Unknown Mdeium-High Grit Japanese Natural Sharpening Stone 3lb. 1.3oz. (1398.4g),
224mmX60-65mmX40-44mm
It looks very nice shape but the one of the bottom corner does not have a corner piece.
I do not know which mine came from, but it might be hard heavy Aoto.
Hardness-------------8.8
It raises good amount of slurry quickly.
It is hard side in Japanese fine grit stones, but it is medium- high grit to me.
It looks it does not need tomo nagura or the device to raise the slurry (worn Diamond lapping stone), because it is smooth on the 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----------7.8
It makes my blue II steel kasumi blade knife Jigane became frosted silver color, and Hagane also became silver frosted color.
(Scale; 1 to 10, 1-3 give deep scratch marks to the steel, 3-5 is delete the 1-3 scratches, 5-8 makes 3the 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.