Not seen salvaged slate posted. If you got them, lets see them.
This broken slate wing banner from Fayette County IN was made into a smaller banner. 2 1/4 inches wide x 1 1/2 inches, conical hole cane drilled through salvaged wing, with worm track on one side.
here is a wing bannerstone which was drilled. broken bannerstones are sometimes drilled and then tied together. however this broken wing bannerstone has had the broken area ground smooth. which could mean it was used for an alternate purpose.
Very nice artifacts you've recovered! In the last 70 years i have walked many miles and never found a banner stone. I have found many gorgets, beads, pipes, axes and celts. Good luck to you in your future hunts!