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 ______________________________________________ Meteorite-list mailing list [email protected] http://six.pairlist.net/mailman/listinfo/meteorite-list
