from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun An opal that is almost opaque when dry but transparent when wet.

from The Century Dictionary.

  • noun A partly translucent whitish or light-colored variety of opal, which absorbs water upon immersion and then becomes transparent. Also called oculus mundi.

from the GNU version of the Collaborative International Dictionary of English.

  • noun (Min.) A semitranslucent variety of opal that becomes translucent or transparent on immersion in water.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun mineralogy A semitranslucent variety of opal that becomes translucent or transparent on immersion in water.


from Wiktionary, Creative Commons Attribution/Share-Alike License

Ancient Greek


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  • The fifth variety in order of value, is that known as the "hydrophane," which has an interesting characteristic in becoming transparent when immersed in water, and only then.

    The Chemistry, Properties and Tests of Precious Stones

  • Thus the deportment of various minerals, such as hydrophane and tabasheer, the transparency of tracing paper used by engineers, and many other considerations of the highest scientific interest, are involved in the simple enquiry of this unsuspecting little boy.

    Fragments of science, V. 1-2

  • The Shandorian runner was gone for two days, the Moessian for three; ample time for Dirrach to reassure himself that the fresh windfall of mana was genuine and resided, not in outlander sorcery, but in hydrophane opals.

    The Magic May Return

  • He discovered the knot-loosening spell after sundown, and wasted time gloating while a warm breeze dried the last of the moisture from the hydrophane.

    The Magic May Return

  • She went on to describe Bardel's Acrobatic ascent, the gleam of the hydrophane on his fereast as he sweated to the topmost extent of a vine

    The Magic May Return

  • The properties of, hydrophane opal were unknown even in Shandor; Gethae had been jesting about magic.

    The Magic May Return

  • Bardel acknowledged the applause, hung the great hydrophane amulet around his own sweaty neck, pledged packtrains of Lyrian wine as gifts for Moess and Shandor.

    The Magic May Return

  • A fine quality of quartz amethyst has been obtained, and also hydrophane, known for its peculiar property of becoming transparent when immersed in water.

    Rambles in the Islands of Corsica and Sardinia with Notices of their History, Antiquities, and Present Condition.

  • It was milk-white, and became translucent in water, like that beautiful variety of opal, the hydrophane.

    White Shadows in the South Seas


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