Okunomon Awasedo Japanese Natural Sharpening Stone 1390g (3lb.1oz.) 144mmX155mmX30mm, #4000 to #6000 grit on for chisel blade or Japanese plane or high carbon cooking knife
Okunomon mine is located on west side of Atago Mountain in Kyoto. It is located on the next to Ohira mine where is very famouns major Suita and Uchigumori quarry, and Okunomon had yielded suita and awasedo.
Okunomonn whetstones are getting harder to see in natural whetstone market little by little because of quantity of supply are getting less and less.
Hardness-------------8.0
It raises great amount of slurry quickly. It does not need tomo nagura or Diamond lapping stone to raise the slurry. It is very smooth stone and also fast cut stone. (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--------- 8.4
My blue II steel blade knife Jigane became light grayish silver color, and Hagane became from silver color to semi-mirror finish. (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)
Natural whetstone cannot be compared with artificial whetstone hardness and particle size. Probably #4000 to #6000 or higher grit with the same as artificial whetstone.
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.