The Arachnid Consortium uses Gas/Hydrogen.  Their frequency is intermittant, but, the catch is that they are almost always large & huge.  This helps to balance out the quantity problem for me.  The problem *I* have is trying to decide which to research next...Ice or Rock...it seems like I always pick the wrong one   
 
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Spyder, Chairman of the Arachnid Consortium
[This message has been edited by Spyder (edited 05 March 2001).]