rottenstone
— Noun
– English
~ a weathered and decomposed siliceous limestone; in powdered form it is used in polishing
rotter
— Noun
– English
~ a person who is deemed to be despicable or contemptible; "only a rotter would do that"; "kill the rat"; "throw the bum out"; "you cowardly little pukes!"; "the British call a contemptible person a `git'"