Re: Is this a rock or a cannon ball?
Regarding the picture you posted asking if this was a rock or a cannonball:
If you compute the weight of a 5" diameter sphere made of iron, you'll see that it is too light to be an iron cannonball (unless it is hollow). The 6 pound weight is more consistent with rock.
A simple test for iron would be to see it a magnet is attracted. If a magnet is not attracted, then you most likely have a rock.
It is possible for rocks to be shaped very round by natural processes. I have found scour stones inside the eroded potholes in rock river beds that were amazingly round.
Another possibility is your object may be a native American artifact. Wouldn't hurt to show it to an authority on artifacts from your area.
From Bob Keller - July 14, 2014 at 16:51:24