Unknown Mine Japanese Natural Sharpening Stone 1lb. 8oz. (678g) 186mmX74mmX22-24mm
Please click here to see video
It might be #4000 for lower range in the fine grit It is muddy stone. I do not know which mine it derived from.
It raises large amount of the stone color slurry quickly. It is smooth stone, but it is muddy stone, so it is sticky little bit. It does not need tomo nagura or the device to produce the slurry (worn Diamond lapping 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----------8.2 . It makes my blue II steel kasumi blade knife; hagane became bright silver finish to semi-mirror finish. Jigae became frosted silver color 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 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.