I think the stone is an old world one ? But maybe an Arkansas It is irregular cut or worn from use. One end is about 7/8" and the other end is 1" thick. The stone is very smooth on the top side and the bottom isn't finished as well, but smooth. The stone is 7" X 2' X 1". It weighs 590 grams on my scale. It is a dark grayish too black color. It is a very hard type stone.
There are corner and edge chips. Also some scratches. I feel with my fingernail and see a very small divot on the not quite finished or bottom side. Maybe you will know the type of stone this one is ?
Thanks for looking and if you have any questions, just message me. I will pack well for shipping.