Another mystery hone thread

[joke1176]

I know, I know...

Anyhow, this one really has me stumped. It came in a pretty neat carved wood box, is about 7/16" x 8" x2".

At first I thought it was the usual arkansas stone until I cleaned and lapped it (I bought it for the box it came in). Now I'm not so sure.

It is grey-ish, olive-ish in color, has a very light cream/olive slurry, and cuts fast (faster than BBW), cuts at approx 6k (as compared to BBW, coticule and DMT 1200 or 8k plates). It also starts to release a trace of slurry with approx 5-10 moderate pressure passes of a razor.

It has sparkly bits as you can see in this pic of it dry.


It kinda striped, veined, whatever you would call it as seen in these dry pics.



However, when I when I get it wet it looks speckled/mottled instead of striped.



Any ideas dudes? I am kinda stuck.