Has the look and patina of Old Copper Complex manufacture.
Some claim dates back 7000 yrs ... I think a "generic date" of 3000 yrs. is reasonable without extensive analysis.
N. Wisconsin is exactly where you'd want to find one given the best chance of it being authentic and ancient.
(it looks very promising, to me, ... going solely by the pictures ... a cool find !)
Does that hole clean out, near the base ?