Nacre vs. Opal

Nacrenoun

(obsolete) A shellfish which contains mother-of-pearl.

Nacrenoun

A pearly substance which lines the interior of many shells; mother-of-pearl.

Nacrenoun

A pearly substance which lines the interior of many shells, and is most perfect in the mother-of-pearl.

Nacreadjective

Having the peculiar iridescence of nacre, or mother-of-pearl, or an iridescence resembling it; as, nacré ware.

Nacrenoun

the iridescent internal layer of a mollusk shell

Nacre

Nacre ( NAY-kər also NAK-rə), also known as mother of pearl, is an organic–inorganic composite material produced by some molluscs as an inner shell layer; it is also the material of which pearls are composed. It is strong, resilient, and iridescent.

Opalnoun

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

Opalnoun

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

Opalnoun

(entomology) Any of various lycaenid butterflies of the genus Nesolycaena.

Opalnoun

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

Opalnoun

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

Opalnoun

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

Opal

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.