What is this grey brick?

I dont remember when or how I got it.
Its very soft.

 

It's an Omura 180x

 

I was going to say bleu cheese, but I'd trust Dave's answer more.

 

Thanks Dave!
A friend gave me an enormous old slicer that I was trying to sharpen up and this rock created a huge amount of swarf and did not seem to cut too efficiently. Is there a type of task it would preform more optimally on?

Thx

 

I had a brief love affair with this stone and then we went through a bad break up, I'm glad it's over though.

The stone can cut crazy fast BUT ONLY if you stop every 5 seconds and flatten it. If you don't do the constant flattening it starts to dish faster and faster and then you start rounding over your edge and then the stone gets more dished and on and on until you're screaming at it. Really wide bevels that have a lot of surface area seem to be the best match for this stone.

 

I found it worked well to remove scratches from a DMT XXC when thinning. I agree with Dave's assessment about having to flatten it frequently.