Ozuku Mizu Asagi Japanese Natural Sharpening Stone 1076g (2lb. 6oz.)
Approximately size is 195mmX65-67mmX30mm
#8000 to #10000 for razor or high carbon cutlery
It produces very little of black slurry. It might need Tomo Nagura or a device that produces slurry. It is a very hard hone.
Hardness--------- 8.9
(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-------------- 8.9
(Scale; 1 to 10, 1-3 give deep scratch marks to the steel, 3-5 is delete the 1-3 scratches, 5-8 makes the steel cloudy, 8-10 makes the steel semi-mirror finish or mirror finish)
It makes my blue II steel blade knife Jigane is semi-mirror finish with some very fine whetstone marks, and Hagane is from semi-mirror to mirror finish.
Ozuku is a mine where is located on the east side of Atago Yama mountain in Kyoto same like Okudo and Nakayama. Ozuku is very hard hone and fine slurry, but some people say, it is too hard to sharpening without scratches, so we can solve the problem with using Ozuku Tomo Nagura.
Probably #8000 to #10000 grit with the same as artificial whetstone. When we sharpen it with usual amount of force from the top of cutlery, it might be around #8000 to #10000 grit. However, when we sharpen it with just cutlery weight of force gently, it might be #15000 to #25000 grit. Natural whetstone has wider capacity than artificial whetstone, and actually, we do not know until sharpen blade on the hone for a while. Because artificial whetstone molecules do not break down to smaller sizes, but Natural whetstone molecules are possible to break down to smaller sizes, and those molecules are mixed with sharpened steel molecules, and make Jigane as suitable Jigane color, and Hagane as suitable Hagane color. It is natural mystics.