opals

Noun

opal (plural opals)

1. A mineral consisting, like quartz, of silica, but inferior to quartz in hardness and specific gravity, of the chemical formula SiO₂·nH₂O.
   • Although there are dozens of different types of gems, among the best known and most important are […] . (Common gem materials not addressed in this article include amber, amethyst, chalcedony, garnet, lazurite, malachite, opals, peridot, rhodonite, spinel, tourmaline, turquoise and zircon.)2012 March, Lee A. Groat, “Gemstones”, in American Scientist, volume 100, number 2, archived from the original on 14 Jun 2012, page 128
   1. A precious gem, an iridescent gemstone found in the opal-silica mineral substrate (potch)
2. The colour of opal: any shade of blue with bright flecks of other colours, such as white, yellow, and red.
   • The witchery of the dawn turned the grey river-reaches to purple, gold, and opal; and it was as though the lumbering dhoni crept across the splendors of a new heaven.1889, Rudyard Kipling, “Only A Subaltern”, in Under the Deodars, Boston: The Greenock Press, published 1899, page 141
3. A colloquial name used in molecular biology referring to a particular stop codon sequence, "UGA."
4. Any of various lycaenid butterflies of the genus Nesolycaena.

See all 12 meanings of opal