Unknown Mdeium-High Grit Japanese Natural Sharpening Stone 1lb. 9.4oz. (717.2g)

Unknown Mdeium-High Grit Japanese Natural Sharpening Stone 1lb. 9.4oz. (717.2g), 184mmX70mmX22mm   It looks very nice shape. I do not know which mine came from, but it might be Kuro Nagura.    Hardness-------------7.8 It raises great amount of slurry quickly. It looks soft side Japanese mideum-high grit stone.   It looks it raises more than enough slurry. (Scale; 1 to 10, 1-3 is very soft muddy rough grit whetstone 3-6 is soft medium grit whetstone, 6-8 is hard medium grit whetstone; 8-10 is fine grit whetstone) Particle Size----------8.0 It makes my blue II steel kasumi blade knife Jigane became frosted silver color, and Hagane also became silver frosted color. It is hard to tell, but it might be entry class fine grit stone. (Scale; 1 to 10, 1-3 give deep scratch marks to the steel, 3-5 is delete the 1-3 scratches, 5-8 makes 3the steel cloudy, 8-10 makes the steel semi-mirror finish or mirror finish) Natural whetstone has wider capacity than artificial whetstone, and actually, we do n