1. Also called precious moonstone. a semitransparent or translucent, opalescent, pearly-blue variety of adularia, used as a gem.
  2. any of several adularescent feldspars, as certain varieties of albite, labradorite, or oligoclase, used as gems.
  3. (not used technically) any milky or girasol stone used as a gem.

Origin of moonstone

First recorded in 1625–35; moon + stone Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for moonstone

Historical Examples of moonstone

  • "I am going to read 'The Moonstone' out in the garden the whole afternoon," she replied.

    The Beth Book

    Sarah Grand

  • You may discover so much by reading the "Moonstone," that monument of ingenuity and absurdity.


    Arthur Machen

  • The opal and the moonstone are the gems most often figuring in these tales.

  • Nobody in Moonstone ever found what Wunsch's first name was.

    Song of the Lark

    Willa Cather

  • The wickedness of Denver and of Chicago, and even of Moonstone, occupied her thoughts too much.

    Song of the Lark

    Willa Cather

British Dictionary definitions for moonstone


  1. a gem variety of orthoclase or albite that is white and translucent with bluish reflections
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012