Another Black hone to ID:
Black Hone stone: 30mmx150mmx15mm; 1 5/32 x 5 7/8ths x 5/8ths. Old, I had to lap off about a half mm to flatten it. The back had some signs of having been glued at one time. It appears to be a slate type and is not a Thuringer...as near as I can tell. Too hard. It is similar to another black/green hone I have from the British isles, but finer and the slurry is not greenish nor gray. It has a barely perceptible light smoky streaking of white and red. It feels so good to the touch that I don't want to set it down once it is warm.Very nice to hone upon! sticky when at the final polishing strokes.

Water on the stone