These Nakayama, Okudo, Narutaki and other mine tennen toishi koppa came from a hoard of neglected and nearly forgotten stones that I bought in Japan this past year.
The whole lot had been stored in an Air Raid Shelter below the floor boards of a building in a small town.
I found that each and every stone was hand hewn, the sides were hand sawn and hand scraped and many of the stones have kawa mineral skin on 3 or 4 sides indicating that they were harvested from narrow nooks and cavities within the mine complex. The seller, who is 71 years old, told me that his grandfather bought the stones at least 90 years ago and that because the family never had been a stone or tool store, he said that they just never really sold enough to bother with over the years.
The use of hand saws to shape tennen toishi sharpening stones from the Kyoto mines began hundreds of years ago and ceased for good at the dawn of the 20th century. By the 1920s most if not all of the mines had circular saws. Historic wood block prints show crews of men shaping the stones with nokogiri saw work, chisels and adzes. Samples of the Hoard stones were estimated by a prominent Tokyo authority to be from no later than the middle Meiji Period.
As a group, but really from stone to stone, this collection is made up of the fastest cutting stones I have ever owned or tested. The fastest of them will remove and replace King 1k or Shapton 2k scratches within 15 strokes or fewer if a slurry is made from the base using a #1200 diamond plate. Without slurry and just clear water the stone will
polish a Henckels razor for a bright finish with just a little effort and a few strokes.
I have found that each stone is so similar in hardness (slightly softer than modern stones), cutting speed and fineness and that as a group they all follow each other in these respects. As I bought them it came down to size, shape and inclusions or inclusion free to determine the price. Each stone ascribes to those attributes unless otherwise noted.
All of my stones come with a money back guarantee minus the return shipping.
Although I have washed and scrubbed them, the stones seen on the right here are in
generally the same condition as when I found them in that 5 by 6 by 5 foot high shelter.