Mikawa Shiro Nagura Chu Nagura 2lb. 0.7oz. (927g) Japanese Natural Sharpening Stone
Approximately 178mmx60mmx42mm
It is pretty nice shape to sharpen on the Chu Nagura.
Koma, Mejiro, and Tenjyo are fine grit (medium high grit to entry class of fine grit) layers of Mikawa Shiro Nagura.
Botan and Atsu (Chu Nagura) are medium grit to medium high grit stone.
Hardness-------------8.7
It raises very good amount of black color slurry quickly.
It is kind of hard condensed 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----------6.5
It makes my blue 2 carbon steel blade Hagane became mirror frosted silver with fine scratches looking like medium grit.
Jigane also became medium grit scratches and frosted silver 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 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.