Nice!!! Also could be a Japanese water stone. I've seen a black one that looked kinda like what you described. If it is either one then that's like a 50-90$ stone lol. Which is freaking awesome!!!I have a stone I found at a yard sale in a box of metal lathe junk that I paid .50 cents for. At first I thought it was black Arkansas but now I'm not so sure.I use a set of 3 Arkansas stones then a super fine dmt diamond stone for one sharpening. Sometimes I'll do it again depending on how often I use the knife. Then I just maintain the edge regularly with a diamond rod or strop or both. If you ever have anything you want sharpened and don't want to do it yourself you can always send em my way. It's my favorite way to de stress.How do you get it so sharp?Yup. I have shaved with almost all my knives. But that one in Particular has been used to shave countless times lol.Did you say shave?
On the bottom is a piece of paper glued to it and someone wrote 1926 on it. It's the smoothest stone I've ever felt. Smooth as glass.