This is a flaked and ground Munsungun chert adze.It is not the norm as Maine adzes go.It is not the usual pecked hardstone adze that I find.I have never seen another example of flaked and ground in Maine...mjm
Isn't that interesting. I wonder- was it found in a still water area or where it might have been tossed around a bit? Or did you dig it? Hard to tell from the pics if the flaking was intentional or incidental.