I just don't know about this one. Looks like an artifact I've seen before,but not the same material.Is it a scraper or celt or just a rock? It has been in my what's it box for years and am just wondering about it.
The first photo makes it look like something natural but the others make it look like a celt. To me it looks a little odd, from your photos it doesn't have the classic shape. In the first photo the rounded end toward your wrist, does it come to a blade edge or is it rounded off and the other edges come to a knife edge. Does it have the shape of a clam ? I may be just looking at it wrong.
From Ky myself, I have found two just like yours, (in a rock shelter)...made of limestone....yours looks like limestone as well. Neither of mine show any sign of hard usage (like yours) but the leading edge on both of mine are celt like. They must of been some sort of light duty tool.
Limestone will weather like that naturally so I would say it's just a natural piece. Limestone is really to soft to make mush of a Tool out of it. It was used for Pendants, Pipes, and other things, but not really for tools.
1320, I have seen pieces just like yours and I actually have one similar. Yes, that is an Axe and it is Limestone. But it didn't always look like that. At one point that piece more than likely had a hard outer cortex that has since broken up and eroded off. A buddy of mine found one almost identical to yours years ago that had almost every bit of the outer core gone except for one spot about 2" x 3" on one side. I have this one below that has a softer material on the inside and the outer covering had started to break up and fall off and it would all have fallen off eventually if it hadn't been found.
The original piece above looks like just a naturally eroded piece of Limestone and not a Celt. Just my opinion but the creeks in my area are full of piece just like that. It is caused by the water running over them.