It does look similar, but what I'm not seeing is the growth rings changing size much which seems to be very characteristic of black locust. They are normally very tight rings when you're and they begin to open up as they get older.So, looking online, the wood that I thought was mulberry, looks similar to black locust.
I’m trying to find the pics of when it was alive this summer, as it had fallen onto my bridge that goes into my woods.
I think splitting it you'll be able to tell real quick, crack a round open and report back .