AOTO Natural Sharpening Stone from Kameoka, Tanba 1446g (3lb. 3oz.)---2
200mmX57mmX57mm It should be around #1000 grit (medium grit)
It is a nice size excellent shape Aoto whetstone that is hard to come by nowadays.
***the bottom and one side of the side face has one large size crack. it is typical Aoto crack, and I already sealed it, so it should be no problem to sharpen the top sharpening surface. please check it up the detail with the pictures***
Hardness-------------7.6
It raises great amount of slurry quickly, and it is normal hardness Aoto, but it is kind of soft side hardness Aoto.
(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--------- 6.6
(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)
My blue II steel blade knife Jigane became vivid dark frosted silver color, and Hagane became bright dull silver color. Probably, it might be around 1000 grit in the synthetic sharpening stone.
It was from Kameoka, Kyoto. It has been very hard to find nice Aoto nowadays since all Kameoka mines had closed years ago, and the most of whetstone companies run out of Aoto stock now.
AOTO whetstone from Kameoka, Kyoto is very famous as Tanba no Aoto in Japan as medium to medium high. It has been mined from Kameoka , Kyoto since Muromachi era (1338-1573).
Natural whetstone has more wide capacity than artificial whetstone, and actually, we do not know until sharpen blade on the stone. Sometimes, treasure whetstone is found after used it for a while. Never know until then.