Opaline vs. Opal — What's the Difference?

A mineral of hydrated silica.

Opal is a hydrated amorphous form of silica (SiO2·nH2O); 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.

A gemstone made of this mineral, noted for its rich iridescence.

A gemstone consisting of a form of hydrated silica, typically semi-transparent and showing many small points of shifting colour against a pale or dark ground

Resembling opal in having a milky white iridescence.

A mineral of hydrated silica.

A clear to white liquid secreted by sea hares (genus Aplysia) that becomes viscous upon contact with water.

A gemstone made of this mineral, noted for its rich iridescence.

(mineral) Any of several minerals resembling opal, including a variety of yellow chalcedony.

(mineral) A mineral consisting, like quartz, of silica, but inferior to quartz in hardness and specific gravity, of the chemical formula SiO₂·nH₂O.

Syn of opal glass

(gemology) A precious gem, an iridescent gemstone found in the opal-silica mineral substrate (potch)

Of, pertaining to, or like, opal in appearance; having changeable colors like those of the opal.

A colloquial name used in molecular biology referring to a particular stop codon sequence, "UGA."

An opaline variety of yellow chalcedony.

Any of various lycaenid butterflies of the genus Nesolycaena.

Opal glass.

A mineral consisting, like quartz, of silica, but inferior to quartz in hardness and specific gravity.

An opaline color or expanse.

A translucent mineral consisting of hydrated silica of variable color; some varieties are used as gemstones

Having a play of lustrous rainbow-like colors;