These have been discussed a number of times—though oddly the past threads do not show-up in an Archive Search (!).
http://beadcollector.net/cgi-bin/anyboard.cgi?fvp=/openforum/&cmd=iYz&aK=40529&iZz=40529&gV=0&kQz=&aO=1&iWz=0
In recent years the Chinese have been making a LOT of beads and elements from this fossil stone. They have invented at least two new names for them. One is "script stone." I forget the other (because I just find many new names to be annoying).
Jamey
Bi-valves. cool
My eye's would have never figured this one out...
THANKS