Thanks guys I can't be 100 per cent sure it is an Escher or thuringian but I do posses a genuine escher waterbhone in it's small wooden box and light blue label with the goblet, this stone I m having problems behaves very much like it giving a good mirror polished edge. I t may be the case that it is slate but would you still get a fine edge of slate. Years ago when I started my apprenticeship as a wood pattern maker I got a Mason to cut me a piece of slate the size of an oilstone it was great for sharpening planes chisels etc I treated it roughly but it never behaved like this. Would slate be fine enough to produce an edge comparable to an escher? I ll try and post some pic in the next few day. I t didn't cost me a great deal in the region of £5.00 or 7 dollars so it's purely curiosity as to why this could be happening.