[meteorite-list] do meteorites fluoresce??

From: Jeff Grossman <jgrossman_at_meteoritecentral.com>
Date: Wed, 28 Feb 2007 20:21:38 -0500
Message-ID: <OF084FC65B.235D1D28-ON85257291.00077B02_at_usgs.gov>

At 05:49 PM 2/28/2007, Mr EMan wrote:
>In the "for what its worth" category, the degree of
>fluorescence in feldspar chondrules is the means for
>defining the intermediate grades within the 3 grades,(
>e.g 3.1, 3.2 , etc.) I don't know what wavelength is
>the standard for that examination. If you've the
>fluorscent microscope and knowing those standards you
>might be able to observe this in common chondrite thin
>sections but I think it would be in some form we
>wouldn't easily recognize. A coverslip would of course
>block UV, but uncovered slides attract lint which
>glows brightly.

Actually, the property that is used to determine the petrologic types
of chondrites is thermoluminescence (TL), not fluorescence. TL is
the emission of light in response to heating a sample, and it is a
very small effect. The fluorescence you are talking about is the
emission of light after absorption of light of a different wavelength
(often UV).

In point of fact, many meteorites do show a spectacular variety of
luminescence, namely cathodoluminescence (CL). This is emission of
light in response to bombardment with an electron beam, as in
CRTs. Type 3 ordinary chondrites are particularly beautiful, with
different minerals glowing red, blue, and yellow. Check out the work
of Derek Sears at:
http://www.uark.edu/depts/cosmo/research%20projects/CL%20mosaics/
There are small, portable instruments that can be used to look at CL,
but probably they won't be found outside of labs.

jeff


Dr. Jeffrey N. Grossman phone: (703) 648-6184
US Geological Survey fax: (703) 648-6383
954 National Center
Reston, VA 20192, USA
Received on Wed 28 Feb 2007 08:21:38 PM PST