I knocked around on it with a boulder. I have never flintknapped before, so I have no reverence. When I hit it the right way, nice clean flakes come off.
Ncsnipe, you're right, the stuff in the picture was too freeze cracked and did not hold up. Also, to produce the break you see in the pic, I just smashed it onto a rock repeatedly.
But I have gotten some larger slabs of recently exposed material. It has some lovely colorations in grey and rose as well. I had never considered this stuff because it is common around here. And because it isn't glossy.
Meanwhile I've also found pics of local neolithic artefacts that are doubtlessly made from exactly this stuff, two conic bladecores.
So I'll read up on how to heat treat this and get some kind of antler billet. How about a bone or cow horn or maybe some firehardened dogwood? We don't have any large Deer here.