Small coti and another stone

[xiaotuzi]

A little while back I won a lot of dirty bench stones, bidding on it because I saw a coticule among them. 3 of the stones were regular dirty old silicon carbide two-siders, one of them was indeed a coticule (though smaller than it looked in the pictures) and one was some other very hard natural stone, maybe its a hard Arkansas but I don't know my Arkansas stones very well.

The coti is a slender 6" x 1" 5/16 x 13/16. I like hand-held honing and the length is fine, it's just the slenderest hone I own so I will be careful not to tilt the blade off the narrow surface. It cleaned up and lapped relatively easily with wet/dry on a piece of glass.

The other stone is 8" x 2" 1/4 x 7/8" and was one seriously hard mamma-jamma to lap. I used an 8 x 16 slab of concrete with sand and water to flatten it. I've used this method before, and it works very well on most stones that are dished, but this stone was quite a lot of work. After that I lapped, and lapped, and lapped it on wet/dry on glass. It ate sandpaper for breakfast. Seems to be maybe good for knives but of limited use (if any) for razors? It's not translucent at all. Try it and see seems to be the method of figuring out what it will be best for. Water or oil with this one?

[eKretz]

The hard stone could possibly be a Washita or Soft Arkansas. I would use only oil with that one, YMMV.

[Iceni]

I'm tempted to say it might be a lily white washita or something similar. If it cuts at about 4K grit then it would be a good guess.