From: root@mauve.demon.co.uk   
      
   Lynndel Humphreys  wrote:   
   > Is the spectrographic color change at the bounce(Mars) marks due to   
   > physical or chemical change?   
      
   Physical.   
   The exposed dirt is a different colour. (this may be due to chemical processes   
   that make the dust colour different on the surface over time)   
   There was no time for chemical reactions.   
      
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    * Origin: you cannot sedate... all the things you hate (1:229/2)