Thats a fined grained igneous rock. Maybe diabase?? Thats the right rock for making an ax or Celt or club. And, the groove does look like it was made from pecking. I’m on the fence whether natural are Indian work. I too would have brought it home regardless.
Appreciate all the replies as you guys are the experts.
This is an area with much Native American activity with a salmon bearing river very close. Here is a point that I found a few years back from the vicinity.