- a mineral, an amorphous form of silica, SiO2 with some water of hydration, found in many varieties and colors, including a form that is milky white.
- an iridescent variety of this that is used as a gem.
- a gem of this.
Origin of opal
- a female given name.
Examples from the Web for opal
The rebels then turned their guns on the family huddled in the Opal.‘Argo’ in the Congo: The Ghosts of the Stanleyville Hostage Crisis
November 23, 2014
One of the more positive parts of your personal life is your marriage to Opal Stone Perlman, which has lasted over three decades.Ron Perlman's Secret Suicide Attempt
October 28, 2014
That clock has four faces made of opal, estimated at a value of $10-20 million.Grand Central Terminal: 100 Years, 100 Facts
February 1, 2013
In that case, at least, Little, Brown responded by pulling Opal from the bookshelves.Another Memoir Meltdown
April 18, 2011
The hues of the opal, the light of the diamond, are not to be seen if the eye is too near.Essays, First Series
Ralph Waldo Emerson
She was like an opal—all sparkle when you move it, and at rest dull, most undeniably dull.Audrey Craven
To live in Venice is like being domesticated in the heart of an opal.Italy, the Magic Land
The top of the mountain, like that of Shasta, in direct sunlight is an opal.
There was also an Australian opal and an Asian emerald, the latter greener than the grass.The Paliser case
- 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
Word Origin and History for opal
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.).
- 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: SiO2·nH2O.