Umaji Yama Awasedo Natural Whetstone 734g (1lb.10oz. )
193mmX67-68mmX21-23mm, #6000 to #8000 grit on for chisel blade or Japanese plane or high carbon knife
It raises very good amount of black slurry quickly, so it does not need Tomo Nagura or a devise that generates slurry. It is not too hard and not too soft, ideal hardness to me. (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)
(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)
It makes my blue II steel Hon kasumi blade knife; Hagane to bright from silver color to semi-mirror finish, and Jigae to from bright frosted silver color.
Umaji Yama is located on a line of Ohira, Mizukihara, and Umaji Yama, so Umaji Yama produces similar whetstone with those mines. Usually, Umaji Yama hones are very soft, but there are also hard hones like this one. Natural whetstone cannot be compared with artificial whetstone hardness and particle size. Probably #6000 to #10000 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.