Some of the best flint I have ever bashed with a firestriker was stuff I picked up out of the knapping pit at Pappy's farm during the Tennessee Classic. Someone had come in with a pickup load of this really fine grain dark grey stone that was pert-near as hard as my head! Most of the pieces I picked up had some light-colored rind on them that seemed to draw spark as good as the core material. I believe I remember saying that they brought it down from Kentucky and that it might have been called Kentucky hornstone.
Next best stone I have ever found is the lovely dark caramel-colored Knife River flint from North Dakota. What I would give to have someone knap me a dozen gun flints from that stuff, seeing how I come from up that way once upon a time.
