Composter, I too am interested in this subject, but find the information elusive. I saw an episode of B Organic (a little tv show about organic ideas and creative practices) and the host interviewed a seed grower who used the rock dust. I found it fascinating, but have not been able to find the source of the rock dust or much about it. I am only calling it rock dust now, because of it being reffered to it in this thread. He had a specific name for it and talked about it containing all the minerals that fertilizer lacked. He also used some super fine for immediate nutrients and some ground course that would decompose slowly over the season. Unfortunately for me, it was deleted from the tv storage bank
Boo hoo, but I have been looking into it ever since. This should be a real interesting thread!
Lindsey