Some of us have been discussing a long trip to the Lake Superior region next summer, Thunder Bay amethyst, Keweenaw Peninsula copper and more, Petoskey stones, and, of course all those Lake Superior agates.  If you like agates, or want to see what we might be able to collect there, I can recommend the following book by Dan and Bob Lynch and published by Adventure Publications in 2011.  It lists for $19.95 online, but I found mine at Barnes and Noble.