A old iron log splitting wedge

[adalabama]

Found in the bowels of my yard. My house sits on land that was owned by a mill owning family about 150 years ago. Part of the grist mill is still sitting in my neighbors yard (The race of a water wheel). My husband clears a path with the quad and I hunt, otherwise Id be afraid of snakes and digger bees.
I found this wedge. It measures about 10" by 4" and is solid iron.
I see a lot of them online but I cant find any with this rectangle opening.

 

[creskol]

It doesn't appear to be tapered, so I don't think it is a splitting wedge. I have a hunch that it is a wheel key from the old mill.

 

[adalabama]

I cant find what a wheel key looks like so I cant compare.

 

[creskol]

This isn't the best of pics, but it may give you the general idea.

 

[pa plateau hiker]

Creskol is right as usual. It definitely is not a wedge.