igneous rocks, in limestones, and in mineral veins. It also occurs in the silica-rich shells of certain marine organisms. Chemical formula: SiO ₂ ·nH ₂ O.

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Usage

What does opal mean? An opal is a gemstone that’s best known for its iridescent, milky-white variety.Other varieties are black and gray, but it can be almost any color. As a mineral, opal is a form of silica.Unlike many of the other gemstones used in jewelry, opal is not crystalline, meaning it does not form in a crystal structure—it looks like a stone, as opposed to a faceted jewel like a diamond.Opal gemstones are classified as common or precious. Precious is a label given to certain gemstones that are high in value. Opals labeled precious are typically those that display a high level of iridescence.Opal is the traditional birthstone for the month of October. It is associated with the zodiac signs Libra and Scorpio.Example: The opal pendant had flecks of green, pink, and blue.

Other Word Forms

• opal-like adjective

Etymology

Origin of opal

1350–1400; Middle English < Latin opalus < Greek opállios opal, gem; probably from a source akin to Sanskrit upala precious stone