Sharpening stone identifiaction please

[digitalbot]

Can anyone give me an idea as to what this stone is?

Came across it in a junk shop a few weeks back. It was completely black when I got it. Got around to cleaning it this weekend and it seems to be a natural stone of some sort. It's very smooth to the touch now it's been cleaned and flattened; smoother than my two oilstones I already own anyway. Any info welcome.

 

[bugbear]

What size is it? I'd guess around 8"x2"x1"?

BugBear

 

[D_W]

Hindostan.

A second line stone compared to novaculites. You'll find it to be a bit slow and not as fine as you'd expect for the slowness, but something you can use if you have to.

 

[digitalbot]

Yes, it's 8"x2"x1".
I did have a look on the google but I couldn't see anything similar. At first I thought it might be some sort of sandstone due to the markings but it's too smooth for that. And there is very little translucency. I've since tried it out and it seems to polish more than hone if my amateur skills are anything to go by.

 

[adrspach]

Coarser Hindostan.