[TML] Alien ecologies

[darby eckles]

I had a dream lastnight that I was somplace where the vegetation was all shades of purple.  It got me thinking about how in most Traveller games I've been a player in the worlds we visited seemed to be either very Earth like, with green clorophyle based flora, or very arid/desert like.  When I run games, I like to have very alien planets.  I really liked the graphic book Expedition by Barlow, thre are some far out critters there...
 
Anyways, I digress...
 
So, what I am wondering is: is it possible to have purple photosynthetic plants?  Is it just a matter of the chlorophyl/whatever processing UV spectrum light or reflect purple based colors, or would it necessitate some completely different system of light usage?  

Also, what minierals have a purple hue?  Amethyst?  Can that be broken down and used by living creatures?