What makes japanese water stones great?

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Antoine M.

Mar 16, 2011
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Since I started producing my own steel in a bloomery furnace, I spent some time checking 19th century/early 20th geological survey to find sutable ore deposits.
In my readings I discovered that there were a few quarries that produced grind stones and a couple where the quarried razor hones (I'm planning to check those during the summer).
I'm not sure what exactly those local stones are made of, still searching...

So i was wondering what was the composition of japanese water stones as to have something to compare those with. Is it the type of stone in itself or maybe "impurities" like the garnet in coticule stones?

Thank's for your help!

I've been looking into this myself. There are also Belgian Coticule stones which are very popular amongst straight razor folks, but this link explains the main differences:

As far as what makes them great, you really have to use them! Some just glaze over before they can be useful, and natural stones vary so widely that IMO it is a crapshoot when you purchase one if it's any good or not.
I think it is just how they were made, the specific conditions in that particular region.
Thank you for the link John. It seem that the stone that was quarried here is a form of mica slate. I'll check that out...

Yeah, I'm looking into finding some good North Texas sandstone, since it is a clay binder with quartz abrasives bound up in it. There are ancient examples of whetstones made from sandstone that were dug up, and I'd love to at least experience that kind of history.

It's good to have local flavor, and cool to imagine talking shop with a stone age man.
Antoine, what is your avitar? It lokos pretty interesting.
Hé hé, sorry to have called you John! Eamon right?
I'm trying to use local for some project clay, stone and ores and it gives us a good reason to drive around!

Kalaeb, it is a small bloom furnace to make steel, "tamahagane". HERE is a complete explanation.

Nice! I'll give you credit, that is a heck of a lot of work to end up with the amount steel that remains. I have wanted to do something like this for a long time, but tough to do in the city. Looking forward to seeing some of your finished blades!

Great work. Really interesting reading for us rockhounds :)
Keep it up, man! I need to get me one of those microscopes....

I know only one scientific article about which you can read free.
Its in Japanese but has English abstract and tables and graphs are in English too.
It has also some reference in English so you can read them online if you have access to scientific literature.


BTW you should know that the mine name is Narutaki for all the mines near Kyoto.
The whetstone seller will indicate the mines as Nakayama, Oozuku, Shoubudani, Narutaki etc. but in scientific world they all belong to Narutaki mine.