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From: cooper@pbsvax.DEC (Topher Cooper DTN-225-5819)
Newsgroups: net.sci,net.physics
Subject: An opalescent puzzle.
Message-ID: <2420@decwrl.DEC.COM>
Date: Thu, 17-Apr-86 14:04:47 EST
Article-I.D.: decwrl.2420
Posted: Thu Apr 17 14:04:47 1986
Date-Received: Fri, 18-Apr-86 21:30:48 EST
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Organization: Digital Equipment Corporation
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Xref: watmath net.sci:731 net.physics:4122

The following was part of a posting in a local bulletin board.

    I frequntly wear opals, and have some that are brilliantly coloured
    and beautiful.  [My grandmother] told me she could not wear opals, and
    proved it.  She took my blue Australian opal triplet (opal covered in
    [quartz] crystal and backed with black onyx - protects a soft stone and
    deepens the colour) and held it in her hand.  It turned milky white and
    lost all colour.  I took it back and the colour returned.

Does anyone have any explanations for this phenomenon?

People may post their responses, or mail them to me.  I will summarize any
of the latter.

		Topher Cooper

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