First, let me say I suck at sharpening knives. I have watched youtube videos and have read a lot of info but still cannot get it right. I have a couple of stones that do a pretty good job but I just can't get a razor edge. Maybe somebody out there can helpme with a question. When I was a kid, my Dad had a stone that he inherited from my Grampa (who was a farmer). When my Dad passed away years ago, I looked for it in his small tool shed and couldn't find it. It was a hemispherical stone about the size of half a soft ball as I recall. My Dad used to refer to it as a soap stone but I don't think that's what it was. All I recall is that it was very finely grained and had some natural striations in it so I am sure it was not man made as my Gramps probably inherited from his. My dad let me use it a few times as a kid to put an edge on my old Barlow knife and he would always use it to put a fine edge on a scythe or scickle or any blade. Does anyone have any idea what this stone might have been? If any help, we grew up in Southwestern PA (Pennsyltucky).