opal

Definition

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

Etymology

In Florio’s A World of Words 1598 as opale, from French opale, from Latin opalus, from Byzantine Greek ὀπάλλιος (opállios), from Sanskrit उपल (upala, “gem, stone”), from उपरि (upári, “the upper millstone”). Distantly related to over.

Example Sentences

• "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.)"
• "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."