is this a sharpening stone?

[BobW]

I was given what I think is a sharpening stone, it is 9 1/2" x 3" x 1", black or dark grey, and weighs 1.6lbs. There is a depression on one face with the word 'Battersea' below an oval with a capital letter 'A' in the middle of the oval. I was thinking it might be an Arkansas stone but seems terribly light in weight. Can anyone identify this. Thanks for any help.

 

[AndyT]

I've no idea from the description, but why not give it a try? You have nothing to lose! (I'm assuming that you also do woodwork and have tools you need to sharpen.)

 

[BobW]

It will put an edge on a chisel but just creates a black slurry mess. I'll put it away until I figure out what it is.

Thanks
Bob

 

[Jacob]

Some sort of brick? Perhaps to do with the power station?