David Weaver
This stone is generally used with oil, but can be used either way. Thanks to John Aniano, I have a fresh one to test (the welsh slate is also John's). This one is free of oil, so I used it on water.

I think these stones are silica. They're slow cutting for their fineness, but once the loose particles are dealt with, I think you could manage that characteristic (wide flatter grooves) and get a "Soft" feeling edge out of it. One that's not that toothy.

Definitely fast enough to use practically, but in nearly new shape, this one does have some large particles running around making for some slurry dulling.