I did a little research and feel that it is safe to grind the vermiculite.
The % allowable is stated 0.1%, not 1% in the link below. Also, the contamination problem was over 20 years ago and the industry does have testing put in place.
http://www.vermiculite.net/
http://www.schundler.com/verm-...
From schundler link "Vermiculite itself does not contain asbestos; it was just the Libby, Montana mine which was contaminated because of the presence in the mountain of a secondary mineral called diopside. (To read more about diopside, go to sites like The Mineral Diopside.)"
I will continue to grind the little amount that I do.
