It is kind of hard stone.
Hardness--------8.9
It produces good amount of black slurry, so it might need Wakasa Tomo Nagura or a devise that raises slurry. It has very smooth sharpening surface.
(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 became shiny bright silver color, and Hagane became semi-mirror finish to mirror finish.
