en.wikipedia.org/wiki/Donkey_stone
A donkey stone was a type of scouring block, used mostly in the mill towns of the North of England to clean stone steps.
I remember it well, watched my mother doing it and I had to do it when I was older. Don't know how this ended up in site suggestions, I have copied it in cb
It was a cruel past-time which the RSPCA banned in the 1960s. It involved pelting the rag and bone man's horse with pre-cut rocks until he gave you a balloon.
The practice has largely been irradicated except for a few isolated pockets where it went underground and illegal betting takes place on the outcome. Recently there was a Channel 4 documentary following police as they made raids in Stalybridge and Barnoldswick.