Unknown Natural Smooth Oil Sharpening Stone

Couldn't work out what stone this is, at first I thought Turkey but now I am unsure about that, I have not tried to take this out the box and left as is.

Please study the photo's to examine the stone.

There is a slight dip in the stone and what looks like a possible crack but without taking it out the box I just do not know.

Very smooth to the touch.

Around 8 7/8" x 2 3/8" and showing 3/8" depth from box.