Fyron,
Thanks for the link. I thought your post was about silica structures secreted by certain prokaryote cells, but I see that the link actually refers to Dr. Tom Gold's (so far unconfirmed) speculations on the existence of true silicon-based organisms on Earth. Dr. Gold's book was indeed published in 1999; I found a review here:
http://www.findarticles.com/p/articl...80/ai_56022636
Unfortunately, none of the reviews I read mentions any discussion of silicon-based life. The focus of the book is Dr. Gold's theory of a deep underground biosphere supported by an abundance of hydrocarbons (oil and gas) left over from the formation of the Earth (i.e. of non-biological origin). Of relevance to our forum discussion is his suggestion to look for extraterrestrial life BELOW the surface of such bodies as the moon, Mars, and Saturn's moon Titan.